Bulk and surface properties related to composite filler size

There are few studies that fully characterize the effect of the filler size on the surface, optical and mechanical properties of resin composites. AIM: To determine the influence of the filler size content on surface, optical and mechanical properties before and after accelerated aging. METHODS: Seven resin composites were investigated: Filtek Supreme® (3M/ESPE), Estelite Σ Quick® (Tokuyama), Evolu-X® (Dentsply), Esthet-X HD® (Dentsply), Opallis® (FGM), Herculite XRV Ultra® (Kerr) and Filtek Z250® (3M/ESPE). Elastic modulus (EM) and flexural strength (FS) were determined by three-point bending of specimens immersed or not in absolute ethanol for seven days. Roughness (Ra) and gloss (G.U.) analyses were determined before and after ethanol storage for seven days and CIELAB color change (ΔE*) was obtained with a spectrophotometer. Results were analyzed by two-way ANOVA (general linear model) for EM and FS, with repeated measures for roughness and gloss, and one-way ANOVA for ΔE*. All comparisons were performed by Tukey's test (5%). Pearsons' correlation test was performed to determine the correlation between EM, FS, roughness, gloss, and ΔE* with the mean filler sizes. RESULTS: Mechanical properties decreased for all materials when submitted to immersion in ethanol. Increasing filler size gradually increased EM, FS and roughness values; gloss values decreased and didn't significantly affects ΔE*. Nanofiller composites presented higher gloss values than the others. CONCLUSIONS: It was possible to determine that the average filler size is a good predictor just for FS and gloss retention.

Avaliação da abrasividade de escovas dentais com cerdas macias / Abrasion assessment of soft bristle toothbrushes

Uma ampla variedade de escovas dentais está disponível no mercado com diversas indicações clínicas. Entretanto, poucos estudos na literatura avaliam a abrasão de escovas de diferentes marcas sobre as restaurações de resina composta. Objetivo: o presente estudo buscou avaliar a abrasividade de três escovas dentais com cerdas macias: Oral B Indicator Plus®, Colgate Extra Clean® e Dr. Veit Soft® em um compósito restaurador. Materiais e método: discos do compósito (8 mm x 2 mm) Tetric Ceram® foram produzidos e fotoativados com uma fonte de luz LED por 40 segundos cada. Dezoito amostras foram confeccionadas e divididas em três grupos experimentais (n = 6). Foram avaliadas a rugosidade superficial (Ra) e a massa em gramas (g) de cada espécime. Em seguida, os espécimes e as escovas foram posicionados em uma máquina simuladora de escovação (ODEME®, Luzerna, SC, Brasil). Os grupos foram submetidos a ciclos que simularam o uso contínuo das escovas por 3 meses. Para cada amostra, foi preparada uma pasta contendo a proporção em massa 1:2 de água destilada e pasta dental. Após a abrasão, a rugosidade e massa foram novamente mensuradas. As extremidades das cerdas foram observadas em um estereomicroscópio com magnitude de 45x. Os resultados foram submetidos ao teste estatístico de Análise de Variância com medidas repetidas no tempo (5%). Resultados: Não houve diferença estatística em massa para nenhum grupo antes e após abrasão (p = 0,727). No entanto, as escovas Oral B Indicator Plus® e Colgate Extra Clean® produziram superfícies mais rugosas (p = 0,002) quando comparada com Dr. Veit Soft® após abrasão. Conclusão: os resultados mostraram que existe variação no potencial de abrasão de escovas dentais classificadas comercialmente como cerdas macias de diferentes fabricantes.

There is a wide variety of toothbrushes available in the market with various clinical indications. However, there are few studies in literature that assess the abrasion of toothbrushes of different brands on composite resin restorations. Objective: the present study assessed the abrasion of three brands of soft bristles toothbrushes: Oral B Indicator Plus™, Colgate Extra Clean™, and Dr. Veit Soft™ on a restorative composite material. Materials and method: discs of composite material (8 mm x 2 mm) Tetric Ceram™ were produced and light cured with an LED unit for 40 seconds each. A total of 18 samples were made and divided in three experimental groups (n = 6). Superficial roughness (Ra) and mass in grams (g) of each sample were assessed. Then, the samples and toothbrushes were placed in a toothbrushing simulating machine (ODEME™, Luzerna, SC - Brazil). The groups were submitted to cycles simulating the continuous use of toothbrushes for 3 months. A paste containing the proportion in mass 1:2 of distilled water and dental paste was prepared for each sample. After abrasion, roughness and mass were measured again. The ends of the bristles were observed with a stereomicroscope at 45x magnitude. The results were submitted to ANOVA test with repeated measures over time (5%). Results: there was no statistical difference in mass for any group before and after toothbrush abrasion (p = 0.727). However, Oral B Indicator Plus and Colgate Extra Clean toothbrushes produced rougher surfaces (p = 0.002) than Dr. Veit Soft after abrasion. Conclusion: the results showed that there are variations in the potential for abrasion of toothbrushes commercially classified as soft bristles from different manufacturers.