Influence of 2% chlorhexidine digluconate on bond strength of a glass-fibre post luted with resin or glass-ionomer based cement

ObjectivesThis study evaluated the influence of 2% chlorhexidine digluconate (CHX) on the bond strength (BS) of a glass-fibre post to the root canal, regarding the cements (dual-cured resin or resin-modified glass-ionomer cement), the root thirds and the time of storage.MethodEighty bovine roots were selected and endodontically treated, before being randomly assigned to the following groups according to the luting protocol: ARC (RelyX ARC); ARC + CHX; RL (RelyX Luting 2); and RL + CHX. After 24 h of luting, the roots were sliced to obtain 1 mm-thick slices. Half of each group was submitted to either 7-day or 6-month storage in artificial saliva (n = 10). The specimens were subjected to push-out tests with a crosshead speed of 0.5 mm/min. The data were analysed with four-way ANOVA and Tukey's test (P ≤ 0.05). The failure modes were analysed with a digital microscope (50× and 200×).ResultsARC yielded a significantly higher BS compared to RL (P < 0.001). Despite CHX exerted a significant effect; it depends on the interaction with the luting cement and time (P < 0.001). Thus, CHX decreased the values of BS to those of ARC after 6 months (P < 0.001). On the 7th day of storage, the ARC + CHX presented higher BS to the cervical and middle thirds compared to RL + CHX (P = 0.012). Time solely was not a significant factor (P = 0.081). Adhesive cement-dentine type and mixed failures were predominant modes for the ARC groups. For the RL groups, the main failures were adhesive cement-post and mixed modes.ConclusionsGlass-fibre posts luted with RelyX ARC dual-cure resin cement exhibited higher BS than those luted with RelyX Luting 2 resin-modified glass-ionomer cement. Furthermore, CHX was not effective to improve the BS and negatively affected the BS of RelyX ARC after 6 months of storage.Clinical significanceThe use of chlorhexidine solution seems not to improve the bond strength of fibre posts to root canals, disregarding the composition of the luting cement.