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 - AfterCl. 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. TypesA. 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. CompositionA. 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 – 10-25 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
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C. Chemicals – promotes polymerization
1. Self-curing system:
a. benzoyl peroxideb. amine
2. Light-curing system:
a. camphoroquinoneb. 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
Hybrid ZoneEtched to remove smear layer
p. 48
p. 51
Resin
VI. PolymerizationA. Two major considerations -
1. Polymerization shrinkagea. overall volume shrinksb. creates marginal gaps – breaks chemical sealResult – sensitivity, 2º decay
2. Extent & depth of curinga. 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. FinishingA. 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 ChartBlack’s Classification I – VI Know them!!
Dental charting on a paper chart – hand-out #2
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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 1st - filler particles exposed- as chewing continues – filler particles are pulled out- result: small holes, rough surface, traps plaque, microbes, stains
Before After
b. Contact/Attrition wear – results from direct contact with opposing dentition
- 3 - 4 times more extensive damage then abrasive wear
KHN: enamel = 350
amalgam = 165
composite = 40 – 80 – 120+
- 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.