Influence of Enamel Protection on Stability of Dentin Bond Strength

Objective: To evaluate the dentin bonding durability of two one-step self-etch adhesive systems with and without the presence of surrounding enamel.

Material and Method: Tri-S bond (Kuraray Medical Co.) and G-bond (GC Co.), as of commercially available adhesive systems, were used in this study. The occlusal enamel was removed in order to form a flat dentin surface from the mid-crown. These two adhesives were applied to both dentin and the surrounding enamel surfaces according to the respective manufacturer's instruction. Resin composite (Clearfil AP-X, Kuraray medical Co.) was placed and irradiate for 40 seconds. Half of the bonded specimens were sectioned perpendicular to the adhesive interface into 0.7 mm thick slabs and then trimmed to form hour glass configuration with a 1 mm² cross-sectional area before water storage. Whereas, the remaining half of bonded teeth were stored in water for six months.  As of control groups, additional bonded specimens were also stored in water for 24 hours.  After the designated periods of water storage, specimens were prepared from each tooth as described above. The micro-tensile bond strength (mTBS) test was carried out at a crosshead speed of 1.0 mm/min. The data were statistically analyzed using three-way ANOVA and post hoc tests (T-test and Tukey's tests).

Result: Following table presents mean bond strength  SD (MP, n=10). Statistical analysis revealed that there was significant difference between materials and also storage periods in case of direct exposure of resin dentin bonds, but not significant difference between periods with the presence of enamel. Moreover, the test reveals that there is significant difference between the two different applied methodologies.

Conclusion: It is possible that good stability of resin-dentin bonds is associated with the presence of surrounding enamel.