Comparison of pulse activation vs conventional light-curing on marginal adaptation of a compomer conditioned using a total-etch or a self-etch technique

Objectives: This study investigated the effect of two factors: conditioning methods and light-curing techniques on the marginal adaptation of Dyract AP (Dentsply DeTrey, Germany). The 'pulse activation' curing technique was compared with a conventional light-curing technique for their effectiveness in reducing marginal gaps in restorations that were conditioned with three different protocols. Materials and methods: Cylindrical cavities, 3 mm in diameter, were prepared in extracted human molar teeth. They were restored with Dyract AP using PrimeBond NT (PBNT; Dentsply DeTrey) as the adhesive. Cavities were etched with: Conditioner36/PBNT (group 1), Non-Rinse Conditioner (NRC)/PBNT (group 2), and PBNT only (group 3). Either conventional or the 'pulse activation' technique was used for light-curing of the material. Epoxy resin replicas were obtained from longitudinal sections of the specimens, and the restoration-tooth interfaces were examined using scanning electron microscopy. Marginal qualities along the resin-dentin interfaces were further measured using image analysis and analyzed using nonparametric statistical methods. Results: With the conventional curing technique, enamel margin fractures were frequently observed. Marginal gaps were found along the compomer-dentin interfaces irrespective of the conditioning protocol. A significantly lower percentage of gap-containing margins were found in cavities that were conditioned with 36% phosphoric acid. With the 'pulse activation' technique, no marginal gap was found along compomer-dentin interfaces that were etched with either Conditioner36 or NRC. More than 90% of the total margin length were excellent. No cohesive failure of enamel could be observed along cavosurface margins. Significance: The 'pulse activation' curing technique significantly improves the marginal integrity of Dyract AP when Conditioner36/Prime&Bond NT and NRC/Prime&Bond NT are used as conditioning/bonding systems. The use of Prime&Bond NT without etching is not recommended, as marginal gaps are present irrespective of the curing techniques employed. (C) 2002 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.