Direct tooth colored restorations Flashcards
Direct
inserted as soft, ex composite, GI
Indirect
outside of mouth - cemented and bonded later. Veneers, onlays, etc.
Composites
polymer base, static, mechanically like amalgam, wear resistance a concern in the past, micromechanical retention - resin tags and a hybrid layer.
GI
water based, dynamic fluoride reservoir, decrease mechanical properties, wear resistance is good, chemically bonds (ionic bond not strong), recharge with fluoride varnish.
Posterior Composites - Advantages
Esthetic
• Conservative to tooth structure
• Easier preparation
Posterior Composites - Disadvantages
Technique sensitive
• Effects of polymerization shrinkage
Posterior Composites - Indications
In small/moderate-sized Class I & II preparations
• Areas where esthetics is of prime importance
Posterior Composites - Coutnerindatations
Complete moisture control is inadequate
• Heavy occlusal stresses
• The larger the preparation and the more posterior location
If a lot of attrition, bruxism, grinding
no composite
Resin matrix
soft phase, bis-GMA, TEGMA
BIS-GMA
main monomer, viscous oligomers
TEGMA
small linear molecule ~30% of composite oligomers
Filler
reinforcing phase
Max degree of conversion for composite
65-70%
Residual monomers =
30-35%, will plasticize, leak BPA
Filler
irregular or spherical particles
Degree of conversion
of double bonds of a monomer converted to single carbon bond during polymerization. This shrinks polymer, causing stress.
If stresses exceed binding agent,
debonding will occur.
Minimizing Gaps: 1.
Incremental/Layering Technique: Reduces bulk volumetric shrinkage
Minimizing gaps 2.
Placing a low viscosity material such as flowable composite prior to composite “Elastic theory”
Concept filler
improve in mechanical behavior
More filler = less resin , less polymerization shrinkage, decrease coefficient of thermal expansion
Glass particles and spheroidal silica particles Shape: spherical, irregular, combination
Size: range
Large fillers
under sliding force or wear, soft matrix can be removed leaving large filler exposed. This dislodges easily, exposing underlying resin (discolors as well). A cycle.
Nanosized - don’t
overload, this increases surface area and thus viscosity is too high.
Nanosized
no plucking, less wear
high polish
Too little = slump and sticky
Too much = hard to handle.
Macrofill
Very large filler particles -Particles are plucked out forming a very rough surface-low wear resistance
Adaptive, concise
Homogenous Microfill
Very small size fillers .04 microns/40 nm
• Polishability and wear resistance were optimal
• Indicated in esthetic non stress bearing area in young patients (filler loading 25-42%Vol)
Why are microfills aesthetic
chameleon effect - 40nm particles. Light comes through and never deflects.
Homogenous microfilled did not
work as posterior composites:
Increased the filler content
As they increased the nanoparticles
Problem:
High viscosity-difficulty in handling Clustering /agglomeration
Large cluster –esthetics is compromised
Heterogeneous Microfilled for posterior composites
Example: Heliomolar
Contains Prepolymerized fillers (PPF)
(Cured the microfilled composite and crushed it and incorporated in uncured composites)
The bond between PPF and the cured composite was weak …Debonding
Increase filler loading to 50%
Found big fillers debonded, this caused people to shy away from this.
Conventional hybrids
combined microfillers with macro filled. Once used as posterior, but large particles still dislodged.
Microhybrids
filler size range <1 microm. 60% loading capacity, good handling, used as anterior and posterior restorations. **reduced size of large particles, these increase filler loading to 60% and work well.
Nanofill
no glass fillers, only silica particles in the range 5-100 nm and aggregations of silica particles (nanoclusters). MOst common, filler loading 70-75%, POLISH WELL
Nanohybrids are
different in handling, more viscous, need to push against walls.
Nanoclusters, silicone (same as nanofill) but also SMALL GLASS. ALso universal, main ones available, no clinical evidence between nano and microhybrids.
Classification By Consistency
1- Conventional Putty Like consistency
2- Flowable: Light consistency
3- Packable aka Condensable/Moldable/HD
Distance of curing tip
~1.0mm Thickness of composite = 1.5mm
Flowable
use as intermediate layer.
Proximal contact difficult, this helps
heavy density
Bulk Fill Technique; Advantages
More efficiency particularly in larger restorations
Bulk Fill Technique: Disadvantages
1- Remember depth of cure!!!
Will the light be able to cure the innermost layers? Bulkfil resin that cure as a depth of 4mm
2- Remember Polymerization shrinkage as the resin cures!!! Shrinkage happens as the double bonds break to form single bonds Cumulative shrinkage as the material shrinks at the same time
3- Proximal contact are inadequate
Example: Sonicfill (Kerr dental) Tetric Evoceram (Ivoclar)
Comes in capsules that engage in a slow speed
Vibration of the slow speed makes the material less viscous during extrusion.
Stress relievers minimize the material from pulling cavity walls from
A special photo-initiator that increases the depth of cure
Thiexotropic
up to 4-5mm of restoration.
Layering Technique
Placement of composites and curing in increments Oblique or horizontal increments
Advantages
1- Minimizes the stress
from the polymerization shrinkage
Layering in the anterior teeth-
Use different shades to achieve a blending effect
Retainer systems
1- Tofflemire with circumferential bands
3- Sectional matrix
2- Retainless Tofflemire Absence of matrix retainer
Jetsoft bands (sectional matrix
thinner - 0.001”
Rings
prongs on rings produce the separation between teeth, some made of plastic others with silicone pads. Sectional need to be burnished well for contour.
Bands
precountoured sectional matrixband - thin 0.001”
Material - metal, polyester (clear or blue)
Thickness from 0.0015 to 0.001”
Wedges
seal margin to prevent overhang.
Should be of a height that does not prevent the formation of proximal contact
Wedges adjacent teeth to adjust for band thickness.
Steps
1- Anesthetic- Isolate- select shade- 2- Etch with Phosphoric acid 3- Rinse thoroughly : air-water spray copious water 4- Lightly air dry 5- Apply adhesive-cure 6- Apply and cure composite in layers
1.
Examine the margins of the preparation, have a plan
2.
Profound Anesthetic + shade selection+ check occlusion

3.
isolation
4.
Etch 37% phosphoric acid for 15 s
Rinse thoroughly
Gently dry never desiccate
5.
Apply 1-2 coats of adhesive lightly dry it
cure for 20s
Need , otherwise radiographs will look weird.
6.
Apply selected shade of composite in increments. Cure for 20s.
Etch with 37% phosphoric acid
Apply etchant for 15-20 seconds. Rinse thoroughly, dry.
Enamel drying following etching
bone dry is fine.
Dentin drying after etching
Don’t dry too much, collapse dentin, evaporate water outo f tubules. Bite sensitivity increases.
1- Total etch system: etch, rinse, apply bonding agent
- PH=2
- Preferred when there is enamel margins
- Two step: 2 bottle system etch, prime + bond
- Three step (conventional): 3 bottle etch, prime, bond
Self etch adhesive “No Etch and Rinse step”
- PH=3-5
- Two step: 2 bottle acidic primer, bonding agent
- One step: 1 bottle acidic primer + bonding agent
**doesn’t remove smear layer, smear layer just becomes a part of matrix layer.
Composite instruments
Contact former, BBL, CVIPC, 8A
Use bur for
lots of flash.
Air inhibited Layer
Bis-GMA and TEGMA are bifunctional monomers that harden by free radical induced polymerization. This reaction is strongly inhibited by free radical scavengers such as oxygen. The inhibition resulting from oxygen diffusing from atmosphere into curing resin is responsible for formation of a soft, sticky superficial layer on freshly polymerized resin, referred to as oxygen inhibited layer
Oxygen inhibited layer is always present when bonding agent or composite is polymerized in air. The oxygen inhibited layer is primarily composed of unreacted monomers and oligomers and possesses a liquid-like consistency
This layer not only readily adopts the overlying material to increase contacting area but also allows materials on both sides to cross the interface and blend together to form an interdiffused zone where copolymerization can take place to produce a chemical bond. All these actions will tend to strengthen layer-layer interaction
Air inhibited layer only
6-8 microns thick. Undercured, tacky and soft. Helps bond layers (soft to soft). POlishing and finishing removes this.
