principles of cavity preparation? Flashcards
who classified cavities and when?
greene vardiman black
1896
what is a class one cavity?
occlusal surfaces of pre molars and molars
buccal pits of molars
what is a class two cavity?
approxial surfaces of molars and pre molars
what is a class 3 cavity?
approximal surfaces of incisors and canines
what is a class 4?
incisal edges of incisors and canines
what is class 5?
cervical margins
what are the disadvantages of blacks classification?
pre adhesive materials- retentive cavities needed to be cut
removes more tooth substance than is necessary
does not include root caries and secondary caries
what are the principles of cavity prep?
outline form resistance form retention form tx of residual caries correction of enamel margins cavity debridement
what is outline form?
gaining access to caries
traditionally but cutting through overlying enamel
what is resistance form?
to resist occlusal forces
the enable to restoration and remaining tooth structure to withstand masticatory forces
cavity floor at rights angle to occlusal forces
at least 2mm depth
what should be considered re. resistance form for amalgam
no unsupported enamel should remain
unsupported enamel will fracture if overloaded
what should be considered re. resistance/retention from for adhesive materials?
don’t require retention or resistance form
what is retention form?
to allow material to be retained in the cavity
what are forms of retention?
grooves in cavity walls undercut cavity occlusal keys bonded amalgams dentine pins- no longer used
what is meant by treatment of residual caries?
caries removed from ADJ first
soft dentine should be removes
stained, but firm dentine can be let
preserve oblique ridge where possible in max molars
how is caries removed?
slow rotating bur
finished with hand excavation
what is meant by correction of enamel margins?
removing unsupported, weak enamel
facilitate placement of matrix
bevel to increase surface area for bonding
what is meant by cavity debridement?
cavity should be thoroughly washed to remove debris and bacteria
what is a line angle?
where two lines/surfaces meet
what is a cavosurface angle?
where cavity wall meets tooth surface (crown)
should be 90-110 degrees
what is point angle?
where 3 lines/surfaces meet
