Synergistic effects of proanthocyanidin, tri-calcium phosphate and fluoride on artificial root caries and dentine collagen.

Background: Proanthocyanidin has been shown to enhance dentine collagen stability and remineralization of artificial root caries.

Objectives: To evaluate the effect of proanthocyanidin (PA) in combination with tri-calcium phosphate (TCP) and fluoride (F) on resistance to collagen degradation and remineralization of artificial caries lesions.

Methods: Demineralized root fragments (n=75) were randomly divided into five groups based on treatments: (i) 6.5% PA, (ii) TCP+F, (iii) TCP+F+6.5% PA, (iv) 1000ppm fluoride (Positive control) and (v) deionized water (control). Each specimen was subjected to pH cycling at 37 C for 8days. Lesion depth and mineral loss were evaluated using microradiography and confocal laser scanning microscopy. The type of crystal formation was determined by XRD spectra. To evaluate the stability of root caries lesions against collagenase challenge, highly purified type VII collagenase from Clostridium was added to obtain a remineralizing solution that contained 7.5U/mL collagenase and pH cycling was repeated. The different remineralizing solutions were collected after the pH cycling to assess the amount of hydroxyproline release. Collagen degradation depth and lesion depth were evaluated using transverse microradiography. Resistance to collagen degradation was determined using hydroxyproline assay. Data were analyzed using one-way ANOVA and Tukey multiple comparison tests.

Results: Results of one-way ANOVA showed that the test solutions had a significant effect on mineral loss (p<0.001) and lesion depth (p<0.001) of artificial root caries. The lowest lesion depth and mineral loss were observed in the TCP+F+PA (p<0.05) group. The XRD patterns showed hydroxyapatite formation on TCP+F-treated artificial caries lesions, which were not altered by the addition of PA. The addition of PA to TCP+F significantly reduced collagen degradation depth, when compared to TCP only group (p<0.001). Lesion depth was the lowest in the PA and TCP+F+PA groups following collagenase degradation (p<0.001). The addition of PA to TCP+F also decreased hydroxyproline release, when compared to TCP+F group (p<0.001).

Conclusion: The addition of PA to TCP+F reduced collagen degradation, inhibited demineralization and enhanced remineralization.