Class III and V Composite Preparations Flashcards
What is a class three prep?
interproximal areas in the anteriors
What is the first part of a class III pre-prep?
Clean the tooth!
◦ Pumice slurry
◦ Consepsis
◦ CHX
◦ No emollients that would affect bond
When should you select the shade of composite?
before placing the rubber dam
- dehydrating the tooth affects the shade
What do you do if you are unsure of what shade of composite to use?
Cure small blob of composite on tooth to check shade
- don’t etch and bond and the composite will flick off
What are the three color esthetic zones of the tooth?
- gingival = opaque
- middle = blend of incisal and gingival
- incisal = translucent
TAKE SHADE FROM PORTION OF SHADE GUIDE THAT IS…
MOST SIMILAR TO THICKNESS OF RESTORATION
When should you mark occlusion?
before applying the rubber dam
What is the shape of the class III prep?
wedge shape
Avoid margins of prep ending in…
occlusal contact areas
Where are the caries for a class III prep?
◦ Usually more lingual than facial
◦ Gingival to contact area
Where should you approach from doing a class III prep?
lingual
Why do you approach from the lingual on a class III prep?
◦ Caries tend to be more lingual
◦ Esthetics improved
◦ Discoloration and deterioration is less visible
◦ Color match is easier
◦ Facial enamel is conserved
◦ May be acceptable to leave unsupported enamel on facial and incisal wall of prep
Do you drill the incisal edge for a class III prep?
NO, Preserve incisal contact
◦ It may be acceptable to leave sound undermined enamel here
How should you do a class III prep?
Begin outline form
◦ Prepare PERPENDICULAR to long axis
Inciso-gingival height
◦ 1.5 on maxillary lateral
◦ 2.0 on maxillary central
Mesial distal width
◦ 1.0 on maxillary lateral
◦ 1.5 on maxillary central
Gingival contact is broken
Incisal contact is intact
For a class III prep you enter _________ to the long axis of the tooth
perpendicular
What should the inciso-gingival height be for the class III prep?
◦ 1.5 on maxillary lateral
◦ 2.0 on maxillary central
What should the mesial distal width be for the class III prep?
◦ 1.0 on maxillary lateral
◦ 1.5 on maxillary central
Where is the incisal point retention for a class III prep?
incisal portion of prep
- place with a 1/2 or 1/4 round
Where is the gingival groove retention for a class III prep?
at the gingival-axis line angle
- place with a 1/2 or 1/4 round
How deep are the retention points/grooves for the class III prep?
◦ Place point and groove where they would be in an ideal prep (even if the prep is deep)
Where do you bevel for a class III prep?
gingival and lingual boxes
◦ Place 1mm bevel lingual (or facial)
◦ 45 degrees
◦ Smooth, even
◦ Flame-shaped diamond bur
How much contact to you break facially?
minimally
If you would have heavy contact on the margin of a class III prep what can you do?
dovetail
- don’t bevel
◦ Enamel wears better than composite
◦ Enamel is stronger than composite
What do you do if caries are on the facial for a class III prep?
◦ Facial approach
◦ When lingual access may involve only centric contact of tooth
◦ Irregular tooth alignment or rotation
◦ Extensive caries on the facial
◦ Existing defective restoration on the facial
What is the root surface caries class III?
- same class III prep but do not bevel on dentin or cementum
What is a class V prep?
-Carious lesion in gingival third of tooth
◦ Can be buccal or lingual
What are the first things you do for a class V prep?
- clean the tooth
- select the shade
You mightuse a _____ clamp for class V preparation
212 clamp
What amount of light is required for sufficient output for composite?
more than 550 mW/cm^2
What is the axial wall of a class V preparation?
convex
What are the mesial and distal walls of the class V prep?
diverged
What is the axial depth of a class V prep?
1.0 mm
What is the incisal gingival height?
1.5 mm
What burs should you use to bevel a class V prep?
DIAMONDS
Where do you not bevel on a class V prep?
below CEJ
What is the modification for shallow caries or decalcified enamel ajacent to class V caries?
extend the bevel
What should you know about class V prep bevels?
◦ Increases surface area
◦ Increases retention
◦ Reduces microleakage
◦ Reduces margin discoloration
◦ Eliminates white “halo” effect= better esthetics
◦ Bevel ENDS of enamel rods
◦ Add Retention grooves
What are reasons for a class V prep besides caries?
- abrasion (wear with toothbrush, grinding)
- erosion (caused by acid; bulimia, GERD)
- abfraction (mechanical loss of tooth structure)
What can happen with a class V restoration on root surface?
- Polymerization shrinkage
- Causes contraction gap
- adding a retention groove can help
- maybe use other materials (amalgam, RMGI)
If someone needs class V preps for abrasion what do you tell patient?
◦ Discuss habits with patient, including brushing
◦ Bond strength to natural sclerotic dentin is 25-40% lower than to sound cervical dentin- REMOVE with bur
If someone needs class V preps for erosion what do you tell patient?
Discuss diet
◦ Chew/suck on lemons
◦ Frequent soda/energy drink intake
Discuss medical history
◦ Acid reflux
◦ Bulimia
◦ Dry mouth from medications
◦ Lack saliva to buffer acid
What causes abfraction?
◦ Flexure and fatigue of enamel and dentin
◦ Caused by occlusal forces (Microfractures, Heavy occlusal force in lateral or eccentric occlusion)
◦ Stress is concentrated at cervical area of tooth, causing fractures
When do you treat non-carious cervical lesions?
◦ Lesion is deep enough to compromise tooth
◦ Sensitivity
◦ Involved in partial denture design
◦ Defect is approaching pulp
◦ Defect contributes to a periodontal problem
What is the hydrodynamic theory of dentin sensitivity?
◦ Pain caused by dentinal fluid movement
◦ From mechanical or chemical stimuli
◦ Temperature changes
◦ Air drying
◦ Osmotic pressure
What are the causes of tooth sensitivity?
- Caries or leaky restoration
- Void- fluid flows into void
- Premature occlusion
- Exposed dentin (Recession or incomplete formation of CEJ)
- Exposed cementum
- Post- perio surgery
- Abrasion and erosion
What are noninvastive treatments for sensitivty?
◦ Topical fluoride
◦ Desensitizing dentifrices (toothpastes)
—Potassium nitrate in OTC
—Prevident 5000 Sensitive (prescription)
◦ Desensitizing agents (Gluma)
What is the goal of treatment for sensivity?
Aim is to occlude tubules to stop fluid movement
What is fluoride varnish?
a sticky, yellow, semi-liquid containing 5% NaF in a resin base mixed with alcohol to dry quickly after application
Patient should avoid brushing teeth for at least __ hours after application
6 hours
Densensitizing toothpastes may take ____ months for results to show
1-3
What is in sensodyne?
Strontium chloride 10% and Potassium Nitrate (KNO-gunpowder)
What is the process of applying gluma?
◦ Place after etching (for composite restorations)
◦ Lightly dry
◦ Place bonding agent
◦ Place composite
◦ Can also be used with amalgam, but fewer steps
If you have sensitivity in class V lesions when do you restore?
- Esthetic desire of patient
- Lesion >1.0mm depth
- Possible pulp exposure
- Structural integrity of tooth is threatened
Why does treatment/restorations for sensivity work?
blocks tubules
Why do treatments work to stop sensivity?
- Protein coagulation
- Enzyme interference, blocking nerve impulses
- Induction of tertiary dentin
- Various precipitates in dentinal tubules block fluid movement
- Destruction of odontoblasts
- Placebo effect (40% of patients respond to application of distilled water)
