Avaliação do grau de conversão monomérica de resinas compostas ortodônticas / Degree of conversion evaluation of an orthodontics composite resins

Este estudo avaliou o grau de conversão de uma resina composta utilizada em tratamentos restauradores, Filtek Z 250 - 3M ESPE (Z250), e duas resinas ortodônticas: Orthocem - FGM (OC) e Transbond XT - 3M Unitek (TB) por meio da espectroscopia no infravermelho por transformada de Fourier (FTIR). Para isto, foram confeccionados quinze corpos de prova fotopolimerizados para cada resina. As medidas de grau de conversão foram realizadas imediatamente após a confecção das amostras. Os espectros de absorção no infravermelho foram obtidos num espectrofotômetro Parkin Elmer do Brasil. Os resultados das amostras tiveram sua normalidade aferida por meio do teste Kolmogorov-Smirnov e analisadas pelo teste ANOVA um critério, que demonstrou haver diferença estatística entre os grupos (p<0,05). (AU)

This study evaluated the degree of conversion of a composite resin used in restorative treatments, Filtek Z 250 - 3M ESPE (Z250), and two orthodontic resins: Orthocem - FGM (OC) and Transbond XT - 3M Unitek (TB) by means of infrared spectroscopy Fourier transform (FTIR). For this, fifteen bodies of light cured specimens were fabricated for each resin. Measures of degree of conversion were performed immediately after preparation of the samples. The infrared absorption spectra were obtained on a Parkin Elmer spectrophotometer Brazil. The results of the samples were measured using normality of the Kolmogorov-Smirnov test and analyzed by ANOVA criterion, which showed no statistical difference between groups (p<0,05). (AU)

Potential of desensitizing toothpastes to reduce the hydrogen peroxide diffusion in teeth with cervical lesions.

PURPOSE: To evaluate the occlusive potential of four toothpastes by atomic force microscopy (AFM) before and after bleaching and quantify the hydrogen peroxide (HP) diffusion into the pulp chamber after application of desensitizing toothpastes in teeth with cervical lesions. METHODS: In 52 human extracted premolars, 2-mm deep artificial cervical lesions (ACL) were prepared and rinsed with EDTA for 10 seconds. Then teeth were adapted in a brushing machine and brushed with one of the following toothpastes [Regular toothpaste with no occlusive compounds Colgate Cavity Protection (CP), Oral-B Pro Health (OB), Colgate ProRelief (PR) and Sensodyne Rapid Relief (RR)] under constant loading (250 g; 4.5 cycles/seconds; 3 minutes). In 13 teeth (control group), no artificial cervical lesion was prepared. After that, the teeth were bleached with 35% HP with three 15-minute applications. The HP diffusion was measured spectrophotometrically as a stable red product based on HP reaction with 4-aminoanthipyrine and phenol in presence of peroxidase, at a wavelength of 510 nm and the dentin surfaces of ACL were evaluated before and after bleaching by AFM. Data was statistically analyzed by one-way ANOVA and Tukey's test (alpha = 0.05). RESULTS: In the AFM images, some modifications of the dentin surface were observed after application of OB and RR. However, only for RR the formation of a surface deposit was produced, which occluded the majority of the dentin tubules. Also, only for RR, this deposit was not modified/removed by bleaching. Despite this, all groups with ACL showed higher HP penetration than sound teeth, regardless of the toothpaste used (P < 0.001).