Marginal adaptation of a new compomer under different conditioning methods

Objectives: This in vitro study evaluated the marginal adaptation of compom er restorations placed using three different conditioning protocols. Materials and methods: Thirty extracted caries-free molars with 3 mm diamet er cylindrical cavity preparations were divided randomly into three groups based upon the conditioning treatment used: (I) 36% phosphoric acid; (II) n on-rinse conditioner (NRC, Dentsply DeTrey); and (III) no conditioning. Cav ities were restored with Dyract AP using Prime&Bond NT (Dentsply DeTrey) as an adhesive. Silicone impressions of the briefly etched enamel surfaces we re taken after finishing the restorations. Each sample was then longitudina lly sectioned and impressions were taken. Epoxy resin replicas were prepare d for SEM analysis. Qualitative and quantitative assessment were performed separately for the enamel- and dentine-restorative interface. Results: Enamel fractures and open margins along the enamel-restorative mar gin were observed in some specimens in each group. No statistically signifi cant difference was found in the percentage of gaps/cohesive failures betwe en specimens prepared using different conditioning methods. For the dentine -restorative interface, uniform hybrid layers and long resin tags were ofte n observed in Groups I and II. The hybrid layer in Group Ill was irregular and discontinuous along the interface. A significant difference (p < 0.01) in the proportion of marginal gap was found between Group I (2%) and Group III (30%). Conclusions: Pre-treating the cavity with 36% phosphoric acid significantly improved the adaptation of the compomer and adhesive to dentine compared w ith no etching. The marginal quality at the enamel-compomer interface was n ot affected by the conditioning method used. (C) 2000 Elsevier Science Ltd. All rights reserved.