Biomimetics Milicich Handout.pdf - Mehta Orthodontics

1/10/2017

Copyright 2017 G W Milicich. Private use only. 1

Non‐invasive Caries Risk Assessment Management of a diseased biofilm. Caries and Perio.

Non‐invasive surface‐protection techniques using Re‐min and/or GIC

Minimally invasive restorative techniques and preparation techniques to preserve biomechanical integrity

Restorative techniques to avoid pulp exposures, help retain pulp vitality and restore long term function using biomechanical /biomimetic concepts and techniques

Maximum Intervention, Minimal Invasion

Doctor Engineer and Artist

Technologies that are standing the test of time• Air‐abrasion• Hard and soft tissue lasers• Magnification – loupes and microscopes• Digital X‐rays and imaging• DIAGNOdent and other cavity diagnostic

systems• Ozone• Adhesive ceramic restorations. CADCAM or Lab.

Scientific method• Observation• Hypothesis• Experiment• Analysis – support or reject hypothesis

• New Hypothesis• Experiment

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Scientific method• Problem‐ Cavity in a tooth• Hypothesis‐ Amalgam might work• Experiment ‐ Fill millions of teeth• Analysis – sort of works ‐ Lots of teeth fracture in the long term

• New Hypothesis‐ Amalgam still might work

• New Experiment‐ Place more amalgams

Tooth Structure Biomechanics

All occlusal cavity preparations decreased the strength of the tooth in proportion to

the width of the preparation

All occlusal cavity preparations decreased the strength of the tooth in proportion to

the width of the preparation

Fracture Strength of Human Teeth With Cavity Preparations

Mondelli, Steagall, Ishikiriama, de Lima Navarro & SoaresJourn Pros Dent; 43(4):419‐422, 1980

Fracture Strength of Human Teeth With Cavity Preparations

Mondelli, Steagall, Ishikiriama, de Lima Navarro & SoaresJourn Pros Dent; 43(4):419‐422, 1980

The width of the occlusal portion of the preparation affects the strength of the crown.

The width of the occlusal portion of the preparation affects the strength of the crown.

Effects of Prepared Cavities on the Strength of TeethLarson, Douglas & Geistfeld

Op Dent;6:2‐5, 1981

Effects of Prepared Cavities on the Strength of TeethLarson, Douglas & Geistfeld

Op Dent;6:2‐5, 1981

The addition of minimal proximal boxes do not further significantly reduce the strength of the tooth.

The addition of minimal proximal boxes do not further significantly reduce the strength of the tooth.

Effects of cavity designs on tooth flexure

CT Scan‐Based Finite Element Analysis of Premolar Cuspal Deflection Following Operative Procedures. Magne P, OganesyanMSInter Journ of Periodontic and Restorative Dent:, 2009:29 (4).:361‐369.



Cuspal Widening

No cavity2.7µm

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Cuspal Widening

Amalgam Composite



Amalgam5µm

Cuspal Widening

Composite3.5µm



Cuspal Widening

Amalgam5µm

Composite3.5µm



Cuspal Widening

Amalgam5µm5.4µm

Composite3.5µm3.8µm



Cuspal Widening

Amalgam5µm5.4µm

Composite3.5µm3.8µm



Cuspal Widening

Amalgam5µm5.4µm

Composite3.5µm3.8µm6.9µm

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Long term survival. Composite or Amalgam?

12‐year Survival of Composite vs. Amalgam RestorationsN. Opdam, E. Bronkhorst, B. Loomans and M.HuysmansJ DENT RES 2010 89: 1063 originally online 26 July 2010

12yr retrospective study

Clinically AcceptableFractured/cracked tooth“A large number of amalgam restorations failed in the long term due to tooth fracture and cracked‐tooth symptoms.”“The lower fracture rate of composite‐restored teeth in this study supports the hypothesis that adhesive restorations strengthen tooth structure.”

Long term survival. Composite or Amalgam?

12‐year Survival of Composite vs. Amalgam RestorationsN. Opdam, E. Bronkhorst, B. Loomans and M.HuysmansJ DENT RES 2010 89: 1063 originally online 26 July 2010

12yr retrospective studyAmalgam75.6%10.4%

Composite84.7%1.4%

Clinically AcceptableFractured/cracked tooth

Did extension for prevention wreck these teeth?

Did extension for destruction wreck these teeth?

Tension FracturesEven Gold inlays will not protect the tooth

Tension Fractures

Stress concentration Stress concentration

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New Concept The Peripheral Rim

Moiré FringesA birefringence study of human tooth structure

R Z Wang, S Weiner. Strain Structure in human teeth using Moiré fringes.Journal of Biomechanics 1998 Feb;31(2):135‐141.


Increased width indicates increased stress

Stress concentration occurs where the fringes are close together

The direction of the fringes indicates the direction of the stressEnergy

Sink

R Z Wang, S Weiner. Strain Structure in human teeth using Moiré fringes.Journal of Biomechanics 1998 Feb;31(2):135‐141.


Clinical Presentations of Stress Distribution in Teeth and the Significance in Operative Dentistry.

Milicich GW, Rainey JT:

Pract Periodontics Aesthet Dent 2000:12(7),695‐700

In engineering terms, this concept is known as a tension ring

The Peripheral Rim - compression dome

The enamel on a tooth acts like a compression domeLoad

Designed to keep the dentin in compression

The “upside down tin can” compression dome

Jean‐Baptiste Forien, Claudia Fleck, Peter Cloetens, Georg Duda, Peter Fratzl, Emil Zolotoyabko, Paul Zaslansky. Compressive Residual Strains in Mineral Nanoparticles as a Possible Origin of Enhanced Crack Resistance in Human Tooth Dentin. Nano Lett., 2015, 15 (6), pp 3729–3734

Nano particulate HA crystals in dentin collagen

micro‐ and nanofocused X‐ray beams, reveal that the nm‐sized mineral particles aligned within collagen are pre‐compressed and that the residual strains vanish upon mild annealing. We show the link between the mineral nanoparticles and known damage propagation trajectories in dentin, suggesting a previously overlooked compression‐mediated toughening mechanism.

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“The internal stress works against crack propagation and increases resistance of the biostructure. “

Engineers use internal stresses to strengthen materials for specific technical purposes. Now it seems that evolution has long 'known' about this trick, and has put it to use in our natural teeth.

Nano structure and Macro structureSimilar Functions

The “pre‐stressed” collagen fibrils Keep the dentin in compression, just like pre‐stressed steel tendons in concrete structural beams keep the concrete in compression



The presence of these “intra‐collagenous” nano HA crystals also has HUGE significance to successful long term dentin bonding

Enamel and Dentin tend to behave independently

Vijay K. Goel, Satish C. Khera, Kanwerdip Singh. Clinical implications of the response of enamel and dentin to masticatory loads. Journal of Pros Dent: Vol 64 (4), Oct 1990, Pg 446–454

“despite being organically “bonded,” enamel and dentin responded independently. This unique behaviour with regional variations of these tissues could have serious clinical implications during restorative procedures.”

The Dentino‐Enamel Complex allow two dissimilar materials to function in harmony

Zaslansky P, Friesem AA, Weiner S.Structure and mechanical properties of the soft zone separating bulk dentin and enamel in crowns of human teeth: insight into tooth function. J Struct Biol. 2006 Feb;153(2):188‐99. Epub 2005 Dec 9.

“The 200‐300 micron soft zone of dentin, found beneath enamel in crowns of human teeth, is thought to fulfil important roles in tooth function…. the durability of the whole tooth relies upon a bucco‐lingual asymmetric matching of stiffness by means of an interphase: a cushioning soft layer between enamel and bulk dentin.”

Joining enamel to dentinThe dentino‐enamel COMPLEX

M. Goldberg, D. Septier, K. Bourd, R. Hall, J.‐C. Jeanny, L. Jonet,S. Colin, F. Tager, C. Chaussain‐Miller, M. Garab´edian, A. George, H. Goldberg, S. MenashiThe Dentino‐Enamel Junction Revisited. Connective Tissue Research, 43: 482–489, 2002

“A less simplistic view suggests that the dentino‐enamel junctional complex should also include the

inner aprismatic enamel and the mantle dentin.”

MANTLE DENTIN

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Resin impression of the Dentino‐enamel Complex• The DEC is a more open

structure• Lower mineral content

than enamel or dentin• Acts as a stress breaker

between the enamel compression dome and the dentin

Isao Urabe, Masatoshi Nakajima, Junji TagamiPhysical Properties of the Dentin‐Enamel Junction Region.

AmJDent 2000; 13:129 [intro2]

Joining enamel (or porcelain) to dentin

Resin impression of the Dentino‐Enamel Complex• The DEC is a more open ,

trabeculated structure• Lower mineral content






Cuspal Widening

Amalgam5µm5.4µm

Composite3.5µm3.8µm6.9µm

Who has seen this?

Peripheral Rim Compression Fracture

Compressive load on peripheral rim enamel


Stress cannot be distributed laterally into the dentin due to the presence of the cavity

Stress concentration

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Stress concentrates between the cavity wall and the peripheral rim


Lost energy dissipation

Occlusal enamel fractures out




Occlusal enamel fractures outStress concentration



Differentiation between occlusal enamel and peripheral rim enamel

The most enduring components in ruins are the compression arches and decussation faces (stones intersecting at angles in buttresses)

Rievaulx Abbey Rievaulx Abbey Talley Abbey

Keystone

Skewback

Domes and arches, inside arches, inside arches.

Salisbury Cathedral Wells Cathedral Scissor Arch

Compression arches and domes work just as well if they

are upside down!

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What would happen to the stability of this compression

arch if this area was removed?

CUT AN OCCLUSAL!

Chirk Aqueduct

Cusp Tips

CUT AN OCCLUSAL

SkewbackSkewback Skewback

KeystoneWhat would happen to the stability of

these compression arches if this area was removed?CUT AN

OCCLUSAL!Chirk Aqueduct

Cusp Tips

CUT AN OCCLUSAL

Skewback Skewback

Note prism orientation in relation to a masonry arch!

Skewbackzone

Column or circumferential

wall

The Micro event. Cutting a very small occlusal.

Peripheral rim fracture

The lateral occlusal contact that is distorting the peripheral rim now that the occlusal enamel buttressing has been damaged

The Human Enamel Compression Dome

The mechanical efficacy of a tooth ‐ a natural functionally graded material ‐ is a function of hierarchy of scale and material properties

Timothy G. Bromage, PhD. Professor, Department of Biomaterials and Biomimetics Director, Hard Tissue Research Unit. Email: [email protected].

What is decussation?Where enamel prisms lay beside one another with a completely different orientation. Within one or two prisms, orientation can change by over 30 degrees.It presents as Hunter Shreger Bands and gnarled enamel.Stress distribution, crack limitation mechanism.

At the primary hierarchy of scale is enamel thickness HypothesisAre Hunter Shreger Bands a version of tension rings in a compression dome?

In horizontal X Section, HS bands wrap around each cusp and around the tooth

They are also internal inverted “teacups”, or like a scissor arch being buttressed by the dentin

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HypothesisAre Hunter Shreger Bands a version of tension rings in a compression dome?


3D representation of a single Hunter Shreger Band

Compression domes work both ways. Upside down

or right way up.



3D representation of a single Hunter Shreger Band


or right way up.



3D representation of a single Hunter Shreger Band(approx 10 prisms in width)


or right way up.



J Osborn. Directions and Interrelationship of Prisms in Cuspal and Cervical Enamel of Human TeethJ Dent Res May‐June 1968. Vol 47 No. 3. 395‐402

Hunter Schreger Band stress breaker crack limitation

Remarkable resilience of teeth. Herzl Chai et al.Natl Acad Sci U S A. 2009 May 5; 106(18): 7289–7293.

HS band decussation helps limit crack propagation

Internal tension rings

Florence Basilica

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J Osborn. Directions and Interrelationship of Prisms in Cuspal and Cervical Enamel of Human TeethJ Dent Res May‐June 1968. Vol 47 No. 3. 395‐402


Construction diagram of the Florentine Dome

The Schiller Institute. The Secrets of the Florentine Dome. Karel Vereycken 2013.

The Bio‐Dome

Functional Stress Relief – Vertical Lamellae

Normal in un‐restored teeth

“Calculated stress intensities around crack tips were found to be highly influenced by the elastic modulus mismatch between enamel and dentin and hence, the phenomenon of crack arrest at the DEJ could be explained accordingly via this

elastic modulus mismatch.”

Crack arrest within teeth at the dentino‐enamel junction caused by elastic modulus mismatch.

Bechtle S, Fett T, Rizzi G, Habelitz S, Klocke A, Schneider GA.Biomaterials. 2010 May;31(14):4238‐47. Epub 2010 Feb 18.

Functional Stress Relief – Vertical Lamellae

Note the lamellae are not full length and are in the “surface” of the enamel at the maximum convexity of the tooth.

The driving force. Poisson Effect Distortion.(much more on this later)

Compression dome –tension rings of the Pantheon in Rome

128AD


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The is the wall that supports the compression dome complex

Don’t send it up the suction!!!!

Pantheon ‐ Rome

How valid is this compression dome analogy?

“despite being organically “bonded,” enamel and

dentin responded independently”

This further supports the concept that the enamel is

acting semi‐independently as a compression dome

Goel VK, Khera SC, Singh K. Clinical implications of the response of enamel and dentin to masticatory loads. J Prosthet Dent 1990; 64 (4):446–454.


“electronic speckle pattern correlation interferometry (ESPI) highlight details of the design strategies of the enamel cap. (compression dome) The crown not only deforms but also rotates under load. Much of the load is transferred onto a crucial interphase in dentin just below the dentino‐enamel junction. This relatively soft zone compresses asymmetrically when loaded.This shows that the enamel cap has rotated relative to the central bulk of the crown.”

Zaslansky P, Weiner S. Biomechanical Adaptations. In: Epple M, Bäuerlein E (eds). Handbook of Biomineralization. Design Strategies of Human Teeth. Weinheim: WILEY‐VCH Verlag GmbH & Co. KGaA, 2007:183‐202.


Sangwon Myoung, James Lee, Paul Constantino, Peter Lucas, Herzl Chai, Brian Lawn. Morphology and fracture of enamel.Journal of Biomechanics 42 (2009) 1947–1951

“The question that arises is, if enamel is so brittle, why are teeth so durable? Part of the reason lies in the tooth geometry—the capacity to support and sustain an essentially compressive vertical load, rather like the dome of a cathedral (Lawn and Lee,2009).”


Tension Ring in Masonry DomesStructural Analysis of Historical Constructions, New Delhi 2006 1Mahesh N Varma, Prof R. S. Jangid, Dr. V. G. Achwal ISBN 972‐8692‐27‐7

This is why your bonded buccal composites sometimes fall off

Tension Ring in Masonry DomesStructural Analysis of Historical Constructions, New Delhi 2006 1Mahesh N Varma, Prof R. S. Jangid, Dr. V. G. Achwal ISBN 972‐8692‐27‐7

Use a low modulus composite like Heliomolar that will flex with the tooth

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Does Hoop Stress fracturing happen in teeth?

Chris Ford, Mark B. Bush, Brian Lawn. Effect of wear on stress distributions and potential fracture in teeth. Journal of Materials Science: Materials in Medicine November 2009, Volume 20, Issue 11, pp 2243‐2247

Compression

Tension

“hoop tensile stresses in Fig. 2b are more uniformly distributed around the inner enamel wall, and are responsible for the propagation of radial–median cracks downward from the contact zone or margin cracks upward from the enamel base”

Dentin

Radial Stress

Further evidence of the Compression Dome/Bio‐Dome concept

Magne P, Belser UC. Rationalization of Shape and Related Stress Distribution in Posterior Teeth: A Finite Element Study Using Nonlinear Contact Analysis. Int Jour Perio & Rest Dent. V 22, # 5, 2002 pg 2‐ 11.

Finite Element Analysis

Grey=Compression




Grey=Compression




Grey=Compression



Most of the enamel Bio‐Dome complex is still in compression.Independent of the underlying dentin tension.



Most of the enamel Bio‐Dome complex is still in compression.Independent of the underlying dentin tension.

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Compression dome. Bio‐Dome. Bio‐Rim.

The reality is teeth are made up of multiple compression domes

(volume enamel > volume dentin)

(volume enamel < volume dentin)

Sigmoid curve distribution

Sigmoid Curve DistributionPresent in all posterior cusps, (max/mand).More prevalent on functional cusps as a biomechanical reinforcement mechanism with increased enamel volume.The magnitude of the Sigmoid curve increases in expression moving posteriorly.Connecting the buccal and lingual inflection points, one derives the inflection plane.

The inflection plane is found to bisect the crown roughly in the middle allocating Volumetric dominant distribution (V enamel : V Dentin)

CORO

NAL Compression Dome

Bio‐Dome

Bio‐Rim


Adjacent Bio‐domes act as buttresses to one another.The occlusal surfaces of the adjacent bio‐domes also act like a scissor arch!


This demarcation stress line in the Bio‐Dome highlights the interface between the peripheral rim and the “ inverted scissor arch” of the occlusal enamel

New Concept Occlusal Effect Caries

Clinical Presentations of Stress Distribution in Teeth and the Significance in Operative Dentistry.

Milicich GW, Rainey JT:

Pract Periodontics Aesthet Dent 2000:12(7),695‐700

Cut an occlusal and you can cause interproximal cavitation

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Functional Stress Relief – Vertical Lamellae“The enamel lamellae are shown to be a permeable pathway, allowing caries‐

producing bacteria access to the dentin‐enamel junction. Caries can thus be established within the tooth, without

visible evidence at the surface”

Enamel cracks. The role of enamel lamellae in caries initiation Walker BN, Makinson OF, Peters MC Aust Dent J 1998 Apr;43(2):110‐6

Only in specific

circumstances

Normal in unrestored teeth

Adult caries often begins under enamel cracks

Walker et al

Caries developing in fractures is extremely difficult to detect with conventional radiography


Adult caries often begins under enamel cracks

Decay developing and spreading in dentino‐enamel complex at the base of an enamel fissure. No enamel demineralization.


Occlusal Effect

Compression distortion

Occlusal Effect Caries

Compressiondistortion leads to a tension fracture in the mesial and/or the distal peripheral rim enamel

Occlusal Effect Caries

Because the underlying dentin is not in tension, it does not fracture, only the enamel fractures

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Walker et al

Occlusal Effect Cariesno dentin fracture

What is the It is the wall that supports the compression dome complex

Pantheon ‐ Rome

What is the It is the wall that supports the compression dome complex

Pantheon ‐ Rome

If occlusal enamel is so important, what should we do?

• Diagnose early and accurately� Laser or light fluorescence, light transmission, caries detection dye, good lighting and magnification

• Treat with minimally invasive techniques� Requires an understanding off occlusal microanatomy.

� Micro‐air abrasion guided with CDD, microburs, good lighting and magnification.

Teach the importance of occlusal micro‐anatomy in the schools

• Diagnose early and accurately� Laser or light fluorescence, light transmission, caries detection dye, good lighting and magnification

• Treat with minimally invasive techniques� Requires an understanding off occlusal microanatomy.

� Micro‐air abrasion guided with CDD, microburs, good lighting and magnification.

Occlusal Effect CariesWhy doesn’t it show on an X‐ray?

ROCK WP, KIDD EAM.Br Dent J. 164(8): 243‐47, 1988.

“… decay is difficult to detect in radiographs unless larger than

2mm to 3mm deep into dentin, or 1/3 the bucco‐

lingual distance.”

2mm deep “cavity”

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3mm deep “cavity” 4mm deep “cavity”

1/3 occlusal width



Less than 1/3 width of tooth


Greater than 1/3 width of tooth


The evidence is before us, but at the same time, invisible to us, because it is fragmented and

dispersed in the research literature. However, when the pieces of the puzzle are assembled in a certain way, a new picture is

beginning to emerge.

Biomimetic Dentistry Mimicking Mother Nature as closely as we can with current materials, techniques and technologies.

Dentin tension fracture

Load is placing the underlying dentin

into tension

No enamel demineralization

Large M/D dentin fracture

Rainey T. A sub‐occlusal transverse ridge: identification of a previously unreported tooth structure: the Rainey Ridge. Journal of Clinical Pediatr Dent. 21(1); 9‐13, 1996.

Sub-occlusal oblique transverse ridge

Note the use of CDD to guide focused micro‐preparation

No pink, NO CUT.

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There are many subtle, but critical anatomical structures that we are indiscriminately removing

35yr old lower molarRainey T. A sub‐occlusal transverse ridge: identification of a previously unreported tooth structure: the Rainey Ridge. Journal of Clinical Pediatr Dent. 21(1); 9‐13, 1996.



35yr old lower molar










Sub‐occlusal Oblique transverse RidgeSuspensory Web of EnamelPeripheral Rim of Enamel



65yr old Greek. Owns a Citrus Grove!Some instability developing

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Maxillary Web

Rainey JT: The maxillary molar mesial‐sub occlusal enamel web: Identification of a previously unreported tooth structure: the maxillary Rainey web. Pediatr Dent. 22(3); 195‐198, 1998

Maxillary Web

Rainey JT: The maxillary molar mesial‐sub occlusal enamel web: Identification of a previously unreported tooth structure: the maxillary Rainey web. Pediatr Dent. 22(3); 195‐198, 1998

Retained intercuspalX‐Brace

Fractured occlusal – peripheral rim interface

Restorations over 30yrs old

One more upper molar sub-structure

Anatomy textbooks describe these grooves as fissuresThey are not all fissures!

One more upper molar sub-structure

Anatomy textbooks describe these grooves as fissuresThey are not all fissures!

These areas are fissures

The rest are simple developmental folds in the enamel

One more upper molar sub-structure One more upper molar sub-structure

Keeping the occlusal and peripheral rim of enamel intact keeps the tooth stable

Maxillary web removed and peripheral rim transectedEvery cusp fractured plus a M/D fracture!NOT A BRUXER!

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Copyright G W Milicich 2017. Private use only 1

Do adhesive ceramics work?

22 years old

19 years old

12 year oldfracture

19 years old


28 years old

25 years old

12 year oldfracture

19 years old19 year old feldspathic onlay


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7

Resin impression of the Dentino‐enamel Complex• The DEC is a more open

structure• Lower mineral content



Isao Urabe, Masatoshi Nakajima, Junji Tagami Physical Properties of the Dentin‐Enamel Junction Region.

AmJDent 2000; 13:129 [intro2]


and sensitivity and on chewing (any or all of the above)

There are six types of tooth fracture

• Teeth are designed to work in compression• Disturb the compression dome system” and areas become exposed to tension

• Fractures are driven by a compressive load creating a force

that places either enamel or dentin into

There are six types of tooth fracture

1. Occlusal effect fractures – vertical in the enamel peripheral rim2. Occlusal effect fractures – occlusal abfraction – loss of tooth

between peripheral rim enamel and the restoration3. Vertical mesio‐distal fractures4. Oblique cusp fractures – most common form5. Randomly oriented Poisson Effect vertical fractures in the

dentin core6. Catastrophic point overload fractures (trauma and foreign

objects in food)

The three basic forces driving fractures

Tensile Force Shear Force Torsional ForceREVIEW OF THE FRACTURE TOUGHNESS APPROACH Karl‐Johan SoderholmDepartment of perative Dentistr Co ege of Dentistr niversit of orida pg

Cyclical stresses and strains well below the single load failure load cause crack

propagation over time.

The time part of the equation in teeth is 20‐40yrs

This high cycle fatigue load can be as low as only 25% of the failure load for dentin.

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Then there are the catastrophic fractures

Virgin tooth. A foreign object in the food created an unexpected point overload.

You need an Erbium Laser! Closed flap bony crown lengthening

Or the subtle diagnostic challenges

• Patient presented with intermittent pressure sensitivity on lower right.

• Pointed to the 46.• Removal of the old amalgam exposed a dentin fracture. • Restoration did not resolve the symptoms!• Similar treatment to 47, another fracture.• Still no resolution after treatment.• Patient still pointing to the 46!• The 46 and 47 had “symptomless” dentin fractures

Or the subtle, diagnostic challenges

The unrestored 48 had a vertical mesio‐distal fracture halfway down the mesio‐buccal cusp incline!Restoration instantly resolved the symptoms.

Mesio‐distal Vertical Cracked Tooth Differential Diagnosis

The BIG question ‐ Reversible or Irreversible Pulpitis?• Reversible

Transient hot or cold sensitivityPressure sensitivityNo percussion sensitivityRecovers from stimulus very quicklySome teeth have no symptoms at all, but you can see the crackRemove the restoration and have a look

• Tx. Adhesive Onlay – warn patient of possible need for future endo

The BIG question ‐ Reversible or Irreversible Pulpitis• Irreversible

Spontaneous painProlonged response to hot or coldPercussion sensitivity

• If there is associated periodontal bone loss ‐ extract• Start Endo ‐ If crack extends to involve pulpal floor – extract• If pulpal floor is intact ‐ Adhesive restoration as per endo

protocol and advise re the potential for the crack to continue extending

Mesio‐distal Vertical Cracked Tooth Differential Diagnosis

Cracks with Reversible Pulpitis

• Don’t kill the pulp!• Deal to the fractures without exposing the pulp• Don’t leave unstable dentin above oblique cracks• Recreate the compression dome without preparing full crown coverage

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Two basic dentin fracture typesOblique under the cusps

Two basic dentin fracture typesOblique under the cusps

Two basic dentin fracture typesVertically oriented mesiodistal cracks

Longitudinal fractures

Seo DJ,Yi YA, Shin SJ, Park JW. Analysis of factors associated with cracked teeth.J Endod. 2012 Mar;38(3):288‐92. doi: 10.1016/j.joen.2011.11.017. Epub 2012 Jan 5.

72.0% of longitudinal tooth fractures occurred in restored teeth28.0% were found in intact teeth.

RESTORATION METHODBONDED: Resin (4.7%) or Porcelain (0.9%)NON‐BONDED: Gold (20.5%) or Amalgam (18.7%)

As a group, BONDED RESTORATIONS worked better

We contribute to dentin failure!

The Mechanical Properties Of Human Dentin: Critical Review And Re‐evaluation Of The Dental Literature. J.H. Kinney, S.J. Marshall, G.W. Marshall.Critical Reviews in Oral Biology & Medicine. 14(1):13‐29 (2003)

Dentin has a fatigue limit. For stresses smaller than the normal stresses of mastication, 30 MPa, a flaw‐free dentin specimen apparently will not fail. However, a more conservative approach based on fatigue crack growth rates indicates that if there is a pre‐existing flaw of sufficient size 0.3‐1.0 mm , it can grow to catastrophic proportion with cyclic loading at stresses below 30 MPa.

Then there are disasters!

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Mesio‐distal fracture in a virgin tooth

hat causes this


hat causes this Oblique occlusal forces

TENSION


hat causes this

Oblique cusp fractures once the occlusal integrity has been destroyed


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The bricks above the crack in the wall are NOT CONNECTED to the base. A big shove and they will tip off.

The dentin above the oblique fractures is NOT CONNECTED to the underlying dentin


The bricks above the crack in the wall are NOT CONNECTED to the base. A big shove and they will tip off.

The dentin above the oblique fractures is NOT CONNECTED to the underlying dentin

Flicked off with a probe!

How do we account for mesio‐distal and bucco‐lingual fractures in teeth with existing oblique fractures?

Same tooth with oblique fractures removed


Same tooth with oblique fractures removed Poisson Effect

Poisson’s ratio

For a linear isotropic material subjected only to compressive (i.e. normal) forces, the deformation of a material in the direction of one axis will produce a deformation of the material

along the other axis in three dimensions.

Where:

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Same tooth with oblique fractures removed Poisson Effect

Tension

Compression

This effect is three dimensional


Same tooth with oblique fractures removed Magne P, Belser UC. Rationalization of Shape and Related Stress Distribution in Posterior Teeth: A Finite

Element Study Using Nonlinear Contact Analysis. Int Jour Perio & Rest Dent. V 22, # 5, 2002 pg 2‐ 11.

FE analysis: ClenchingGrey = Compression.Stress greatest in the layer of dentin directly over the pulp





TENSION

This effect is independent of the forces creating the oblique fractures under the cusps

How do we account for random mesio‐distal and bucco‐lingual fractures in teeth with existing oblique fractures?

Deeper cavities= less dentin over the pulp= increased stresses in the remaining dentin

Primary fracture is a vertical M/D fracture



Primary fracture is a vertical M/D fracture

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Independent of the M/D fracture is an area of Poisson Effect fracturing under the old amalgam


Note: buccal and palatal enamel have not been reduced down to the dentin



Independent of the M/D fracture is an area of Poisson Effect fracturing under the old amalgam


The three dimensional nature of the Poisson effect accounts for the multi‐directional nature of the fractures

Note: the Poisson Effect radial fractures are centred under the site of the amalgam, independent of the mesio‐distal fracture


J. Ivancik, N.K. Neerchal, E. Romberg, and D. Arola. The Reduction in Fatigue Crack Growth Resistance of Dentin with Depth. J Dent Res 2011 90(8):1031‐1036.

Deep dentin exhibited the lowest resistance to the initiation of fatigue crack growth, and the highest incremental fatigue crack growth rate (over 1000 times that in peripheral dentin). Cracks in deep dentin underwent incremental extension under cyclic stresses that were 0 lower than those required in peripheral dentin. Molars with deep restorations are more likely to suffer from the cracked‐tooth syndrome, because of the lower fatigue crack growth resistance of deep dentin.


J. Ivancik, N.K. Neerchal, E. Romberg, and D. Arola. The Reduction in Fatigue Crack Growth Resistance of Dentin with Depth. J Dent Res 2011 90(8):1031‐1036.

Deep dentin exhibited the lowest resistance to the initiation of fatigue crack growth, and the highest incremental fatigue crack growth rate (over 1000 times that in peripheral dentin). Cracks in deep dentin underwent incremental extension under cyclic stresses that were 0 lower than those required in peripheral dentin. Molars with deep restorations are more likely to suffer from the cracked‐tooth syndrome, because of the lower fatigue crack growth resistance of deep dentin.


The three dimensional nature of the Poisson effect accounts for the multi‐directional nature of the fractures

Note: the Poisson Effect radial fractures are centred under the site of the amalgam, independent of the mesio‐distal fracture

1/10/2017


Poisson Effect Fractures

Not

Not

Poisson Effect Fractures

Not

A bonded restoration prevents the horizontal slip between the restoration and the underlying dentin

Ribbond bonded directly to dentin

Reduces lateral distortion from Poisson Effect


Bonding allows• distribution of stress and strain • prevents the load limit of dentin

from being reached


Poisson Fracture Treatment• Fractures under old amalgams –

Bonded Ribbond and a bonded restoration

Preventing Poisson Fracture • Don’t place amalgams• Place bonded restorations

What to do?• If any of these cracks types are treated incorrectly, the pulpal symptoms will not resolve….

• Then unnecessary/avoidable endo is performed to stop the patient complaining

• Diagnose correctly and treat accurately and the pulp will survive

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Clinical example of differential treatment of a fracture

These both look like Occlusal Effect Caries


The driving loads are completely different and the treatment is totally different


Load vectors create tension on the underlying dentinCompression > tension in enamel


Occlusal Effect CariesCompressive distortion of peripheral rim of enamel >Tension in enamel onlyNO DENTIN RACTURE

Treatment: Simply remove the caries and fracture and restore with a bonded restoration


DANGER! Tension in dentin as wellMesio‐distal dentin fracture.Tooth at extreme risk!

Simply restoring the distal crack with a bonded restoration will doom this tooth to failure.Treatment:• Dissect out oblique cusp fractures

and distal enamel fracture.• Splint M/D fracture with Ribbond.• Fill core with everX Posterior.• Recreate disrupted enamel

compression dome with bonded e.max onlay.

• Puts dentin back into compression.

Occlusal Effect or Vertical Tension Fracture?

?

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Check the occlusion.

Looks like occlusal overload splitting

the distal half of the tooth.

Patient is only 24 and can’t afford any

dentistry.


Check the occlusion.

The CULPRIT!


Still looks like Occlusal Effect

Caries


Fine, vertical mesio‐distal fracture.

NOT Occlusal Effect Caries.

Needs complex reconstruction.


STABILIZE!Distal wall built up incrementally.Ribbond across

floor.


Dentin replaced with fibre reinforced

EverX Posterior

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Completed restoration

DEAL WITH THE CULPRIT!

Occlusion shifted away from a

centralized splitting force


Or, create a fibre reinforced BioBaseand finish with a One Visit CEREC

inlay/onlay restoration

Where is the strength in a tooth?

Take a solid plastic rodRemove the core


We are left with a pipe of the original diameter and a smaller diameter rod

Where is the strength in a tooth?3mm

. mm

4.52 = 20.25

1.5mm walls

32 = 9 Beam theory states that the load‐carrying capacity of a beam is proportional to the square of the distance from the neutral axis centre, to the tensile side. The part of the tooth that remains after crown prep has the least load resisting capacity of the original clinical crown. That is assuming that there is much remaining central “tooth structure”.This is why full crowns on laterals and premolars fracture so often!

1/10/2017



Approximately half the “strength” of the original rod still resides in the walls of the pipe

The other half is in the core. The strength is proportional to the square of the radius.

3mm

. mm

1.5mm walls

Subtract the core from the original rod

20.25 – 9 = 11.25

Where is the strength in a tooth?3mm

. mm

1.5mm walls

Subtract the core from the original rod

20.25 – 9 = 11.25


In the cervical half of the tooth, this “pipe” is the This is where the tooth’s strength resides. Conserve it.


Imagine this an endo premolar with a large internal cavity and access hole.Now do a full crown prep!

Where is the strength in a tooth?From another perspective.Take the same diameter rod.Without reducing its diameter, cut 2mm off the top.

Where is the strength in a tooth?The remaining rod is still the same diameter.It is still just as “strong” and retains all of its load carrying capacity.

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Cementation requires the destruction of all the



Minor margin modification following fracture

Zero pulpal stress. The tooth was symptomless

Adhesive designs, ceramic or direct composite, retain the

If you cemented a ceramic

restoration on with a SE cement,

it will fall off!

Cementation demands a ferrule. Without a ferrule, even with pins, a cemented crown will overload a core

0 reduction on bonded core

surface

Cementation demands a ferrule. Without a ferrule, even with pins, a cemented crown will overload a core

0 reduction on bonded core

surface

1/10/2017



Ferrule cementation designs remove most, if not all of the Pulp

unhappy

Ferrule Cementation >17% endo in 5 years (CRA)


Placing an aesthetic margin removes all of the

Pulp very unhappy

4 million dentin tubules/cm2

are exposed in a crown prep

Plus it puts the pulp at high risk

U of South Carolina ‐1 endo rate under full crown preps per year!!


This was the final prep

Retained BiorimHappy Pulp

You would expect a bonded composite crown to survive, why not a bonded ceramic?


If there is no room for a conventional cementation ferrule, and you are not using adhesive techniques, you are then forced to do an endo, core and crown

1/10/2017


David Rudo

S.Belli, O.Eraslan, G.Eskitascioglu, V.Karbhari. Monoblocks in root canals: a finite elemental stress analysis study. International Endodontic Journal,44,817–826,2011

Primary = 1 interfaceSecondary = 2 interfacesTertiary = 3 interfaces

Increasing numbers of interfaces increases stress concentrations into the dentin (less stress is absorbed by the core)

Which technique matches dentin the best?


Reinforcing tooth structure

Evaluation of Fracture Resistance of Reattached Vertical Fragments with Fibre Reinforced Composites: An in‐vitro study. B Shiva Kumar et al.J Contemp Dent Prac Ju ug ( )

1. Restored with dual cure bonded Z1002. Restored with dual cure resin cement and

Ribbond polyethylene woven fibre3. Restored with dual cure resin cement and

Stick‐Net unidirectional e‐glass fibre

Restored teeth then re‐fractured using the same technique

45 root filled teeth deliberately fractured vertically through the root





None of the Ribbond reinforced teeth re‐fractured along the same plane as the original fracture

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Bonded Ribbond/Composite Core

Distributes and helps absorbs loads and stresses without transferring all the stresses into already weakened

tooth structurePolyethylene Fibre Leno weave

Tensile strength 435,000psi – 3.0GPaModulus of Elasticity 24,800,000psi – 171GPa(high strength fishing lines, bullet proof vests)


4 Primary Ribbond EffectsDepending on where and how it is used and

how it is applied:1. Reinforces tooth structure2. Reinforces composite3. Help control C‐Factor shrinkage stresses

(decoupling)4. Distributes stress and reduces stress

concentration

Fibre Reinforced Composite Engineering Tough fiber composite architecturesTriaxial braid and Leno weave

THM Ultra

Tough fiber composite architecturesTriaxial braid and Leno weave

Stress distribution via multiple load paths

Finite Element Analysis : Triaxial Stress Reduction

Eskitascioglu et al. J Dent. Research 2006; Vol. 85Special issue A

i ond eno wea e Unidirectional glass

Multi‐directional linear orientation

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a rac approaches a wea inter ace

Inter ace rea s ahead o main crac

c T shaped crac stopper

EDJ/Ribbond

David Rudo ‐ Ribbond

Cook‐Gordon Mechanism for stopping cracks at a weak interface

Enamel

Dentin

Fracture planes occur along the decussationinterfaces) of the Hunter Shregerbands(prism groups in opposite planes

Arrest at the DEC



Segments polymerization shrinkageNodes inhibit micro‐cracks from coalescing into real cracksStops crack propagation, encapsulates crack growth

No fibre

THM Ultra

Multiple crack

stopping events

Drs. Selim Erkut and zlem Acar


Area under the graph = amount of energy absorbed

THM Ultra

Multiple crack

stopping events

Drs. Selim Erkut and zlem Acar

No fibre

Redirecting Cracks

BIOMECHANICAL PROPERTIES AND CLINICAL USE OF A POLYETHYLENE FIBRE POST‐CORE MATERIALSEMA BELLI & G RCAN ESKITASCIOGLU INTERNATIONAL DENTISTRY SOUTH AFRICA VOL 8., NO 3

The Ribbond should have been at the bottom of the beam!

Note: the composite fractures above the Ribbond look just like the enamel tufts in the SEM

Micro events determine global response

Liberty Ship

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Energy absorption mechanismi.e., toughness of enamel and fiber composites

hearin o protein la ers etween apatite cr stalsailure mechanism is the tou henin

ener a sor in mechanismStructural Integrity of Enamel: Experimental and Modelling Z. Xie, M.V Swain and M.J. HoffmanJ DENT RES 2009; 88; 529

Enamel has been regarded as a hard ceramic like material with very limited toughness. In the past two years, reports have emerged showing that enamel behaves in a somewhat more metal‐like manner in terms of elastic and plastic properties (including creep) (He and Swain, 2007b). Using SEM analysis, we provided direct evidence for the first time showing that the ability of enamel to absorb energy and sustain deformation without catastrophic failure is attributed to its viscoelastic protein layers.

In cross section, tension will cause separation between individual fibres within a strand

(does not effect longitudinal strength)

Decoupling ‐ C‐Factor shrinkage stress control

The Effect of C‐Factor and Flowable Resin or Fiber Use at the Interface on Microtensile Bond Strength to Dentin. Belli S, Donemz N, Eskitasciogiu G. J Adhes Dent;8:247‐253.



Decoupling ‐ C‐Factor shrinkage stress control

Bond is protected

Shrinkage Stress

Decoupling disconnecting



This phenomenon is used in David Alleman’s technique to control C‐Factor shrinkage stresses when bonding to very deep,

compromised dentin (schlerotic or affected dentin) where bond strengths may only be

10‐15MPa

Ribbond C‐Factor stress breaker

Erkut. Microleakage in Over flared Root Canals Restored with Different Fiber Reinforced Dowelsperative Dentistr 33‐1

Figure 10: Scanning e ectron micrographs from the apica section of the interfacia a ers bet een dentin resin based uting agent and RD in the R group.D dentin L uting agent h brid one RT resin tag R Ribbond (origina magnification ).

Polymerization shrinkage occurredwithin the Ribbond luting composite region.There was no gap formation betweenthe canal walls and the Ribbond‐lutingcomposite region.

Effect of Bondline Thickness Vistap.M.Karbhari Ph.D.

The closer the fibre is to the substrate; the greater is the fibre effect.The further away the fibre is from the substrate, the greater is the resin effect.

1/10/2017


Fiber effectsPositive Fiber effects

• Segments and minimizes polymerization shrinkage• Encapsulates, inhibits, stops, redirects crack propagation• Stops micro‐cracks from coalescing into real cracks• Toughening mechanism• Load carrying and stress distribution mechanism

The three most common sources of post treatment pain

• Failure of a dentin bond under composite

• Undiagnosed or inaccurately treated dentin fractures

• Consequences of deep decay

Bouschlicher,Vargas,Boyer. Effect of composite type, light intensity, configuration factor and laser polymerisation on polymerisation contraction forces

Am J Dent 1997 Apr,10(2)88‐96

C = BONDED WALLSUNBONDED WALLS

Smooth surface

C = 1 BONDED5 UNBONDED

C‐Factor 0.2Facial VeneerVery shallow buccal


C‐Factor 0.5

Two walled cavity

Cl IV cavity

C‐ actor 0.

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C‐Factor 1

Three walled cavity

Cl III cavity


C‐Factor 2

Four walled cavity

Cl II cavity


C‐Factor 5

Five walled cavity

Cl I cavityCl V deep cavity

Feilzer AJ, De Gee AJ, Davidson CL; uantitative determination of stress reduction by flow in composite restorations.Dent Mater 6:167‐171 July 1990

Polymerization stress reduction by flow was shown to depend on C‐Factor

• C = 0.5 71% of polymerization stress was relieved by flow

• C = 2 35% of stress was relieved by flow• C = 5 negligible stress reductionThe MOST DIFFICULT restoration in dentistry is a

bonded composite “core” in an endo pulp chamber!

The Clinical Implications Incremental build up

Horizontal increment


Horizontal incrementKeep at 1mm

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Horizontal incrementKeep at 1mmThis reduces C‐FactorC‐ actor 0. ‐ 1.0Large free surface


Sectional increment


Sectional incrementTouching 2 wallsC‐ actor 0.Large exposed free surface


Sectional incrementTouching 2 wallsC‐ actor 0.Large exposed free surface

The ultimate in polymerization stress control.A sectioned, 1mm thick layer


C‐Factor 0.5 increments over a Bio‐base

Effects of Layering Techniques on Bond Strengths

Influence of C‐Factor and Layering Technique on Microtensile Bond Strengths to Dentin. S Nikolaenko, R.Fankenberger et alDental Materials 2004, Voll 20: 579‐585

4mm Bulk Fill

4 Increment Vertical Fill

4 Increment Oblique Fill

4 Increment Horizontal Fill

1/10/2017


Effects of Layering Techniques on Bond Strengths

Influence of C‐Factor and Layering Technique on Microtensile Bond Strengths to Dentin. S Nikolaenko, R.Fankenberger et alDental Materials 2004, Voll 20: 579‐585

5

10

15

20

25

30

35

MPa

ObliqueBulk Fill Vertical Horizontal

1 layer (4mm)

2 layers (2mm)

4 layers (1mm)

11

1617.6 19

15.7

31

19.8


Occlusal dentin shade is concave

Putting all the concepts together

Where is the decay? Symptomless tooth!

Putting all the concepts together• 2 separate cavities prepared• Triodent wedge guard used to

protect adjacent tooth• Enamel margins bevelled • Affected dentin left to avoid a

pulp exposure

Putting all the concepts together• 2 separate cavities prepared• Triodent wedge guard used to

protect adjacent tooth• Enamel margins bevelled • Affected dentin left to avoid a

pulp exposure• 2mm wide sound dentin and

enamel margin

Putting all the concepts together• Selective acid etch enamel

margins• 2 step SE Bond ‐ Clearfil SE Bond 2• Scrub in primer 20 sec, air dry• Apply resin, blot excess out with a

micro‐brush, cure

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Putting all the concepts together• 0.5mm layer of radio‐opaque

flowable• Cure • Consider this to be a part of your

dentin hybridization step

AdDent Composite Warmer

Attachments for either compules or syringes Pre‐dispensed increments

Placement instruments. Micro‐brush and Ash 6 Probe.

Putting all the concepts together• A square of Ribbond THM Ultra is

placed into a thin layer of warm composite and pressed right through to the underlying set flowable.

• Use the microbrush that was usdto apply the bonding resin B

• This wets the fibres at the same time as placing

• Keep away from the margin

Putting all the concepts together• Place a thin layer of warm enamel

shade to the height of the marginal ridge

• Split the increment vertically –don’t join two opposing walls

Putting all the concepts together• Fill in the rest of the interproximal

enamel

Putting all the concepts together• 1mm layer of dentin shade

1/10/2017


Putting all the concepts together• 2nd 1mm layer of dentin shade• Contoured with probe into a

concave fissure pattern, 1mm below the final surface

Putting all the concepts together• Enamel shade contoured with

probe• The depth of the fissures is

almost down to the underlying dentin shade.

• This gives colour depth without having to stain

Putting all the concepts together• White enamel shade applied to

match the initial tooth

Putting all the concepts together

The Clinical ImplicationsMismanaged polymerization shrinkage


Weak deep dentin bond:‐Deep caries Schlerotic dentinContaminated dentinIncreased density of dentin tubulesThick smear layerOver etchingIncorrect technique

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Uncontrolled debondPost insertion sensitivityMicroleakage



Poor bonding protocolContaminated surfaces


Poor bonding protocol

1. Debond1


Good bonding protocol

2. Tension causes fracturing of enamel margin

2


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Poor bonding protocolPoor bevel design

1. Margin debondMicroleakage

1


Good bonding protocolPoor margin design

2. Fracturing of enamel margin

2


Good bonding protocolGood margin design

Weak cusp


Good bonding protocolGood margin designPoor control of shrinkage stresses. Too large an increment.

Weak cusp

Cusp pulls in and fractures the enamel


MANAGEMENTGood bonding protocolsGood layering protocols

Decoupling the composite from the underlying dentin:‐

Autocure GIC (Fuji 9) closed sandwich base

Ribbond THM base layer

Decoupling with time:‐no more than 2mm base in 5 minutes

No1 Problem

Total Failure!

NO bondNO sealPost insertion sensitivityRecurrent decay

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The Adhesive Equation

G L Unterbrink, W H Liebenberg. Flowable resin composites as “filled adhesives”: Literature Review and Clinical Recommendations. uintescence Int 1999; 30:249‐257

“Adhesive dentistry could be expressed as a simple relationship between bonds and stress. If the bond can

withstand the stress, the restorative technique will be successful”

What about uncontrolled stress in the tooth?

The Biomechanical EquationThe other half of the equation

“Following a successful restoration, if the remaining tooth structure can successfully absorb the loads and stresses, the tooth will also survive. A successful restoration does not

necessarily guarantee the stability or survival of the tooth”

1/10/2017


Cracked Tooth Syndrome

Amalgam cavityStress concentration

The importance of a knowledge of fatigue in design is emphasized by one estimation

that 90% of all failures are caused by fatigue (cyclical stress concentration over time) and 90% of these fatigue failures

result from improper design. (Disrupting the compression dome

Sharp angles)ashington.edu me a chap

TIME DEPENDENT BEHAVIOUR: CYCLIC FATIGUE

Cracked Tooth Syndrome

Amalgam cavity

Mesio‐distal vertical fracture

Oblique fracture

Vertical mesio‐distal fracture

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Transected dentin tubules

Oblique fracture

Vertical mesio‐distal fracture

Weakest plane of cleavage is at right angles to the dentin tubules (endurance strength 44MPa, cf 24MPa parallel to tubules)Cavity design creates the focal point for fracture propagation

Tubule orientation and the fatigue strength of human dentinDwayne D.Arola , Robert K. Reprogel. Biomaterials 27(2006)2131‐2140

Odontoblast processes extend from the pulp, out to the EDJ

The Hydrodynamic Theory of Dentinal Pain: Sensation in Preparations, Caries, and the Dentinal Crack Syndrome. BrannstromM.Journ Endo; VOL 12, NO. 10, OCTOBER 1986

Cusp flexure

Hydraulic decompression, recompression cycles of the odontoblastprocesses causes pressure transfer to the odontoblastsleading to pulpal inflammation


Cusp flexure




Cusp flexure


NOT THIS WAY!!!!

A restoration bonded over the crack will remain sensitive.Dentin is compressible, therefore continuing flexure of the crack will produce the same symptoms from the odontoblastprocesses

1/10/2017


NOT THIS WAY!!!!

A crack left like this will produce the same symptoms that the patient presented withThe symptoms of a failed direct composite bond are also the same

Dissect out the oblique fractures

These fractures are easy.It is the ones that stay attached that cause all the problems.


Remove!


Dissect out the oblique fractures Dissect out the oblique fractures

Removal of an oblique fracture means the exposed surface is now no different than a conventional cavity prep surface

1/10/2017


Setting yourself up for a problem.Patient comes back complaining of post insertion sensitivity!

Immediate dentin sealing and Bio‐base over the fractures

Would you apply new paint before removing old flaking paint?

Setting yourself up for a problem.Patient comes back complaining of post insertion sensitivity!

The RISK! Strong possibility of post insertion sensitivity. Probably diagnosis – chronic pulpitis, lets do endo!

Dissecting out vertical fractures

Vertical fractures do not transect many dentin tubules so they do not always produce the classic pain on release of tension

Often, the first clue is acute pulpal symptoms

Dissecting out vertical fracturesNo deeper than 3mm from the DEJ to avoid the pulp horns (dissect out before doing the cusp reduction, use a perio probe as a guide)

Use a 1mm diameter diamond bur

Dissect out vertical fracturesNo deeper than 3mm from the DEJ to avoid the pulp horns (dissect out before doing the cusp reduction, use a perio probe as a guide)


Dissect out vertical fracturesNo deeper than 3mm from the DEJ to avoid the pulp horns (dissect out before doing the cusp reduction, use a perio probe as a guide)


Clean off smear layer with air‐abrasion

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Dissect out vertical fractures

Overlying dentin tubules transected by the crack are now disconnected from the underlying dentin.

Movement in the overlying dentin will not directly effect the tubules in the deeper dentin

Selectively acid etch enamel margins and rinse.Apply primer and bond as per manufacturer’s instructions and cure.

SE Primer and bond resin

Creating the Bio‐Base

0.5mm flowable

Apply a very thin layer of flow over the bond and into the depths of the prepared crack and cure

0.5mm composite

Place a very small increment of composite and compress it out to 0.5mm thick with a microbrush. Do NOT cure.

Ribbond THM pressed into compositeUsing a microbrush, pick up a strip or square of Ribbond THM and press it completely into the composite

Ribbond THM pressed into composite

Using a microbrush, pick up a strip or square of Ribbond THM and press it completely into the composite

1/10/2017


Ribbond THM pressed into composite

This is the DECOUPLING use of Ribbond to protect weak dentin bonds on deep affected or schlerotic dentin

To splint and reinforce a crack, the Ribbond should be applied directly to the bonded surface

Thin layer of Flow to wet Ribbond

Wet with a very thin layer of flowable and cure

This is a stress breaker system that is a part of the BioBase which can also include the BioRim

Decoupling with timeNo more than 1.5mm thick

in the first 5 minutes

Onlay bonded restoration

Flowable

Composite and Ribbond

BondFlowable

e.max CAD or pressed or Indirect Composite

Direct composite restoration

Flowable

Composite and Ribbond

BondFlowable

Direct Composite

Direct composite restorationLarge volume direct composites place significant stresses on the dentin bond • uncontrolled high C‐Factor

shrinkage vectors • large volume • large increments

The Ribbond layer acts as a DECOUPLING stress breaker• protects and preserves the

integrity of the underlying dentin bond

Ribbond C‐Factor stress breaker

Erkut. Microleakage in Over flared Root Canals Restored with Different Fiber Reinforced Dowelsperative Dentistr 33‐1,

Figure 10: Scanning e ectron micrographs from the apica section of the interfacia a ers bet een dentin resin based uting agent and RD in the R group.D dentin L uting agent h brid one RT resin tag R Ribbond (origina magnification ).

Polymerization shrinkage occurredwithin the Ribbond luting composite region.There was no gap formation betweenthe canal walls and the Ribbond‐lutingcomposite region.

1/10/2017


What does an e.max compression dome prep look like?

Look where the prep stops!

What does an e.max compression dome prep look like?Average thickness 1mmEven at 1.5mm on the

working buccal cusp, the prep is still in enamel

1. mm

1mm


2 striper 2004.7 (8 & 9)Two Striper TS2000 Diamond Burs

G, Coarse, GreenTaper Round End, # 2004.7 1.6 mm Major Diameter, 1.1 mm Minor Diameter, 7.0 (8 & 9)mm Length Premier Dental Products Patterson Item #:572‐7268 Mfg Item #: 2000047

Meisinger or Brasslerdepth cutting burs





1/10/2017


Remove old restorationsOcclusal reduction. 2004.7. Bury Bur full diameter horizontally, (1.1mm) into cusp, maintain that depth on both occlusal reductionsThen use same bur to create the basic margin bevelThen smooth any edges Use a flat ended bur to deal with the interproximals(using 2004.7 interproximally will

create J shaped margins or damage the adjacent tooth)


Or use a round diamond to create the buccal and lingual compression chamfer


Why does it look like this?We are mimicking Mother Nature’s brilliant design!

We are staying in the zone of the tooth where radial and meridional forces are all compressive

Sigmoid curve of the dentino‐enamel complex



Inflection points. DEC changes from concave to convex



Inflection plane.Cants lingual in lower, buccal in upper.

Inflection points. DEC changes from concave to convex


1/10/2017


Enamel compression dome is in radial compression above the inflection planeCompression dome below the inflection plane is in tension (hoop stress)


Radial orces compression/tension

Radial Hoop Stress


Meridional orces all compression


(volume enamel > volume dentin)

(volume enamel < volume dentin)

What is the restorative significance of the sigmoid curve and the inflection plane in the Bio‐dome?

Supportive Bio‐rim is below the inflection plane

Compression Bio‐dome is above the inflection plane

Clinical Significance: DO NOT REMO E THE BIO‐RIM

Inflection plane

Enamel above the concave sigmoid curve is retained

Biomimetic engineering



Biomimetic engineering

1/10/2017


Keeping as much enamel as possible is important

Load‐bearing properties of minimal‐invasive monolithic lithium disilicate and zirconia occlusal onlays: finite element and theoretical analyses. Li Ma, Petra C. Guess, Yu Zhang.Dent Mater. 2013 Jul; 29(7): 742–751.

When bonded to enamel (supported by dentin), the load‐bearing capacity of lithium disilicate can approach 75% of that of zirconia, despite the flexural strength of lithium disilicate (400 MPa) being merely 40% of zirconia (1000 MPa). When bonded to dentin (with the enamel completely removed), the load‐bearing capacity of lithium disilicate is about 57% of zirconia, still significantly higher than the anticipated value based on its strength.



It is important to note that stresses in the cement layer were predominantly compressive in nature, owing to the stress shielding effect of the ceramic overlay and the low elastic modulus of cement relative to enamel



“the stiff ceramic onlay provides stress‐shielding of the underlying cement and tooth support, preventing the substrate from significant plastic deformation”

Reduces the risk of further crack propagation in early diagnosed vertical fractures.

Design from an engineering perspective.

The Incas worked this out!

Machu Picchu

Design from an engineering perspective.

The internal fitting surfaces are designed to create a strong self‐centering compression effect when the wall is shaken by an earthquake. The stones become locked in every direction.


This design creates the same multi‐directional self‐centring effect when the onlay is under compression

1/10/2017



The peripheral chamfer, mainly in enamel, places the cusps in compression


Stay above the inflection plane unless previous dentistry or decay

dictates otherwise

Prism orientation and margin bevels

Unsupported enamel. Separates along the prism long axis when placed in tension. HITE LINES

Prism orientation and margin bevelsComposite shrinkage is powerful enough to pull enamel apart!

Unsupported enamel. Separates along the prism long axis when placed in tension. HITE LINES


Supported enamel. Strong in tension.


In the bottom of a deep proximal box, DON T cut of the last thin layer of enamel

1/10/2017


Supported enamel. Strong in tension.



The resin bond strength is identical, regardless of prism orientationThe weakness is related to prism orientation to the cut surface



The resin bond strength is identical, regardless of prism orientationThe weakness is related to prism orientation to the cut surface

Bevel cut along long axis of prisms


Missing enamel in a crack

Design from a biomimetic engineering perspective.


When bonded to enamel (supported by dentin), the load‐bearing capacity of lithium disilicate can approach 75% of that of zirconia

Mesio‐distal fracture

Design from a biomimetic engineering perspective.




“the stiff ceramic onlay provides stress‐shielding of the underlying cement and tooth support, preventing the substrate from significant plastic deformation”

Design from a biomimetic engineering perspective. Beware the opposing plunger cusp

latten and round off cusp.Reduces steep inclines.Provides room for the restoration.

1/10/2017


Bone loss in PDL associated with an untreatable vertical fracture

Untreatable vertical M/D fracture

Untreatable vertical M/D fracturePressure and temperature sensitive tooth.Mesio‐distal vertical fracture diagnosed.Irreversible pulpitis.Remove pulp and reassess.

Untreatable vertical M/D fractureEmergency pulpotomy.Fracture extends down to involve the pulp chamber floor.Fracture has therefore extended down into the roots.Unlikely to be successfully stabilized.Extract.

Listen to the symptomsPatient went to his dentistSymptoms:‐Tooth painful. History of bruxism.

(the fracture in this image was not present at that appointment)Nothing showed on the X‐rayTooth responded to coldVague, intermittent achingReferred to Oral surgeon. 3D cone beam showed nothing conclusive.Referred to Endodontist. Nothing conclusive, might have a crack.

Altered image

Listen to the symptomsPatient persisted until the pain got to the point he insisted the tooth be removed.

What should have been done?

When patients have vague symptoms and the tooth has a large amalgam, or a visible fracture in the marginal ridge:

REMO E THE OLD DENTISTR ANDHA E A LOO !

(Cheaper than referring to a specialist)

1/10/2017


Classic vertical fracture symptoms

If the old dentistry had been removed at the beginning, it may have been retrievable.

Wear of enamel against e.max CADNo significant difference

The Effect of Different Dental Ceramic Systems on The Wear of Human Enamel: An in vitro Study by E huni Rabie ., M.S., TUFTS UNIVERSITY SCHOOL OF DENTAL MEDICINE, 2013, 46 pages; 1537272

Wear of enamel against e.max CADNo significant difference

Prof Max Guazzato ‐ Sydney

Removal of smear layerLow pressure air abrasion

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Bur cut surface. 60µm grooves. Lots of collagen fibres transected. Smear layer.

Yellow polishing diamond60‐80µm crown diamonds

AA surface. 5‐15µm random divots. Far fewer collagen fibres transected. No smear layer.

27µm aluminium oxide 27µm aluminium oxide

Yellow polishing diamond

27µm aluminium oxide

Smear layer is like sanding wet woodIt leaves a sticky mush on the surface

The danger is comparing laboratory generated bond strengths to clinical reality

Laboratory surfaces ‐ 600 grit paperClincally ‐60‐80 grit diamonds

Polishing or cleaning with air‐abrasion provides the best clinical surface free of smear layer

Which is the Strongest Bond, Enamel or Dentin?

Microtensile Bond Strengths of an Etched & Rinse and Self‐Etch Adhesive to Enamel and Dentin as a Function of Surface Treatment.Van Meerbeek B, De Munk J, Mattar D, VanLanduyt K, Lambrechts P.Operative Dentistry, 2003, 28‐5:647‐660.

10

20

30

40

50

60

Micro TBS

MPa

Air Abrasion

Sonicsys Er:YagLaser

Diamond Bur

Enamel

Dentin

SIC Paper

Selective Acid Etch of enamel increases bond strength

Clearfil SE Bond. 2 STEP SELF ETCHSelective enamel etch not used in study

Which is the Strongest Bond, Enamel or Dentin?

Microtensile Bond Strengths of an Etched & Rinse and Self‐Etch Adhesive to Enamel and Dentin as a Function of Surface Treatment.Van Meerbeek B, De Munk J, Mattar D, VanLanduyt K, Lambrechts P.Operative Dentistry, 2003, 28‐5:647‐660.

10

20

30

40

50

60

Micro TBS

MPa

Air Abrasion

Sonicsys Er:YagLaser

Diamond Bur

Enamel

Dentin

Optibond Fl TOTAL ETCH

SIC Paper

Containing the dust

Cut off the end of a disposable plastic suction tipBond into the end of a 2 litre Coke bottle that is cut into the above shape, using Tak One thermoplastic beads or cold cure acrylic

1/10/2017


If you are using air abrasion or a

sandblaster, get one of these abrasion resistant sapphire crystal mirrorswww.crystalmark.com

Danville PrepStart H2O Crystalmark

www.crystalmark.com

US 4950 700 shipping

Moisture Control – Isolite and Isodryisolitesystems.com Moisture Control ‐Optragate

Direct restoration of oblique fracture Direct restoration of oblique fracture

1/10/2017


Wrong overlay preparation

On‐going post treatment temperature and pressure sensitivityFailed Tx, no resolution of symptomsLET S DO ENDO!

Fracture dissected out

Potential movement in the overlying dentin will not directly effect the tubules in the deeper dentin.Overlay the remaining cuspKeep the prep margin supragingival.If there is a “white line” in the enamel, remove all the cusp.

Overlying dentin tubules transected by the crack are now disconnected from the underlying dentin.

Fracture dissected out Direct bonded composite onlay

Margin is:SupragingivalIn enamelEasy to get a matrix onEasy to restoreEasy to finish

Direct bonded composite onlay

These two surfaces are now equally well bonded and equally stable.

Case Study

Patient presented having bitten on a hard sweetVery cold sensitivePressure sensitive

Dentin fracture dissected out, only removing dentin from the occlusal side of the fracture.

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This technique allows you to assess whether the fracture transects the pulp or not, without risking a traumatic exposure.

If the enamel is not fractured, leave it and overlay the cusp.


Cusp overlay No horizontal fracture in the enamel

Bonding

Bonding highlights the near miss on the pulp horn.

Note how the new V4 Ring from Triodent does not distort the band in the region of the missing cusp.

Plumbers tape

Reconstruction

Thin layer of radio‐opaque flowable composite

Plumbers tape

Reconstruction

1mm thick incremental build up of vertical wall of composite to replicate enamel

everX Posterior (GC)

GC everX Posterior, eglass fibre reinforced composite dentin replacement

everX Posterior is an anisotropic material.It has different mechanical properties in the X,Y and Z axis.No stronger in compression.Stronger in tension. Because the fibres tend to orient in the horizontal plane, they primarily resist tension on the horizontal plane. Resists crack propagation.Resist Poisson Distortion.

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• GC EverXPosterior fibre reinforced composite placed into the core of the cavity

• 2mm below occlusal table (to leave room for the final e.max onlay)

Crack Limiting and Stress Reduction Core

Mea

n Fracture Loa

d (N)

1800

900

everX Posterior Z250

Mean Fracture Load

Garoushi S, Lassila LV, Vallittu PK. Fiber‐reinforced composite substructure: Load bearing capacity of an onlay restoration. Acta Odontol Scand; 2006, 64:281‐285

Resists crack propagation

Reconstruction

1mm horizontal layer of everX Posterior eglass fibre reinforced composite

DO NOT use a bulk fill technique to replace the dentinYou WILL fracture the thin enamel wall!

Correct management of C‐Factor shrinkage is paramount to avoid pulling the cusp inwards and fracturing the enamel

Reconstruction

2nd 1mm horizontal layer of everXPosterior fibre reinforced composite

Reconstruction

Missing enamel rebuilt with either C‐Factor sectioned composite or incremental area build up.



Patient reported complete recovery from symptoms when contacted the next day

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Overlay or cusp removal?

White lines in the enamel.These are easy!

Remove the cusp.

It is the incomplete fractures that are not dealt with correctly that cause all the on‐going problems.

Alternative option to a cusp overlay

When the fracture extends all the way out to the enamel,completely remove the

fracture.

Direct bonded composite onlayor CADCAM onlay

Ribbond‐Direct Compositeon an Endo Premolar Sometimes a crown is a poor option

The Problem. What to do next?• Best aesthetics will be to leave

the facial enamel intact.• The risk – the tooth is

biomechanically weak following removal of caries and completion of endo.

• Fracture risk.• Note: the mesial decay

removal was not joined to the distal. Retain all sound tooth structure!

The Problem

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• Almost all the remaining tooth structure is removed with a crown prep.

• Now, most of the load will be on a post!

• This is a high risk treatment option on premolars.

What about a crown?

• Create a Ribbond torsion box inside the tooth to prevent crack propagation and create energy dissipation

The Solution

The SolutionRestorative toolsAsh 6 Probe

Microbrush

• GP removed 2mm into canals

• Margins bevelled• V4 Ring and sectional matrix

• Isolation with an Isolite

• Completed Triodentsectional V4 Rings and non stick matrices

• Keep the height of the matrix at the marginal ridge to act as a build up guide

• Enamel margins selectively etched

• Bonded: Kuraray SE Protect

• Critical cross bracing retained

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• Thin layer of radio‐opaque flow placed only on the gingival margins.

• Because Ribbond works best when applied directly to the dentin.

• First interproximal increment of A1 (enamel shade) <1mm thick. (GaenialPosterior nano‐hybrid)

• Both cavities at the same time

• Accurately built to height of marginal ridge

• 2nd interproximal increment of A1 (enamel shade)

• Both cavities at the same time

• 2mm wide Ribbond THM Ultra place bucco‐linguallyand pushed down into each canal

• Place a THIN layer of warm nano‐composite on floor and compress Ribbond right through the composite

• Remove excess

• The Ribbond in the canal entrances creates a torsional lock, stabilizing the core bucco‐linguallyand mesio‐distally

• The Ribbond in the canal entrances creates a torsional lock, stabilizing the core bucco‐linguallyand mesio‐distally

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Resistance to bucco‐lingual, mesio‐distal and rotational movement

• Wrap a 3mm wide length of THM Ultra completely around the walls of the cavity and interproximal composite

• Wrap a 3mm wide length of THM Ultra completely around the walls of the cavity

• This creates the walls of a fibre torsion box

• The Ribbond on the vertical walls prevents vertical crack propagation in the tooth

Circumferential Ribbond wrap. On vertical dentin wall from buccal to lingual, as well as the enamel walls and composite.

Resists vertical splitting forces and torqueing forces

Distributes and dissipates stresses

• Place 3mm wide length of THM Ultra buco‐lingually

• Down the buccal wall, across the floor and up the palatal wall to stop at the dentino‐enamel junction

• Place 3mm wide length of THM Ultra buco‐lingually

• Down the buccal wall, across the floor and up the palatal wall to stop at the dentino‐enamel junction

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• EverX Posterior (GC) glass fibre reinforced composite placed to stop 2mm from the occlusal surface

Completion of the Ribbond torsion box core

• EverX Posterior (GC) glass fibre reinforced composite placed to stop 1.5mm from the occlusal surface

Completion of the Ribbond torsion box core

• 1st layer of A1 GaenialPosterior with the fissure pattern and cusp lobes created with an Ash 6 probe

• (Jason Smithson technique)

Aesthetic Composite Reconstruction

• 2nd layer of Bleach Gaenial Posterior with the fissure pattern and cusp lobes created with an Ash 6 probe

• Brown stain place in depths of fissures


• 3rd layer of Bleach Gaenial Posterior with the fissure pattern and cusp lobes created with an Ash 6 probe

• White nano‐composite placed on cusp lobes


• Completed case


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Aesthetic Composite Reconstruction Aesthetic Composite Reconstruction

Ribbond appears mottled in Radiographs

Remember this tooth? What did I do?

Enamel above the concave sigmoid curve is retained

Biomimetic engineeringDisrupted compression dome.

Mesio‐distal and Poisson effect fractures.

Tooth vital and symptomless.

Mesial fracture open enough to retain a probe.

Crack Limiting, Stress Reduction Bio‐Base

1/10/2017


Restorations removed

Basic e.max onlay prep outline

Note: enamel still present over the buccal contours of the preps


Mesio‐distal fracture carefully dissected out as far as possible, avoiding a pulp exposure


Tooth air‐abraded, bonded

Ribbond THM Ultra layered bucco‐lingually into the dissected mesio‐distal fracture


Second layer of Ribbond THM Ultra

Splint the Poisson effect fractures and the central area of the mesio‐distal fracture


Central volume of cavity filled with everXPosterior fibre reinforced composite

Note: everXPosterior is not a replacement for Ribbond. It does not reinforce the tooth, the fibres only reinforce the composite


Completed onlay preparation


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Reconstruction of the Compression Bio‐Dome

Completed bonded e.max onlay

1/10/2017


Assoc Prof. Dr Kosmas Tolidis

Conventional amalgam crown core

Conventional amalgam crown core Full coverage crown removes large volumes of critical supporting enamel and dentin, exposing the core and remaining teeth to unnecessary, excessive stresses


I have a huge number of amalgam onlays in my practice. If the patient insists, based on aesthetic concerns, I will

now convert it to a bonded ceramic onlay.

amalgam endo core and onlays

The boring stuffNagasiri R, Chitmongkolsuk S.J Prosthet Dent. 2005 Feb;93(2):164‐70.Long‐term survival of endodontically treated molars without crown coverage: a retrospective cohort study.

Overall survival rates of endodontically treated molars without crowns at 1, 2, and 5 years were 96%, 88%, and 36%, respectively.

Tikku AP, Chandra A, Bharti R.J Conserv Dent. 2010 Oct;13(4):246‐8.Are full cast crowns mandatory after endodontic treatment in posterior teeth

Endodontically treated posterior teeth present numerous problems because of coronal destruction from dental caries, fractures, and previous restorations or endodontic techniques. The result is loss of tooth structure and a reduction in the capacity of the tooth to resist a myriad of intraoral forces. A summary of this review article suggests that coronal coverage significantly improves the clinical success rate of endodontically treated posterior teeth.

1/10/2017


The boring stuffStavropoulou AF, Koidis PT. J Dent. 2007 Oct;35(10):761‐7. Epub 2007 Sep 5.A systematic review of single crowns on endodontically treated teeth.(One thousand six hundred and nine references were found, and they were subjected to a systematic review procedure.)

RCTs restored with crowns show an acceptable long‐term survival of 10 years, while direct restorations have a satisfactory survival only for a short period.

Aquilino SA, Caplan DJ. J Prosthet Dent. 2002 Mar;87(3):256‐63.Relationship between crown placement and the survival of endodontically treated teeth.

endodontically treated teeth not crowned after obturation were lost at a 6.0 times greater rate than teeth crowned after obturation (95% confidence interval: 3.2 to 11.3).

Kolker JL, Damiano PC, Caplan DJ, Armstrong SR, Dawson DV, Jones MP, Flach SD, Warren JJ, Kuthy RA. J Am Dent Assoc. 2005 Jun;136(6):738‐48; 805‐6.Teeth with large amalgam restorations and crowns: factors affecting the receipt of subsequent treatment after 10 years.

the odds of teeth with large amalgam restorations receiving a catastrophic treatment being 2.1 times the odds of teeth with crowns receiving catastrophic treatment.

Not this way!!!!

Not this way!!!!

MOD cavities in endo molar teeth reduce their fracture

resistance by 80%

Steele A, Johnson BR. In vitro fracture strength of endodontically treated molars.J Endod 1999;25:6–8.

Can you please fix my chipped filling?

Yes, it did have an amalgam onlay.

Problem? The design!The bevel onlays went the

wrong way, acting like a wedge and placed the underlying

cusps into tension

Steele A, Johnson BR. In vitro fracture strength of endodontically treated molars.J Endod 1999;25:6–8.

Not even this way!!!!Poorly bonded composite

core then FULL PFMNO tooth left!

The important boring stuffVan Thompson. Journal of Dental Research Vol. 91 Supplement 1 July, 2012 p.175

reports: Results suggest that the root canal failure rate (root canal therapy plus restoration) in general practice is higher than previously reported (28%) JADA 143 (7):In press

Teeth that have both RCT and full coverage showed a 28% failure in 10 years

3% failure rate per year

1/10/2017


What about a Monoblock e.max endocore onlay?

Ceramic core is too stiff and transfers stresses to the surrounding tooth

rather than helping absorb them


Forces and stresses need to be evenly distributed and absorbed,

and the core system should match the behaviour of dentin


Destruction of the BioRim leads tooverloading of cores and remaining tooth

High C‐Factor

• Highest C‐Factor of any restoration

• Largest Volume

• Greatest risk of uncontrolled shrinkage stress and debonding of all the restorations we place!!

Irreversible Pulpitis

• OptionsEndodontics and restorationExtraction• Partial denture• Bridge• Implant

1/10/2017


To restore or extract?that is the question

• Remove the old dentistry• Create endo access and remove pulp• If the fracture in the mesial/distal wall extends into the pulp chamber floor, extract

• If there is any perio involvement associated with the fracture, extract

To restore or extract?that is the question

• If the pulpal floor is intact an option to offer is endo and restoration on the understanding that there is a failure risk

After endo:• Retain the BIORIM• Ribbond reinforced fully bonded core• BONDED e.max onlay or Lava Ultimate onlay

M/D crack under old amalgam leading to irreversible pulpitis Ribbond/composite bonded core

the was maintained

Forces and stresses need to be evenly distributed and absorbed

and the core system should match the behaviour of dentin


David RudoPersonal communication

“It requires a cultural leap to go from an understanding of the dental restorative complex based on strength to an

understanding of the complex based on the components of the complex functioning in strain harmony. When the

components of the restorative complex function in strain harmony, they mimic the behavior of the dentin, enamel, and root regions of the intact tooth functioning together through

a continuum of graded interphases.”

1/10/2017


Minimal intervention Monolithic ceramic endo onlay IPS e.max CAD or Pressed, Celtra Duo, Suprinity

ulp loor onl canal entrances

sealed with I

The BIOMIMETIC restorationRibbond controls C‐Factor shrinkage stresses

Acts as a stress decoupler – protects the bond integrity

Reinforces the core

educe cusps or a mm o erla with mm rounded cham er mar in

eep contours so t lowin and rounded mimic mother nature

Ribbond THM(thin high modulus)Cut to length to fit down walls and across chamber

floor

Polyethylene FibreLeno weave

Tensile strength 435,000psi ‐ 3.0GPaModulus of Elasticity

24,800,000psi – 171GPa(high strength fishing

lines, bullet proof vests)

Ribbond THM(thin high modulus)Cut to length to fit down walls and across chamber

floor

Wetted first with unfilled BISGMA resin NOT flowable or primer

Excess resin removed then sticky securing flowable applied

i ond onded uccolin uall in pulp cham er or mm wide strip

The Effect of C‐Factor and Flowable Resin or Fiber Use at the Interface on Microtensile Bond Strength to Dentin. Belli S, Donemz N, Eskitasciogiu G. J Adhes Dent;8:247‐253.

In vitro Fracture Resistance of Fiber Reinforced Cusp‐replacing Composite Restorations. Fennis WM et alDental Materials 2005;21:565‐572

Ribbond THM (thin high modulus)

4mm The effect of fibre insertion on fracture resistance of root filled molar teeth with MOD preparations restored with composite. S. Bellil, A. Erdemir, M . Ozcopurr, G. Eskitascioglu.Int Endo Journ, 38, 73‐80, 2005

second strip o i ond placed into the next increment o composite lea in the central area empt then illed a ter

curin the nd i ond la erC‐Factor polymerization stress controlPrevention of fracture propagation

second strip o i ond placed into the next increment o composite lea in the central area empt then illed a ter curin

the nd i ond la er

maintained.

Increased fracture resistance.

Overlay with CAD porcelain or bonded high modulus composite

1/10/2017


e creatin the stress distri ution s stem o the tooth

maintained.



maintained.



maintained.


Even a bonded composite would be expected to survive!

A CEREC generated onlay would be even better


A fully bonded structure, starting at the floor of the pulp chamber. Re‐creates the structural volume required to absorb and evenly

distribute biomechanical stresses and re‐create strain harmony


R Z Wang, S Weiner. Strain Structure in human teeth using Moiré fringes. Journal of Biomechanics 1998

Feb;31(2):135‐141.

Re‐create the energy sink

The is the wall that supports the compression dome complex

Don’t send it up the suction!!!!

Pantheon ‐ Rome

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dhesi el onded e max D or pressed onla crownremains intact iomechanicall sta le

Increased ul

increases racture resistance

ar ins are in a one that a oids impression perio

ondin and inishin pro lems

ndo teeth with one or more missin walls

Creating a stable full bonded core

A closed box or cylinder is torsionally and laterally stableTensile forces on one side get distributed throughout the structure

Strong

Strong Strong

Strong

Strong

Creating a Ribbond Torsion Box

Endo teeth with one or more missing walls


Canal entrances sealed with GIC. Keep off pulp chamber floor. (or cut it off after it is set.)

Creating a Ribbond Torsion Box Creating a Ribbond Torsion Box

1/10/2017



A 2nd piece of Ribbond is run buccolingually

Creating a Ribbond Torsion BoxDIRECT COMPOSITETwo buccolingual strips of Ribbond

Ensure the cusp reduction leaves enough room

Slots can be cut in the cusp tips to accommodate the Ribbond

Creating a Ribbond Torsion BoxTooth can be prepared for an adhesive onlay any time in the future without having to re‐address the endo core.

B‐L transversing techniqueRibbond in occlusal

increased fracture resistance 57 %S. Belli, A. Erdemir, C. Yildirim, Reinforcement effect of

poylyethylene fibre in root‐filled teeth: comparison of two restoration techniques, Internationa Endodontic Journa (2005)

Vol 38:1‐7.

When loaded in ossa i ond acts in tension

pullin cusps to ether


B‐L transversing techniqueRibbond in occlusal

increased fracture resistance 57 %S. Belli, A. Erdemir, C. Yildirim, Reinforcement effect of poylyethylene fibre in root‐filled teeth: comparison

of two restoration techniques, Internationa Endodontic Journa (2005) Vol 38:1‐7.

What do we call this t pe o restoration

I I D D IT

Unprotected endo tooth fracture!!Ensure there is mechanical lock in the pulp chamber (1/2 round bur)

Stable compression cusps

Ribbond Torsion Box

THM Ribbond reinforced bonded core

Waterlase closed flap bony crown lengthening

1/10/2017


Protected endo tooth!!

Note all the retained buccalenamel and

Ribbond torsion box/stress breaker ring

Protected endo tooth!!Conservation of the

buccal

Complex Ribbond Endo Core

Bondede.max

The core is fully bonded to the tooth The restoration is fully bonded to the fibre reinforced bonded core as well as the remaining tooth

Complex Ribbond Endo Core

Energy distributionNot energy concentration

Non‐reinforced core – Full CrownComposite on its own is not strong enough

This was all the dentin that remained!

Mechanically retained coreShear forces cleaved the core

1/10/2017


There was no stress distribution

The strongest part of the tooth has already been sent up the suction!

Then the weaker core had the guts cut out of it!

There was no stress distribution

All the torque and shear forces were on the unreinforced composite core.It was only a matter

of time!

There was no Energy Sink or stress distribution, only stress concentration!

Overload

Moire ringe Stress Pattern

The gold onlay did not protect the buccal cusps

Circumferential Ribbond THM Ultra

First layer of Ribbond THM Ultra and sticky flow is laid down circumferentially around the pulp chamber

Ensure there is mechanical lock in the pulp chamber (1/2 round bur)

2nd Bucco‐lingual layer

2nd layer of Ribbond THM Ultra and sticky flow is laid down bucco‐lingually

1/10/2017






3rd Mesio‐distal layer

3rd layer of Ribbond THM Ultra and sticky flow is laid down mesio‐distally





Core build up

The internal core is built up incrementallyComposite is also added to the outside of the Ribbond walls

1/10/2017


Completed Ribbond reinforced core

Laser gingivectomy on distal

First cord packed

Bonded CADCAM e.max crown

Occlusal table has been kept narrow to reduce cantilever and torsional forces on the core

Bonded CADCAM e.max crown

Occlusal table has been kept narrow to reduce cantilever and torsional forces on the core

4 years later

Compression cusp or Tension cusp?That is the question

All cusps are dentin tension cusps

Buccal cusps are compression cusps

Lingual cusps are dentin tension cusps

Check occlusal contacts with bite paper after removal of old restoration

Compression ‐Usually safeCompression ‐Usually safe

Tension ‐Risk of fractureTension ‐Risk of fracture

1/10/2017


Chewing motion with bite paper

Compression cusps. If the base is wide, safe to leave.

Tension cusps. Overlay, they will eventually fracture

LoadDirection

Firm in principle, flexible in practice


Buccal Tension Cusp has already been lost

LoadDirection



Removal of the amalgam revealed a near vertical fracture

under the palatal cusp.Danger of eventually transecting

the pulp horn.



Careful dissection of the fracture, staying on the

palatal side of the fracture line.

Most of the fracture could be dissected out.



Air abraded prior to bonding an e.max E4D CADCAM

restoration

The invisible margin trick

After bonding, a bead of warmed composite is placed

onto the buccal margin before seating the restoration

into the unset composite

1/10/2017



Compression dome reconstructed and retainedInvisible margin


Endo tooth. Lingual cusp was in tension. Catastrophic fracture!Buccal compression cusps are still intact.

Consider the opposing culpritRecontour if needed

What can I save?Chewing motion with bite paper

Not under lateral tension load

Tension loads Compression load Recheck contacts

Tension load on distobuccalcusp removed by adjusting

upper occlusion

Dry and check all the fracture has been removed

What can I save?Chewing motion with bite paper

This is not an occlusal effect caries compression fracture.

It is a tension fracture.There is a crack in the dentin.

Occlusal load shifted from distolingual cusp to central occlusal

Protecting a cusp that is not in occlusionThe “bear hug”

Rule : No lateral occlusal tension guide facets show with bite paper

Protecting a cusp that is not in occlusionThe “bear hug”Premier Two‐striper 776.4F

1/10/2017


Cusps – to overlay or not?Distolingualcusp was cracked

Mesiolingual cusp was sound and has a wide buccolingual base

Mesiolingual cusp was wrapped with a bear‐hug of porcelain for

additional support

Completed e.max HT “bear hug”

3 years later

Completed e.max HT “bear hug”

3 years later

years later

1/10/2017


Endo Onlay CrownConserve valuable tooth structure with adhesive ceramics

Keep margins in enamel if at all possible

A hole in one!

Keep margins in enamel if at all possible

Cutting a full ferrule prep not only destroys the but also removes all the enamel which is the best bonding

surface we have!

Straight out of the furnaceNo occlusal adjustment neededOcclusal forces kept compressive

and centralized Limited torqueing moment

Accept some discolouration in the cervical region to preserve

the

On previously compromised teeth, restore the compression

dome/tension ring/peripheral rim complex and maintain the with onlay adhesive restorations to restore true function to the tooth

and reduce the potential for on‐going collapse

1/10/2017


So Much Information!What do I do on Monday Morning?

Do nothing, or put in a progressive plan to instigate controlled change?

The plan is different for everyone, depending on where you currently are

Without a written plan, nothing will change.

So Much Information!What do I do on Monday Morning?

• Preparation designs; Oblique fractures, Mesiodistalfractures, Adhesive Onlays, Ribbond endo cores

• Bonding systems• Materials. Ribbond THM, everXPosterior• Adhesive options, direct and indirect• Air‐abrasion• Magnification• CADCAM

Bibliographywww.advancedental‐ltd.com

(Bibliography tab)

[email protected] of Endo Core Technique

Documents

Biomimetics Milicich Handout.pdf - Mehta Orthodontics