Pre-veneered Stainless Steel Crowns

Pre-veneered stainless steel crowns resolve some of the problems associated with stainless steel crowns, open faced stainless steel crowns, and composite strip crowns. They were introduced in the mid 1990’s. They are aesthetic, placement and cementation are not significantly affected by hemorrhage and saliva and can be placed in a single appointment. The stainless steel crown is covered on its buccal or facial surface with a tooth colored coating of polyester/epoxy hybrid composition.

A clinical disadvantage is they are relatively inflexible as the resin facing is brittle and tends to fracture when subjected to heavy forces or crimping. Because only the lingual portion of the crown can be adjusted (crimped), significant removal of tooth structure must be performed to fit the tooth to the crown rather than the crown to the tooth. There is limited shade choice. They are more expensive to purchase than stainless steel crowns and strip crown forms (approximately $18 vs. $6) yet less expensive than zirconia crowns ($18 vs. $25).

Pre-veneered stainless steel crowns are available from various manufacturers (Kinder Krowns, Mayclin Dental Studios, Minneapolis, MN; Dura Crowns, Space Mainttiners Laboratory, Van Nuys, CA; NuSmile Primary Crowns, Houston, TX; Cheng Crowns, Peter Cheng Orthodontic Laboratories, Philadelphia, PA).

Advantages

  • They are aesthetically pleasing.
  • They require relatively short operating time.
  • They have the durability of a steel crown.
  • They are less moisture sensitive during placement than composite strip crowns.

Disadvantages

  • They are 3 times more expensive than stainless steel and strip crowns ($18 vs. $6) but less expensive than zirconia crowns ($25-$30).
  • The technique does not allow for major recontouring and reshaping of the crown.
  • The tooth is adjusted to fit the crown, rather than adjusting the crown to fit the tooth.
  • As crimping is limited to lingual surfaces there is not close adaptation of crown to tooth.
  • There are reports of the veneer facing fracturing, however it can be easily repaired using the open faced stainless steel crown technique.


fig45
Pre-veneered Stainless Steel Crown Technique
  • Size the crown to the tooth by placing the incisal edge of the crown against the incisal edge of the tooth.


fig46
  • Prepare the tooth as for a standard stainless steel crown, however more circumferential tooth reduction required.


fig47
  • Refine the prep to fit the crown.
  • Do not force the crown on the tooth.
  • A properly fitted crown has a passive fit.
  • The crown should extend 1mm past the gingival margin.


fig48
  • The length of the crown is altered by trimming the gingival margin with a diamond bur and water spray.


fig49
  • The lingual aspect of the crown may be crimped slightly with a no. 137 Gordon plier.
  • Too much crimping of the metal substructure may cause fractures in the veneer material.


fig50
  • The crown is cemented with glass ionomer cement.
fig51
fig52
  • The excess cement is removed and the remainder is allowed to set.
fig53
  • After cementation the incisal edges may be contoured with a finishing disk or point.
fig54
  • The smaller lateral crowns may be used on lower anterior teeth.
  • Cold sterilization in glutaraldehyde is recommended.
  • If the veneer fractures a similar technique to the open-faced crown may be used for repair.
fig55