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Flexible resin denture presentation power point
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By
Ahmed Mostafa Hussein
Assisstant lecturer
Dental Biomaterial Department
Faculty of Dentistry, Mansoura University
2013
FLEXIBLE DENTURE
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Disadvantages of cast RPD
Disadvantages of conventional rigid acrylic RPD
(PMMA 1930)
Advantages of nylon flexible denture (1955)
Disadvantages of nylon flexible denture
Controversial and/or need more research
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Indications of nylon flexible denture
Contraindications of nylon flexible denture
Main composition
Manipulation
Commercial products
Uses of thermoplastic resins
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Disadvantages of cast RPD
1 .Expensive
2 .Need high skill in preparation
3 .Time consuming mouth preparation
4 .Technique-sensitive casting
5 .More difficult
6 .Visibility of metal clasp
7 .Heavy weight
8 .Brittle
9 .Difficult in relining & repairing
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Disadvantages of conventional rigid acrylic RPD
(PMMA 1930)
1 .Brittleness of PMMA, so frequent fracture occurs.
2 .Allergy to MMA monomer
3 .High porosity
4 .Irritation of mucosa
5 .Foul smell
6 .Difficult to insert in undercut areas
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7 .High water sorption
8 .Dimensional changes and polymerization shrinkage
9. There are many factors in the laboratory procedure
that can lead to alteration of denture occlusion and
results in significant increase in vertical dimension
after processing.
10. Denture wearers use dentures adhesive which
causes its own problems.
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VALPLAST FLEXIBLE DENTURE BASE
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Advantages of nylon flexible denture (1955)
1 .Soft and inherent flexibility:
Ability to engage undercuts for retention.
No need for periodic adjustment of clasp to
keep them tight.
Low modulus of elasticity
2 .Will not warp or become brittle.
3 .clinically unbreakable.
4 .Good biocompatibility: because it is free of
monomer and metal.
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5 .No porosity, so no bacteria can build up within it!!??.
6 .No gingival inflammation
7. More comfortable
8. Absorb small amounts of water to make the denture
more soft and tissue compatible.
9. Less bulky (thinner) and lighter weight
10 .Better chewing efficiency
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11 .Better esthetics: Translucent, so it allows natural gum to show through, making it invisible. Clasps rest on the gums surrounding the natural teeth. They are indistinguishable from the gums. No metal framework
12 .More retention and stability
13 .Retention depends mainly on the tissue and only a small portion of abutment tooth. No evidence of
excessive abutment mobility
14 .Ease of fabrication (in comparison with cast RPD)
15 .Reduces chair side time (shorter fabrication time)
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Disadvantages of nylon flexible denture
1.Intended only for provisional or temporary
applications.
Flexible dentures are generally only used when
traditional dentures cause discomfort to the patient
and cannot be solved through relining.
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2. A major drawback is de-bonding of the acrylic teeth
from nylon denture base. Nylon polyamide denture
base material does not bond chemically with acrylic
resin/porcelain, so mechanical undercuts (diatorics)
are made in each tooth. It cannot be used with
patients having low vertical dimension and closed
bite.
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3.Tend to absorb the water content and will discolor often.
4.Discoloration and gradual fading of denture base color are reported after 1-2 years !!?? .
5.High surface roughness. This may lead to bacterial and fungal colonization. ??!!N.B: Brushing a Valplast appliance is not recommended as this may remove the polish and roughen the surface over time.
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6.The procedure is technique sensitive. Extreme
caution is necessary when processing to avoid
skin contact with the heated sleeve, cartridge,
furnace, hot cartridge, injection insert, hot flasks
and heat lamps.
7.Difficult to adjust and polish.
8.When grinding this prosthesis, proper ventilation,
masks and vacuum systems should be used.
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9.Lower hardness
10.Lacks important elements of RPD, in particular,
occlusal rests and a rigid framework, So it won't
maintain vertical dimension. It is contraindicated for
unilateral distal extension.
11.Usually cannot be relined, so stability is a concern if
the alveolar ridge resorbs.
Usually cannot be repaired .
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Controversial and/or need more research
اّد�عاء – : Claimed to have.1يّد�عى
High creep resistance, fatigue endurance, wear characteristics, dimensional stability and solvent resistance. N.B: Injection moulded denture base material has better accuracy than compression moulded PMMA
2 .Bacterial and fungal colonization: Although it has no porosity, it has high surface roughness.
3 .Color stability
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Indications of nylon flexible denture
1.Bilateral undercuts
2.Allergy to acrylic resin
3.Patients who do not want a fixed restoration and metal clasps.
4.No enough bone for fitting dental implant
5.Bruxism
6.Patients with compromised neuro-motor function
7.Single denture
8.Obturators
9.Rehabilitating the anomalies such as ectodermal dysplasia.
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Contraindications of nylon flexible denture
1 .Unilateral distal extension
2 .Low vertical dimension and closed bite
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Nylon flexible denture Conventional rigid acrylic denture
Not brittleClinically unbreakable
Brittleness of PMMA, so frequent fracture occurs
Good biocompatibility: because it is free of monomer and metal
Allergy to MMA monomer
More comfortable, not irritant to mucosa
Irritation of mucosa
Soft and inherent flexibilityAbility to engage undercuts for retention
RigidDifficult to insert in undercut areas
Better esthetics, esthetic clasp Less esthetics, metal claspShorter fabrication time Longer fabricaion time
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Nylon flexible denture Conventional rigid acrylic denture
Temporary only PermanentMechanical retention between acrylic teeth and nylon denture.De-bonding is a major disadvantage.
Chemical bond between acrylic teeth and acrylic denture
Lower hardness Higher hardnessHigh surface roughness.Brushing increases surface roughnessUsually cannot be relined and repaired
Can be relined and repaired
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Main composition
Polyamide nylon thermoplastic material
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Manipulation
Injection molding technique:
It is highly sensitive to the position and size of sprue
placement.
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1. Investing in a special flask (e.g valplast flask) and spruing.
Sprue designing: For complete maxillary dentures, sufficient width sprue is attached to the posterior border of the denture with an extension over the palate area to allow adequate flow of the material throughout the palate area.
For partial dentures and mandibular complete dentures, the sprue is attached to both lingual extensions as well as in the midline.
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2.Wax elimination by boiling.
3. Undercuts (diatorics) are made (prepared) in the centre of each tooth so that the melted fluid polyamide will flow into the undercuts for mechanical retention.
After preparation, each tooth is cemented back into its place in the top half of the flask with valcement (cement provided with the valplast system).
N.B. Cyanoacrylate is contraindicated, because it bonds permanently with the teeth surface.
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4. Thermoplastic nylon is melted at temperatures from 274 to 302°C for 11 min before injection.
The opened flask is placed directly in a pre-heated oven maintained at 65-80°C. Furnace timer was set for 17 minutes.
The flasks halves are assembled with brackets and together with the cartridge containing melted nylon; they are placed on to the injection unit. The injection molding pressure is maintained at 5 bars for 1 min. The dental flask is bench-cooled before deflasking.
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FLEXIBLE DENTURE INJECTION SYSTEM
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INJECTION CASTING PROCEDURE
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FLEXIBLE DENTURE RETRIEVED
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Commercial products
Valplast, Flexiplast, Duraflex, Impak, Lucitone FRS,
Flexite, Flexite M.P., Flexite Plus, Sunflex and Proflex.
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1.Valplast (Valplast Int. Corp. - USA)
Nylon polyamide thermoplastic.
Light weight
Monomer free
2.Flexiplast (Bredent - Germay)
Nylon polyamide
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3.Lucitone FRS (DENTSPLY Trubyte, New York, PA, USA)
Nylon linear polyamide
Monomer free
4.Flexite
Thermoplastic fluoropolymer (Teflon) 1962
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5.Flexite M.P.
Thermoplastic acrylic, a special blend of polymers .
Highest impact rating of any acrylic.
Flexible
Can be relined and repaired.
Easy to adjust and repair.
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6.Flexite Plus
Nylon polamide thermoplastic material
Monomer free
Impervious to oral fluids
May be combined with a metal framework to
eliminate the display of metal labial clasps .
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7.Sunflex
Nylon thermoplastic
Tissue-colored clasps
More stain-resistant than other flexible acrylics.
Can be relined & repaired.
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8.Pro-flex
Full and partial flexible denture since 1998.
Can be repaired.
Can be relined using Pro-flex soft liner material.
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Uses of thermoplastic resins
1.Flexible RPD
2.Tooth colored clasps
3.Preformed RPD clasps
4.Flexite-metal combination
5.Obturators
6.Impression tray
7.Provisional crowns and bridges
8.Orthodontic brackets
9.TMJ’s, bruxism & anti-snoring devices
10.Sports mouth guards
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Comparison between:
Acrylic soft liner (soft acrylic resin e.g Vertex)
Nylon flexible denture (e.g Valplast)
FOR RESEARCH
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الله ) رسول وسلم قال عليه الله (صلى :
نافعا لما ع* الله لوا س+
ينفع ال ع*لم من بالله تعو�ذوا و
الجامع : صحيح ، حسن 3635إسناّده
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References
Kaira LS, Dayakara HR, Singh R. Flexible denture for
partially edentulous arches – A case report.
www.journalofdentofacialsciences.com 2012; 1: 39–42.
Arafa KA. Evaluation the physical properties between
flexible, cold-cued and hard heat-cured acrylic resin (in
vitro study). Life Sci J 2012; 9: 1707–10.
Gladstone S, Sudeep S, Arum Kumar G. An evaluation
of the hardness of flexible denture base resins: original
study. Health Sci 2012; 1: 1–8.
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Ito M, Miyamoto T, Kawai Y. The combination of a nylon
and traditional partial removable dental prosthesis for
improved esthetics: a clinical report. J Prosthet Dent
2013; 109: 5–8.
Hundal CM, Madan BR. Comparative clinical evaluation
of removable partial dentures made of two different
materials in Kennedy Applegate class II partially
edentulous situation. MJAFI 2012; 1–7.
Yavuz T, Aykent F. Temporary flexible removable partial
denture: a clinical report. Clinical Dentistry and
Research 2012; 36: 41–4.
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Singh JP, Dhiman RK, Bedi RPS, Girish SH. Flexible
denture base material: a viable alternative to
conventional acrylic denture base material. Contemp
Clin Dent 2011; 2: 313–7.
Dhiman CR, Chowdhury LCSR. Midline fractures in
single maxillary complete acrylic vs flexible dentures:
original article. MJAFI 2009; 65: 141–5.
Negrutiu M, Sinescu C, Romanu M, Pop D, Lakatos S.
Thermoplastic resins for flexible framework removable
partial dentures: review articles. TMJ 2005; 55: 295–9.
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Shamnur SN, Jagadeesh KN, Kalavathi SD, Kashinath
KR. Flexible dentures – an alternate for rigid dentures.
Journal of Dental Sciences & Research; 1: 74–9.