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Comparison of pulse activation vs conventional light-curing on marginal adaptation of a compomer conditioned using a
1Faculty of Dentistry, The Prince Philip Dental Hospital, The University of Hong Kong, 34 Hospital Road, Hong Kong.
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, 3mm in diameter, were prepared in extracted human molar teeth. They were restored with Dyract AP using Prime&Bond 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.
