Bond Durability to Dentin Pretreated With Ethanol-based-chlorhexidine Under Intrapulpal Pressure

Objective: To evaluate the bond strength durability of a single-step self-etch adhesive to dentin pretreated with either ethanol-based chlorhexidine (ECHX) or water-based chlorhexidine (WCHX) after aging in artificial saliva and under intrapulpal pressure simulation (IPPS).  

Method: Occlusal enamel of thirty freshly-extracted teeth was trimmed to expose mid-coronal dentin. Specimens were connected to the pulp-pressure assembly after sectioning their roots to expose the pulp-chamber. Specimens were distributed over three groups (n=10) according to dentin pretreatment utilized. In the first group, Adper Easy One (3MESPE) was applied to dentin surface according to the manufacturer’s instructions (control group). In the second group, dentin was pretreated before bonding with 1ml of 2% CHX diacetate dissolved in 100% ethanol (ECHX). Third group received the same pretreatment; however, chlorhexidine was dissolved in distilled water (WCHX). Bonding was done while the specimens were subjected to IPPS. Resin composite (Valux Plus, 3MESPE) buildups were made. After curing, specimens were stored in artificial saliva and under IPPS at 37^oC in a specially constructed incubator either for 24-hour or 6-month prior to testing. Thereafter, bonded specimens (n=5/group) were sectioned into sticks (n=25/group) with a cross-section of 0.9±0.01 mm² and subjected to microtensile bond strength (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 using a scanning electron microscope.  

Result: After 24h aging, control and WCHX groups revealed significantly higher µTBS than ECHX group. After 6-month storage in artificial saliva and IPPS, only the WCHX group maintained its µTBS value. The predominant mode of failure was the mixed type except for ECHX group which was mostly adhesive.

Conclusion: Pretreatment of the dentin with ECHX had a negative effect on bonding of single-step self-etch adhesive, however, WCHX maintained the bonding under IPPS.