stainless steel crowns Flashcards
what are the 6 indications for stainless steel crowns?
- CARIES INVOLVING TWO OR MORE SURFACES
• Extensive carious destruction for which caries control is indicated but retention of the filling material is uncertain.
• In some cases even a large occlusal lesion (high caries risk and extensive occlusal involvement) - RAMPANT CARIES
- RECURRENT CARIES
- FOLLOWING PULP THERAPY
- ENAMEL OR DENTINE DEFECTS
Such as hypoplastic enamel, amelogenesis imperfecta, or dentinogenesis imperfecta - Teeth used as abutments for space maintainers
what do you need to do before you prep for a SSC? HOW DO YOU DO THE OCCLUSAL REDUCTION AND INTERPROXIMAL REDUCTION?
• Good Anaesthesia • Rubber dam
prior to rubber dam placemtne check for any: occlusal changes, extrusion of opposig teeth and mesial drift due to carious involvement of adjacent teeth. these situations may greatlay complicate a relatively easy procedure.
rubber dam should be used as it retracts and protects the interproximal tissues and prevents accidental ingestions or aspiration of the crown. The dam may have to be removed to check the final fit and occlusion prior to final cementation.
Wedges can be placed interproximally to help protect adjacent tooth surfaces and help retract the gingival tissues.
OCCLUSAL REDUCTION
• A tapered diamond
• 1–11⁄2mm
• Compare to marginal ridge of adjacent tooth
AFTER YOU HAVE DONE YOUR OCCLUSAL REDUCTION, DO A BEVEL ON THE BUCCAL AND LINGUAL AND THEN SMOOTH THAT OUT, BUT YOU DO THE BEVEL SO YOU DON’T HAVE TO TAKE OUT AS MUCH TOOTH STRUCTURE WHEN YOU ANGLE YOUR BUR TO GET DOWN INTO THE GINGIVA AND CREATE THAT KNIFE EDGE ANGLE
INTERPROXIMAL REDUCTION
Slice the mesial and distal surfaces with a K1 diamond or a No. 169 L bur
• Avoid damage on adjacent teeth
• Hold bur slightly at an angle to the long axis of the tooth
“Smoothing”
For a SSC prep, how do you do the buccal and lingual reduction?
- Follow contour
- Minimal reduction - especially in the lingual.
- Extend to gingival margin
how do you get retention of the SSC?
RETENTION: Withinthe1 mm of tooth at the cervical constriction beneath the feather margin
the final outline should be reflected by the internal outline of the SSC
for crown selection what is an ION crown? UNITEK crown? what are the indications for them?
1) Pre contoured/crimped and trimmed - need very little if any modification on ideal preparations (ION)
- ideal situations they can be used with relative ease.
2) Not pre contoured/crimped and trimmed - which do require trimming and crimping for all preparations. (UNITEK)
- required in non ideal situations, i.e. teeth with extensive caries and deep subgingival caries. can also be used in ideal situations but require more crimping and trimming
what are the comparative success rtes of Class II amalgam restorations versus stainless steel crowns?
- 7% of class II amalgam restorations required replacement
30. 0% of SSCs required replacement.
For the unitek speaking of adaptation, how should crowns be selected?
select a crown with adequate mesio-distal width that re-establishes contact with the adjacent teeth. The contralateral tooth in the arch if it is sound can be used to determine the original mesio-distal sidth of the prepared tooth, especially if it was extensively involved with caries.
the crown should clear the occlusion and extend 0.5-1 mm subgingivally after trimming and crimping.
Try the crown on the tooth. Initially the crown may be 2-5 mm too long. To trim it to the appropriate length, maintain finger pressure on the crown, scribe a line with a scaler on the crown representing the free gingival margin, on the buccal and lingal surfaces
Remove the cornw from the tooth. Using crown and bridge scissors cut the crown 1mm below the scribed line.
Retry the crown on the tooth. The margins of the crown should now extend roughly 1mm subgingivally. If gingiavl blanching occurs the crown may be overextended subgingivally and requires further trimming of the margins. If the crown does not seat fully; further occlusal reduction may be necessary or the crown is either too large or too small.
Remove the crown and use the contouring pliers to recontour the gingival 1/3 of the crown
Use the crimping pliers to slightly crimp the margins of the crown (gently bend the margins only).
Retry the crown on the tooth, it should snap into place with firm pressure. Check the margins with an explorer. If they are excessively open use the pliers to re-crimp the area.
After trying the crown on the tooth, it may be necessary to again use the crown crimping pliers to re-establish the desired contour and retention of the gingival third of the crown before cementing.
Ball and socket pliers or howe pliers can be used to modify or establish mesial and distal contacts in the stainless steel crown.
what direction should the SSC be tried on?
Try on lingual and rotate to the buccal. It should snap into position.
what is usually required in the way of crimping or trimming for ION and UNITEK crowns?
For ION crown – may need to trim but rare – will usually crimp
UNITEK or untrimmed/contoured – will need to trim, contour and crimp
what type of pliers do you use for contouring the gingival third?
no. 114 pliers
what pliers do you use to crimp at the margins?
800-417 pliers
What do you use howe pliers for? what about ball and socket pliers?
howe for flattening the contacts of the crown.
ball and socket to expand the contacts.
what advantages does finishing and polishing have?
finishing and plishing the margins of the modified stainless steel crown reduces plaque retention and minimizes gingival irritation in the finished restoration.
- using a green stone finishes the cervical margins of the crown to a smooth thin edge.
- polish the margin with a rubber wheel
For cementation, how is it performed?
- rubber dam may have to be removed to evaluate occlusion. USE EXTREME CAUTION TO PREVENT ASPIRATION OF THE CROWN!!!!!
- remove any debris from the tooth surface by gently washing the area with warm water.
- if the rubber dam has been removed, isolate the quadrant to be treated with cotton rolls and dry the teeth with an air stream.
- polycarboxylate or zinc phosphate cement is mixed to inlay consistency and placed in the crown. Seath the crown from lingual to buccal until snap.
- remove any excess cement after it has set with an explorer or scaler. Both mesial and distal contacts must be flossed to remove cement lodged in these areas. Any cement left interproximally or subgingivally will severely irritate the periodontal tissues.
does it matter if the cement gets a little bit wet?
no, there is also fluoride in the cement
