Stainless steel crowns were introduced to pediatric dentistry by the Rocky Mountain Company in 1947 and made popular by W. P. Humphrey in 1950. Until then the treatment for grossly decayed primary teeth was extractions. Stainless steel is composed of iron, carbon, chromium, nickel, manganese and other metals. The term stainless steel is used when the chromium contents exceeds 11% (usually a range of 12 to 30%. The chromium oxidizes and forms a protective film of chromium oxide which protects against corrosion. While originally intended for the restoration of posterior primary and young permanent teeth, its use was expanded to badly decayed anterior teeth. Although, more durable and retentive than amalgam or composite they are unaesthetic, especially on the anterior teeth. With aesthetics of their child’s smile of extreme importance to parents, many opted for extraction and prosthetic replacement of severely decayed teeth rather than placement of stainless steel crowns. The advent of composite bonding, allowed for a composite facing to be placed on the facial surface of the tooth, thus improving aesthetics. Open faced stainless steel crowns combine strength, durability and improved aesthetics, however they are time consuming to place as thecomposite facing cannot be placed until the stainless steel crown cement sets. Bleeding of the color of the metal margins surrounding the composite adds a grayish tinge to the tooth that is accentuated next to the white enamel of an adjoining or opposing primary tooth.
Manufacturers of anterior stainless steel crowns are: 3M Espe-Unitek Crowns, St. Paul, MN; Cheng Crowns, Exton, PA; Hufriedy Manufacturing Inc, Chicago, IL and Acero Crowns, Seattle, WA.
The advantages and disadvantages of stainless steel crowns and open faced stainless steel crowns are summarized as follows:
Although stainless steel crowns, as a standalone technique for anteriorrestorations, are rarely used, mastering the technique is necessary forfabrication of the more aesthetic open faced stainless steel crown.
Stainless Steel Crown Technique
Anterior crowns are manufactured with an ovoid shape with a small facio-lingual dimension. Change the shape to allow the crown to passively slip on the tooth. Squeeze the crown slightly mesio-distally with a pair of Howe no. 110 pliers to increase the facio-lingual dimension.
Reseat the crown. The crown should extend 1mm under the gingival margin. The fit of the crown should be snug without rocking.
Contouring and crimping are necessary to insure a good marginal fit. Use a no. 137 Gordon plier to adapt the margin. Check the marginal fit with an explorer.
Repeat the procedure for the remaining teeth.
While more aesthetic than a conventional stainless steel crown, a shortcoming of an open faced stainless steel crown is the bleeding of the metal color from the lingual and interproximal surfaces through the composite resulting in a grayish tinge to the facing.