Does Simulated Intrapulpal Pressure Affect Adhesives Bonding to Coronal/Radicular Dentin?

Objective: To evaluate the microtensile bond strength (µTBS) of different adhesives to coronal versus radicular dentin after storage in artificial saliva and under intrapulpal pressure simulation (IPPS) for 24 hours. 

Method: Roots of eighteen freshly-extracted premolars were sectioned 5mm below CEJ and pulp tissue was removed. Buccal enamel and cementum of each tooth segment were trimmed and polished to obtain standardized flat dentin surface. Specimens were divided into three groups according to the adhesives utilized; two-step etch-and-rinse adhesive, SB-Adper Single Bond 2, 3MESPE; two-step self-etch adhesive, SE-Clearfil SE Bond, Kuraray Medica Inc. and single-step self-etch adhesive, AE-Adper Easy One, 3MESPE. Resin composite (Valux Plus, 3MESPE) buildups were made. Adhesives and resin composite were applied while the specimens were subjected to IPPS. After curing, specimens were stored in artificial saliva at 37^oC in a specially constructed incubator while the IPPS was maintained for 24h prior to testing. Coronal and radicular composite built up were color-coded. Bonded specimens (n=6/group) were sectioned into sticks (n=24/group) with a cross-section of 0.9+/-0.01 mm² and subjected to µTBS testing using a universal testing machine. Data were statistically analyzed using two-way ANOVA with repeated measures; one-way ANOVA tests, and Bonferroni post-hoc test (p<0.05). Failure modes were determined for all tested beams using scanning electron microscope at x100 magnification. 

Result: Two-way ANOVA with repeated measures revealed statistically significant effect for the adhesives (P<0.001), however, it revealed no statistical significant effect for dentin substrates (P>0.05) as well as their interaction (P>0.05). For both dentin substrates, SE revealed statistically significant higher µTBS (P<0.001) than the other two adhesives (SB and AE) which were not statistically significantly different (P>0.05). Modes of failure were mainly adhesive and mixed. 

Conclusion: 24-h bond strengths of tested adhesives were not sensitive to the structural differences between coronal and radicular dentin even under IPPS. Bottom of Form