The effect of proanthocyanidins on the bond strength and durability of resin sealer to root dentine.
OBJECTIVE
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.


METHODS
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.


CONCLUSIONS
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.
Discipline of Prosthodontics, Operative Dentistry and Endodontics, National University of Singapore, Singapore city, Singapore.
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D001711:Biotransformation; D017364:Collagenases; D003432:Cross-Linking Reagents; D001840:Dental Bonding; D003804:Dentin / Q000187:drug effects; D056604:Grape Seed Extract / Q000494:pharmacology; D006801:Humans; D006909:Hydroxyproline / Q000737:chemistry; D008422:Materials Testing; D018613:Microscopy, Confocal; D008855:Microscopy, Electron, Scanning; D044945:Proanthocyanidins / Q000494:pharmacology; D019279:Resin Cements; D013312:Stress, Physiological; D014092:Tooth Root
D003432:Cross-Linking Reagents; D056604:Grape Seed Extract; D044945:Proanthocyanidins; D019279:Resin Cements; D017364:Collagenases; D006909:Hydroxyproline