AIM: To investigate the effect of proanthocyanidins (PAs)-rich grape seed extract on the biodegradation resistance of demineralized root dentine and on the bond strength and durability between resin-based sealer and root dentine.
METHODOLOGY: Single-rooted premolars (n = 28) were divided into PAs-treated and nontreated specimens. Root canals were instrumented to apical size 40, filled with RealSeal SE sealer/Core, sectioned into slices of 1 mm thickness from middle and coronal thirds and stored for 1 week or 3 months in distilled water. Specimens were subjected to push-out strength testing with the load applied perpendicularly in an apical to coronal direction using a universal testing machine. Remaining apical thirds were viewed by scanning electron microscopy after 3-months storage. Additional root canals were filled with rhodamine-B-labelled sealer and viewed by confocal laser scanning microscopy. Unfilled roots (n = 6) were sliced, demineralized, PAs-treated or left untreated and exposed to 24 h collagenase to determine hydroxyproline release in the supernatant. Two-way anova was used to test the effect of both dentine treatment with PAs and anatomical locations on bond strength and hydroxyproline release. Tukey-Kramer multiple comparison post hoc test was used to compare between groups.
RESULTS: No difference in bond strength was found after 1-week storage between both PAs-treated (crosslinked) and untreated (noncrosslinked) groups in the coronal thirds. However, treatment with PAs revealed higher 1-week bond strength values (P ≤ 0.05) in the middle thirds. Generally, 3-month storage decreased the bond strength compared to 1-week within each of the crosslinked and noncrosslinked groups. However, the decrease in the bond strength after 3 months was less for the crosslinked specimens compared to the noncrosslinked specimens. Confocal images revealed a relatively uniform fluorescent interfacial layer and tubular penetration after 1 week in both groups. SEM images revealed more intact resin sealer/dentine interfaces with PAs crosslinking after 3 months. In addition, hydroxyproline release was significantly less (P ≤ 0.05) with crosslinked specimens.
CONCLUSION: Treating root dentine with PAs-rich grape seed extracts improved the biodegradation resistance of demineralized root dentine and enhanced the bond strength and durability between resin-based sealer and root dentine after short-term water storage.