Marginal integrity of composite resin restoration in class I cavities prepared by hydro-abrasion

Aim To evaluate and compare the marginal integrity of composite resin restorations made by two different preparation techniques: conventional drill and hydro-abrasion. Materials and methods Forty extracted human premolars with simple occlusal caries were used. The teeth were fixed with sticky wax to the base of plastic cylinder. The cylinder was filled with self-curing acrylic resin so that only root was embedded within the self-curing acrylic resin. The teeth were randomly divided into two main groups (n = 20) according to the preparation technique. Group I: class I cavity preparation was done by the conventional drill method using a #245 Carbide bur and contra angle high-speed hand piece with water coolant. Cavity design was restricted to remove caries with no undercuts, and no beveling. Group II: class I cavity preparation was done by Aquacut Quattro air hydro-abrasion unit which uses a gamma irradiated aluminum oxide particle as abrasives (29 μm), cutting fluid and a hand piece of 0.6 mm diameter tip. The preparation in both groups was restored by the same composite resin (Grandio) and adhesive systems (Futurabond U) following the manufacturer's instructions. All specimens were thermocycled. Impressions for each tooth was made using a polyvinyl Siloxane material. The impressions were then poured with epoxy resin. These replicas were examined under scanning electron microscope. Scanning electron microscope photographs of tested samples were used for the gap evaluation. Results It was found that, group I recorded higher mean value of marginal gap length (157.57 ± 35.15 μm) than group II that recorded (69.55 ± 20.02 μm). Also, group I recorded higher mean value of marginal gap length ratio (10.72 ± 2.47) than group II that recorded (7.44 ± 2.69). Conclusion Conventional drilling technique was faster than the hydro-abrasion technique for cavity preparation. Hydro-abrasion technique showed more marginal adaptation than conventional drilling technique.