Dental Composites (Year 2) PDF

Topic 4: Composite Resin Restoration Lecturer: Dr. Lamia A. T. Bin Yehia BDS, Clinical MSc in Pediatric Dentistry Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS....

Topic 4: Composite Resin Restoration Lecturer: Dr. Lamia A. T. Bin Yehia BDS, Clinical MSc in Pediatric Dentistry Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 1 MSc. History Of Tooth Coloured Filling Materials 1st aesthetic restorative material Silicates Cements Historical (No Longer Found In Market) 2nd aesthetic restorative Unfilled Resin Restoration material PMMA (Poly Methyl Methacrylate) 3rd aesthetic restorative Filled Resin Restoration material Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. Dental composites 2 MSc. 1  Silicate Cements Commercially found as: Powder (ground fluoro-alumina-silicate glass) : liquid (phosphoric acids) Advantages: Disadvantages: 1. They provided initial decent aesthetics. 1. Poor physical properties 2. They are oral fluid soluble releasing high 2. Poor color stability fluoride ions i.e. anticariogenic effect recurrent caries rarely occurs underneath it. Clinical importance: Powder formula is used GIC Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 3 MSc. Restorative resin Type I (other names; unfilled resins / acrylic resins) This material was introduced before the discovery of micro-mechanical adhesion and Bowen’s resin. They are largely replaced nowadays by the composite resins (type II). Advantage: Good Initial Aesthetics Poor conductor of heat Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 4 MSc. 2  Disadvantages in comparison to dental composites Mechanical properties Lower than dental composites 3X more than dental composites causing >> contraction of the material and creation of gaps in the tooth – material interface (cavity margins) leading to micro-leakage Polymerization shrinkage causing: ✓ High rate of recurrent caries ✓ Post-operative sensitivity Water absorption Higher than dental composites Adhesion No adhesion to enamel nor dentin Biocompatibility Poor; monomer is a known irritant to the pulp Evolution Of Composite Resins (not in exam): 1955: M. Buonocore introduced the acid-etch technique. 1956: Dr. Raphael Bowen formulated the BIS-GMA resin (undergoes lessened degree of polymerization shrinkage). 1962: introduction of silane coupling agents Mid- 1980s: hybrid composites. + macro-filled composites. 1996: flowable composites. 1970: first photo-cured composites by UV light. 1997: packable composites. 1972: first photo-cured composites by visible light. 1976: first micro-filled composites. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 6 MSc. 3  Restorative resin Type II (filled resin / dental composites): A combination / mixture of Resin material (highly cross-linked polymeric material) reinforced by filler material (amorphous silica, glass, crystalline, mineral, or organic resin filler particles and/or short fibers), these 2 components are bonded together by a coupling agent. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. 7 BDS. MSc. Advantages Of Composites as restorative material 1. Excellent esthetics 6. Repairable 2. Less complex in comparison to indirect restoration (i.e. applied chair 7. No corrosion side) 8. No health hazard in comparison to 3. Almost used universally (Ant. + post) amalgam filling (mercury toxicity) 4. Adds strength to tooth structure 9. Cheaper than porcelain 5. Bond to tooth structure Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 9 MSc. 4  Oral application / Indications: 1. Restoration of anterior and posterior teeth. 2. Pits and fissure sealants. 3. Bonding mat. for ceramic veneers. 4. Cementing mat. for fixed prosthesis. 5. Core build-up mat. 7. Repair of old filling. 8. Restoration for pt. allergic to metals. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 10 MSc. Disadvantages Of Composites 1. Polymerization shrinkage 6. Low MOE 2. Polymerization heat generation 7. Lack anti-cariogenic properties 3. Staining 8. Laborious / time consuming 4. Higher CTE 9. Technique sensitive 5. Increased occlusal wear 10. Higher cost in comparison to amalgam Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 11 MSc. 5  Contraindication: 1. Inability to establish moisture control / Isolation 2. Unfavourable occlusion (high stress area or presence of traumatic occlusion or para-functional habits e.g. bruxism or clenching) 3. High caries risk e.g. acute / rampanent caries (composites do not have preventive capabilities) 4. Poor oral hygiene 5. Gingivitis or periodontitis 5. Sub-gingival area or root surface (poor adhesion) Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 12 MSc. Composition Of Dental Composites: Major components Other components Resin matrix Inhibitors Coupling agents Optical modifiers / opacifiers Pigments (various pigments, usually Inorganic fillers consisting of minute amounts of metal oxide particles) Activator – initiator system Color stabilizers / UV absorbers Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 13 MSc. 6  1. Resin Matrix: It is the continuous phase that surrounds and binds to the filler particles via the coupling agents. It provides plasticity for the dental composite for easy placement and shaping of the material. It hardens / solidify by polymerization reaction (highly cross-linked polymer). It chemically bonds to the adhesive system. This component causes the majority of dental composites disadvantages such as: decrease CTE, CS, TS, MOE and H and AbR (mechanically weakest), increase water absorption causing easy staining (minimized by the filler content). Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. 14 BDS. MSc. Resin Types Principal monomers / oligomers Diluent monomers (highly viscous due to high molecular weight, (decrease viscosity allowing increase decrease polymerization shrinkage, better corporation of high levels of fillers + mechanical properties and cross-linking) better manipulating) 1. BIS-GMA (aromatic) 1. TEGDMA (aliphatic) 2. EGDMA 2. UDMA 3. HEMA Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 15 MSc. 7  2. Filler: They are reinforcing particles and / or fibers. ✓ 2 forms: 1. Crystalline: quartz, tridymite and crystoballite. 2. Non-crystalline: glass, modification of ions (Li, Al, Ba, Zn, Y, St, Zr) and fibers. They are dispersed in the resin matrix to enhance the mechanical properties of the material, e.g. strength, abrasion resistance, esthetics and handling. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 16 MSc. Advantages Increase MOE, Compressive and tensile strength Increase Hardness (abrasion resistance) >>Decreases Wear Increase Fracture resistance Increase Viscosity (ease of manipulation, placement and tackiness) Increase Radiopacity (aids in radiographic visualization of leaking margins, 2°ry caries, poor proximal contact) Increase Esthetic: e.g. translucency Decreases Polymerization shrinkage Decreases Thermal expansion and contraction Decreases Water sorption (less prone to abrasive wear and staining) Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 17 MSc. 8  Advantages, usage and types of dental composites are affected by the following filler factors: 1. Filler size / surface area: determines surface smoothness (larger particles = rough surface) and esthetics. 2. Filler content: (higher filler content means less resin content, therefore better mechanical properties e.g. strength, hardness and abrasion resistance). 3. Filler distribution Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 18 MSc. 3. Coupling Agents: It is bi-functional molecule that aids in binding / adhering filler (via OS / Siloxane bonds by their silanol group) to resin matrix (via covalent bonds by their methoxy group). Example: Organo-silanes (3 methoxy-propyl- trimethoxysilanes) Advantage: 1. Improves the mechanical and physical properties (transmission of stresses from the resin to filler). 2. provide hydrolytic stability (i.e. prevent leaching by preventing water from Year – penetrating along the resin filler 2 (Term 1): Dentalinterface) Material. Dr. lamia A. T. Bin Yehia. BDS. 19 MSc. 9  4. Activator – Initiator System: The resin polymerizes by addition polymerization process which is initiated by the formation of free radicals. The activator – initiator system are the components that that convert the resin paste from a soft, mouldable filling material to a hard, durable restoration. Based on the activator – initiator system, dental composites are of 2 types: chemical / auto / self-cured or light-cured or dual-cured or heat- cured. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. MSc. 20 1. Chemical activation composites (self – cure / auto-cure): The dental composite is supplied as two pastes: base and catalyst. Initiator – activator system: Initiator = benzoyl peroxide. Activator = an aromatic tertiary amine (e.g., N, N-dimethyl-p-toluidine). The two react and form free radicals initiating the addition polymerization of resin. The self-cured composites are rarely used in dentistry; mainly used nowadays as core build-up material. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 21 MSc. 10  Advantages in comparison to light-cured composite 1. Material is cheaper than light cure. 2. Procedure is convenient and simple (no equipment needed). 2. Material has long-term storage stability. 3. Curing process duration more than light-cured >> Less marginal stress build-up. 4. Dentist can manipulation the working/ setting time by varying proportions (unadvisable). 5. Degree of cure equal throughout material if mixed properly. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 23 MSc. Disadvantages in comparison to light-cured composite 1. Manual mixing cause oxygen trap, porosity >>> causes weakened material that is susceptible to staining. 2. Colour instability (turns yellow with time): due to the oxidation of aromatic amine accelerators. 3. Unequal degree of cure in the composite mass resulting in poor mechanical properties >>> due to: Difficult to mix evenly. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 24 MSc. 11  2. Visible light activation (called light – cure composite): Most commonly used restorative material nowadays. Supplied in single paste. Activator =Historically UV light but nowadays blue visible light (has improved cure depth, a controllable working time, does not cause retinal damage and skin cancer). The visible light excites the photosensitizer amine activator (e.g. DMAEMA) which breaks the initiator; camphorquinone (both are found in small quantity 0.1 Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 25 -0.2%wt). MSc. Advantage 1. No mixing needed >>> low porosity, less staining, stronger. 2. Due to incremental build-up: ✓ The use of multiple shades within a single restoration is allowed. ✓ Less polymerization shrinkage. 3. “Command” setting (upon exposure to an intense blue light which is controlled, at will, by the clinician). 4. No aromatic amine accelerator: thus greatly improved color stability. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 26 MSc. 12  Disadvantage 1. Special lamp is needed to photo-initiate curing. 2. Limited cure depth: necessary to build up in layers of about 2 mm increments. 3. Poor lamp accessibility in posterior and interproximal areas; requires extra exposure time and care in placement and maintaining lamp tip angle and distance for optimal results. 4. Mildly sensitive to normal room illumination (thus a crust will form when exposed too long to an examination light). 5. Darker shades require longer exposure times. 6. High marginal stress build-up during curing than in self-cured resins due to faster cross- linking and thus reduced time for chains to slide and relax among themselves. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. MSc. 27 3. Dual activation: Setting reaction: chemical + light Material comes in thick 2 barrel syringe with special mixing tip needle. One barrel contains the initiators e.g. benzoyl peroxide and camphorquinone and the other contain the aromatic and aliphatic tertiary amine accelerator and Photosensitizer amine activator (e.g. DMAEMA) activators. Used mainly in: (any situation that does not allow sufficient light penetration to produce adequate monomer conversion) A. Core build-up B. Cementation of bulky ceramic restoration Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. C. Cementation of fiber-post. MSc. 29 13  Advantage Disadvantage Assurance of completion of cure Porosity caused by the required throughout, even if photo-cure is mixing. But this has been greatly inadequate. alleviated by the use of mixing syringes Less color stability than with the Air inhibition photo-cure resins owing to the aromatic amine accelerators. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 30 MSc. 5. Inhibitors: A typical inhibitor is butylated hydroxytoluene (bht >>> concentrations = 0.01% by weight. Mode of action: Inhibitors minimize spontaneous or accidental premature polymerization of monomers by acting as a radical scavengers that reacts with free radicals Inhibitors have 2 functions: 1. To extend the resin’s storage life. 2. To ensure sufficient working time. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 31 MSc. 14  6. Optical modifiers: Provide the translucency and opacity necessary to simulate enamel and dentin. All optical modifiers affect light transmission through a composite. Dark shades: absorbs all of the light. Light shades: reflects too much light. Thus, darker shades and greater opacities have a decreased depth of light-curing ability and require either an increased exposure time or a thinner layer when cured. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 32 MSc. Classification Of Dental Composites: I. Based On The Mean Particle Size Of The Major Filler And Distribution II. Based on method of polymerization III. Based On Their Consistency Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 33 MSc. 15  I. Based On The Mean Particle Size Of The Major Filler And Distribution: 1. Traditional / conventional / macro-filled: 10 to 100 µm 2. Small particles: 0.1 and 10 µm 3. Micro-filled: (agglomerates of 0.01- to 0.1-µm inorganic colloidal silica particles embedded in 5- to 50-µm resin filler particles). 4. Hybrid: mixed filler systems containing both microfill (0.01 to 0.1 µm) and small particle (0.1 to 10 µm) fillers 5. Nano-filled Composites: (nanoparticles - 1 to 100 nm >>> 0.001 - 0.1µm). Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 34 MSc. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 35 MSc. 16  Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 36 MSc. 1. Traditional / Macro-filled Composites (Historical): Filler size = 10 – 100 µm Filler type = grinded or milled ground quartz or glass Macro-filled composite are no longer used due to their several disadvantages. Advantages: 1. Can be incorporated in high percentages into the resin matrix (78% by wt.) 2. It has good mechanical properties (making it functional in high stress areas >>> posterior restoration). Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 37 MSc. 17  Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 38 MSc. Disadvantages: 1. During service / with time >>> the resin matrix wears easily leaving a rough surface made of the large size filler particles >>> this causes 2 problems: A. Opposing tooth wear during service / with time B. Poor aesthetics during service / with time / stain easily. 2. Due to the large sized filler used >>> 2 problems occur: A. Poor polisability B. Poor translucency Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 39 MSc. 18  2. Small-particle >> mini-filler / midi-filler Composites: Filler size = 0.1 - 10 µm sized (mini = 0.1 – 1 µm) (midi = 1 – 10 µm) Filler type = mainly glasses containing heavy metals and ground quartz. Disadvantages: Poor translucency: therefore their aesthetic is not perfect. Uses: in hybrid composites = mixed with micro-particles (colloidal silica) for general anterior composite use. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 40 MSc. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 41 MSc. 19  3. Micro-filled Composites: Filler size = 0.01- to 0.1-µm i.e. 10 – 100 nm Filler type = inorganic colloidal silica Uses: low-stress bearing areas in anterior teeth (gingival positioned class III and V and some class IV). Advantages: 1. Excellent polishability (High scattering of light) >> Due to their smaller size 2. Excellent aesthetics (high translucency - excellent transmission of light) Disadvantages: poor mechanical properties due to low filler loading. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 42 MSc. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 43 MSc. 20 ❑ 2 types of micro-fillers: 1. Homogeneous micro-filler (0.01- to 0.1-µm silica): have very large surface area causing poor filler loading (of 50 – 60% by wt.) producing: 1. Dental composite of poor mechanical properties. 2. Dental composite of high resin percentage (Poor mechanical properties + high water sorption + High CTE + higher polymerization shrinkage) 2. Heterogeneous micro-filled (0.01- to 0.1-µm silica mixed with pre-polymerized resin particles containing 40-nm silica) : created to overcome the poor filler loading of homogeneous micro-filler (60% to 70% by weight, about 50% by volume) >> provides a high degree of hardness and strength but also brittleness Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 44 MSc. Type of Composite Filler size uses Homogeneous micro- 0.01- to 0.1-µm silica Low-stress and sub-gingival filled areas that require a high luster and polish Heterogeneous micro- (1)0.01- to 0.1-µmsilica Low-stress and sub-gingival filled (2)Pre-polymerized resin areas where reduced shrinkage particles containing 40- is essential nm silica Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 45 MSc. 21  4. Nano-filled Composites: More recently developed Filler size = 1 to 100 nm >>> i.e. 0.001 - 0.1µm Filler type = nano-particle sized silica or zirconia particles >> dispersed as homogeneous independent nanoparticles or nanoclusters (sized as small particles). Uses = anterior and posterior restorations. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 46 MSc. Advantages: 1. Better optical properties than micro-filled composites >> translucency 2. Better workability than micro-filled composites >> i.e. polishability. 3. Has increased filler loading (78% by weight) >> High durability + low polymerization shrinkage. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. MSc. 47 22  5. Hybrid Composites: These are a mixture of small particle fillers with other sized filler particles: ✓ Midi -Hybrid (mid-filled) = small (midi) particle glass size 0.1- to 10-µm + micro-filler silica size 40-nm (Class III & IV & V) ✓ Mini -Hybrid (mini-filled/ SPF*) = small (mini) particle glass size 0.1- to 1-µm + micro-filler silica size 40-nm (Class III & IV & V) ✓ Nano-hybrid: ≤100-nm nanoparticles + Small particle glass or resin micro- particles size 0.1- to 2-µm (Class I - VI) ✓ Packable hybrid: Mid / mini-filled hybrid, but with high filler fraction (Cl. I &II) ✓ Flowable hybrid: Mid-filled hybrid with low filler content (liner cl II) Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 48 MSc. Hybrid composites has the properties of it’s largest particle and this provides it’s use >> Small particle >> small filler size than macro-fillers >> better surface smoothness Small particle has high filler content than micro-fillers >>> good mechanical properties. ❖ Hybrid composites are called general utility / universal composite: i.e. suitable for restoring high-stress-sites and sites with high aesthetic demand e.g. incisal edges and small non-contact occlusal cavities >> i.e. anterior and posterior restoration. Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 49 MSc. 23  Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 50 MSc. II. Based on method of polymerization: 1. Self-cure / auto-cured / chemical cured composites 2. Light-cured composites either UV light or visible light 3. Dual-cured composites: polymerizes initially by light and then setting continuous chemically slowly over time. 4. Heat-cured composites: indirect composites. Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 51 MSc. 24  III. Based On Their Consistency: 1. Light body / Flowable composites: small-particle and hybrid fillers of low content 2. Medium body / regular consistency composite: microfilled, hybrids and nano-filled 3. Heavy body / Packable composites: mini-filled and hybrid Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 52 MSc. 1. Flowable Composites: Fillers >>> hybrids >>> low filler loading = 50 - 70% by weight and < 50% by volume >>> provides 2 things: A. Low viscosity >>> enables the resin to flow readily, spread uniformly, intimately adapt to a cavity form, and produce the desired dental anatomy. B. Reduced mechanical properties (compared to universal composites) Resin >>> high content of resin >>>> easy spreading >>> good adaptation to cavity walls >>> covering the bottom of the cavity in thin layer before adding a more viscous composite >>> Exhibit significant polymerization induced shrinkage (up to 5% by volume). Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 53 MSc. 25  Recommended for specific clinical indications 1. Dentine Substitutes / Liners (better adaptation to cavity walls) Class I-V. 2. Composite repair 3. Core build-up 4. Crown margin repair (not advisable) 5. Enamel defect repair 6. Incisal edge repair 7. Pits and fissures 8. Porcelain repair Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 9. Bulk-fill composites = flowable and can MSc.be placed in 4 mm increments. 54 2. Condensable (Packable) Composites: Composite fillings with regular viscosity composites are time-consuming and demanding procedure due to: Plastic nature of dental composite >>cannot be packed vertically into a cavity + needs careful contouring of matrix band to obtain an acceptable proximal contact. Condensable / packable composites have higher filler content & better distribution + elongated, fibrous filler particles to interlock and resist flow to increase the strength and stiffness of the uncured material and provide a Year 1 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. consistency and handling characteristics MSc. similar to those of lathe-cut amalgam. 55 26  3. Medium Viscosity / Regular Composites: ❑ These are the easy-to-handle composites >>> Their viscosity is suitable for a large number of indications, both anterior and posterior >>> another name universal. (enamel, dentin and intermediate opacity). ❑ Placed in 2 mm increments. ❑ Filler >>> micro-hybrids + nano-hybrids >>> filler loading = 78% by weight / 60% by volume. ❑ Optical properties >>> e.g. opacity >>> manufacturer adjustable based on targeted clinical indicationYear+1 (Term color complexity 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 57 MSc. III. Based On Their Consistency: 1. Light body composites: e.g. Flowable composites 2. Medium body composites (universal): e.g. Homogenous macro-filled, midi-filled and micro-hybrid 3. Heavy body composites: e.g. Packable mini-filled and hybrid Year 2 (Term 1): Dental Material. Dr. lamia A. T. Bin Yehia. BDS. 58 MSc. 27