Evaluation of bond strength and internal adaptation between the dental cavity and adhesives applied in one and two layers.

This research evaluated the influence of the number of adhesive layers of three adhesive systems on microtensile bond strength (microTBS) to dentin and the internal adaptation between the dental structure and the resin composite restoration. Two cavities (C-factor = 3) were made on the buccal surfaces of 30 bovine incisors. Scotchbond Multi-Purpose (MP), Adper Single Bond 2 (SB) and Clearfil SE Bond (CSB) were applied in one layer (MP-I, SB-I and CSB-I) and in two layers (MP-II, SB-II and CSB-II). The cavities were restored with Z250 resin composite. After 48 hours, beams were obtained (n = 15/group) for microTBS testing, and slices containing the two restorations were obtained for internal adaptation analysis. The beams were submitted to the microTBS test on a universal testing machine (EMIC DL-2000) and the failures were analyzed by SEM. The slices were analyzed under an optical microscope and the types and amounts of internal failures (gap, crack, rupture) were classified. The mean values of microTBS (MPa) were: MP-II: 56.92; MP-I: 52:23; CSB-II: 47:71; CSB-I: 42.25; SB-I: 35.12 and SB-II: 34.69. According to two-way ANOVA (alpha = 0.05), the independent variables adhesive system (p = 0.001) and the number of layers (p = 0.025) presented significant difference. The mixed failure was predominant in all groups. For the internal adaptation analysis, the Kruskal-Wallis test (alpha = 0.05) showed statistical differences for cracks and ruptures between the adhesive systems. SB-I and II were shown to have the highest values for cracks, and MP-I demonstrated the lowest. SB-II showed significantly higher values for rupture. The application of two layers promoted a slight increase in microTBS for Scotchbond MP and Clearfil SE Bond, but it did not improve the internal adaptation for the tested adhesive systems.

Optical density and chemical composition of microfilled and microhybrid composite resins.

This study evaluated the optical density of two microfilled and two microhybrid resins, as well as the composition of these materials with regard to their optical density. Cavities prepared in 12 2-mm- or 4-mm-thick acrylic plastic plates were filled with Z250 (3M-ESPE), A110 (3M-ESPE), Charisma (Heraeus-Kulzer) and DurafillVS (Heraeus-Kulzer). The resin increments (2-mm-thick) were light-cured for 40 s. Three 0.12-s radiographic exposures were made of each #2 acrylic plastic plate. DenOptix system optical plates were used to obtain the digital images. Three readings of the composite resin surface were made in each radiograph, totalizing 216 readings. The mean of highest and lowest grey-scale values was obtained. Two specimens of each composite resin were prepared for SEM analysis of the chemical elements related to optical density, using energy dispersive x-ray analysis (EDX). The results were subjected to Shapiro-Wilk's test, ANOVA, Tukey's test at 1% level of significance and Pearson's correlation. The mean grey-scale values at 2 mm and 4 mm were: Z250 = 154.27a and 185.33w; A110 = 46.77b and 63.05y; Charisma = 163.40c and 200.46z; DurafillVS = 43.92b and 58.99x, respectively. Pearson's test did not show any positive correlation between optical density and percentage weight of optical density chemical elements. It was concluded that the microhybrid resins had higher optical density means than the microfilled resins; among the evaluated resins, Charisma had the highest optical density means.

Optical density and chemical composition of microfilled and microhybrid composite resins

This study evaluated the optical density of two microfilled and two microhybrid resins, as well as the composition of these materials with regard to their optical density. Cavities prepared in 12 2-mm- or 4-mm-thick acrylic plastic plates were filled with Z250 (3M-ESPE), A110 (3M-ESPE), Charisma (Heraeus-Kulzer) and DurafillVS (Heraeus-Kulzer). The resin increments (2-mm-thick) were light-cured for 40 s. Three 0.12-s radiographic exposures were made of each #2 acrylic plastic plate. DenOptix system optical plates were used to obtain the digital images. Three readings of the composite resin surface were made in each radiograph, totalizing 216 readings. The mean of highest and lowest grey-scale values was obtained. Two specimens of each composite resin were prepared for SEM analysis of the chemical elements related to optical density, using energy dispersive x-ray analysis (EDX). The results were subjected to Shapiro-Wilk's test, ANOVA, Tukey's test at 1 percent level of significance and Pearson's correlation. The mean grey-scale values at 2 mm and 4 mm were: Z250 = 154.27a and 185.33w; A110 = 46.77b and 63.05y; Charisma = 163.40c and 200.46z; DurafillVS = 43.92b and 58.99x, respectively. Pearson's test did not show any positive correlation between optical density and percentage weight of optical density chemical elements. It was concluded that the microhybrid resins had higher optical density means than the microfilled resins; among the evaluated resins, Charisma had the highest optical density means.

Densidade óptica e composição química de resinas compostas / Radiopacity and chemical composition of composite resins

Verificou-se a densidade óptica de quatro resinas compostas disponíveis atualmente no mercado, bem como a composição desses materiais quanto à presença de elementos químicos responsáveis por sua densidade óptica. As resinas Z250 e Supreme (3M-ESPE), 4Seasons (Ivoclar Vivadent) e EsthetX (Dentsply), foram inseridas em orifícios existentes em 12 placas de acrílico divididas em espessuras de 2 e 4mm. Os incrementos de resina (2mm) foram fotopolimerizados por 40s. Realizaram-se 3 tomadas radiográficas de cada placa com o tempo de exposição de 0,12s. As imagens digitais foram obtidas através do sistema DenOptix. Foram realizadas 3 leituras de cada tomada radiográfica em cada resina no software VixWin, sendo calculada a média dos maiores e menores valores de densidade óptica (em pixels), totalizando 216 leituras. Confeccionaram-se 2 amostras de cada resina para análise dos elementos químicos em Microscopia Eletrônica de Varredura através de Espectroscopia por Dispersão de Energia (EDS). Os resultados foram submetidos ao teste de Shapiro-Wilk, à Análise de Variância, ao teste de Tukey a 1% e Correlação de Pearson. As médias de densidade óptica (pixels) em 2mm e 4mm, respectivamente, foram (valores seguidos de mesma letra não diferem estatisticamente entre si): Z250 = 171,17a e 199,58x; Supreme = 167,78a e 195,30w; 4Seasons =176,32b e 208,50y; EsthetX = 190,85c e 213,56z. Os maiores valores foram obtidos pela resina EsthetX, nas duas espessuras avaliadas. Com base nos resultados encontrados concluiu-se que não houve correlação entre os valores médios de densidade óptica das resinas testadas e o percentual em peso de elementos que lhe conferem esta característica.

Shear bond strength of indirect resin to NiCr with different metal surface preparations.

This study sought to evaluate the shear bond strength of indirect resin to nickel chromium (NiCr) after different surface preparations. Sixty-four metal samples were divided into four groups, according to surface preparation, and two layers of opaque resin and three layers of body resin were applied. Each group was divided into two subgroups based on storage period in distilled water at 37 degrees C. Mechanical shear testing was performed using a universal testing machine with 0.5 mm/minute of cross-head speed. Debonded areas were analyzed and classified according to different failure types, such as cohesive, adhesive, and mixed. The storage periods were compared using a student T-test (alpha = 0.05); Group T (that is, the tin electroplating group) showed the highest average after 24 hours. The macro retentions showed higher shear bond strength than the sandblasted samples (p < 0.05). Tin electroplating did not improve the shear bond strength of metal-resin bonding. The results were not affected by 30-day storage, with the exception of group T (p < 0.05).

Tratamento sintomatológico de pacientes com disfunçäo craniomandibular indicados à reabilitaçäo oral: relato de casos clínicos / Syntomatologic treatment of patients with craniomandibular disorder referred to oral reabilitation: a case report

O presente artigo é um relato de dois casos clínicos de disfunçäo craniomandibular (DCM), onde se optou por um tratamento reversível para restabelecimento da dimensäo vertical de oclusäo prévio a reabilitaçäo protética. Relacionamos a perda dos contatos posteriores, a diminuiçäo da dimensäo vertical de oclusäo e as alteraçöes musculares daí decorrentes com a sintomatologia apresentada em ambos os casos