Four-year randomized clinical trial of oxalic acid pretreatment in restorations of non-carious cervical lesions.

OBJECTIVE: The aim of this study was to evaluate the efficiency of oxalic acid (BisBlock) on restorations of non-carious cervical lesions. MATERIALS AND METHODS: One operator placed 90 restorations randomly divided into two groups in 20 patients under cotton rolls isolation: Control Group-two-step etch-and-rinse adhesive technique; and Experimental Group-two-step etch-and-rinse adhesive technique with oxalic acid pretreatment after acid-etched dentin. The restorative adhesive system used was XP Bond/Durafill. The restorations were directly assessed by two independent examiners, using the modified United States Public Health Service (USPHS) criteria at the baseline and 4 years. Data were statistically analyzed using the Fisher and McNemar tests (p < 0.05). RESULTS: Fifteen patients (75%) were available for recall after 4 years. The McNemar test detected significant differences within the Experimental Group between the baseline and 4-year evaluations for retention (p < 0.05). For the Control Group, there was no significant difference (p > 0.05) between the periods. The Fisher test showed no statistically significant difference between the groups for all other criteria (p > 0.05). CONCLUSION: After 4 years of service, the use of oxalic acid did not influence the clinical performance of restorations when it was used under composite resin restorations.

Resin infiltrant protects deproteinized dentin against erosive and abrasive wear.

Objectives: This study aimed to investigate the anti-erosive/abrasive effect of resin infiltration of previous deproteinized dentin. Materials and Methods: Dentin slabs were randomly assigned to 3 groups (n = 15): Control (no deproteinization; no resin infiltrant applied), RI (no deproteinization; resin infiltrant applied), and DRI (deproteinization; resin infiltrant applied). After undergoing the assigned treatment, all slabs were subjected to an in vitro cycling model for 5 days. The specimens were immersed in citric acid (0.05 M, pH = 3.75; 60 seconds; 3 times/day) and brushed (150 strokes). Between the challenges, the specimens were exposed to a remineralizing solution (60 minutes). The morphological alterations were analyzed by mechanical profilometry (µm) and scanning electron microscopy (SEM). Data were submitted to one-way analysis of variance (ANOVA) and Tukey tests (p < 0.05). Results: Control and RI groups presented mineral wear and did not significantly differ from each other (p = 0.063). DRI maintained a protective layer preserving the dentin (p < 0.001). After erosive/abrasive cycles, it was observed that in group RI, only 25% of the slabs partially evidenced the presence of the infiltrating, while, in the DRI group, 80% of the slabs presented the treated surface entirely covered by a resin-component layer protecting the dentin surface as observed in SEM images. Conclusions: The removal of the organic content allows the resin infiltrant to efficiently protect the dentin surface against erosive/abrasive lesions.

Protective effect of green tea catechins on eroded human dentin: an in vitro/in situ study.

The present study sought to evaluate the protective effect of Epigallocatechin-3-gallate (EGCG) and commercial green tea (GT) on eroded dentin using in vitro and in situ experimental models. For the in vitro experiment, matrix metalloproteinases (MMPs) were extracted from demineralized human coronary dentin powder (citric acid, pH 2.3) and assessed via a colorimetric assay and electrophoresis in gelatin. The gels were exposed to buffers with: control (no treatment), 0.05% sodium fluoride (NaF), 0.12% chlorhexidine digluconate (CHX), GT infusion, and 0.1% EGCG, and their respective activity was analyzed by zymography. For the in situ experiment, 20 healthy volunteers (aged 20-32 years) participated in this single-center, blind, crossover study. The subjects wore upper removable devices containing four human dentin blocks. Erosive challenge (coke-1 min) was performed four times/day/5 days. Blocks were treated for 1 min with: control (No treatment), 0.05% NaF, 0.1% EGCG, and GT. Thereafter, the specimens were subjected to stylus profilometry and SEM. ANOVA was used to evaluate dentin roughness and wear, with a significance level of 5%. In the zymography analysis, 0.12% CHX, GT, and 0.1% EGCG were found to inhibit the action of MMPs; however, in the colorimetric assay, only green tea inhibited the activity of MMPs. There were no significant differences observed in dentin roughness or wear (p > 0.05). Herein, EGCG and GT inhibited the activity of endogenous proteases, resulting in protection against erosion-induced dentin damage; however, they could not prevent tooth tissue loss in situ.

Effect of green tea as a protective measure against dental erosion in coronary dentine.

The aim of this study was to evaluate the effect of green tea as a protective measure on eroded dentin. Disks of human coronary dentin were selected based on surface hardness and randomly assigned to 3 groups (n = 10): DW - distilled water, CHX - 0.2% chlorhexidine digluconate, and GT - green tea. The disks were allowed to acquire pellicle for 2 hours and were then subjected to 3 cycles per day of demineralization (C6H8O7 0.05 M, pH 3.75, 60 s), treatment (DW or CHX or GT, 5 min) and remineralization (artificial saliva, 60 min) over a period of 3 days. Changes in the dentin were determined by loss of surface hardness (%SHL) and mechanical profilometry analysis at the end of each day. Data were analyzed by two-way ANOVA followed by Tukey's test for %SHL and profilometry (p < 0.05). Significant reductions in dentin hardness loss were observed only for the CHX group when compared to the DW group (p < 0.05). However, there was no significant difference between the CHX and GT groups (p > 0.05). A significant difference was observed between DW and GT treatments for wear and roughness measurements (p < 0.05). The green tea extract solution was able to reduce the wear and roughness caused by dentin erosion under the conditions of this study.

Clinical study of the caries-preventive effect of resin-modified glass ionomer restorations: aging versus the influence of fluoride dentifrice.

AIM: The use of fluoride-releasing materials could be compromised due to aging and might also be influenced by other ordinary sources of fluoride. The aim of the present study was to investigate the aging effect on caries development around resin-modified glass ionomer cement (RMGIC) restorations and the influence of fluoride dentifrice use in this process under the oral environment. METHODS: A clinical study was performed in two phases of 14 days each. A total of 16 volunteers wore palatal devices containing dental slabs restored with either a composite resin or RMGIC, either aged or unaged by thermocycling. To simulate a clinical situation of high caries risk, the slabs were exposed to a 20% sucrose solution 10 times per day via the in situ model, where non-fluoride or a fluoride dentifrice was used. Integrated demineralization was determined by cross-sectional microhardness at both margins of the restoration: enamel and dentin. RESULTS: For enamel, higher demineralization around the composite restorations was observed, regardless of dentifrice or aging. For dentin, higher demineralization was observed around the aged composite restorations regardless of the dentifrice type used. CONCLUSIONS: The RMGIC restorations provided more enhanced protection against secondary caries for dentin under aging, and the fluoride dentifrice used in this condition had either no clinically relevance or only a minimal effect.

Protective effect of green tea catechins on eroded human dentin: an in vitro/in situ study

Abstract The present study sought to evaluate the protective effect of Epigallocatechin-3-gallate (EGCG) and commercial green tea (GT) on eroded dentin using in vitro and in situ experimental models. For the in vitro experiment, matrix metalloproteinases (MMPs) were extracted from demineralized human coronary dentin powder (citric acid, pH 2.3) and assessed via a colorimetric assay and electrophoresis in gelatin. The gels were exposed to buffers with: control (no treatment), 0.05% sodium fluoride (NaF), 0.12% chlorhexidine digluconate (CHX), GT infusion, and 0.1% EGCG, and their respective activity was analyzed by zymography. For the in situ experiment, 20 healthy volunteers (aged 20-32 years) participated in this single-center, blind, crossover study. The subjects wore upper removable devices containing four human dentin blocks. Erosive challenge (coke-1 min) was performed four times/day/5 days. Blocks were treated for 1 min with: control (No treatment), 0.05% NaF, 0.1% EGCG, and GT. Thereafter, the specimens were subjected to stylus profilometry and SEM. ANOVA was used to evaluate dentin roughness and wear, with a significance level of 5%. In the zymography analysis, 0.12% CHX, GT, and 0.1% EGCG were found to inhibit the action of MMPs; however, in the colorimetric assay, only green tea inhibited the activity of MMPs. There were no significant differences observed in dentin roughness or wear (p > 0.05). Herein, EGCG and GT inhibited the activity of endogenous proteases, resulting in protection against erosion-induced dentin damage; however, they could not prevent tooth tissue loss in situ.

Effect of chlorhexidine on the bond strength of a self-etch adhesive system to sound and demineralized dentin.

This study evaluated the effect of a 2% chlorhexidine-based disinfectant (CHX) on the short-term resin-dentin bond strength of a self-etch adhesive system to human dentin with different mineral contents. Dentinal mineralization was tested at 4 levels (sound, and after 2, 4, or 8 days of demineralization-remineralization cycles) and disinfectant at 2 levels [deionized water (DW, negative control) and CHX]. Dentin demineralization induced by pH-cycling was characterized by cross-sectional hardness (CSH). Each dentin surface was divided into halves, one treated with DW and the other with CHX (5 minutes). Each surface was bonded with a self-etch adhesive system and restored. The specimens were sectioned and subjected to microtensile bond testing. CSH and microtensile bond strength (µTBS) data were analyzed by regression analysis and ANOVA-Tukey tests (α = 5%), respectively. The groups treated with CHX resulted in mean µTBS similar to those found for the groups in which the dentin was exposed to DW (p = 0.821). However, mean µTBS were strongly influenced by dentin mineralization (p < 0.05): the bond strength found for sound dentin was lower than that found for dentin cycled for 8 days, which was even lower than the bond strengths for dentin cycled for 2 or 4 days. The results suggest that the degree of dentin demineralization affects the bond strength of self-etching adhesives, but the use of CHX does not modify this effect.

Effect of green tea as a protective measure against dental erosion in coronary dentine

Abstract The aim of this study was to evaluate the effect of green tea as a protective measure on eroded dentin. Disks of human coronary dentin were selected based on surface hardness and randomly assigned to 3 groups (n = 10): DW - distilled water, CHX - 0.2% chlorhexidine digluconate, and GT - green tea. The disks were allowed to acquire pellicle for 2 hours and were then subjected to 3 cycles per day of demineralization (C6H8O7 0.05 M, pH 3.75, 60 s), treatment (DW or CHX or GT, 5 min) and remineralization (artificial saliva, 60 min) over a period of 3 days. Changes in the dentin were determined by loss of surface hardness (%SHL) and mechanical profilometry analysis at the end of each day. Data were analyzed by two-way ANOVA followed by Tukey’s test for %SHL and profilometry (p < 0.05). Significant reductions in dentin hardness loss were observed only for the CHX group when compared to the DW group (p < 0.05). However, there was no significant difference between the CHX and GT groups (p > 0.05). A significant difference was observed between DW and GT treatments for wear and roughness measurements (p < 0.05). The green tea extract solution was able to reduce the wear and roughness caused by dentin erosion under the conditions of this study.

Effect of chlorhexidine on the bond strength of a self-etch adhesive system to sound and demineralized dentin

This study evaluated the effect of a 2% chlorhexidine-based disinfectant (CHX) on the short-term resin-dentin bond strength of a self-etch adhesive system to human dentin with different mineral contents. Dentinal mineralization was tested at 4 levels (sound, and after 2, 4, or 8 days of demineralization-remineralization cycles) and disinfectant at 2 levels [deionized water (DW, negative control) and CHX]. Dentin demineralization induced by pH-cycling was characterized by cross-sectional hardness (CSH). Each dentin surface was divided into halves, one treated with DW and the other with CHX (5 minutes). Each surface was bonded with a self-etch adhesive system and restored. The specimens were sectioned and subjected to microtensile bond testing. CSH and microtensile bond strength (µTBS) data were analyzed by regression analysis and ANOVA-Tukey tests (α = 5%), respectively. The groups treated with CHX resulted in mean µTBS similar to those found for the groups in which the dentin was exposed to DW (p = 0.821). However, mean µTBS were strongly influenced by dentin mineralization (p < 0.05): the bond strength found for sound dentin was lower than that found for dentin cycled for 8 days, which was even lower than the bond strengths for dentin cycled for 2 or 4 days. The results suggest that the degree of dentin demineralization affects the bond strength of self-etching adhesives, but the use of CHX does not modify this effect.