Effects of Cavity Preparation and Lamination on Bond Strength and Fracture of tooth colored restorations.

Resident: Swan
Article Title: The Effects of Cavity Preparation and Lamination on Bond Strength and Fracture of Tooth-Colored Restorations in Primary Molars
Author: Suwatviroj, et al.
Journal: Pediatric Dentistry 25:6, 2003
Main Purpose of Article: Examine Bond Strength (ultimate load at failure) and Fracture modes between different preparation types and different layering of restorative materials
Methods: 80 extracted primary second molars carious on one surface only were mounted and randomly divided to be prepped with box-only or dovetail preparation according to standardized measurements. Teeth were divided into 4 subgroups for each restorative procedure. T-band was adapted and teeth were restored in one of 4 ways:
1: Packable Composite 2: RMGIC 3: RMGIC/PC (open sandwich) 4: RMGIC/PC with experimental bonding agent (K-14). Restorations were tested for ultimate load at fracture using a unversal mechanical testing machine placing force directly on the marginal ridge of each restoration. Surfaces of teeth and restoration were examined microscopically and classified as adhesive, cohesive, or mixed fractures.
Statistical Analysis: ULF were recorded and means and SD's were compared using ANOVA.
Results: There was no effect of type of restorative procedure on ULF, nor any effect of cavity preparation type on ULF. The predominant fracture mode for both types of preparations was "mixed." The distribution of fracture modes in the two preparation types differed significantly, with no adhesive fractures occurring in any restorations in dovetail preparations. The other comparisons of fracture modes between materials did not differ significantly. Adhesive fractures were limited to box-only preps restored with RMGIC. RMGIC restorateions in box-only preps sustained a lower load than PC restorations before fracturing.
Conclusions: Conservative restorations are just as durable as dovetail restorations. Probably a good idea to use dovetail if electing to use just RMGIC.