export_jvd2014314use of composite restoration materials COPY Flashcards
Foundations: Use of Composite Restoration Materials, Ellen D. Domnick
JVD 2014 Winter 31(4) p280-288
Goals of restoration
- pain-free, functional esthetic tooth
- withstand normal occlusal forces
- retain natural tooth structure as much as possible
Preparation of the tooth to be restored
scaled supra and subgingivally, polished with non fluoride paste so as to not interfere with chemical bonding
Preparation of tooth according to Black
- resistance
- retention
- convenience
- pathology removal
- wall and preparation cleansing forms
Beveling tooth’s cavosurface margins is recommended in what class of cavity? why?
in class III - VI, greater retention strength due to greater enamel surface area and improves esthetics.
Cavity classification: Class I
Class I: pit and fissure caries
What is a Class II cavity?
Class II lesions are the extension of the Class I lesion into the proximal surfaces of premolars and molars
Class III Cavity
cavities in proximal surfaces of cuspids and incisors that do not involve the incisal edge
What is the proximal surface of a tooth?
Surface of tooth facing towards adjoining teeth in the same dental arch (mesial, distal)
Class IV Cavity
Interproximal surface to include incisal edge
-mesial/distal of anterior teeth
cavity classification class V
cavities of the gingival third of the labial, buccal, or lingual surfaces of the teeth.
Beveling of occlusal cavosurfaces in class I and II preparations is contraindicated because..
enlarges the surface area of the restorative in occlusion
What tool can be used to smooth and remove all unsupported enamel rods or undercuts secondary to pathology?
hand curette, or excavator
What type of bur can be used to remove rough edges
a round taper fine diamond bur, conical arkansas white stone bur followed by sanding discs to further smooth fractured dentin and enamel
What type of acid etch is recommended and at what concentration for dentin and enamel?
phosphoric acid is most common,
10 - 38% in dentin, 35 - 38 % in enamel
purpose of the acid etchant
- removes smear layer
- opens micropores in enamel and dentin to allow resin to penetrate
- dentin demineralized
- roughens surface of enamel
How long should enamel be etched?
dentin?
20 sec enamel
10 - 15 sec dentin
How long is the etch rinsed?
15 to 20 sec rinse to fully remove the etchant
What happens when there is prolonged drying?
flattens the collagen fibers, decreasing bond strength
Bonding agents
-liquid
-unfilled or lightly filled resins of a primer and adhesive
-Newer bonding agents combine the primer and adhesive
improve retention of restorative, prevent leakage, decrease discoloration and pulp sensitivity
How long will the bonding agent provide protection?
3 to 12 months, allowing time for the tooth to repair itself
How deep does bonding agent penetrate
200 - 400 microns
All teeth that have been sealed should be radiographed ___ to___ months post procedure
6 - 12 months, to be sure the tooth has not become infected or non vital.
Enamel and dentin composition
Enamel- 96% mineral, 4% water and organic
Dentin- 70% mineral, 30% water and organic
Cementum even softer
Was dentin etched in 1st and 2nd gen bonding agents?
no etch, bonding was with smear layer, had poor bond strength and easily hydrolyzed and cracked
third generation bonding agents
- oxalate bonding agent
- separate primer and adhesive
- used etchant to remove or modify smear layer
- time consuming and unpredictible
fourth generation bonding agents
- remove smear layer completely
- better bond strength
- create beneficial hybrid layer from polymerized methacrylate and dentin
- resin monomers penetrate demineralized dentin and polymerize
- TWO BOTTLES (PRIMER AND ADHESIVE)
- TOTAL ETCH TECHNIQUE
Etch “Total Etch technique”
3 step method– etch is a separate step and acts as a conditioner and cleanser, 37% phosphoric acid, purpose: alters or removes the smear layer
FIFTH generation bonding agent***
one bottle bonding system
- combines primer and adhesive, after using total etch
- micromechanical interlock with etched dentin with resin tags, adhesive lateral branches, formation of hybrid layer, high bond strength to enamel and dentin
development of bonding agents: 6th Generation type 1
mid to late 90s
no phosphoric acid
self-etching primer and adhesive
applied separately
less reliable results
eliminate collagen collapse
development of bonding agents: 6th Generation type 2
- mid to late 90s
- acidic primer and adhesive are mixed before application
- less reliable
- acid etch and rinse not required
development of bonding agents: 7th Generation
early 2000s
phosphoric acid only for ground enamel
self etching primers and primer adhesives
some release fluoride
similar bond and seal to 6th generation
“All-in-one”solutions
What are the two phases of composite resins?
- polymerizable resin base
2. filler particles
How are composite polymerized?
- light cure
- chemical cure
- dual cure
light cure wavelength
460 to 480 nm
How deep should the composite layer be applied?
< 2 mm deep and in layers to allow proper light cure and polymerization
Flowable composite resin
- better handling
- less fillers
- more controlled setting and working times
- good for grooves and smaller preps
Filler size and content affect the characteristics of the composite, what are the 4 types
- macrofill
- microfill
- intermediate fill
- hybrids
Which has the best durability and strength
macro and intermediate fill composite resins
what are disadvantages of macrofill
grainy, least esthetic, do not polish well
What are good and bad quality of microfills
polish well, best esthetics, but least resistent to fractures
hybrid composites
includes more then one type of filler particle, usually glass & silica; combine micro and intermediate sized filler particles
less polymerization and good flexural strength
stronger & less likely to fracture in high-stress areas
thickness enamel cats and dogs
cats 0.1-0.3 mm
dogs 0.1-1.0.mm
Crossley JVD 1995
Current theory of nerve stimulation in the tooth is due to ____
fluid dynamics
Can a tooth repair itself and how long does it take?
Yes, but it takes 8 weeks to begin
