More Related Content
Similar to Esthetic Biomaterials and Principles
Similar to Esthetic Biomaterials and Principles (20)
Recently uploaded
Recently uploaded (20)
Esthetic Biomaterials and Principles
- 1. Esthetic Biomaterials & Principles - 2 Muhammad Amber Fareed BDS (Lahore), MSc (London), PhD (Birmingham), FRACDS (Sydney), FDSRCPS (Glasgow), DipMedEdu (Cardiff) Professor of Restorative Dentistry College of Dentistry, Gulf Medical University Ajman, United Arab Emirates 1
- 2. Learning Outcomes • Discuss the different esthetic restorative materials • Understanding the importance of polymerization shrinkage • Illustrate strategies used to reduce polymerization shrinkage stress • Discuss the commonly used restorative materials (GIC, RMGIC, MTA, Resin Cement) and the oral environment Prof MA Fareed 2
- 3. Resin-based Composites – Composition 1. Resin monomer – (bis-GMA, UDMA, TEGDMA,) 2. Reinforcing fillers – (macro, micro, nano, hybrid, etc) 3. Silane coupling agent – (bonds fillers and resin) 4. Optical modifiers – Composite Shade (TiO2, Al2O3 ) 5. Initiator/Light-activator – (Camphorquinone) 6. Inhibitor – (Butylated-hydroxytoluene) 3
- 4. Resin Composite - Filler Particles Benefits • Filler particles reduce the amount of matrix (resin) materials to control the shrinkage of the composite during polymerization. • Provide the appropriate degree of translucency and are radiopaque • Increase hardness and strength, also increasing viscosity (75 wt.%) • Reduce wear, water sorption / staining and • Reduce polymerization shrinkage and thermal expansion/ contraction • Small filler particles are more polishable 4
- 5. Composite Resin – Classification 1. According to the polymerization reaction initiation Light cure Camphorquinone (photo initiator) Chemical cure Duel cure both light and chemical cure, used as cement 2. According to the filler particle size Micro-hybrid, nanohybrid, packable and flowable, low-shrinkage composite (silorane technology), bulk-fill composite 5
- 6. Composite Resin - Manipulative Variables • Compsite resin should not be cured in thick section > 2mm, • Curing light should be checked periodically with radiometer • The closer the light, the greater the irradiance • Major deficiency inherent polymerization shrinkage (2.2%–2.4%) • Substantial contraction gaps between the restorative material and the cavity margin, can result in postoperative sensitivity and recurrent caries. • The shrinkage of composite resin materials cannot be avoided, but the stress created by the shrinkage can be reduced Prof MA Fareed 6
- 7. Polymerization Shrinkage Reduction Tips Reducing polymerization shrinkage stress prevent microleakage 1. The incremental composite placement technique is recommended (always keep C-factor in your mind) 2. Create a relatively thick primed layer with dentin bonding agent (low modulus, deform slightly while curing composite to absorb stress) 3. Place a thin layer (0.5 mm) of flowable composite to (absorb stress) 4. Use of ‘soft-start’ polymerization prolong the composite curing time 5. Use a thin layer of resin-modified GIC under composite (RMGIC bond to the tooth and have low modulus to absorb shrinkage stresses) Prof MA Fareed 7
- 8. Properties of Resin-based Composites Biocompatibility: Generally biocompatible but should be treated as potentially harmful materials, handled with caution, pulp protection Depth of Cure Reduced exposure time and less depth of cure Light absorption and scattering reduce the power density and degree of conversion with depth of penetration Degree of conversion –(typical 50-70% are achieved) and it depends on resin composition; the irradiance of the light source; the light transmission; concentrations of sensitizer, initiator, and inhibitor. Curing depth is limited to 2-3 mm 8
- 9. Resin Composites – Polymerization shrinkage More resin, more shrinkage (micro hybrid shrink less than mircro-filled), Larger polymer/copolymer molecules less shrinkage More fillers less shrinkage, volumetric contraction is around 1.0-4.0% Shrinkage compromises the marginal seal at tooth-restoration interface Minimized with incremental technique (2 mm) while doing restoration. Post operative sensitivity in about 10% cases More likely due to micro-leakage or induced internal stress, which can be minimized with better clinical skills (isolation, pulp protection, incremental build-up) 9
- 10. Resin Composites – Mechanical Properties Mechanical Properties depends upon filler contents, filler type, efficiency of filler-resin coupling process and the degree of porosity in the set composite Most composite have good mechanical properties but fail in tension Compressive strength of mircohybrid have higher than microfilled Strength generally increase with volume fraction of fillers Elastic modulus or stiffness = increase with increase in volume fraction of fillers. Lower filler contents of microhybrid composite result in elastic modulus to one-fourth to one-half compared to highly filled microhybrid composite 10
- 12. Bonding - Acid-etch Technique Functions • Remove smear layer – Enamel (completely), Dentin (partially) • Remove contaminants from enamel and dentine • Create microporosities to generate high-energy tooth surfaces • Promote wetting of adhesive monomers Prof MA Fareed 12
- 13. Factors Contributing in Bonding • Good adhesive and bonding is achieved by: 1. Surface energy and wetting 2. Interpenetration (formation of a hybrid zone) 3. Micromechanical interlocking 4. Chemical bonding Prof MA Fareed 13
- 14. Bonding Agents - Mechanisms of Adhesion • Adhesion bonding occurs either through chemical attraction and/or micromechanical interlocking • The fundamental mechanism of adhesion to tooth involves: 1) Removing hydroxyapatite to create micropores 2) Resin monomers infiltration in micropores and forming resin-tags • Bonding with tooth structure requires three conditions: 1. Sound tooth structure must be conserved 2. Optimal retention must be achieved 3. Microleakage must be prevented Prof MA Fareed 14
- 15. Acid-etch Technique – Enamel Etching • Bruonocore first reported phosphoric acid for acid-etching • Phosphoric acid (37%) removes the smear layer and about 10 microns of enamel to expose prisms of enamel rods • Create a honeycomb-like, high-energy retentive surface • The higher surface energy ensures that resin monomers will readily wet the surface, infiltrate into the micropores, and form resin tags • Resin tags are 6 μm in diameter and 10 to 20 μm in length • Stronger bonding occurs if the smear layer is removed to allow resins to directly bond to the intact tooth hard tissue Prof MA Fareed 15
- 16. Acid-etch Technique – Dentin Etching • Dentin etching (37% phosphoric acid) is more technique sensitive than enamel • Dentine etching removes hydroxyapatite and expose a microporous collagen • Etched enamel must be completely dry to form a strong bond • Etched dentin must be moist to form a hybrid layer • If insufficient water is present, the collagen network will collapse, no hybrid layer • If too much water remains, resin infiltration cannot occur in the collagen network • Priming step maintains a hydrated collagen network while removing excess water • After dentin-etching hydrophilic resins can infiltrate into the dentin • A hybrid layer structure forms very strong resin bonds through the micromechanical interlocks at the resin–hybrid layer interface Prof MA Fareed 16
- 17. Acid-etch Technique – Moist Dentin Insufficient water - collagen network will collapse, too much water resin infiltration cannot occur in collagen network to form hybrid-layer Prof MA Fareed 17
- 18. Dentin-Bonding Agents – Composition 1. Etchants – 37% phosphoric acid (pH = 1-2) gel applied with brush 2. Primers – HEMA, phenyl-P, 10-MDP, 4-MET, 4-META, and MAC-10. 3. Solvents – Water, ethanol, and acetone 4. Adhesives – bis-GMA, TEGDMA, UDMA and HEMA 5. Initiators – photosensitizer (camphorquinone), co-initiator (tertiary amine), a self-cure system (benzoyl peroxide), dual-cure system 6. Filler particles – Nanometer-sized silica fillers (20-40 nm) 7. Other ingredients – desensitizer, antimicrobial, fluoride, chlorhexidine Scotchbond Universal by 3M is shown in the picutre Prof MA Fareed 18
- 19. Dentin-Bonding Agents – Classification A. Etch-and-Rinse Adhesives • Three Step (Fourth Generation) 1) Application of an acid-etchant 2) Application of the primer 3) Application of the bonding resin. • Two Step (Fifth Generation) 1) Application of an acid-etchant 2) Application of combined primer and adhesive resin into one B. Self-Etch Adhesives No separate etching step • Two Step (Sixth Generation) 1) Application of an acidic monomer (conditioning and priming) 2) Application of the bonding agent • One Step (Seventh Generation) 1) A single step combines dentin conditioner, primer, and bonding resin Prof MA Fareed 19
- 20. Enamel and Dentin-Bonding 1. Total-etch technique enamel and dentin etched simultaneously 2. Selective-etch technique ONLY enamel is etched selectively 3. Etch and rinse technique = total-etch technique (etchin + washing) 4. Self-etch technique etching and bonding done together (no wash) • Enamel-bonding agents bis-GMA and TEGDMA • Dentin-bonding agents bis-GMA, TEGDMA, UDMA, HEMA, 10- MDP, 4-META Prof MA Fareed 20
- 22. GIC – Classification Based on Usage • Type I: Luting crowns, bridges, and orthodontic brackets • Type II a: Esthetic restorative cements • Type II b: Reinforced restorative cements • Type III: Lining cements and bases • Pit and fissure sealant • Metal modified GICs (cermet, miracle mix) for core-build-up • Resin modified GICs (compomer etc) for core-build-up, restoration • Prevention of caries, have high F-ions (Fuji VII) • Atraumatic restorations (Fuji VIII) • Pedodontics and geadiatric (Fuji IX)
- 24. Clinical Applications and Indication of GIC • Used as liner / Base under composite restorations • Sandwich technique (GIC followed by composite) • Permanent restorations for primary teeth • Luting cement for indirect restorations (crowns, inlays, veneers) • Retrograde filling material after surgical endodontic treatment (RCT) • Temporary/intermediate restorative materials for permanent teeth , or • Fissure Sealant for permanent teeth (low viscosity) • Root Caries Cervical Restoration (Class-V) • Core bulid-up materials • Atraumatic Restoration
- 25. GIC Modifications – Resin-modificed (RMGIC) • Conventional GIC are moisture sensitive and have low early strength • Hybrid materials containing the properties of both GIC and composite were developed (Hybrid ionomer, dual cure, tri-cure, compomers) • The monomers in hybrid glass-ionomer cements make the cements more translucent
- 26. RMGIC – Compositon and Setting Reaction • Available in capsules, two-paste system, and powder/liquid system which contain water-soluble polymerizable monomers in a liquid • RMGIC Powder fluoroaluminosilicate glass particles, resin (bis- GMA/HEMA), coupling agents (silanes), Initiators (light activation, chemical or both), Benzoyl peroxide (Chem), Camphoroquinone (Light) • RMGIC Liquid Poly(acrylic acid) and copolymers solution, PAA is modified with methyl-methacrylate or HEMA, Light activators (diethyl aminoethyl methacrylate • Setting Reaction Dual-cure (acid-base and light activation setting reaction) tri-cure (acid-base reaction, light-curing and chemical curing)
- 27. GIC + Composite = Compomer • Compomer is available in a one-paste restorative system (water-free) • Compomer, a combination of GIC and composite integrates the fluoride releasing capability of GIC with the durability of composite • Composition non-reactive inorganic filler particles, reactive silicate glass particles, sodium fluoride, a polyacid-modified monomer (e.g., di-ester of HEMA with butane carboxylic acid and photo activators. • Setting reaction Set by a polymerization reaction, and then absorb water from the saliva to initiate the slow acid–base reaction between the acidic functional groups and silicate glass particles • Compomer require a dentin-bonding because not self-adhesive (GIC)
- 28. Resin Cements • Resin cements are low-viscosity versions of resin-based composites. • Self-cured and dual-cured resin have two pastes (base and catalyst) • Compositon matrix of methacrylate monomers (HEMA, 4-META, MDP), dispersed fillers, silane coating on the filler particle surfaces. • Acid-etching and bonding is required for most same as composite • Not all resin cement systems require a bonding agent (self-etch system) • Polymerization (Setting) Self-cure, light-cure or dual-cured (common) • Used for cementing ceramic veneers and direct bonding of ceramic or polymeric orthodontic brackets • Most esthetic resin cements are light-cured as have better color stability
- 31. Thank you! Prof MA Fareed 31