In vitro study of enamel and dentin marginal integrity of composite and compomer restorations placed in primary teeth after diamond or Er:YAG laser cavity preparation.

PURPOSE: The aim of this in vitro study was to evaluate the effect of laser vs diamond instruments on Class II and Class V cavity margins in primary teeth with SEM after restoration with composite and compomer materials and subsequent thermocycling.

MATERIALS AND METHODS: Class V cavities with margins completely located in enamel were prepared in 36 extracted primary teeth to examine the restoration-enamel interface. Eighteen cavities were prepared with an Er:YAG laser operated at 3 Hz, 300 mJ/pulse, and 18 with a spherical fine diamond bur. In 24 primary teeth, Class II cavities with cervical proximal margins located in dentin were prepared for examination of the restoration-dentin interface. All Class II cavities were prepared with a conventional cylindrical diamond bur. In 12 cavities, the margins located in dentin were conditioned with an Er:YAG laser (1 Hz, 100 mJ/pulse). All cavities were restored with a fine hybrid composite resin or a compomer material.

RESULTS: SEM examination of Class V cavities after thermocycling (between 5 degrees C and 55 degrees C, 2500 cycles) revealed over 90% "perfect" margins in all composite fillings and in those compomer restorations applied after conventional preparation and acid etching. Compomer restorations placed without acid etching revealed a significantly superior marginal integrity in laser-prepared cavities (81% perfect margins) vs conventionally prepared cavities (60% perfect margins). SEM analysis of the dentinal margins of both compomer and composite restorations in Class II cavities showed mean percentages of perfect marginal adaptation ranging from only 13% to 66%.

CONCLUSION: Er:YAG laser treatment can be recommended for composite restorations in Class V cavities in primary teeth. Compomer restorations can be placed after conventional preparation of Class V cavities and acid etching or after laser preparation. Dentin bonding in Class II cavities in primary teeth is not sufficient and cannot be improved with Er:YAG laser pretreatment.