Faculty Bibliography

OBJECTIVE:Marginal leakage of amalgam restorations may lead to secondary caries and pulpal damage. The purpose of this study was to determine the effect various cavity liners might have on microleakage. METHOD AND MATERIALS/METHODS:Mesio-occlusodistal amalgam restorations with margins on enamel and dentin were treated with different liner materials (an adhesive system, a topical fluoride gel, a cavity varnish, and a glass-ionomer cement) in vitro. Following restoration, the teeth were submitted to thermocycling in a stained solution and sectioned to allow assessment of microleakage. RESULTS:On enamel, the control group (no liner) and the glass-ionomer-lined group had equivalent leakage scores and were superior to every other group. On dentin, only the glass-ionomer specimens had superior performance. The cavity varnish and fluoride-lined specimens exhibited the highest leakage scores. CONCLUSION/CONCLUSIONS:The use of liners does not reduce microleakage on amalgam restorations when the cavity margins remain on enamel. On dentin margins, a glass-ionomer liner can reduce microleakage.

The purpose of this in vitro study was to compare marginal leakage of class 2 light-cured composite resin restorations, with different insertion and polymerization techniques. Fifty sound premolars extracted for prosthetic purposes were used in the study. Conservative class 2 (MOD) preparations were made in all teeth, with one proximogingival margin on enamel and the other on cementum. All the preparations and restorations were performed by the same operator utilizing the same restorative materials. After restoration the teeth were thermocycled and their gingival margins exposed to a dye. Results showed that the kind of matrix system had no significant influence upon the degree of marginal leakage on enamel. On cementum, oblique and horizontal incremental insertion and polymerization techniques using the collimator cone exhibited the least leakage, while the clear matrix band/reflective wedge technique presented the greatest leakage.

The development of advanced adhesive systems has made it possible to bond various substrates, e.g., composite resin and vital or nonvital tooth structures. The management of coronal and coronoradicular fractures in the maxillary region with these adhesive materials is easier, safer, and more efficacious than the use of traditional treatment alternatives that involve the use of posts and cores and/or other mechanical devices to obtain retention. Ability to bond the dislocated segment of the fractured tooth constitutes a significant step forward in the management of this clinical condition.

The purpose of this study was to establish the influence that finishing and polishing of existing amalgam restorations might have on the decision to replace them. Forty extracted teeth, in which amalgam restorations had been placed in vivo, were individually examined by 60 practitioners and students prior to and following standard finishing and polishing procedures. Examiners, who had not been informed of the study's methodology or objective, opted either for maintaining or replacing the restoration in question. The main reasons for replacement were also registered. Finishing and polishing significantly reduced the number of decisions to replace restorations in all groups and for all practitioners. "Appearance" (anatomic shape) was the most frequently cited reason for replacing restorations before finishing and polishing, followed by marginal defects and secondary caries.

A new technique for the performance of resin composite direct restorations on posterior teeth is presented. A clear acrylic resin matrix, fabricated prior to the preparation of the occlusal and proximal surfaces, is employed. The matrix allows the fast and accurate reproduction of the anatomic details from the original occlusal surface of the tooth, as well as the marginal ridges in the case of Class II (occlusoproximal) restorations. Advantages and limitations of the procedure are discussed.