principles of tooth preparation Flashcards
what is an indirect restoration
it is a restoration that is made in the lab such as a crown which requires a impression to be taken on a model
what are the types of indirect restorations
crown
veneer
onlay
inlay
why do we need indirect restorations
aesthetics
comfort
function
stability
what can be the issues with indirect restorations
take longer to make
longer attendance
cost more
why do we need to prepare the tooth
To allow for space to be created
When making the poured model we use a die spacer to create some room for the cement
what happens if there is no preparation of the tooth
If there was inadequate cement it would lead to a bulky appearance
how do we prepare the tooth tissue
We need to consider at least the two planes on the buccal aspect- the bucco incisal plane must also be reduced adequately and the natural shape of the tooth should be followed
The space will vary according the the material of choice but we should take into consideration the functional cusp which provide support. And the type of margin where a shoulder is thicker for porcelain compared to a chamfer for a metal finish line
what re the issues with under preparing
inadequate space for the ECR,leading to thin material
what are issues with underpreparing at the chamfer
can lead to fracture and exposure of the tissue tooth
what are some issues with over preparation
leads to XS tooth tissue being lost and closeness to the pulp
define retention
prevents the removal of the ECR along the path of insertion
maintaining the tooth in place from horizontal forces
define resistance
prevents dislodgement from lateral forces
why do we need to make the tooth a taper shape
the more retention and resistance
what are we aiming for in regards to taper
6-12 degrees
what should optimal tooth tissue have
Preserve tooth tissue Provide good retention and resistance Allow visible finish line Allow adequate seating of the ECR Between 6-12 degrees is a clinically acceptable taper
