Adaptation of composite resin restorative materials to retentive grooves of Class I cavity preparations.

An in vitro study was conducted to determine the adaptation of composite resin restorative material to rounded and acute-angled retention grooves of Class I cavity preparations on 24 extracted premolars. Two chemically cured (P-IO ® and Miradapt ®) and 2 light-cured (Prisma-Fil ® and FulFil ®) composite resin materials, after being coded to create a blind study, were injected into cavity preparations containing rounded and acute-angled retention grooves. The restored premolars were cut in half and examined via SEM at 50 x magnification. A standardized method was used to determine the adaptation of each composite resin to the grooves. Interjudge evaluation showed all composite resin materials adapted well to both rounded and acute-angled retention grooves. Mean and standard deviation values revealed no significant difference in the average dentin-resin gap between treatment groups and between the 2 types of retention grooves. There was only 0.6M difference between the lowest and highest mean values. Retention form is an essential component of cavity preparations in primary teeth. 1,2 Retention form to resist displacement of an amalgam restoration can take several forms: dovetail shapes on the occlusal surface to resist horizontal displacement; truncation of the occlusal portion of the cavity preparation as well as the lateral walls of the proximal box to resist vertical displacement; and grooves placed within the dentin at the junction of the occlusal walls and pulpal floor to ensure intimate adaptation of the restoration material to the cavity preparation. 3-7 Heim, while investigating the ability of an amalgam restorative material to be condensed into retention grooves, demonstrated that acute-angled retention grooves were less likely to be filled completely by this material than were rounded retention grooves, s His research suggested that rounded retention grooves allow better adaptation of amalgam restorative materials than do acute-angled retention grooves. Retention of composite resins to cavity preparations can occur through acid etching of the enamel margins followed by bonding of the resins to these walls. 9-17 Retention of posterior composite restorations could be enhanced by utilizing both enamel conditioning and retention grooves. Retention groove use in cavity preparations should be based on evidence of whether or not posterior resin restoration materials can adapt to such retention grooves. The purpose of this investigation was to determine whether chemically cured and light-cured composite resin restorative materials adapt to rounded and acute-angled retention grooves of Class I cavity preparations. Caries-free premolars extracted for orthodontic purposes from patients …