scr - restorative & professionalism Flashcards
caries on radiograph
if 2/3s way through enamel dentine affected
* caries always deeper than what it looks on radiograph
if caries subgingival
difficulty achieving moisture control & if reaching pulp = RCT / XLA
what to check when considering to restore or not to restore
TAP
t - tooth
a - apical tissues
p - periodontal tissues
principles of caries removal
- identify carious lesion
- remove enamel to extent of lesion at ADJ
- remove caries at outer extent moving circumferentially deeper
- remove deep caries over the pulp
- smooth cavosurface margins & check occlusion
- internal design modification = line angle, point angle
when would you select a crown
as a last resort:
- failed previous restoration
- insufficient tooth tissue present to retain comp / AM / veneer
- RCT of molar as gives cuspal coverage
- RCT of anterior
note - pt requires stabilised gingival margins
risks of crowns
- risk of pulp exposure
- crown margins = caries risk & perio
- crown #
- metal showing at margins due to recession of gingiva
- wear to opposing teeth
- only expected to last approx 10 yrs
benefits of placing crowns
- aesthetics
- function
- reduced risk of # of extensively restored teeth
- retentive & strong
- only restorative option left other than XLA & space fill
principles of crown prep
- preserve tooth structure
- retention (6 degree taper) & resistance (longer walls)
- structural durability - occlusal reduction, axial reduction, functional cusp bevel
- marginal integrity;
chamfer - for metal / veneer & shoulder - for MCC (wider margin required for thickness of metal & ceramic) - preservation of periodontium; margins should not impinge on supra crestal attachment
- aesthetics - should be least destructive to tooth tissue / least destructive to opposing dentition
to check diameter of crown prep
BPE probe tip = 0.5mm
flat fissure bur = 1mm
shoulder bur = 1.3mm
chamfer = 1.1mm
+/- of MCC
increased strength
increased labial reduction (to fit ceramic & metal) so more destructive
possible metal shine through (anterior)
1.5-2mm occlusal reduction
0.5mm lingual chamfer
1.3mm buccal shoulder
metal = CoCr
ceramic = zirconia / lithium disilicate
+/- all ceramic crowns e.g. emax
LiDiSi
glass based & etchable, bonded with resin cement, better aesthetic, more expensive, low strength, won’t mask underlying dark colour
occlusal reduction 1.5-2mm
axial reduction 1.2-1.5mm
margins = 1-1.5mm chamfer (or shoulder depending on core used)
gold crown +/-
not aesthetic but less destructive so can be useful in posterior
zirconia / alumina crown +/-
high strength, opaque so masks underlying dark colours, not etchable, cemented with resin cement, wear of opposing teeth, increased cost
for aesthetics margins should be
sub gingival
if not for aesthetic zone prep should be supragingival
if GI used to cement crown what post op advice do you give pt
avoid sticky / chewy foods in first 24-48hrs until GI has fully set