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 37o 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.

Effect of chemomechanical caries removal on bonding of self-etching adhesives to caries-affected dentin.

PURPOSE: To evaluate the effect of enzyme-based (Papacárie) and sodium-hypochlorite-based (Carisolv) chemomechanical caries removal methods on bonding of self-etching adhesives to caries-affected dentin, in comparison to the standard rotary-instrument caries removal method. MATERIALS AND METHODS: Seventy-eight carious permanent molars exhibiting frank cavitation into dentin were used. Forty-eight teeth were randomly divided into three groups, according to the caries excavation methods: (i) Papacárie, (ii) Carisolv and (iii) a round steel bur. After caries removal, each group was subdivided into two groups for two-step (Clearfil SE Bond) or one-step (Clearfil S3 Bond) self-etching adhesive application and resin composite buildups. Bonded specimens were sectioned into beams for microtensile bond strength testing. Bond strength data were analyzed using three-way ANOVA and Tukey's test. For interfacial nanoleakage evaluation using a field-emission scanning electron microscope, caries was similarly removed from the remaining thirty carious molars, bonding was performed as for bond strength testing, and the teeth were sectioned. RESULTS: RESULTS of three-way ANOVA revealed that bond strength was significantly affected by "adhesive" (p<0.001) and "dentin" (p<0.001), but not "caries excavation methods" (p>0.05). The bond strength of the two-step self-etching adhesive was significantly higher than that of the one-step self-etching adhesive (p<0.001). Conversely, the bond strength of self-etching adhesives to sound dentin was significantly higher than to residual caries-affected dentin (p<0.001). Greater silver penetration was observed in the bonded interfaces of residual caries-affected dentin and in interfaces bonded with the one-step self-etching adhesive vs those bonded with the two-step self-etching adhesive. CONCLUSION: Chemomechanical caries removal did not affect the bonding of self-etching adhesives to caries-affected dentin as compared to caries excavation with rotary instruments.