DH220 Dental Materials Lecture #4 Prof. Lamanna RDH, MS

Restorative Dentistry: Composite Ivoclar 4 Seasons Composite System®

I. Use - Repair/replace tooth structure that has decayed or fractured: Cl. III, IV, V, VI, & small Cl. I & II Cl. V -Before Cl. V - After Cl. IV Cl. I Cl. II Cl. III Cl. VI

- Enhance esthetic appearance of teeth: veneers, close diastemas, contour (reshape) teeth Veneers Diastemia closed Recontour peg laterals

- Cores for cast restorations -Repairing fractured/chipped porcelain restorations

II. Characteristics ↓ thermal conductivity ↑ thermal expansion (percolation) Polymerization shrinkage ↑ sorption Color stability (staining due to surface roughness, internal change) Strength: tensile similar to amalgam; ↓ compressive ↓abrasion resistance Retention mechanism: chemical Mechanical retention Chemical retention

III. Types A.Self-curing -Supplied as a 2-part paste system: base & catalyst -Limitations: fixed working time (hardens w/in several minutes) B.Light-curing -Supplied as direct placement paste; syringe – compule dispensation -Limitations: must be layered to achieve proper polymerization; utilizes blue light for curing; potential hazard for retinal damage; use of filtered eyewear -Advantage: more working time C.Dual-curing -Self and light cure capacities

IV. Composition A.Polymer (resin) matrix 1. BIS-GMA (bisphenol-A glycidal methacrylate) 2. Triethylene glycol dimethacrylate B.Glass particles (fillers) 1. Ground quartz, glasses, silica particles *Always coated with a coupling agent: silane. WHY? Enhances adherence of matrix (resin) to the filler particles. 2. Particle size a. Macrofills – µ - ↑ strength - ↓ polishability - ↓ wear resistence (KHN – 55) - quartz - primarily used for orthodontics (luting brackets) and cores

b. Microfils – 0.04 µ - ↓ strength - ↑ polishability - silica c. Small particle – 1 – 5 µ - strength, but not as strong as macro - polishable, but not as smooth as micro - glasses d. Hybrids (micro + small particle) - ↑strength - ↑polishability - glasses - radiopaque Composite surface Magnified particles p. 59

C. Chemicals – promotes polymerization 1. Self-curing system: a. benzoyl peroxide b. amine 2. Light-curing system: a. camphoroquinone b. amine D. Pigments – provide different shades to match existing teeth ● inorganic oxides

V. Handling and Placement A.Self-curing composite · equal portions base & catalyst spatulated together · limited working time B. Light-curing composite · direct dispensation into site · increased working time · use of clear matrix · exposure to blue light - polymerization

Chemical Retention ● Step #1 – Acid etchant – 10-37% phosphoric acid; removes smear layer on dentin, opens enamel rods - applied, rinsed, dried ● Step #2 – Primer - wetting agent- ↑ penetration into dentinal tubules - applied, not rinsed, dried sparingly ● Step #3 – Adhesive (resin material) - interlocking with dentin to achieve chemical retention – referred to as “hybrid zone” - applied, light-cured Chelating agent Dentin Enamel

Process of decalcifying & removing tooth structure by chemical means. Return

Ground dentin & cytoplasmic cells that are mixed together as the tooth is prepped. It is sticky and adheres to the tooth surface; “smeared” inside the tooth prep. Return

Hybrid Zone Etched to remove smear layer p. 48 p. 51 Resin

VI. Polymerization A.Two major considerations - 1. Polymerization shrinkage a. overall volume shrinks b. creates marginal gaps – breaks chemical seal Result – sensitivity, 2º decay 2. Extent & depth of curing a. exposure time – ☼ quantity of light shone on material – do not under cure; impossible to over cure ☼ quality of light of shone on material – bulb should be checked regularly on meter b. Composite depth – built-up in thin (1.5-2 mm) layers to ensure proper curing; aids in polymerization shrinkage outcome

Material Placement – incremental layering

Vll. Finishing A.Can be finished & polished after placement B.Wet field, carbide burs, diamonds, discs with varying grades of abrasiveness C. Polishing – aluminum oxide or diamond pastes; composite polishing kits (lab)

Dental Charting – Paper Chart Black’s Classification I – VI Know them!! Dental charting on a paper chart – hand-out #2 24

IX. Clinical Success A.Anterior Placement 1. high level of success – 10 years 2. certain cases only 3 – 4 yrs (operator variability??) 3. major reasons for failure: 2º decay, marginal discoloration – due to inadequate marginal seal 4. Cl. III – low wear/stress - ↑ rate of success Cl. IV - ↑ stress exposure – rechipping Cl. V – least success – incomplete sealing due to dentin/cementum at gingival margin - mat’l of choice: glass ionomer WHY? Cl. III - low stress app’l Cl. V Cl. IV – before high stress app’l Cl. IV – after - rechipped Cl. IV

B. Posterior Placement - wear and marginal breakdown 1. Wear – 2 types: abrasion & attrition a. Abrasive wear – results from the movement of food, toothpaste, etc over the entire surface - occurs in a uniform manner - resin matrix (least resistant) – wears 1 st - filler particles exposed - as chewing continues – filler particles are pulled out - result: small holes, rough surface, traps plaque, microbes, stains BeforeAfter

b. Contact/Attrition wear – results from direct contact with opposing dentition times more extensive damage then abrasive wear KHN: enamel = 350 amalgam = 165 composite = 40 – 80 – Studies have shown that composites last 7-10 years, which is comparable to amalgam except in very large restorations, where amalgam lasts much longer than composites. 2. Premolars – less wear than molar placement due to less force during mastication 3. Contraindication to placement: bruxism, grinding 4. No “self sealing” mechanism 5. Exposed filler particles could abrade opposing enamel 6. RDH clinical management – a. OHI – no disclosant on composite; use coating of pet. jelly to protect. b. Instrument choices – no metal or ultrasonic directly on composite. c. Fluoride choices – no APF; use neutral sodium Fl.