indications for crowns and pre-operative assessment Flashcards
(25 cards)
remember
Crown is an indirect full coverage extra-coronal restoration that is cemented/luted to a prepared tooth. They can also be used to retain a prosthesis e.g. partial denture
what can crowns be made of? 4
Gold alloy
Ceramic
Metal bonded to ceramic
Non precious metal alloy - cobalt chrome, nickel chromium
indications for crowns 7
repeated failure of direct restoration
difficulty creating direct restoration
minimise risk of tooth fracture
aesthetics
for denture abutment teeth
bridge abutment
replacement of existing crown
a crown is indicated when u can’t achieve what 3 things with a direct restoration?
Contour - difficult to maintain good OH -> caries, perio disease, poor aesthetics
Contact point - food packing, difficult cleaning -> perio disease, 2* caries
Occlusal contacts - increased risk of restoration fracture, microleakage and 2* caries
when is a tooth with cracks unrestorable?
if cracks extend to root
how can crowns include design characteristics to accommodate a metal based removable prosthesis
incorporated rest seat and long guide plane
when can u justify a crown as a bridge abutment?
already heavily restored tooth
what do u need to consider if you r wanting to replace an existing crown?
why the crown failed to assess suitability of another crown
which has a better survival rate: crown or MOD amalgam?
crown has double the survival rate
molar teeth that are root treated or not root treated have an increased risk of root fracture?
root treated
RCT teeth with crowns have a higher or lower risk of root fracture?
lower risk of fracture
what is Supra-crestal attachment / gingival/biological width
Area of gingival attachment above the alveolar bone
how does Area of gingival attachment above the alveolar bone important to consider with crowns?
- If crown encroaches on the biological width can get rejected by gingivae leading to loss of support of the tooth
what are the two categories of crown failure?
mechanical failure
aesthetic failure
give 3 examples of mechanical failure of crowns
Ceramic fracture
occlusal wear
cement failure
give 3 examples of aesthetic failure of crowns
Visible margins, colour, shape and size
give 3 risks of crown prep
Heat can damage the pulp
Exposure of dentine tubules - bacterial ingress to the pulp and sensitivity
Pulp exposure
remember
Crowned teeth are one step closer to needing extraction - less tooth remaining to restore
5 indications to not use a crown
lifestyle factors that negatively affect oral health
active caries or perio disease
inadequate crown height
inadequate access
more minimally invasive option
give examples when access might be affected meaning that a crown can’t be given?
cant open mouth wide enough
Sclerosis - scleroderma, post radiation changes
Post surgical changes
The pre-operative assessment allows us to find out if a crown is a good idea
give patient factors to consider 3
Pt concerns, expectations, can u meet these?
Can the pt tolerate the procedure -> anxiety, gagging
Will the pt be able to maintain the restoration -> physical impairment - tremors, arthritis
The pre-operative assessment allows us to find out if a crown is a good idea
what factors in the mouth need to be considered? 8
OH - good
active disease?
occlusal dysfunction
sound tooth foundation
endodontic state
enough tooth tissue
enough space - OVD
occlusal relationship - guidance
how does crown prep affect vitality?
tooth more likely to become non-vital after crown prep
do we want canine guidance or group function for a crown?
canine guidance
