Effect of hydrochloric acid commercial presentation for microabrasion technique on loss of enamel structure and surface / Efeito da apresentação comercial de ácido clorídrico para técnica de microabrasão na perda de estrutura e superfície do esmalte

Introdução: A técnica de microabrasão pode ser realizada através de pasta pronta para uso, disponível comercialmente, ou o profissional pode manipulá-la no consultório. Objetivo: Verificar o efeito da apresentação comercial do ácido clorídrico a 10% na manipulação de pasta para microabrasão sobre a superfície do esmalte. Metodologia: Foram selecionados incisivos bovinos e divididos em dois grupos, de acordo com a apresentação comercial do ácido clorídrico (líquido ou em gel). O tratamento foi realizado através de dez aplicações com 10s de duração cada, intercaladas por lavagem de 10s. Vinte incisivos (n=10) foram utilizados para se determinar a perda de estrutura do esmalte. Cada amostra foi pesada, em balança analítica, antes e após submissão à microabrasão. Outras 20 amostras (n=10) foram utilizadas para determinação da rugosidade superficial média (Ra) utilizando-se um rugosímetro. Três amostras de cada grupo do experimento anterior foram selecionadas, aleatoriamente, e outras três amostras adicionais foram preparadas como controle (baseline) para análise em MEV. Resultados: Verificou-se diferença estatística significativa entre a massa final e a inicial e rugosidade superficial das amostras, independente da apresentação comercial do ácido. Nas imagens de MEV observou-se presença de superfície regular para o grupo controle (baseline). Nas demais imagens verificou-se superfície com considerável irregularidade e dissolução discreta do esmalte. Conclusões: O tratamento realizado causou perda significativa de estrutura e aumentou a rugosidade superficial dos espécimes, independente da apresentação comercial do ácido e sem apresentar diferença entre os grupos ao final. A apresentação comercial do ácido não parece ser um fator a interferir no tratamento. (AU)

Introduction: The microabrasion technique can be performed using a commercially available paste, or the dentist can prepare it in his office. Objective: To verify the effect of hydrochloric acid commercial presentation in the handling of microabrasion paste on the enamel surface. Methodology: Bovine incisors were divided into two groups, according to the commercial presentation of 10% hydrochloric acid (liquid or gel). The treatment was carried out through ten applications of 10 s duration each, intercalated with a 10s wash. Twenty teeth (n=10) were used to determine the loss of enamel structure. Each sample was weighed on an analytical balance before and after submission to microabrasion. Another 20 teeth (n=10) were used to determine the average surface roughness (Ra) using a rugosimeter. Three samples from each group of the previous experiment were selected, randomly, and another three additional samples were repared as a control (baseline) for SEM analysis. Results: There was a statistically significant difference between the final and initial mass and the surface roughness of the samples, regardless of the acid commercial presentation. In the SEM images, a regular surface was observed for the control group (baseline). In the other images, there was a surface with considerable irregularity and a slight dissolution of the enamel. Conclusions: The treatment carried out. (AU)

Evaluation in vivo of biocompatibility of differents resin-modified cements for bonding orthodontic bands

ABSTRACT The focus of this study was to test the hypothesis that there would be no difference between the biocompatibility of resin-modified glass ionomer cements. Sixty male Wistar rats were selected and divided into four groups: Control Group; Crosslink Group; RMO Group and Transbond Group. The materials were inserted into rat subcutaneous tissue. After time intervals of 7, 15 and 30 days morphological analyses were performed. The histological parameters assessed were: inflammatory infiltrate intensity; reaction of multinucleated giant cells; edema; necrosis; granulation reaction; young fibroblasts and collagenization. The results obtained were statistically analyzed by the Kruskal-Wallis and Dunn test (P<0.05). After 7 days, Groups RMO and Transbond showed intense inflammatory infiltrate (P=0.004), only Group RMO presented greater expression of multinucleated giant cell reaction (P=0.003) compared with the control group. After the time intervals of 15 and 30 days, there was evidence of light/moderate inflammatory infiltrate, lower level of multinucleated giant cell reaction and thicker areas of young fibroblasts in all the groups. The hypothesis was rejected. The Crosslink cement provided good tissue response, since it demonstrated a lower level of inflammatory infiltrate and higher degree of collagenization, while RMO demonstrated the lowest level of biocompatibility.

Thickness and nanomechanical properties of protective layer formed by TiF4 varnish on enamel after erosion

Abstract The layer formed by fluoride compounds on tooth surface is important to protect the underlying enamel from erosion. However, there is no investigation into the properties of protective layer formed by NaF and TiF4 varnishes on eroded enamel. This study aimed to evaluate the thickness, topography, nanohardness, and elastic modulus of the protective layer formed by NaF and TiF4 varnishes on enamel after erosion using nanoindentation and atomic force microscopy (AFM). Human enamel specimens were sorted into control, NaF, and TiF4 varnish groups (n = 10). The initial nanohardness and elastic modulus values were obtained and varnishes were applied to the enamel and submitted to erosive challenge (10 cycles: 5 s cola drink/5 s artificial saliva). Thereafter, nanohardness and elastic modulus were measured. Both topography and thickness were evaluated by AFM. The data were subjected to ANOVA, Tukey's test and Student's t test (α = 0.05). After erosion, TiF4 showed a thicker protective layer compared to the NaF group and nanohardness and elastic modulus values were significantly lower than those of the control group. It was not possible to measure nanohardness and elastic modulus in the NaF group due to the thin protective layer formed. AFM showed globular deposits, which completely covered the eroded surface in the TiF4 group. After erosive challenge, the protective layer formed by TiF4 varnish showed significant properties and it was thicker than the layer formed by NaF varnish.

Esthetic perception of facial profile after treatment with the Thurow appliance

The objective of this article was to investigate the perception of esthetic changes in the facial profile of bilateral Class II patients treated with the Modified Thurow Appliance for extraoral treatment. Silhouettes were traced of profiles of patients who initially presented a bilateral Class II molar relationship and who, post-treatment, presented molars in a Class I relationship. Three groups were formed: the first composed of patients with maxillary protrusion (SNA >84°), the second with maxillary retrusion (SNA <80°), and the third with a well-positioned maxilla (SNA 80-84°). A panel of 200 lay evaluators judged the profile esthetics by a randomized drawing of the silhouettes. The multiple analysis results showed that the profile esthetic scores for the three positions of the maxilla were greatly influenced by significant interactions with the characteristics (like sex and age) of the evaluators: retrusive maxilla (Score *Age Group, p< 0.001), normal maxilla (Score *Sex, p= 0.024; Score *Age Group,p= 0.050) and protrusive maxilla (Score *Age Group,p< 0.001). It was observed that the profile of Class II patients with protrusion, normal relationship and retrusion of the maxilla, improved in their esthetic post-treatment result; however, the evaluators showed greater satisfaction with the groups of protrusion and normal position of the maxilla. The Modified Thurow Appliance provided significant improvements in the esthetics of the profile of patients who presented protrusion and normal position of the maxilla. However, its use was not the best treatment option for patients with maxillary retrusion.

Estudo in vitro da captação e liberação de flúor de cimentos ionoméricos reforçados com resina / In vitro study of fluoride release and uptake of resin-reinforced ionomer cements

A liberação de fluoreto por cimentos ortodônticos é fundamental para a prevenção da desmineralização dentária. O objetivo dos autores foi avaliar o desempenho de cimentos de ionômero de vidro reforçados com resina, quanto à capacidade de liberação e captação de flúor. Os materiais foram divididos em 3 grupos: 2 cimentos de ionômero de vidro reforça-dos com resina e 1 cimento de ionômero de vidro convencional utilizado para a cimentação de bandas ortodônticas: Grupo UB (Ultra Band Lock, Reliance), Grupo UP (Ultrapermaband, OrthoSource) e Grupo M (Meron, Voco), como controle. A liberação de flúor foi medida após 1h e no 1°, 3°, 7°, 14°, 21° e 28° dia, utilizando-se um eletrodo íon seletivo conectado a um analisador de íons. Para avaliação da recarga de flúor, os espécimes foram expostos à solução de fluoreto de sódio (1000 ppm de flúor) no 28°, 30°, 31° e 32° dia. O teste não paramétrico de Kruskal-Wallis e o teste de comparações múltiplas de Dunn foram utilizados para análise estatística.

The fluoride release by orthodontic cements is crucial to prevent dental demineralization. The aim of this study was to evaluate the performance of resin-reinforced glass ionomer cements, regarding its ability to release and uptake fluoride. Materials were divided into 3 groups: 2 resin-reinforced glass ionomer cements and 1 conventional glass ionomer cement used on orthodontic bands cementation: Group UB (Ultra Band Lock, Reliance), Group UP (Ultrapermaband, Ortho Source), and Group M (Meron, Voco), as control. The fluoride release was measured after 1h and at 1, 3, 7, 14, 21 and 28 days, using a selective ion electrode connected to an ion analyzer. To evaluate the recharge of fluoride, the specimens were exposed to sodium fluoride solution (1000 ppm fluoride) on days 28, 30, 31 and 32. The nonparametric test of Kruskal-Wallis and the Dunn multiple comparisons test were used for statistical analysis.