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

Impact of laminar flow velocity of different acids on enamel calcium loss

Objective: The aim of the study was to evaluate the impact of flow velocity under laminar flow conditions of different acidic solutions on enamel erosion. Material and methods: A total of 240 bovine enamel specimens were prepared and allocated to 30 groups (n = 8 each). Samples of 18 groups were superfused in a flow chamber system with laminar flow behavior using 1ml of citric acid or hydrochloric acid (HCl) of pH 2.0, 2.6 or 3.0. Flow rates in the sample chamber were adjusted to 10, 60 or 100μl/min. To simulate turbulent flow behavior, samples of six groups were immersed in 1ml of the respective solution, which was vortexed (15min, 600rpm). For simulating non-agitated conditions, specimens of the remaining six groups were immersed in 1ml of the respective solution without stirring. Calcium in the solutions, released from the enamel samples, was determined using Arsenazo III method. Results: For acidic solutions of pH 2.6 and 3.0, erosive potential of citric acid was equivalent to that of HCl at a flow of 100μl/min. The same observation was made for the samples subjected to turbulent conditions at pH 3. At all other conditions, citric acid induced a significantly higher calcium loss than HCl. Conclusion: It is concluded that under slow laminar flow conditions, flow rate variations lead to higher erosive impact of citric acid compared to hydrochloric acid at pH 2.0, but not at pH ≥ 2.6 and increasing laminar flow or turbulent conditions. Clinical relevance: Erosive enamel dissolution under laminar flow conditions is a complex issue influenced by flow rate and acidic substrat

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

Marginal adaptation of ceramic and composite inlays in minimally invasive mod cavities

Objectives: This study aims to evaluate the effect of a minimally invasive mesial-occlusal-distal (mod) preparation on the marginal adaptation of ceramic and composite inlays with the aim of saving sound dental substance. Materials and methods: Class II mod cavities were prepared in 50 extracted human molars and randomly allocated to five groups (n = 10). In all groups, the mesial-proximal box margins were located in the dentin, 1mm below the cementoenamel junction (CEJ), while the distal box margins were 1mm above the CEJ. In groups A and B, conventional standard preparations with a divergent angle of α = 6° were prepared. In groups C, D, and E, minimally invasive standard preparations with a convergent angle of α = 10° were prepared. In groups A and D, composite inlays and, in groups B and C, ceramic inlays were fabricated (chairside economical restoration of esthetic ceramics (CEREC)) and adhesively inserted. In group E, a direct composite filling using the incremental technique was placed. Replicas were taken before and after thermomechanical loading (1,200,000cycles, 50/5°C, max. load 49N). Marginal integrity (tooth-luting composite, luting composite-inlay) was evaluated by scanning electron microscopy (×200). The percentage of continuous margins in the different locations was compared between and within groups before and after cycling, using ANOVA and Scheffé post hoc test. Results: After the thermomechanical loading, no significant differences were observed between the different groups with respect to the interface of luting composite-inlay. At the interface of tooth-luting composite for preparations involving the dentin, groups A and B behaved significantly better compared to the control group E, which in turn were not different to groups C and D. Conclusion: Composite and ceramic inlays inserted in minimally invasive prepared mod cavities result in margins not different from those of inlays placed in conventional mod preparations. Direct composite filling margins, however, were inferior to those attained by conventional indirect restorations. Clinical relevance: Minimally invasive preparations for mod inlays with undercuts show marginal adaptation equal to that of conventional inlay preparation design

Zahnverfärbungen nach Trauma - Möglichkeiten von Aufhellungsverfahren

Zahntraumata können Zahnverfärbungen auslösen, die vor allem im Frontzahngebiet als ästhetisch störend empfunden werden. Zur Therapie der Verfärbung bieten sich neben restaurativen Vorgehensweisen auch Aufhellungsverfahren an. Bei einer avitalen Pulpa oder einem endodontisch behandelten Zahn kann hier ein internes Bleichverfahren (Walking-Bleach-Technik) in Betracht gezogen werden. Zur Therapie vitaler Zähne eignet sich ein externes Bleichverfahren, wobei nach heutigem Kenntnisstand die Anwendung von Hitze im Rahmen externer Aufhellungsverfahren keinen zusätzlichen Nutzen bringt. Es liegen aber keine Daten aus der Literatur vor, die einen Hinweis darauf geben, welches Bleichverfahren bei posttraumatisch verfärbten Zähnen die höchste Erfolgschance verspricht

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