REGENERATIVE MATERIALS

Dr. Krishnaraj

Dept Of Periodontics

• Introduction• Definitions• Results of conventional procedures• Concepts of regeneration• Biology of regeneration• Osseous grafts and regeneration• Guided tissue regeneration and periodontal

regeneration• Resorbable, bioabsorbable and non-

resorbable barrier membranes

• Role of growth factors in periodontal

regeneration

• Tissue engineering

• Summary & Conclusion

• Future directions

INTRODUCTION

Definitions

• Regeneration: growth and differentiation of new cells

and intercellular substances to form new tissues or parts

• Reproduction or reconstitution of a lost or an injured part

in such a way that the architecture and function of the

lost or injured part is completely restored. (GPT 1992)

• Repair: restoration of the continuity of diseased marginal

gingiva and re-establishment of a normal gingival sulcus at

the same level on the root as the base of the periodontal

pocket.

• New attachment: formation of new cementum with inserting

collagen fibers on a root surface deprived of periodontal

ligament tissue

• Re-attachment: the reunion of surrounding soft tissue and a

root surface with preserved periodontal tissue

Results of conventional procedures

• Eliminate the etiologic factors

• Removes the pocket lining/wall

• Accessible for plaque control

How about this?

• Long JE!!

• Parallel fibers

• Altered root surface!!

• Reduced periodontium

What next?

• Need for regeneration

• Support

• Function

• Aesthetics

• Better maintenance

Possible??- Let’s see..

• Melcher hypothesis (1976)

• Epithelial cells

• Gingival connective tissue

• Bone cells

• Periodontal ligament cells

Regenerative methods

• Earlier regenerative methods

• Bone grafts

• Guided tissue regeneration

• Tissue engineering

Root surface and its importance

• Altered

• Connects pdl and bone

• Citric acid, tetracycline, fibronectin, growth

factors, EDTA etc..

• Good or bad??

• Role of cementum – is it only attachment??

OSSEOUS GRAFTS

Osseous grafts

• Graft or substitute?

• Autograft

• Allograft

• Hetero or Xenografts

• Alloplasts.

Ellegaard (1973) and Nielsen (1980):

• Osteoproliferative (osteogenesis)

• Osteoinduction

• Osteoconduction

Osseous grafts

Definition and requirements

• Requirements:- 1. Should help in the formation of new bone2. Be inert and biocompatible3. Easy to obtain4. Predictable5. Cost effective6. Non toxic7. No root resorption or ankylosis.8. Strong and resilient

Autografts – Gold Standard??

• Intra-oral / Extra –oral.• I/o – extraction sockets

edentulous ridges symphysis ramus maxillary tuberosity

• E/o – iliac crest femur calvaria

• Bone swaging• Osseous coagulum• Bone blend

Autografts – Gold Standard??

• The cells contained in graft start forming new bone.

• The transplanted osteocytes die due to anoxia but osteoclasts survive and may initiate resorption of graft.

• However, adequate revascularization may ensure increase osteoblastic population.

• Cortical chips, osseous coagulum and a blend can also be used.

• Larger particle size of cortical bone may however be sequestered

Procedures

• Trephines; available in different sizes

• Olympic ring and significance

• Bone core; compact and cancellous.. Can be crushed

• Only cancellous can also be used.

• Potential greater for cancellous bone.

Advantages and Disadvantages

• Better predictability• No antigenicity

• Time consuming• Second surgical site• Insufficient quantity• Root resorption!

Risks associated• Nerve damage.• Mentalis• Depressor labii inferioris• Maxillary sinus• Inferior alveolar nerve

Is it still the Gold standard?? – Decide..

ALLOGRAFT – BOON OR BANE?

2 TYPES;

• Demineralized freeze dried bone allograft (DFDBA)

and freeze dried bone allograft (FDBA)

• Mellonig (1981) – FDBA is an alternative to

autograft for use in periodontal defects.

• Urist and robinson (1979) - DFDBA

Why an Allograft?

• The demineralization – essential; as bone mineral

blocked the effect of the inductive agent; BMPs.

• Osteoinduction: DFDBA (Urist 1970)

• Osteoconduction: FDBA (Goldberg and Stevenson

1987)

Rate of bone formation with Rate of bone formation with DFDBADFDBA

Rapid from day 14 to day 28 and declines Rapid from day 14 to day 28 and declines thereafter, esp from day 35 to day 42.thereafter, esp from day 35 to day 42.

Low osteogenic index at the beginning but Low osteogenic index at the beginning but rapidly increases.rapidly increases.

Whereas the FDBA has osteogenic index at Whereas the FDBA has osteogenic index at the start which does not increase post-the start which does not increase post-grafting.grafting.

Particle SizeParticle Size

Shapoff 1980 reported that smaller particle size Shapoff 1980 reported that smaller particle size causes more osteogenesis; but disproved when 44 um causes more osteogenesis; but disproved when 44 um failedfailed

Urist 1967 - 250 – 420 inhibits bone formation, but Urist 1967 - 250 – 420 inhibits bone formation, but larger particles of 1000 – 2000 um do not.larger particles of 1000 – 2000 um do not.

Mellonig and levy concluded that 250 –750 um is Mellonig and levy concluded that 250 –750 um is ideal for periodontal grafting procedures.ideal for periodontal grafting procedures.

Recent evidence suggests 317 um as an ideal size.Recent evidence suggests 317 um as an ideal size.

Pore size is just as crucial as it determines the Pore size is just as crucial as it determines the

neovascularization.neovascularization.

Pore size of 100 to 200 um is considered optimal Pore size of 100 to 200 um is considered optimal

for endothelial and fibroblastic ingrowth (Bhaskar for endothelial and fibroblastic ingrowth (Bhaskar

1971, Hulbert 1970, Topazian 1971). 1971, Hulbert 1970, Topazian 1971).

Fate of GraftFate of Graft

Reynolds and Bowers (1996) showed that this the only Reynolds and Bowers (1996) showed that this the only

graft which, if more residual particles remain post graft which, if more residual particles remain post

grafting, results in significantly greater amounts of grafting, results in significantly greater amounts of

new attachment.new attachment.

DFDBA may show delayed neovascularization as DFDBA may show delayed neovascularization as

compared to autologous bone.compared to autologous bone.

Antigenicity of FDBAAntigenicity of FDBA

Anti – HLA antibodies.Anti – HLA antibodies. Friedman (1984); 9 out of 43 patientsFriedman (1984); 9 out of 43 patients Quattlebaum 1988 – concluded that the FDBA has Quattlebaum 1988 – concluded that the FDBA has

markedly reduced antigenicity stating that the freeze markedly reduced antigenicity stating that the freeze drying procedure may spatially distort the three drying procedure may spatially distort the three dimensional presentation of the HLA antigens on dimensional presentation of the HLA antigens on FDBA affecting immune recognition.FDBA affecting immune recognition.

Advantages and DisadvantagesAdvantages and Disadvantages

Commercially availableCommercially available Less time consumingLess time consuming Predictable and rich source of BMPsPredictable and rich source of BMPs

Suspicion of disease transfer (1 in 8 million).Suspicion of disease transfer (1 in 8 million). ExpensiveExpensive Age of donorAge of donor

Another disadvantage is that the poor physical Another disadvantage is that the poor physical

properties of the graft impairing the retention of the properties of the graft impairing the retention of the

graft in the site.graft in the site.

Blumenthal 1986 – combined the bone graft with Blumenthal 1986 – combined the bone graft with

microfibrillar collagen. This combined graft helped microfibrillar collagen. This combined graft helped

to;to;

1.1. Bind and retain the particles in the defect,Bind and retain the particles in the defect,

2.2. Created space between particles – ingrowthCreated space between particles – ingrowth

3.3. Collagen material attached to root.Collagen material attached to root.

Recent evidence indicates that the age of donor is Recent evidence indicates that the age of donor is

significant in the transfer of BMPs.significant in the transfer of BMPs.

The graft obtained from donors over the age of 45 years The graft obtained from donors over the age of 45 years

shows reduced amount of BMPs.shows reduced amount of BMPs.

Jin et al (2003) have shown that gene therapy of bone Jin et al (2003) have shown that gene therapy of bone

morphogenetic protein – 7 demonstrated rapid morphogenetic protein – 7 demonstrated rapid

chondrogenesis with subsequent osteogenesis, chondrogenesis with subsequent osteogenesis,

cementogenesis and predictable bridging of periodontal cementogenesis and predictable bridging of periodontal

defectsdefects

Human tendon collagen dehydrated. When rehydrated Human tendon collagen dehydrated. When rehydrated

it expands to fill the defect.it expands to fill the defect.

Good replacement for the blood clot.Good replacement for the blood clot.

Has been an integral part of DFDBA grafts available Has been an integral part of DFDBA grafts available

ever since..ever since..

Recombinant BMPs (rhBMP-2) can be incorporated Recombinant BMPs (rhBMP-2) can be incorporated

in a variety of graft materialsin a variety of graft materials

XenograftsXenografts

Grafts available free of the organic componentGrafts available free of the organic component Kielbone, calfbone used earlier.Kielbone, calfbone used earlier. Bovine anorganic cancellous bone (BACB); produced by a Bovine anorganic cancellous bone (BACB); produced by a

special process which removes the organic part, retains the special process which removes the organic part, retains the inorganic part.inorganic part.

Another product is the porcine non-antigenic collagen Another product is the porcine non-antigenic collagen (PNAC), the collagen of which undergoes prolonged (PNAC), the collagen of which undergoes prolonged alkaline treatment, producing a bilayer structure alkaline treatment, producing a bilayer structure eliminating any risk of bacterial or viral contamination.eliminating any risk of bacterial or viral contamination.

Telopeptides are split off, the areas most Telopeptides are split off, the areas most concerned with the antigenicity of the molecule.concerned with the antigenicity of the molecule.

Specific purification processes remove residual Specific purification processes remove residual fat or protein.fat or protein.

PNAC is produced as a block, which can be PNAC is produced as a block, which can be crushed to the desired size or consistency.crushed to the desired size or consistency.

The composite graft of BACB and PNAC shows The composite graft of BACB and PNAC shows no antigenicity (Cohen 1994).no antigenicity (Cohen 1994).

Earlier xenografts showed rejection ..chemical Earlier xenografts showed rejection ..chemical detergent extractiondetergent extraction

PepGen – 15PepGen – 15 Contains a synthetic 15-amino acid sequence with steric Contains a synthetic 15-amino acid sequence with steric

similarities to the cell binding sites of Type I collagen.similarities to the cell binding sites of Type I collagen. Promotes binding of fibroblasts to anorganic bovine Promotes binding of fibroblasts to anorganic bovine

bone mineral.bone mineral. Enhanced expression of alkaline phosphatase.Enhanced expression of alkaline phosphatase. Increased nucleic acid and protein synthesis.Increased nucleic acid and protein synthesis. Though can be used in combination with Though can be used in combination with

DFDBA,FDBA and Alloplasts, it shows rapid DFDBA,FDBA and Alloplasts, it shows rapid attachment to xenogeneic grafts.attachment to xenogeneic grafts.

Vitronectin and fibronectinVitronectin and fibronectin

SYNTHETIC BONE SUBSTITUTES SYNTHETIC BONE SUBSTITUTES – SAFEST BET?– SAFEST BET?

Porous hydroxyapatitePorous hydroxyapatite

Nonporous hydroxyapatiteNonporous hydroxyapatite

Tricalcium phosphateTricalcium phosphate

HTR polymerHTR polymer

PLA-PGAPLA-PGA

Bioactive glasses.Bioactive glasses.

Porous hydroxyapatitePorous hydroxyapatite

Uniform pore size, facilitates vascular ingrowth and Uniform pore size, facilitates vascular ingrowth and subsequent new bone growth.subsequent new bone growth.

250 – 45- um in size.250 – 45- um in size. Easy to handle.Easy to handle. Resorbs over a period of 12 months.Resorbs over a period of 12 months. Quite predictable results.Quite predictable results. SEM shows the presence of spreading osteoblasts SEM shows the presence of spreading osteoblasts

and newly formed bone (Krejci 1987).and newly formed bone (Krejci 1987).

Non-porous hydroxyapatiteNon-porous hydroxyapatite

Resorbs slowly.Resorbs slowly. Does not get replaced by new bone.Does not get replaced by new bone. Increased chances of fibrous encapsulation.Increased chances of fibrous encapsulation. Minimal pore size hence does not facilitate vascular Minimal pore size hence does not facilitate vascular

ingrowth and fibroblast proliferation.ingrowth and fibroblast proliferation. However, some studies have shown better results However, some studies have shown better results

with nonporous hydroxyapatite (Yukna 1989).with nonporous hydroxyapatite (Yukna 1989).

β - β - Tri Calcium PhosphateTri Calcium Phosphate

Calcium : phosphate = 1.5, Calcium : phosphate = 1.5, β - whitlockiteβ - whitlockite

Thought to stimulate bone formationThought to stimulate bone formation

Proved superior to hydroxyapatite in numerous studies Proved superior to hydroxyapatite in numerous studies

(Fetner 1994)(Fetner 1994)

But lesser than bioactive glass (Wilson and Low 1992).But lesser than bioactive glass (Wilson and Low 1992).

Excellent property..Excellent property..

HTR POLYMER- or is it?HTR POLYMER- or is it?

Non resorbable, microporous biocompatible Non resorbable, microporous biocompatible composite of poly-methylmethacrylate (PMMA) and composite of poly-methylmethacrylate (PMMA) and polyhydroxyethylmethacrylate (PHEMA).polyhydroxyethylmethacrylate (PHEMA).

550- 880 um with a pore size of 50 – 300 um form 550- 880 um with a pore size of 50 – 300 um form the core of the material.the core of the material.

No inflamm reaction.No inflamm reaction. The beads are then coated with Ca(OH)2/CaCO3, The beads are then coated with Ca(OH)2/CaCO3,

which comes in contact and forms new bonewhich comes in contact and forms new bone

Provided in a fine, granular form.Provided in a fine, granular form. Stahl et al (1990) reported bone in-fills of upto Stahl et al (1990) reported bone in-fills of upto

60%60% Limited handling characteristicsLimited handling characteristics

HTR POLYMER – contd..HTR POLYMER – contd..

Bio-Active GlassesBio-Active Glasses

Used widely in treatment of periodontal defects Used widely in treatment of periodontal defects

develop a layer of hydroxy–carbonate –apatite on develop a layer of hydroxy–carbonate –apatite on

their surface following exposure to body fluids.their surface following exposure to body fluids.

Incorporates collagen fibers into it.Incorporates collagen fibers into it.

SiO2 – CaO – Na2O – P2O5SiO2 – CaO – Na2O – P2O5

Bio Glasses..contdBio Glasses..contd

Flexural strength, fracture toughness less than Flexural strength, fracture toughness less than

bone. Elastic modulus is more than bonebone. Elastic modulus is more than bone

Hench and Wilson 1984, Hench and West Hench and Wilson 1984, Hench and West

1996.1996.

Theory of BioactivityTheory of Bioactivity

Bioactive indexBioactive index

Highly bioactive glasses show both osteoproduction Highly bioactive glasses show both osteoproduction

and osteoconduction, while low bioactive glasses and osteoconduction, while low bioactive glasses

show only osteoconduction.show only osteoconduction.

Osteoproduction – defined as the process in which the Osteoproduction – defined as the process in which the

bio-active surface is colonized by osteogenic stem bio-active surface is colonized by osteogenic stem

cells from the adjacent bone.cells from the adjacent bone.

Wilson 1994 showed that highly bioactive Wilson 1994 showed that highly bioactive 45S5 Bioglass produced more bone than 45S5 Bioglass produced more bone than autogenous bone.autogenous bone.

Two classes of bioactive materials; Classes A Two classes of bioactive materials; Classes A and B.and B.

Class A – osteoproduction and Class B – Class A – osteoproduction and Class B – osteoconduction.osteoconduction.

Class A = produces both extra and Class A = produces both extra and intracellular responses.intracellular responses.

Class B = produces only extracellular Class B = produces only extracellular response.response.

Class AClass A

Release soluble silicon in the form of silicic acid Release soluble silicon in the form of silicic acid

due to surface ion exchange with H+ and H3O+ on due to surface ion exchange with H+ and H3O+ on

contact with body fluids.contact with body fluids.

The conc of silicon in solution keeps on increasing The conc of silicon in solution keeps on increasing

and is finally precipitated forming complex silicate and is finally precipitated forming complex silicate

phasesphases

Intracellular response is by the release of Intracellular response is by the release of siliconsilicon

Extracellular effect is by the chemabsorption Extracellular effect is by the chemabsorption of of bone growth promoting factors such as of of bone growth promoting factors such as TGF-TGF-β on their surface.β on their surface.

Class AClass A

Class BClass B Very low or zero ion exchangeVery low or zero ion exchange Release very low amounts or zero amounts of Release very low amounts or zero amounts of

silicon.silicon.

Role of SiliconRole of Silicon

The released silicon is chemically combined with The released silicon is chemically combined with

glycosaminoglycan – protein complexes, which glycosaminoglycan – protein complexes, which

surround collagen and elastic fibrils and cover the surround collagen and elastic fibrils and cover the

surface of cells (Carlisle 1986).surface of cells (Carlisle 1986).

Potent mitogen for osteoblasts (Keeting 1992), Potent mitogen for osteoblasts (Keeting 1992),

increases the mitotic rate of osteoblasts by 3 fold.increases the mitotic rate of osteoblasts by 3 fold.

• Enhances the rate and amount of release of alkaline phosphatase from these cells.

• Enhances the release of osteocalcin (Possibly an autocrine response).

• Accelerates the precipitation of amorphous calcium phosphate within the pores of the silica gel layer..heterogenous nucleation mechanism

Role of Silicon..contd

• Class A glasses show development of cyrystalline hydroxy-carbonite-apatite layer within a few hours whereas Class B glasses may take weeks.

Role of Silicon..contd

Bioglass Reaction Layers

Bulk Bioglass Bulk BioglassSilica Rich Layer

Bulk BioglassSilica Rich Layer

HCA

Bulk BioglassSilica Rich Layer

HCACollagen & Proteins

Anti-Microbial Results

• Staphylococcus aureus - 105 reduction• Pseudomonas aeruginosa - 104 reduction• Aspergillus niger - 105 reduction• Candida albicans - 106 reduction• Escherichia coli - 104 reduction

• effects remain from 2 to 5 days in culture

• Procedure – Solid Bioglass

samples cultured with dilute Type I bone collagen in TRIS buffer - 37oC

• Results - 24 hours– Calcium phosphate

nodules formation– Proteins observed

attached to surface

In Vitro Development of Bonding Surface Layer

• Results - 7 days– Calcium phosphate

nodules cover entire surface

– Calcification of entrapped collagen fibers observed

– Large increase in surface area

BioGlass and Hemostasis

• PerioGlas has been shown to be hemostatic, decreasing clotting time in lab tests by 25% when compared to controls. (Lee and White 2003)

• While the actual origin of this affect has not yet being ascertained, two potential causes are the development of a positive surface charge that forms on the Bioglass after implantation and the release of calcium ions during material dissolution

Advantages - Ease of Use

Mixed with blood Mixed with cortico-cancellous chips

Summary

• Particles bind to collagen release of silicon

laid down prevents epithelial downgrowth

faster rate of bone and cementum formation.

Cementum Stimulants – Emdogain DEVELOPMENT REVISITED!!• Dental papilla• Dental follicle, HERS• Disruption..• Cementogenesis???• Concept of enamel matrix proteins• Role of enamel matrix proteins

EMDs..contd

• Amelogenins = 90%• Proline rich non-amelogenins , tuft proteins,

tuftelin, serum proteins and atleast one salivary protein = 10%.

• DNA Sequencing = ameloblastin (Krebsbach 1996) and amelin (Cerny 1996).

• 3 vehicles were tested for EMD , PGA, Hydroxyethyl cellulose and dextran and Hammarstrom (1997) showed that PGA in combination with the amelogenin fraction resulted in significant regeneration.

• PGA also shows antibacterial action against P.Gingivalis

EMDs..contd

Mode of Action

• The EMD in PGA adsorbs to hydroxyapatite and

forms spherical insoluble complexes and remains for

2 weeks.

• It promotes the repopulation of root surface by

fibroblast-like cells.

• Forms mineral nodules on root surface.

Availability

• Powder form or gel form

• Comes with EDTA as a root conditioner prior to application

• Can itself be used as root conditioner.

• Variety of clinical applications..

• The AEFC formed helps in formation of new pdl and alv bone.

Composite Grafts

• β -TCP + HA

• FDBA + DFDBA

• Allograft + Autograft

• Glasses + autograft

Summary of Osseous Grafts

• Predictability

• Limitations – handling & retention

- resorption

- regeneration

GUIDED TISSUE

REGENERATION

- Current Concepts

Introduction

• Importance of selective cell repopulation

• Need for excluding gingival epi and conn tissue cells.

• Nyman 1982

• Act as barrier..also called barrier membranes

• Principles of GTR

• Indications and contra-indications of GTR.

• Clinical procedure

• Pros and cons of resorbable and absorbable

membranes

• Non-resorbable membranes.

• AAP 1992- term used to define procedures wherein

regeneration of lost periodontal structures is sought

via selective cell and tissue repopulation of the

periodontal wound

• 1996 WWP – procedures attempting to regenerate

lost periodontal structures through differential tissue

responses.

• Type of periodontal tissue formed is determined

by the cells attached to the root surface.

• PDL cells primarily important (Gottlow 1984)

INDICATIONS

• PATIENT SELECTION

• SMOKING

• NARROW 2 OR 3 WALL DEFECTS

• CLASS II FURCATION WITH MEDIUM TO

LONG ROOT TRUNK

• RIDGE AUGMENTATION

• ROOT COVERAGE

• REPAIR OF APICOECTOMY DEFECTS

• AILING/FAILING IMPLANTS

INDICATIONS-contd..

CONTRAINDICATIONS

• GENERALIZED HORIZONTAL BONE LOSS

• CLASS III FURCATION, MESIAL AND DISTAL

FURCATION

• ADVANCED DEFECTS WITH MINIMAL

PERIODONTIUM

• MULTIPLE ADJACENT DEFECTS

• INADEQUATE ATTACHED GINGIVA

• ADVANCED MOBILITY OF TEETH

CONTRAINDICATIONS-contd..

FACTORS AFFECTING

OUTCOME OF GTR

PROCEDURES

(Causes of Failure)

Barrier-Independent Factors

• Poor plaque control

• Smoking

• Occlusal trauma

• Sub optimal tissue health (I.e. Inflammation persists)

• Mechanical habits (e.g.. Aggressive tooth brushing)

Overlying gingival tissue– Inadequate zone of keratinized tissues.– Inadequate tissue thicknesssurgical technique- improper incision- Traumatic flap elevation and management- Excessive surgical time- Inadequate closure or suturing

Barrier-Independent Factors-contd..

• Post surgical factors- premature tissue challenge

* Plaque recolonization* Mechanical insult

- Loss of wound stability (loose sutures, loss of fibrin clot).

Barrier-Independent Factors-contd..

Barrier – Dependent Factors

• Inadequate root adaptation (absence of barrier effect)

• Non sterile technique

• Instability (movement) of barrier against root.

• Premature exposure of barrier to oral environment

and microbes.

• Premature loss or degradation of barrier.

Nonresorbable membranes

• Preoperative considerations; 3 factors

- adequate gingiva to cover the barrier.

- cervical enamel projections, narrow furcal

openings.

- surgical access.

• Predictability

- degree of destruction

- compliance

- technique sensitive, requiring excellent

surgical skills

Nonresorbable membranes

• PTFE (Teflon, dense or full body PTFE)

• e-PTFE (expanded PTFE).

• Older ones; millipore filters, ultrathin semipermeable silicone barrier.

• Sterilized rubber dam.

• e- PTFE considered gold standard, but now we are moving back to the full bodied, dense PTFE.

Nonresorbable membranes

E-PTFE

• Concept of e-PTFE, microporosities

• Prob assoc with e-PTFE (Fleszor 1990)

• Importance of primary closure.

• Titanium reinforcement

Barrier placement

• Trimmed with scissors

• 3mm overlap of bone in all directions.

• Remove sharp corners to prevent flap perforation

• Interproximal barriers require special handling as

they need to be folded and passed in the

interproximal area.

Membrane stabilization

• Titanium screws (can give ‘tent effect’).• Bone tacks• Sutures; e-PTFE sutures are of choice,

biocompatible,strongdoes not wick.

Sling sutures are reliableInterproximal membranes need not be sutured.

Postoperative care

Resorbable membranes

• Desirable properties of resorbable membranes1. Nontoxic,nonantigenic.2. Acceptable handling props;

- malleable - preserves and maintains space.

- conforms to defect shape.- ability to customize for unique situations

Desirable properties of resorbable membranes – contd..

3. Adherence to or ability to approximate root

surfaces.

4. Promotes tissue coverage and reduces barrier

exposure rates.

5. Promotes flap attachment after surgery.

Desirable properties of resorbable membranes

6. Resists bacterial seeding and contamination.

7. Promotes selective cell repopulation.

8. Absorbs/resorbs at a rate parallel to regenerative

tissue formation.

Collagen Membranes

• Initially used as a gel or matrix to fill or cover

periodontal defects.

• 1987, Yaffe and Shoshan, application of collagen

prevented epi downgrowth.

• Blumenthal 1993, reported the successful formation of

pdl, cementum and alv bone with collagen

• Usually type I collagen is preferred derived from various sources; bovine or porcine, tendon or dermis.

• Made by extrusion-coagulation and air-drying to form sheets of material from dilute collagen (1%) solutions.

• Resorbed within 20-21 days; insufficient callus formation.

• Need to extend the resorption time

Collagen Membranes

Cross-Linking

• Increases the resorption time

• Also reduces the antigenicity.

• Physical;

gamma or ultraviolet radiation or

• Chemical;

formaldehyde

processing methods

• Minabe 1989 increased regeneration with cross-linked than non-crosslinked collagen.

• Brunel 1996 reported increased bone even in GBR procedures.

• Helps in preventing the epi. downgrowth

Cross-Linking – contd..

Important properties of collagen

• Natural component of tissues; well tolerated.

• Weak immunogen; favorable tissue response.

• Malleable – shaped and manipulated.

• Semipermeable to nutrients and gases.

• Possesses hemostatic properties through its ability to

aggregate platelets.

• Supports cell proliferation via lattice structure and cell binding domains.

• Facilitates early wound healing and stabilization.• Substrate for attachment of cells.• Chemotactic for fibroblasts.• Promotes cell migration;potential to reduce barrier

exposure.• Absorbed naturally;replace by host tissues, increases

the bulk of tissue.

Important properties of collagen

Collagen Resorption

• Starts with action of collagenase, splitting the molecule at several sites.

• The resultant fragments become temp sensitive

• Denatures at 37 C to gelatin.• Gelatinases and other proteinases degrade

gelatin to oligopeptides and amino acids.

Disadvantages

• Reduced strength

• Reduced space maintaining ability

• Difficult to manipulate in vivo.

• Gets resorbed by 48 days; cannot be used when

large increases in ridge height or width are desired.

• Difficult to suture the membrane.

Recent advances – New Improved!!

• Tendon derived collagen has been extensively studied and shows the weakest immunologic reaction.

• Incorporation of antibiotics into collagen membranes improves the effect;

• Incorporation of tetracycline decreases the degradation of collagen membrane (Chin Jin 2003)

• Addition of metronidazole and amoxicillin have been

tried out with clinically beneficial results.

• Myrand (1985) found reduced amounts of

P.gingivalis, B. melaninogenicus in sites treated with

collagen membrane impregnated with antibiotics.

Material name

Company Source Crosslink Components

Biomend Sulzer, CA Bovine tendon Formaldehyde 100% type I

Periogen Collagen Inc,CA Bovine dermis Glutaraldehyde Type I and III

Paroguide Coletica, France Calfskin DPPA 96% type I + 4% chondroitin

sulfateBiostite Coletica, France Calfskin DPPA Collagen plus

hydroxyapatiteBiogide Geistlich,

SwitzerlandPorcine dermis DPPA Types I and III

Tissue guide Koken, Japan Bovine dermis+tendon

HMDIC Atelocollagen plus tendon

collagen

SX-COL Dr. Pitaru (Israel)

Rat tail tendon Not treated 100% type I

Absorbable membranes –Viable alternative?

• Primarily degradable polymers.

• Synthesized by co polymerization of different forms

of PLA,PGA or mixtures of PLA and PGA.

• PLA increases the strength of the membrane

• PGA improves the handling properties of the

material

PLA-PGA Polymers

• Degradation of PLA PGA polymers occurs by

hydrolysis of ester bonds,

• Initiation of degradation depends upon.. 30 to 60 days

depending upon the composition of the polymer.

• Available membranes include; Guidor, Vicryl,

Atrisorb, Resolut and EpiGuide

Membrane Company Components

Guidor Butler Co, Chicago PLA & acetyltributyl citrate

Vicryl Ethicon Lab, NJ PLA/PGA

Atrisorb Atrix Labs,Collins,CO PLA/PGA

Resolut W.L.Gore, Flagstaff, AZ

PLA/PGA

Epiguide THM Biomedical,MN PLA (D,L forms)

Biofix Bioscience,Finland PGA

GUIDOR

• Hydrophobic barrier – PLA with citric acid ester

softening agent.

• Bilayered; external layer (facing gingival tissue) with

rectangular perforations (400-500/cm2).

• Internal layer with smaller circular perforations

(4000-5000/cm2).

• Available with attached suture at the collar.

• Designed to resist degradation for 3 months.

• Gradually replaced by newly regenerated periodontal tissue.

• Gottlow –1993- comparable with e-PTFE

• Gottlow 1994 and Rocusso 1996 also used in the coverage of denuded roots,augmentation of alveolar ridges and regeneration of implant related osseous defects.

GUIDOR

VICRYL

• Periodontal mesh (Polyglactin 910), copolymer of

glycolide and lactide used in sutures.

• Available as woven or knitted mesh

• Larger pore size with better handling properties.

• Degrades over 3-12 weeks.

Supporting Studies

• Moon 1996 – better than flap debridement.

• Caton 1994 – useful in furcations.

• Sander 1995 – comparable to e-PTFE.

• Moon 1997 – composite treatment is not more

effective than vicryl alone.

ATRISORB• Polymer of lactic acid, poly (D,L-lactide), dissolved in

N-methyl-2-pyrrolidone (NMP).

• Prepared as a solution that sets to firm consistency on contact with water or other aqueous solutions.

• Can be trimmed and adapted to the defect.

• Solidifies completely within the fluids of the periodontal environment, obviating the need for suturing.

• Difficult to use in interproximal defects as the

flexible, semisolid nature makes it difficult to pass

through intact contact point.

• Membrane applied from both sided and bonded in

between in situ.

• Difficult in surgical field.

ATRISORB..contd

Supporting studies

• Polson 1995 – useful in intrabony defects.

• Bogle 1997 – 71% defect regeneration in class II

furcation defects.b

• Garrett 1997 – reduced incidence of postoperative

suppuration and abscess formation

RESOLUT

• Copolymer of PLA and PGA.

• Degrades over a period of 4 weeks to 8 months.

• Comparable to e-PTFE (Lindhe 1995).

• Useful in class II furcations, 2 wall defects

• Resolut-XT – titanium reinforced, more strength

and structural stability (ridge augmentation).

Epi-Guide

• Hydrophilic membrane from PLA (L,D forms).

• Flexible open cell structure; thought to encourage

uptake of fluid blood and adherence to tooth

surface.

• Internal void spaces (sponsor blood clot formation.

• Vernino 1995 - effective

Degradation of PLA-PGA

• Enzymes in Kreb’s cycle• Whether change in pH occurs is not clear but

insignificant• PLA degradation: 2 stages;• 1st; random non-enzymatic cleavage of the

polymer,• 2nd, loss of mechanical strength and weight

• Degradation releases lactic acid,

metabolized in liver CO2 and water

Degradation of PLA-PGA..contd

Material Company Components

Periosteum - Collagen

Connective tissue graft

- Collagen

Freezedried duramater

Miami tissue Bank Collagen

Alloderm Dentsply, CA Acellular dermal matrix

Lambone Pacific coast, LA DFDB sheet/plate

Grafton Osteotech, NJ Allograft gel

Cementum impregnated

gelatin

Nishimura (Japan) Cementum particles + gelatine gel

Material Company Components

Emdogain Biora Inc, IL Enamel matrix proteins

Surgicel Johnson &Johnson, NJ Oxidized cellulose

Gelform Upjohn Pharma, MI Cellulose

Gengiflex Biofill products, Brazil Alkali cellulose

Capset Lifecore, Brazil POP

Hapset Lifecore, Brazil POP + HA

Cargile memb Ethicon, NJ Cecum of ox

Elastin fibrin matrix

Etikpatch, France Elastin, fibrin, type I collagen and fibronectin

Advantages of resorbable barriers over non resorbable barriers

• Elimination of 2nd stage surgery may

1. Reduce operator time

2. Reduce costs

3. Reduce treatment morbidity

4. Inc patient compliance

5. Reduced risk of loss of regenerated attachment

• Biologically resorbable membranes hold potential to:

1. More tissue-friendly

2. Integrate with host tissue.

3. Enhance tissue coverage.

4. Reduce barrier exposure.

5. Resist or reduce microbial colonization.

Advantages of resorbable barriers over non resorbable barriers – contd..

COMBINED REGENERATIVE PROCEDURES

• Mostly used in resorbable and absorbable

membranes.

• Similar or greater results.

• Controversial..

Summary of GTR materials

• Patient selection and compliance

• Criteria for selecting membranes determined by the

type of defect, vascularity and severity of destruction.

In retrospect, are we in the right

direction????

GROWTH FACTORS –

REGENERATION REVISITED!!

• 6 tissue types must be restored for regeneration; ging

epi, ging conn tissue, pdl, cementum, alv bone and

surrounding vasculature.

• Growth factors – general term used to denote a class of

naturally occurring proteins that function in the body to

promote the mitogenesis (proliferation), directed

migration and matrix synthesis (3M).

• For growth factor to help in regeneration, it must play

a role in mineralized and non mineralized tissues

Various growth factors and their origin

Growth factor

Major source at wound site

PDGF Platelets, macrophages,endothelial cells

TGF – B Platelets, macrophages,osteoblastsEGF/TGF–A Platelets, macrophages,epi cells, eosinophils

IGF-1 Plasma, epi cells, fibroblasts, bone matrixbFGF Macrophages, endo cells, osteoblasts

PDGF – The key factor!

• Chemotactic for neutrophils, macrophages and osteoblasts

• Helps in angiogenesis (neovascularization).• Substantially increases the mitotic rate of

differentiated osteoblasts.• Faster mineralization of bone matrix.• Inc collagen synthesis; helps in pdl

formation.

• Acts synergistically with IGF-1, bFGF, TGF-B.

• Helps in re-epithelialization.• Induces receptor on the surfaces of these

cells and stimulates the cell by signal transduction.

• Depending on enviroment, it can also stimulate bone resorption (Cochran 1991)

PDGF – The key factor!

IGF-1

• Present in plasma

• Helps in bone mineralization and collagen synthesis.

• Acts synergistically with PDGF.

• Also acts on endothelial cells.

• bFGF helps in soft tissue matrix formation. Known to form periodontal ligament consistently.

Platelet Rich Plasma

• Nomenclature..concentration

• Growth factor enhancement for regeneration.

• Extensive research

• Realize the synergistic role of growth factors.

• No one factor is individually responsible..

• Can be used with bone grafts, under a membrane or as a membrane per se..

• Availability..• Techniques of procurement..• Safety..• Storage..• Thrombin..

Platelet Rich Plasma – clinical application

• Ratio of mixing

• Lynch et al 1991, Rutherford 1992, Lynch 1989, Niekrash 1992, Terranova 1986, Robert Marx 1998, Lekovic 2002,2003, Camargo 2002, Shanaman 1995, Cortellini 2002, Moon Cho 1996, etc…

Platelet Rich Plasma-Studies

SUMMARY &

CONCLUSION

REFERENCES• Clinical Periodontology – Carranza 6th, 8th and 9 th

edition.• Clinical Periodontology and Implant Dentistry – Jan

Lindhe• Outline of periodontics – Manson and Eley 4th

Edition• Periodontal Regeneration – Alan Polson• Connective tissues of the periodontium – Perio

2000;1999.• DCNA 1988: Advances in Periodontics – II• European Workshop – Regenerative Materials.

• Tissue engineering – Samuel Lynch• Enamel matrix, Cementum and Regenration; JCP

1997 – Hammarstrom• Role of PGA – JCP 1997.• Collagen binding peptide (P-15) in bone grafts; JP• Comparison of FDBA and DFDBA; JCP 1989• Collagen Membranes: A Review; JP• Gene therapy for BMPs in periodontal defects; JP

2003;1:

REFERENCES – contd..

COMBINATION OF THERAPIES

DEFINITELY IS MORE PREDICTABLE!!