Correlation between Bond Strength and Cavity Wall Adaptation

Abstract

The purpose of this study was to evaluate the correlation between bond strength and cavity wall adaptation. Cylindrical cavities, 1mm deep and 3mm in diameter (C-factor=2.3) were prepared on flat bovine dentin surfaces. The teeth were restored with the Clearfil SE Bond (Kuraray Medical) adhesive system followed by Photo Clearfil Bright (PB, Kuraray Medical) hybrid composite or Filtek Flow(FF, 3M ESPE) flowable composite. The resins were light-cured with 600mW/cm² for 40s. After storage for 24h, the teeth were sectioned to a thickness of about 1mm. The remaining dentin thickness (RDT) was measured. The slabs were trimmed (ca. 1mm²) at the adhesive-dentin interface for the micro-tensile bond strength (μ-TBS) test. The trimmed specimens were mounted on a testing apparatus, and stressed to failure under tension at 1mm/min in an EZ test machine. Bond strength and RDT data were analyzed using one-way ANOVA and Fisher's PLSD test. The dye penetration test was carried out on the cut surface. Dye penetration length was calculated as a percentage of the total cavity wall length. Dye penetration scores were analyzed using the Kruskal-Wallis test and Mann-Whitney U test. The flowable composite significantly improved resin composite adaptation to the cavity wall (p<0.05). However, the tensile bond strength of the flowable composite to the dentin cavity floor was significantly decreased (p<0.05). There was no correlation between resin composite bond strength and cavity wall adaptation for the dentin cavity.