A Comparative Study into the Effect of Two Techniques of Cavity Preparation on Microleakage and Interfacial Micromorphology of Tooth-bonded Composite Resin Restorative

Abstract

This study was carried on to compare the effect of two different cutting methods for class V cavity preparation and two different adhesive systems on the marginal integrity of a resin composite restorative material. Eighty-two freshly extracted human molars were randomly divided into two main groups (forty one each) according to the cavity preparation methods. One cavity of each test group was kept without restoration to examine the effect of the preparation technique on the prepared cavity by the S.E.M. The two main groups were further divided into two subgroups (twenty each) according to the adhesive system used (a total-etch adhesive system; Scotchbond Multi-purpose Plus and a self­ etch adhesive system; Prompt-L-Pop). Standardized class V cavities were prepared on the buccal surfaces of the selected teeth using the rotary bur method, producing cavities of depth of 2mrn and diameter of 3mrn. The air abrasion method using the "Microprep Director+" was applied to simulate the rotary bur cavities by using standardized parameters; a medium sized nozzle tip and an angulation of 90° at a tip to surface distance of Smm. The powder used was aluminum oxide powder; of particle size equals to 27J.!, medium flow powder rate with pressure of 120 psi, the time of application was 20 seconds. The tested cavities were bonded with the tested adhesive systems then resorted by Filtek Z250 resin composite material following the manufacturer's instructions. The marginal sealing of the restored samples was assessed using methylene blue dye penetration technique and the margins of sectioned teeth were examined by the stcreomicroscope. Five samples were randomly selected out of each group for S.E.M. to study the morphological differences at the tooth restoration interface. According to the collected data, the sealing performance of the total-etch adhesive system (Scotchbond Multi­ purpose Plus) was almost the same for both methods of cavity