Week 6 - Class IV and V Composites Flashcards
what are the differences between class III prep and class IV
- same principles but incisal angle is missing
- increase the bevel and extend beyond the bevel with the resin for more retention and a better esthetic appearance
what might be necessary on a large fracture for extra retention
a labial veneer or full coverage crown
describe a class V prep
- axial wall is convex
- mesial and distal walls diverged
- incisal gingival height is 1.5mm
- axial depth 1.0mm
what does bevelling do and what bur should you use to do it
- diamonds
- increases surface area
- increases retention
- reduced microleakage
where should you bevel on the tooth
ends of enamel rods
what does the reduction of microleakage decrease
- reduces margin discoloration
- eliminations white halo effect for better esthetics
what do you do for shallow caries or decalcified enamel adjacent to class V caries
basically an extended bevel
what do you need to consider when class V restorations extend onto the root surface
- polymerization shrinkage is greater than bond to cementum or dentin
- causes contraction gap
what can minimize the contraction gap
retention groove
what materials should you consider using in root surface caries and why
RMGI to reduce microleakage
- amalgam
what the are non carious cervical lesions
- abrasion
- erosion
- abfraction
what is abrasion
- wear from toothbrushing, pen chewing, occlusal wear from grinding
what is erosion
- caused by acid
- bullemia
- GERD
- alcoholics
-extreme diet
what is abfraction
- mechanical loss of tooth structure
- loading forces arent where theyre supposed to be
- flexure of tooth and failure of enamel and dentin
dentin wears_____ times easier than enamel
25-125
bond strength to natural sclerotic dentin is ____ lower than to sound cervical dentin- ______
25-40%; remove with bur
what diet can cause erosion
- chewing or sucking on lemons
- frequent soda/energy drink intake
where is stress concentrated on the tooth that causes abfraction
cervical area
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 should you try to do with sensitivity in non carious lesionsbefore treating it with restoration
attempt non surgical treatment such as toothpaste and topical fluoride
do you need to prep abrasion tooth
not really
what should you consider when deciding when to treat sensitivity in class V lesions
- when to restore vs when to leave
- esthetic desire of patient
- lesion greater than 1.0mm depth and progressing
- possible pulp exposure
- structural integrity of tooth is threatened
