The Addition of Propylene Glycol Alginate to a Fluoride Solution to Control Enamel Wear: An in situ Study.

The aim of this study was to evaluate the protective effect of propylene glycol alginate (PGA) associated with sodium fluoride (NaF) against enamel erosion and erosion-abrasion. A 4-phase, split-mouth, double-blind, crossover in situ trial was conducted with the following solutions: F + PGA (225 ppm F- + 0.1% PGA), F (225 ppm F-), F + Sn (225 ppm F- + SnCl2, 800 ppm Sn2+), and negative control (distilled water). In each phase, 12 subjects wore removable mandibular appliances containing 4 enamel specimens, which were submitted either to erosion or to erosion-abrasion challenges for 5 days. Acquired salivary pellicle was formed in situ for 2 h. Erosion-abrasion consisted of acid challenge (1% citric acid solution, pH 2.3, 5 min, 4×/day), exposure to saliva in situ (2 h, 4×/day), brushing (5 s, total 2 min exposure to the slurry), and treatment with the solutions (2 min, 2×/day). For erosion, the same procedures were performed, without brushing. At the end, surface loss (SL; in µm) was evaluated by means of optical profilometry. KOH-soluble fluoride was quantified for erosion-only groups using extra specimens. For both challenges, the SL values found for F + PGA did not differ significantly from those of F and the negative control, and the SL value shown for F + Sn was significantly the lowest. Erosion-abrasion promoted significantly higher SL values than erosion. KOH-soluble fluoride analysis showed that F + Sn had a higher fluoride concentration in comparison with the negative control and F, while F + PGA did not differ from any of the other groups. In conclusion, PGA was not able to improve the protective effect of NaF against erosive enamel wear.

Color stability and surface roughness of composite resins submitted to brushing with bleaching toothpastes: An in situ study.

OBJECTIVE: To evaluate, in situ, the color stability (CS) and surface roughness (SR) of composite resins after toothbrushing with whitening toothpaste. MATERIALS AND METHODS: Specimens (6 × 2 mm/) of composite resin (Tetric N-Ceram, Z250 and Z350) were randomly fixed on thirty participants' upper molars (buccal surface). For an initial standardization (7 days), participants used a soft toothbrush and nonwhitening toothpaste (SDB - Sorrisos Dentes Brancos). Initial CS (Easyshade) and SR (Surfcorder RS) measurements were performed. For SR, impressions of specimens were taken (Express, 3 M ESPE) to produce replicas in polyurethane resin (Axon F16, Abcol). Participants were randomly separated into three groups (n = 10) regarding used toothpaste (SDB; Close up White Now - CWN; Colgate Luminous White - CLW). After 90 days, CS and SR measurements were obtained, and data were analyzed (2-way ANOVA, repeated measures, Bonferroni, P < .05). RESULTS: Z250 showed higher (P < .05) color change than Z350. Tetric N-Ceram presented an intermediary value for ΔE, however, it also demonstrated higher SR (P < .05) after brushing with CLW, compared with SDB and CWN. CONCLUSIONS: The SR change of composite resin after toothbrushing with a whitening toothpaste is material dependent, but the toothpaste abrasiveness does not change the CS. CLINICAL SIGNIFICANCE: Whitening toothpaste do not change the color stability of composites; however, it can alter the restorative composite surface roughness.

Morphological abnormalities in natural populations of the common South American toad Rhinella arenarum inhabiting fluoride-rich environments.

Morphological abnormalities in amphibians may be attributed to contaminants, ultraviolet radiation and trematode parasites, or a synergistic effect between them. In the present study, morphological abnormalities in Rhinella arenarum adults from natural and artificial fluoride-rich environments were identified and evaluated. Three sites were sampled in central Argentina: Los Vallecitos stream (LF-LV), Los Cerros Negros stream (MF-CN), and Decantation ponds (HF-DP), with low (0.33 mg/L), middle (2.03 mg/L) and high (14.0 mg/L) fluoride levels respectively; the latter site is associated with a fluoride mine. Abnormal individuals were photographed and then standard radiographs were taken. Abnormality frequencies and relative percentage of abnormal individuals were calculated for each site. In addition, skeletochronology was used to estimate toad's age. Five abnormality types were identified: syndactyly, ectrodactyly, polydactyly, microphthalmia and ectromelia. Percentages of abnormal individuals per site were: LF-LV = 4%, MF-CN = 21.2% and HF-DP = 6.4%. The MF-CN and HF-DP populations had morphological abnormality frequencies that exceeded the reference value (5%) reported in the literature. The average age did not differ between sites. The results of this study indicate that there is an association between frequency of morphological abnormalities and high fluoride levels.

Effect of open-sandwich vs. adhesive restorative techniques on enamel and dentine demineralization: an in situ study.

OBJECTIVES: To assess in situ the effect of different restorative techniques used with fluoride-releasing materials on enamel and dentine demineralization in the presence of a cariogenic challenge. METHODS: Thirty human molars were prepared for 60 Class V cavities, with enamel and dentine margins. The teeth were divided into four groups (n=15): L1 - open sandwich technique with a conventional glass ionomer cement (GIC), L2 - open sandwich technique with a resin-modified GIC, A1 - total-etch bonding with a fluoride-containing adhesive, A2 - total-etch bonding with a nonfluoride-containing adhesive. All the cavities were restored with a nanofilled composite. Fifteen volunteers used appliances containing one specimen from each group. The cariogenic challenge was carried out with a 20% sucrose solution 8×/day for 7 days. The specimens were sectioned for microhardness test and EDS analysis at different depths below the enamel and dentine margins (25, 50 and 100µm) and distances from the tooth-restoration interfaces (25 and 75µm). The data were analyzed by ANOVA and Games-Howell test (α=5%). RESULTS: Both GICs produced higher hardness in enamel at all depth-and-distance combinations, but only L1 produced higher hardness in dentine (p<0.05). L2 and A1 exhibited similar dentine hardness at 25µm distance for all depths (p>0.05). L1 demonstrated significantly higher amounts of calcium in dentine than the other groups, but had similar amounts in enamel to L2 and A1. CONCLUSIONS: The open sandwich technique using conventional GIC proved more effective in reducing enamel and dentine demineralization at depths of up to 100µm under a cariogenic challenge. CLINICAL SIGNIFICANCE: Conventional GICs should be considered the materials of choice for lining of cavities not having all margins in enamel, particularly using the open sandwich technique.

Formação in situ de biofilme sobre esmalte e cimento de ionômero de vidro em diferentes tensões de oxigênio / In situ biofilm formation on enamel and glass ionomer cement in different oxygen tensions

Objetivo: Avaliar, in situ, o desenvolvimento de biofilme sobre fragmentos de esmalte bovino com restaurações de cimento de ionômero de vidro. Metodologia: Seis voluntários utilizaram um dispositivo intra-bucal removível, semelhante a um aparelho ortodôntico, contendo quatro espécimes de esmalte bovino restaurados com cimento de ionômero de vidro, posicionados para o meio bucal livre ou em contato com o palato. Um examinador cego analisou visualmente a formação de biofilme nos corpos-de-prova em esmalte e em ionômero de vidro utilizando um índice-padrão após 24, 48, 96 e 168 horas (7 dias). Resultados: Não houve diferença significativa na formação de biofilme sobre o ionômero de vidro em relação ao esmalte. Houve um desenvolvimento mais rápido do biofilme nos corpos-de-prova voltados para o palato, independentemente do tipo de substrato. Conclusões: O cimento de ionômero de vidro não afetou a colonização microbiana. O desenvolvimento de biofilme foi maior no local com menor disponibilidade de oxigênio.

Purpose: To evaluate the in situ biofilm formation on enamel fragments restored with glass ionomer cement. Methods: Six volunteers wore removable intra-oral devices similar to orthodontic appliances, containing four fragments of bovine enamel restored with glass ionomer cement. A blind examiner visually analyzed the biofilm formation on enamel and glass ionomer cement specimens by using a standardized index after 24, 48, 96, and 168 hours (7 days). Results: No significant difference was detected between the biofilm formation on enamel and on glass ionomer cement. The results showed a faster biofilm development on specimens facing the palate, independently from the substrate. Conclusions: Glass ionomer cement did not affect microbial colonization. Biofilm development was higher where less oxygen was available.

Genotypic diversity of S. mutans in dental biofilm formed in situ under sugar stress exposure

In situ dental biofilm composition under sugar exposure is well known, but sugar effect on the genotypic diversity of S. mutans in dental biofilm has not been explored. This study evaluated S. mutans genotypic diversity in dental biofilm formed in situ under frequent exposure to sucrose and its monosaccharide constituents (glucose and fructose). Saliva of 7 volunteers was collected for isolation of S. mutans and the same volunteers wore intraoral palatal appliances, containing enamel slabs, which were submitted to the following treatments: distilled and deionized water (negative control), 10 percent glucose + 10 percent fructose (fermentable carbohydrates) solution or 20 percent sucrose (fermentable and EPS inductor) solution, 8x/day. After 3, 7 and 14 days, the biofilms were colleted and S. mutans colonies were isolated. Arbitrarily primed polymerase chain reaction (AP-PCR) of S. mutans showed that salivary genotypes were also detected in almost all biofilm samples, independently of the treatment, and seemed to reflect those genotypes present at higher proportion in biofilms. In addition to the salivary genotypes, others were found in biofilms but in lower proportions and were distinct among treatment. The data suggest that the in situ model seems to be useful to evaluate genotypic diversity of S. mutans, but, under the tested conditions, it was not possible to clearly show that specific genotypes were selected in the biofilm due to the stress induced by sucrose metabolism or simple fermentation of its monosaccharides.

A composição do biofilme dental in situ exposto a açúcares é bem conhecida, mas o efeito dos açúcares na diversidade genotípica de S. mutans no biofilme dental ainda não foi explorada. Este estudo avaliou a diversidade genotípica de S. mutans no biofilme dental formado in situ sob frequente exposição à sacarose e seus monossacarídeos constituintes (glicose e frutose). Primeiramente, saliva de voluntários foi coletada para isolamento de S. mutans e os mesmos voluntários usaram um dispositivo intraoral palatino, contendo blocos de esmalte, que foram submetidos 8x/dia aos seguintes tratamentos: água destilada e deionizada (controle negativo), solução de glicose 10 por cento + frutose 10 por cento (carboidratos fermentáveis) e solução de sacarose 20 por cento (fermentável e indutor de PEC). Após 3, 7 e 14 dias, os biofilmes foram coletados e colônias de S. mutans foram isoladas. A técnica de reação em cadeia de polimerase usando primers arbitrários (AP-PCR) demonstrou que o genótipo salivar foi detectado em quase todas as amostras de biofilme, independente do tratamento, e parece refletir aqueles genótipos presentes em maiores proporções no biofilme. Além do genótipo salivar, outros foram encontrados nos biofilmes, mas em uma menor proporção e foram distintos entre os tratamentos. Os dados sugerem que o modelo in situ é útil para a avaliação da diversidade genotípica de S. mutans. Porém, nas condições do presente estudo, não foi possível demonstrar que genótipos específicos foram detectados no biofilme devido ao estresse induzido pelo metabolismo da sacarose ou fermentação de seus monossacarídeos.