The role of fluoride and casein phosphopeptide/amorphous calcium phosphate in the prevention of erosive/abrasive wear in an in vitro model using hydrochloric acid

OBJECTIVE: To investigate the effect of various fluoride compounds and casein phosphopeptide/amorphous calcium phosphate (CPP-ACP) on the reduction of erosive/abrasive tooth wear. METHODS: Forty enamel samples were prepared from bovine lower incisors, stratified and allocated to 4 groups (1-4). Samples in group 1 remained untreated and served as negative controls. The test samples were treated for 2 min/day as follows: group 2 amine/sodium fluoride gel (pH 4.8; 12,500 ppm), group 3 sodium fluoride gel (pH 7.1; 12,500 ppm) and group 4 CPP-ACP-containing mousse. De- and remineralization cycling was performed for 20 days with 6 erosive attacks for 20 s with HCl (pH 3.0) per day. Samples were stored in artificial saliva between cycles and overnight. Toothbrushing (15 s; 60 strokes/min; load 2.5 N) with a toothpaste slurry was performed each day before the first and 1 h after the last erosive exposure. Tooth wear was measured by comparing baseline surface profiles with the corresponding posttreatment profiles. RESULTS: Tooth wear was significantly reduced in groups 2 and 3 compared with group 1, while the enamel loss of group 4 was not significantly lower compared to the negative control group 1. Between the fluoride groups 2 and 3, no significant difference in tooth wear was recorded. CONCLUSION: Erosive/abrasive tooth wear under the conditions used could be reduced significantly by the daily application of fluoride gels, irrespective of the fluoride compound, while the application of CPP-ACP-containing mousse was less effective

In vitro evaluation of fissure sealants’ wear under erosive, abrasive and erosive/abrasive conditions

Purpose To evaluate and compare the wear of selected resin-based fissure sealants with different compositions properties under erosive, abrasive, and erosive/abrasive conditions. Methods Forty-five samples of the following resin-based fissure sealants were prepared: Fissurit (fluoride free), Fissurit F (with fluoride), Fissurit FX (55 wt.% filler content), Grandio Seal (70 wt.% nano-filler content) and bovine enamel. Fifteen samples from each material were randomly allocated into three groups according to the wear condition they would be subjected to as follows: erosive condition (citric acid, 1 min, pH 2.3), abrasive condition (120 brushing strokes at 2 N, toothpaste slurry RDA value = 69), and erosive/abrasive condition (combination of both). The wear challenges were repeated six times each day for 10 days. The material wear was measured using a stylus profilometer. Kruskal–Wallis and Conover’s test was applied to compare the resulting material wear between the groups. Results Under erosive conditions, Grandio Seal and Fissurit FX showed statistically significantly the least material wear. Under abrasive and erosive/abrasive conditions, Grandio Seal showed statistically significantly the least material wear. Fissurit F showed statistically significantly the highest material wear under abrasive and erosive/abrasive conditions, after dental enamel (p < 0.05). Conclusion Higher filler content in sealants leads to better wear resistance. Incorporating fluoride into sealants seems to reduce their wear resistance at similar filler contents

In vitro re-hardening of artificial enamel caries lesions using enamel matrix proteins or self-assembling peptides

ABSTRACT Objectives To assess the re-hardening potential of enamel matrix derivatives (EMD) and self-assembling peptides in vitro, hypothesizing that these materials may increase the mineralization of artificial carious lesions and improve hardness profiles. Material and Methods Forty-eight enamel samples were prepared from extracted bovine lower central incisors. After embedding and polishing, nail varnish was applied, leaving a defined test area. One third of this area was covered with a flowable composite (non-demineralized control). The remaining area was demineralized in an acidic buffer solution for 18 d to simulate a carious lesion. Half the demineralized area was then covered with composite (demineralized control), while the last third was left open for three test and one control treatments: (A) Application of enamel-matrix proteins (EMD - lyophilized protein fractions dissolved in acetic acid, Straumann), (B) self-assembling peptides (SAP, Curodont), or (C) amine fluoride solution (Am-F, GABA) for 5 min each. Untreated samples (D) served as control. After treatment, samples were immersed in artificial saliva for four weeks (remineralization phase) and microhardness (Knoop) depth profiles (25-300 µm) were obtained at sections. Two-way ANOVA was calculated to determine differences between the areas (re-hardening or softening). Results Decalcification resulted in significant softening of the subsurface enamel in all groups (A-D). A significant re-hardening up to 125 µm was observed in the EMD and SAP groups. Conclusions This study showed that EMD and SAP were able to improve the hardness profiles when applied to deep demineralized artificial lesions. However, further research is needed to verify and improve this observed effect

Effect of the application time of phosphoric acid and self-etch adhesive systems to sclerotic dentin

OBJECTIVES: To evaluate the effect of application time on the resin-dentin bond strength (µTBS) and etching pattern of adhesive systems applied on sclerotic dentine. MATERIAL AND METHODS: A total of forty-two bovine incisors had their roots removed. The 1-step self-etch GO (SDI), the 2-step self-etch Adper SE Bond (3MESPE) and the 35% phosphoric acid (3MESPE) from the 2-step etch-and-rinse Adper Single Bond 2 (3MESPE) were applied on the bovine incisal surfaces according to the manufacturer's instructions or duplicating the recommended conditioning time. After adhesive application, thirty teeth were restored with composite resin, stored for 24 h in distilled water at 37º C, and sectioned into resin-dentin bonded sticks (0.8 mm(2)) and tested according to the µTBS at 0.5 mm/min. The etching pattern of the remaining twelve teeth (n=4 for each material) was examined under scanning electron microscopy. Each tooth was divided into a buccal-to-lingual direction into three thirds, and each third randomly assigned to the groups: control (no treatment), according to the manufacturers' instructions and duplicating the recommended application time. The µTBS and the relative percentage of the tubule area opening were evaluated by two-way repeated measures ANOVA and Tukey's tests (α=0.05). RESULTS: The duplication of the conditioning time favored only the GO adhesive (p<0.05). Both application methods significantly increased the tubule area opening (p<0.05) compared to the controls. CONCLUSIONS: The efficacy of duplicating the conditioning time was only effective for the 1-step self-etch adhesive system tested

Effect of sodium hypochlorite contamination on microhardness of dental core build-up materials

This study aimed to determine the influence of sodium hypochlorite (NaOCl) contamination on the microhardness of build-up composites. Fifty-two samples, from each of three build-up materials (LuxaCore Dual, MultiCore flow and Rebilda DC) were prepared. Half of the samples from each material were stored in physiologic saline (baseline control) while the other halves were stored in NaOCl. After 1 h, the samples were rinsed with tap water, cut axially and measured for Knoop hardness at different depth levels. The results were analysed by ANOVA and unpaired t-tests (p<0.05). Significant differences in microhardness were observed for LuxaCore Dual up to 0.2 mm, Rebilda DC up to 0.3 mm, and for MultiCore flow up to 0.4 mm under the surface level. Contact with sodium hypochlorite on build-up materials causes reduction of the microhardness. The softening is not only limited on the surface, but can also be found in deeper layers of build-up materials

Influence of two different fluoride compounds and an in vitro pellicle on the amount of KOH-soluble fluoride and its retention after toothbrushing

Objective. To determine the influence of two different fluoride compounds and an in vitro pellicle on KOH-soluble fluoride formation - its retention and resistance to toothbrushing. Material and methods. Forty bovine incisors were randomly assigned to four groups (A-D). Of five samples prepared per tooth, one remained untreated and served as a baseline control. Groups A and B were pretreated with artificial saliva and groups C and D with human saliva. Groups A and C were treated with amine fluoride and groups B and D with sodium fluoride. After treatment, samples were brushed with 25, 50, and 75 brushing strokes. The amount of KOH-soluble fluoride formed on the enamel samples was measured at baseline, after application, and after 25, 50, and 75 brushing strokes. Fluoride uptake was calculated by unpaired t-tests and fluoride retention by paired t-tests. Results. No statistically significant differences in the KOH-soluble fluoride uptake of the groups that were pretreated (A vs B and C vs D) or treated equally (A vs C and B vs D) were observed. Retention of the KOH-soluble fluoride in the brushed samples was higher when the samples were pretreated with human saliva and treated with sodium fluoride than when the samples were pretreated with artificial saliva and treated with sodium fluoride. Conclusions. The fluoride compound and the acquired human in vitro pellicle have no influence on the uptake of KOH-soluble fluoride, but show a significant influence on abrasion resistance

Influence of extra- and intra-oral application of CPP-ACP and fluoride on re-hardening of eroded enamel

Abstract Objectives. This in-situ study aimed to investigate the potential of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) crème and fluoride mouth rinse to re-harden erosively softened enamel and to evaluate the influence of an intra-oral or extra-oral application. Methods. Ten volunteers performed five experimental series. Per series, four bovine enamel samples were extra-orally softened by immersion in Sprite light (2 min) and subsequently worn intra-orally for 5 min in intra-oral appliances. Thereafter, samples were treated (3 min) with either 250 ppm AmF/SnF(2) solution (Meridol) (series 1 and 3) or CPP-ACP crème (Tooth Mousse) (series 2 and 4). Application of the substances was performed extra-orally (series 1 and 2) or intra-orally (series 3 and 4). Untreated specimens served as control (series 5). The appliances were worn for 4 h afterwards. Knoop microhardness (KHN) measurement was performed at baseline, after softening and after completing of the respective run. Data were statistically analyzed by ANOVA and Bonferroni/Dunn post-hoc test. Results. No significant difference in baseline microhardness was observed, while immersion in Sprite light reduced the microhardness significantly. Significant re-hardening after intra-oral exposure occurred in all series, but baseline microhardness was not achieved. Microhardness in series 2 was significantly higher than that in series 1 and 5. No significant differences in KHN were detected between series 3, 4 and 5. The re-hardening ΔKHN (final microhardness - microhardness after erosion) was not significant different in all five series. Conclusion. Intra-oral application of CPP-ACP crème or fluoride solution provides no benefit regarding re-hardening of erosively softened enamel

A first study on the usefulness of matrix metalloproteinase 9 from dentinal fluid to indicate pulp inflammation

With a sensitive assay, it was possible to detect an enzyme linked with pulp tissue destruction (MMP-9) in dentinal fluid. However, the collection method needs to be improved to provide predictable fluid yields. Longitudinal studies should be performed to assess the predictive value of molecular markers in dentinal fluid on pulpal pathosis