Investigação do potencial erosivo de gomas de mascar não convencionais / Investigation the erosive potential of unconventional chewing gums

Objetivo: mensurar o potencial erosivo de gomas de mascar não convencionais disponíveis no mercado brasileiro. Material e método: estudo experimental (in vitro) de caráter quantitativo. Foram adquiridos oito sabores de gomas de mascar: Poosh® (pinta língua); Plutonita® (abraço congelante, dentada ardente, baba de bruxa e língua ácida); e TNT® (sangue, lava e tumba). Para análise da acidez, foram realizadas leituras em triplicata do pH e acidez titulável (AT), utilizando um potenciômetro e eletrodo combinado de vidro em soluções obtidas após a maceração das gomas de mascar em água duplamente deionizada. Nas soluções com valores de pH inferiores a 5,5, foi mensurada a AT adicionando-se alíquotas de 100 µLNaOH 0,1 M, até alcançar pH 5,5. Os resultados foram submetidos à Análise de Variância (ANOVA). As comparações das médias de pH e acidez titulável foram realizadas pelo teste de Tukey, com um nível de 5% de significância (p<0,05). Resultados: os valores de pH variaram entre 2,4 (abraço congelante) e 3,5 (baba de bruxa), diferin-do significantemente do controle (água mineral/pH=6,2). Os valores de acidez titulável variaram entre 628µL de NaOH 0,1 M (sangue) e 10700µL de NaOH 0,1 M (abraço congelante). A goma de mascar sabor abraço congelante apresentou o pH mais baixo e a mais elevada acidez titulável, diferindo significantemente dos demais sabores. Conclusões: as gomas de mascar avaliadas são ácidas, mas diferem quanto ao seu potencial erosivo. Seu consumo abusivo pode constituir um fator de risco para erosão dental.(AU)

Objective: to measure the erosive potential of non- -conventional chewing gums available in the Brazilian market. Material and methods: this is an in vitro study using the following flavors of chewing gums from the Brazilian market: Poosh® (tongue cleaner); Plutonita® (freezing hug, burning bite, witch slime and acid tongue); TNT® (blood, lava and tomb). For acidity analysis, pH and titratable acidity (TA) readings were performed in triplicate using a potentiometer and combined glass electrode in solutions obtained after maceration of the chewing gums in double deionized water. In solutions with pH values below 5.5, the TA was measured by adding aliquots of 100 µL 0.1 M NaOH, until pH 5.5 was reached. The results were submitted to Analysis of Variance (ANOVA). Comparisons of pH and titratable acidity means were performed by Tukey test at a 5% significance level (p<0.05). Results: the pH values that ranged from 2.4 (freezing hug) to 3.5 (witch's slime) differed significantly from the control (mineral water/ pH=6.2). Titratable acidity values ranged from 628µL of 0.1 M NaOH (blood) to 10700µL of 0.1 M NaOH (freezing hug). The freezing hug flavor chewing gum had the lowest pH and the highest titratable acidity differing significantly from the other flavors. Conclusions: the evaluated chewing gums are acidic, but differ in their erosive potential. Their abusive consumption may constitute a risk factor for dental erosion.(AU)

Avaliação anatômica por tomografia computadorizada de feixe cônico da fossa submandibular / CBCT anatomical evaluation of the submandibular fossa

Objetivo: descrever a anatomia da fossa submandibular em mandíbulas dentadas e desdentadas, através da análise de imagens de tomografias de feixe cônico. Material e métodos: 60 tomografias computadorizadas de feixe cônico (TCFC) de mandíbulas de pacientes adultos de ambos os sexos, dentados e desdentados, que procuraram o curso de especialização em Implantodontia da Univali, foram selecionadas aleatoriamente para este estudo. Cinco regiões da mandíbula (C1 a C5), distais ao forâmen mentual, até a região do trígono retromolar, com intervalos de 5 mm entre si, foram selecionadas e mensuradas. A anatomia da fossa submandibular foi caracterizada e avaliada em sete medidas, sendo que as mais importantes para a avaliação cirúrgica prévia à instalação de implantes foram a largura da fossa (B), a altura da fossa (F) e a altura do rebordo alveolar sobre a fossa (E). Todas as imagens foram analisadas por apenas um avaliador. Resultados: entre pacientes dentados x desdentados, as faixas de valores foram, respectivamente: medida B (4,7 mm a 5,3 mm x 3,4 mm a 3,7 mm), medida F (15,2 mm a 15,5 mm x 11,9 mm - 12,5 mm), e medida E (8,7 mm a 9,8 mm x 5,4 mm a 6,3 mm). Nos intervalos de C1 a C5, as medidas B, F, e E foram diferentes estatisticamente entre pacientes dentados e desdentados (teste t não paramétrico, valores p < 0,05 e p < 0,01). Conclusão: dentro dos limites deste estudo, a fossa mandibular tem suas dimensões maiores nos dentados do que nos pacientes desdentados, principalmente na altura do rebordo alveolar. Isso aumenta a chance de perfuração em mandíbulas em que houve a extração de um elemento dental na região da fossa submandibular e a instalação imediata de um implante dentário. Entretanto, amostras maiores são necessárias para confirmar esses achados.

Objectives: to describe the anatomy of the submandibular fossa in dentate and edentulous mandibles using a CBCT protocol. Material and methods: 60 CBCT exams of adult patients seeking the Implant Dentistry course of Univali, from both sexes, were random selected in this study. Five mandibular regions (C1 to C5), distal to the mental foramina and to the retromolar region, at 5mm intervals each, were selected and measured. The anatomy of the submandibular fossa was characterized and evaluated by seven parameters, being the most important the fossa width (B), fossa height (F), and the height of the alveolar ridge over the fossa (E). All images were evaluated by the same person. Results: for dentate and edentulous patients, the range of values were: B (4.7 mm-5.3 mm x 3.4 mm-3.7 mm), F (15.2 mm-15.5 mm x 11.9 mm-12.5 mm), and E (8.7 mm-9.8 mm x 5.4 mm-6.3 mm) For C1 and C5, B, F, and E values were statistically different between dentate and edentulous patients (non-parametric t test, p < 0.05 and p < 0.01). Conclusion: within the limits of this study, the submandibular fossa dimensions are larger for dentate and edentulous individuals, mainly at the height of the alveolar ridge. This increases the chance of mandibular perforation at fresh extraction sites and immediate dental implant placement. However, large samples are required to confirm these findings.

Fracture resistance, two point bending strength and morphological characteristics of pulpless teeth restored with fiber-reinforced composite posts

Introduction: Fiber-reinforced composite posts (FRC posts) have been used for tooth reinforcement after endodontic treatment. The mechanical characteristics of FRC posts can influence the clinical prognostic. Objective:The aim of this study was to evaluate the flexural strength and fracture resistance of commercially available FRC posts. Material and methods: Fourteen human single-rooted premolars with completely formed apices were selected and received endodontic treatment. The specimens were divided into two groups related to the post system: i) Group A - cylindrical-conical fiber-reinforced post (White post DC, FGM), and ii) group B - conical fiber-reinforced post (EXACTO, Angelus). The fracture resistance was evaluated and two point bending tests were carried out. The glass fiber characteristics and the tag penetration of the luting material into the radicular dentin structure were evaluated through scanning electronic microscopy in an illustrative way. One-way ANOVA and Tukey's HSD test (α = 0.05) were applied. Results: The values obtained for fracture resistance and two point bending test were, respectively, 399.29 N and 109.5 N for group A, and 386.25 N and 119.5 N for group B. No significant differences in strength values among the groups were found. Conclusion: There were no significant statistical differences between the two post groups regarding to fracture strength and two point bending strength. It can be concluded that the posts selected for this study performed satisfactorily in terms of mechanical properties so that they can be used for tooth reinforcement after endodontic treatment.

Effects of catalase, 2% chlorhexidine gel and 1% sodium hypochlorite on the microtensile bond strength of teeth bleached with 35% hydrogen peroxide

Introduction and objective: Dental bleaching is an effective, relatively simple and noninvasive technique. The aim of this study was to evaluate the effects of catalase, 2% chlorhexidine gel, and 1% sodium hypochlorite on the microtensile bond strength to enamel of bovine teeth submitted to internal and external bleaching with 35% hydrogen peroxide. Material and methods: Sixty bovine incisors were used. They had their debris removed, washed in tap water and stored frozen. The samples were divided into five experimental groups according to the treatment applied after bleaching (n = 12): 1 − control/no bleaching (C); 2 − catalase (CA); 3 − 2% chlorhexidine gel (CG); 4 − 1% sodium hypochlorite (SH); 5 − distilled water (DW). For microtensile test, samples were prepared into blocks of enamel/resin, which were sectioned to obtain hourglass-like specimens. Bond strength was calculated in MPa and data analyzed statistically by Anova (p < 0.05). Results: Microtensile bond strength means decreased in comparison to control group, but no statistically significant difference between groups was found. Conclusion: The substances used after dental bleaching did not result in statistically significant microtensile bond strength means of the tested groups.

Influence of light intensity on mechanical properties of the resin composite

The aim of this study was to evaluate Vickers micro-hardness and flexural strength, of five commercial resin composites cured by two light curing units (LCU) with different intensities. The inorganic filling content of the composite was evaluated by thermogravimetric analysis (TGA) and the morphology of the surface was analyzed by scanning electron microscopy (SEM), in composites cured by different light intensities and immersed into a commercial soft drink or distilled water. The results show an improvement in the mechanical properties when the highest intensity of the halogen light-curing unit was used. At the same intensity of LCU, the highest values for the mechanical properties were found in specimens with a higher percentage by weight of filler. The better values were observed for micro-hardness and flexural strength in hybrid resin composites than in microfill resin composites. When the material was stored in the soft drink, changes occurred in the composite structure. The SEM images show a fractured specimen immersed in the soft drink compared with the control group, maintained in distilled water. The images show the low level of light beam penetration into resin composites, since the removal of resin components at the central part of the specimen was higher than at the surface near the light incidence.