Using Margin Elevation with Bonded Ceramics: A Case Report.

Abstract

Thirty years ago, glass ionomer was first used as a means of bonding resin matrix composite to dentin. Today this method is used to elevate the margin of a preparation to a level which gives the clinician more access to the operating field. This technique has been described in the dental literature with resin composites bonded with resin adhesives. There are still inherent problems with this approach, however, since resin adhesives are subject to hydrolysis, marginal leakage, and recurrent caries. Studies have demonstrated the ability of glass ionomer to chemically bond to dentin; glass ionomer can also be dissolved/etched by phosphoric acid and predictably bonded to resin composites, eliminating the problem of hybrid layer hydrolysis which occurs with resin bonding agents. Margin elevation takes advantage of the favorable properties of glass ionomer cements (adhesion through chemical bond to dentin, fluoride release, biocompatibility, coefficient of thermal expansion similar to tooth structure, and decreased interfacial bacteria penetration/caries activity) while allowing overlaying of a suitable direct or indirect restorative material. This technique should be utilized when a preparation stands an increased risk of contamination or has a gingival margin on dentin/cementum. This case describes restoration of a tooth with a deep subgingival margin located on cervical dentin. The tooth was prepared for a ceramic onlay. Resin-modified glass ionomer was then inserted into the mesial proximal box and re-prepared with the occlusal wall of the glass ionomer becoming the new gingival margin, allowing significantly increased access and isolation. The tooth was then restored with an e.max onlay and cemented with RelyX Unicem. The restoration has been examined at a 6-month recall. With proper case selection and attention to detail, glass ionomer margin elevation is an excellent technique for bonding ceramics to teeth which cannot be isolated adequately for impression and/or resin bonding.