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Direct Polymeric Restorative Materials

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Presentation on theme: "Direct Polymeric Restorative Materials"— Presentation transcript:

1 Direct Polymeric Restorative Materials
DHYG 113 Restorative Dentistry I

2 Objectives Discuss properties of restorative resins: polymerization shrinkage, coefficient of thermal expansion, and abrasion resistance Summarize filler particle, matrix, and the coupling agent of a composite restorative material Explain proper eye protection when using light-cured materials Explain the meaning of ‘addition’ in addition polymerization Describe : depth of cure, addition of material in increments, inhibition by air, unreacted C=C bonds, shades, shortcomings of the matrix Explain the fillers found in dental composites: composition, size, amount, abrasion resistance, refractive index, clinical detection

3 Explain the difference between flowable and condensable composites
Discuss the role of the dental hygienist in the placement and maintenance of pit and fissure sealants Discuss the use of a primer with pit and fissure sealants Describe preventive resin restoration and composite cements Assess the positive and negative characteristics of light-cure and chemical-cure glass ionomer cements Discuss similarities between compomers, glass ionomers, and composites

4 Monomers Functional group participates in polymerization (chemical) reaction Carbon-Carbon double bond (C=C) Free Radical – unpaired electron Addition polymerization – one monomer at a time is added to the chain Initiation – first step (formation of free radical) Heat activated -- Light activated Chemically activated -- Dual cure materials

5 Resin Shrinkage

6 Thermoplastic – can be heated and shaped
Propagation Second step in addition polymerization Termination Free radicals at ends of chain react (stops process) Exothermic reaction Releases heat Thermoplastic – can be heated and shaped Thermoset polymers – most dental resins

7 Working Time Polymerization can happen quickly
Reaction must occur when desired Light cured material Delayed with inhibitor for chemical-cured Hydroquinone (ex.) destroys first free radicals Without delay, the material would set up too fast

8 Shelf Life Liquid components of acrylic resins are almost entirely monomers Free radical could polymerize entire container Manufacturers add inhibitor to monomer materials to prevent them from becoming a solid mass

9 Problems with Resins Polymerization shrinkage
Coefficient of Thermal Expansion High (can be 2-10 times greater than tooth) Problem with percolation Lack strength & abrasion resistance

10 De-bonding Once desiccated, the de-bonding becomes very apparent
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

11 Color Hue – dominant color of the object
Red, blue, yellow (teeth are yellow to yellow-red) Value – refers to lightness of a color Scale of 1 – 10 (1=black, 10=white) Chroma – refers to intensity of color Scale of 1 – 10 (rich or pale)

12 Appearance Translucency – enamel at incisal edges
Opacity – dentin affects light passing through Gingiva affects color at margin Rubber dam Match shade before placing to get best results

13 Composites Dr. Raphael Bowen, 1960’s
Fillers and Silane Coupling Agents Industrial: fiberglass Fillers typically ceramic (silica) particles Silane Coupling agents: work like soap to react with silicon and oxygen on the surface of the ceramic filler Composite strength increases, polymerization shrinkage decreases, limits thermal expansion

14 Composite Components Matrix Monomer
Diluent – added to control viscosity Polymerizes by Addition Polymerization Chemical cure – two paste system Light cure – single paste material

15 Composite Polymer Dr. Bowen developed – for dental composites
Combination of several monomers Oligomer: Bifunctional since each C=C group can participate in formation of growing chain Cross-linking = improved strength Bis-GMA Methyl methacrolate (most common) Triethelene glycol dimethacrylate

16 Fillers Originally quartz materials (sand) Engineered glass materials
Size determines surface smoothness Macrofill – largest size particles, rough texture Microfill – 1970’s, polish smooth, appear similar to enamel, useful for Class III & V restorations due to modulus of elasticity Small particle – 1980’s, 80-85% filled Hybrid – late 1980’s, strong & abrasion resistant (Class I & III)

17 Filler Type Filler Size (µm) Filler Volume (%) Examples Composite
Class Filler Type Filler Size (µm) Filler Volume (%) Examples Conventional Quartz or Glass Average = 20 Range = 1-100 50-60 Adaptic Concise Profile Microfill Fumed Silica PPRF Average = .04 Range = 10-50 30-55 Silar/Silux Durafill Helioprogress Small hybrid Quartz or glass Average = Range = 0.1-3 Herculite XR Z100, Z250 Tetric Ceram Midsized hybrid Fumed silica Average = Range = Average = 0.04 65-70 Bisfil-P Occlusin Clearfil P-50

18 Composite restorations
Composite restorations are shown in centric occlusion from the lingual aspect on the laboratory models. Laboratory models

19 Flowable Composites Class V restorations Micro preparations
Extended fissure sealing Adhesive cementation of ceramic restorations Blocking out cavity undercuts Initial (base) layer in any classification Resin coating technique

20 Self-Curing & Light Curing Resins
Paste A Paste B Paste Monomers Initiator Activator Accelerator Mixing A and B, or light curing the paste causes: Initiator + activator (acclerator) reactive initiator Reactive initiator + monomers reactive monomers Reactive monomers + monomers polymers

21 Adhesives Dentin bonding systems Scotch Bond Multi Purpose EBS-Multi
solvent-free adhesive system for the "Total-Etch" technique

22 Depth of Cure The thickness of composite cured by typical light source
Penetration of curing light – only several mm Depends on time of light exposure, product, shade, and the light If material nearest to pulp is not cured, can result in sensitivity Composites placed in layers to prevent uncured material

23 Incremental Addition Placing composites in layers:
Assures polymerization Allows for shrinkage (normally about 2%)

24 Condensable Composites
Filler particle inhibits sliding of filler particles by one another Results in “thicker, stiffer feel”

25 Placement of Composite Restoration
Diagnose lesion Determine shade needed Isolate area Cut cavity preparation Place cavity liner if necessary Etch, prime, and place adhesive Place composite incrementally; cure Finish

26 Check proximal contacts
Examine for voids and marginal defects Polish Remove rubber dam Check occlusion

27 Sealant & Preventive Resins
Sealants reduce caries in pits and fissures Etch, then bond (light or chemical cured) Preventive resins: combination of sealant and composite restoration Suspicious pit is opened with a bur or air abrasion Tooth is etched, primed, and adhesive placed Prepared pit is filled with hybrid composite Other pits and fissures filled with sealant Conservative – not a Class I preparation

28 Glass Ionomer Chemical cure – first adhesive restorative material
Light-cure, late 1980’s Powder-liquid systems (acid-base setting reaction) Placed directly into cavity preparation Advantages: Fluoride releasing – good for high caries risk, Class V Adhesive Luting cements

29 Glass-ionomers Postoperative Sensitivity Reduced or Eliminated
Masticatory pressure Secondary caries Shrinkage Expansion GLASS IONOMER CEMENTS Finely ground aluminosilicate glass Liquid is a polycarboxylate copolymer The chemical reaction gives rise to a cross-linked gel matrix Bonding to tooth tissue occurs between the polycarboxylate molecules and calcium on the surface of the tooth. There are other cements like: Zinc oxide eugenol cements Zinc polycarboxylate cements For Cementation of inlays, veneers, orthodontic bands and brackets, resin-bonded bridges etc. Postoperative Sensitivity Reduced or Eliminated Chemically and Mechanically Bonds to Tooth Structure Flexes with Tooth, Cushions Occlusal Forces Outstanding Fluoride Release Protects restoration from secondary decay Consistent results, Easy to Use

30 Compomers Combination of Glass Ionomer and Composite/Dentinal bonding materials Bond and set like composites Release fluoride like glass ionomers Example: 3M F2000 tooth structure both react to temperature changes to the same degree and shows an elasticity comparable to microfill restoratives (following slides from 3M conference in South Africa)

31 Compomers "Dyract® AP etch cavities adhesive compomer placed setting

32 Class V Compomer Figure 1 - Class V defect in lower right central incisor. Incisal enamel abrasion points to abfraction as possible contributing cause.

33 Figure 2 - After cleaning, shade taking and preparation, the compomer primer is directly dispensed from the 3M Clicker system into the mixing well.

34 Figure 3 - After shortly mixing the liquids in the well with a brush, the same brush is used to apply the primer to the entire cavity.

35 Figure 4 - After 30 seconds the primer is gently air dried for 5-10 seconds

36 Figure 5 - The primer is light cured for 10 seconds

37 Figure 6 - After light curing the primer, the compomer can be applied
Figure 6 - After light curing the primer, the compomer can be applied. Capsules are preferred because the material can be applied directly into the cavity

38 Figure 7 - A preformed matrix is put on the restorative prior to a 40 seconds light cure to facilitate contouring and finishing of the restoration.

39 Figure 8 - After the use of Sof-Lex finishing and polishing discs the end result shows a good color match and marginal adaptation.

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