Effect of dentifrice containing fluoride and/or baiting soda on enamel demineralization remineralization: An in situ study

The additive effect of baking soda on the anticariogenic effect of fluoride dentifrice is not well established. To evaluate it, a crossover in situ study was done in three phases of 28 days. Volunteers, using acrylic palatal appliances containing four human enamel blocks, two sound (to evaluate demineralization) and two with artificial caries lesions (to evaluate remineralization), took part in this study. During each phase, 10% sucrose solution was dripped (3 times a day) only onto the sound blocks. After 10 min, a slurry of placebo, fluoride (F) or fluoride and baking soda (F+NaHCO3) dentifrice was dripped onto all enamel blocks. The results showed a higher F concentration in dental plaque formed during treatment with F+NaHCO3 than placebo (p<0.05), but the difference related to F dentifrice was not significant. The enamel demineralization was lower, and remineralization was greater, after treatment with F+NaHCO3 than placebo (p<0.05), but the difference related to F dentifrice was not significant. The data suggest that baking soda neither improves nor impairs the effect of F dentifrice on reduction of demineralization and enhancement of remineralization of enamel. Copyright (C) 2001 S. Karger AG. Basel.35210611

Effect of sucrose on the selection of mutans streptococci and lactobacilli in dental biofilm formed in situ

Microorganisms are selected in dental biofilm by the acidic environment created by sugar fermentation, but the effect of extracellular polysaccharide (EPS) on the counts of cariogenic bacteria is not clear. Dental biofilm was formed in situ for 13 days under exposure 8 times a day to distilled-deionized water, glucose + fructose or sucrose solutions. Mutans streptococci (MS) counts were not different among the groups, but lactobacilli (LB) were significantly higher in glucose + fructose and sucrose groups, without significant difference between them, irrespective of the higher insoluble EPS concentration in the sucrose biofilm matrix. The data suggest that exposure to sugar is more relevant for the predominance of LB in dental biofilm than for MS and that insoluble EPS does not change the counts of these microorganisms in the biofilm. Copyright (c) 2006 S. Karger AG, Basel40654654

Effect of a lactose-containing sweetener on root dentine demineralization in situ

Since lactose has been used as an excipient in powdered sweeteners, we evaluated its effect on dentine demineralization, in an in situ crossover study. Twelve adult volunteers wore palatal appliances containing 4 blocks of bovine root dentine, which were submitted 4 times a day to: distilled water (negative control), aqueous solution of powdered sweetener (Zero Cal(R); experimental group), 1.5% lactose solution (active group), 1.5% sucrose solution (positive control). After 15 days, microhardness was determined on dentine surface (SMH) and on the sectioned blocks (CSMH). All groups presented statistical differences in SMH before and after the treatments; water increased, while sweetener, lactose and sucrose decreased SMH. By CSMH, the only significant difference was observed after sucrose treatment. The data suggest that sweeteners containing lactose as a bulking agent may be cariogenic for root dentine. Copyright (C) 2002 S. Karger AG, Basel.36316716

Effect of a calcium carbonate-based dentifrice on enamel demineralization in situ

Since the effect of calcium carbonate (CaCO3) based dentifrice on enamel demineralization is not clearly established, it was evaluated using the IEDT model described by Zero's group in 1992. This study had a crossover design and 10 volunteers were submitted to 3 treatment groups: a negative control, brushing without dentifrice; an active control, brushing with silica-based dentifrice (SiO2/MFP group), and the experimental group, brushing with CaCO3-based dentifrice (CaCO3/MFP). Both dentifrices contained 1,500 mug F/g (w/w) as sodium monofluorophosphate (MFP). Enamel surface microhardness was determined in the dental blocks and the percentage change in relation to baseline was calculated. Fluoride uptake in enamel and its concentration in 'test plaque' were determined. The results showed that the dentifrice containing CaCO3/MFP was more effective than SiO2/MFP in reducing enamel demineralization (p < 0.05). A higher concentration of fluoride ion was found in 'test plaque' treated with CaCO3/MFP than in the negative control (p < 0.05). The results suggest that CaCO3 abrasive may enhance the effect of fluoride present in dentifrice on dental caries control. Copyright (C) 2003 S. Karger AG, Basel.37319419

Effect of interocclusal appliance on masticatory performance of patients with bruxism

This study was designed to evaluate masticatory performance in bruxist patients. The experimental group was composed of 16 dentate volunteers presenting with bruxism and treated by interocclusal appliances and a control group, consisting of 16 dentate volunteers with no symptoms of bruxism. To evaluate masticatory performance, the volunteers chewed .03 grams of peanuts contained in polyvinyl wrapper for four and twelve masticatory cycles. The number of chewed particles was counted using an optical scanning method by Image-Pro Plus 1.4 software (Media Cybernetics, Inc., Silverspring, MD). The score was expressed as the mean of the number of chewed particles for each wrapper. Masticatory performance evaluations were carried out in a single period for the control group and for the experimental group, before interocclusal appliance insertion, and after seven, 15, 30, and 60 days. Comparison between groups, as well as between before and after interocclusal appliance insertion, showed no significant differences (P>.05), irrespective of the number of masticatory cycles.23426426

Effect of new dentures on interocclusal distance during speech

Purpose: The aim of this study was to investigate the changes in interocclusal distance during the pronunciation of /m/ and /s/ sounds in the Portuguese language, in partially edentulous patients before and after insertion of new dentures. Materials and Methods: Subjects were divided into a control group consisting of 18 completely dentate patients and an experimental group consisting of 18 patients who were edentulous in the maxilla and classified as Kennedy Class I in the mandible. The experimental group had new dentures placed and the occlusal vertical dimension corrected. A magnetic jaw-tracking device measured the interocclusal distance during pronunciation of the /m/ and /s/ phonemes. Interocclusal distance evaluations were carried out in a single session for the control group. In the experimental group, the measurements were carried out before insertion of new dentures; immediately after insertion; and after 6 and 24 hours; 2 days; I and 2 weeks; 1, 2, 3, and 6 months; and I year. Results: Comparison between groups revealed significant difference in interocclusal distance for the /m/ sound both before and after insertion of dentures up to 2 months. For the /s/ phoneme, there was no difference between the groups before prosthesis insertion, or after 3, 6, and 12 months of prosthesis use. There were significant differences for the /m/ sound only at 6 and 12 months after new denture insertion, and for the /s/ sound at all periods evaluated. Conclusion: Insertion of new dentures, with the vertical dimension corrected, changes the interocclusal distance of speech during phonation of /m/ and /s/ sounds.16553353

Low-fluoride toothpaste and deciduous enamel demineralization under biofilm accumulation and sucrose exposure

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Because low-fluoride toothpaste (500 p.p.m. F) has not clearly been shown to be effective for controlling caries in caries-active children, this experimental in situ study was conducted to evaluate whether its effect, when compared with a conventional toothpaste (1,000-1,500 p.p.m. F), would depend on the cariogenic challenge. During four phases of 14 d each, 14 volunteers used 500 or 1,100 p.p.m. F toothpaste and wore palatal appliances containing deciduous enamel slabs, on which biofilm was accumulated and exposed to 20% sucrose solution at frequencies increasing from two to eight times per day. The F concentration was determined in the biofilm formed, and enamel demineralization was assessed by surface hardness loss (%SHL) and integrated area of hardness x lesion depth (Delta S). The F uptake by enamel was also determined. Fluoride in biofilm fluid and solids was statistically higher when conventional F toothpaste was used. The toothpastes did not differ statistically in terms of %SHL, Delta S, and F in enamel, but only the conventional F toothpaste significantly reduced caries-lesion progression according to the frequency of sucrose exposure. The findings suggest that the high-F availability in biofilm, resulting from the use of conventional toothpaste compared with low-F toothpaste, may be important for reducing caries-lesion progression in conjunction with a high frequency of sucrose exposure.1184370375Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)FAPESP [2007/05994-3

Effect of sucrose concentration on dental diofilm formed in situ and on enamel demineralization

The relationship between sucrose concentration and cariogenic potential was studied in situ. Adult volunteers wore intraoral palatal appliances containing human dental enamel blocks, which were extraorally submitted 8 times a day for 14 days, to the treatments: deionized distilled water and sucrose solutions from 1 to 40%. The biofilm formed was analyzed with respect to acidogenicity and biochemical composition; enamel demineralization was evaluated by microhardness. The results showed that 1% sucrose is less cariogenic than 5% or higher concentrations, although sucrose solution at 40% was still able to increase the concentration of insoluble polysaccharide in the biofilm formed. The findings suggest that the threshold of sucrose solution concentration for the formation of a cariogenic biofilm is 5%, which provided the same cariogenic potential as that observed for 10 and 20% sucrose solution. Copyright (C) 2006 S. Karger AG, Basel.401283

Influence of ceramic pre-treatments on tensile bond strength and mode of failure of resin bonded to ceramics

Purpose: To evaluate the effect of ceramic surface treatments on tensile bond strength (sigma) and the mode of failure of a resin bonded to a feldspathic glass and a low-crystalline ceramic, testing the hypothesis that a silica coating treatment is unnecessary for both the glass and the low-crystalline ceramic. Methods: 10 blocks of each the feldspathic glass (V7-VITAVM7) and the leucite-based ceramic (E1-IPS Empress) were fabricated and polished. Five blocks of each ceramic were treated as follows: 9.5% hydrofluoric acid for 60 seconds; and silica coating using Cojet System for 15 seconds. After silane coating, an adhesive resin and a composite were applied and polymerized. The composite-ceramic blocks were cut to produce bar-shaped specimens (n=30) that were stored in distilled water at 37 degrees C for 7 days before tensile loading to failure in a universal testing machine. Data were statistically analyzed using analysis of variance, Tukey's test (alpha = .01) and Weibull analysis. Fracture surfaces were examined to determine the mode of failure. Results: The Weibull modulus (m) and mean sigma value (MPa) of Group E1HF (29.8+/-4.5) were significantly higher than other Groups (P=.0001). There was no statistical difference between Groups E1CS (24.6+/-5.6) and V7HF (22.3+/-4.0). Group V7CS showed the lowest m and mean sigma values (15.7+/-6.9) (P=.0001). All fractures occurred within the adhesion zone.20210310