Effect of types of resin cements on the bond strength of fiber post under simulated dives

Background: Changes in barometric pressure conditions that occur during flying and diving under hyperbaric oxygen conditions were found to influence the retention of dental restorations.

Aim: This experimental laboratory study aimed to evaluate the bond strength of glass fiber posts after being cemented with self-adhesive resin cement (RelyX™ Unicem, 3M ESPE) and self-etch adhesive resin cement (RelyX™ Ultimate, 3M ESPE) under normal atmospheric pressure and hyperbaric pressure cycles that simulate diving conditions.

Methods: A total of 40 extracted, single-rooted mandibular premolars were treated endodontically and randomly divided into two groups according to the cements used for fiber post cementation. Each group was further randomly divided into two equal subgroups that were subjected to normal atmospheric pressure conditions and a simulated hyperbaric condition in a hyperbaric chamber. The pull-out bond strength of fiber posts was tested using a universal testing machine. Data were analyzed using one-way analysis of variance with Tukey post-hoc test (p<0.05).

Results: At normal atmospheric pressure the mean value of the pull-out bond strength of RelyX Ultimate cement was significantly higher than that of RelyX Unicem cement. At hyperbaric pressure condition no significant difference was found between the mean values of the pull-out bond strength of RelyX Ultimate and RelyX Unicem cement.

Conclusion: Hyperbaric pressure cycles demonstrated improved pull-out bond strength of glass fiber posts in RelyX Unicem cement but did not have significant effect on pull-out bond strength in RelyX Ultimate cement. Both resin cements have similar pull-out bond strength of glass fibers post after simulated dives.