Microhardness assessment of different commercial brands of resin composites with different degrees of translucence

Owing to improvements in its mechanical properties and to the availability of shade and translucence resources, resin composite has become one of the most widely used restorative materials in present day Dentistry. The aim of this study was to assess the relation between the surface hardness of seven different commercial brands of resin composites (Charisma, Fill Magic, Master Fill, Natural Look, Opallis, Tetric Ceram, and Z250) and the different degrees of translucence (translucid, enamel and dentin). Vickers microhardness testing revealed significant differences among the groups. Z250 was the commercial brand that showed the best performance in the hardness test. When comparing the three groups assessed within the same brand, only Master Fill and Fill Magic presented statistically significant differences among all of the different translucencies. Natural Look was the only one that showed no significant difference among any of the three groups. Charisma, Opallis, Tetric Ceram and Z250 showed significant differences among some of the tested groups. Based on the results found in this study, it was not possible to establish a relation between translucence and the microhardness of the resin composites assessed. Depending on the material assessed, however, translucence variation did affect the microhardness values of the resin composites

Quantitative and qualitative evaluation of the two ceramics in differents surfaces tratment

A característica de superfície representa um fator importante na previsibilidade do comportamento dos materiais cerâmicos quanto ao desgaste. A rugosidade superficial de duas cerâmicas (Duceram Plus e Duceragold) foi avaliada através de dois métodos - análise quantitativa e qualitativa - após diferentes tratamentos. Foram confeccionados 36 corpos de prova de prova para a análise ao rugosímetro, e 24 corpos de prova para a análise ao MEV. Os resultados destas análises demonstraram o comportamento distinto entre os diferentes tratamentos. A análise com o rugosímetro demonstrou que a ação dos polidores EDENTA foi a mais efetiva para devolver lisura à superfície após a realização de desgaste com instrumento abrasivo diamantado rotatório. Todas as técnicas de polimento acarretaram em valores de rugosidade menores que os observados nos espécimes que foram submetidos apenas os glaze". Entre as cerâmicas avaliadas, a Duceragold apresentou valores médios de rugosidade inferiores aos observados na porcelana Duceram Plus na maioria dos tratamentos pesquisados. Pela análise ao MEV não foi possível distinguir diferenças entre as cerâmicas ou entre os corpos de prova polidos ou submetidos apenas ao glaze".The surface characteristic of ceramic material is an important factor to predict its wear behavior. The surface roughness of two ceramics (Duceram Plus e Duceragold) was evaluated trough qualitative and quantitative methods after different treatments. 36 specimens were fabricated for the analysis utilizing a surface profiling instrument, and 24 for the SEM analysis. The results determined different behavior between the two ceramics evaluated due the treatment executed. The analysis utilizing a surface profiling instrument showed that the treatment using the EDENTA polishers was the most effective technique to provide the smoothest surface after trimming. All polishing techniques resulted in better surface properties when compared to the treatment glaze. The Duceragold ceramic presented lower roughness values in most treatments executed when compared to Duceram Plus. The perception trough the SEM analysis of significant differences between treatments or between the two ceramics was not achievable

Fracture strength of teeth restored with ceramic inlays and overlays

This study evaluated the fracture strength of teeth restored with bonded ceramic inlays and overlays compared to sound teeth. Thirty sound human maxillary premolars were assigned to 3 groups: 1- sound/unprepared (control); 2- inlays and 3- overlays. The inlay cavity design was Class II MOD preparation with an occlusal width of 1/2 of the intercuspal distance. The overlay cavity design was similar to that of the inlay group, except for buccal and palatal cusp coverage The inlay and overlay groups were restored with feldspathic porcelain bonded with adhesive cement. The specimens were subjected to a compressive load until fracture. Data were analyzed statistically by the Kruskal-Wallis test at 5% significance level. The fracture strength means (KN) were: Sound/unprepared group = 1.17, Inlay group= 1.17, and Overlay group = 1.14. There were no statistically significant differences (p>0.05) among the groups. For inlays and overlays, the predominant fracture mode involved fragments of one cusp (70% of simple fractures). The fracture strength of teeth restored with inlay and overlay ceramics with cusp coverage was similar to that of intact teeth.Este estudo avaliou a resistência à fratura de dentes restaurados com inlays e overlays de cerâmicas comparadas a dentes íntegros. Trinta pré-molares humanos íntegros foram divididos em 3 grupos: 1-Dentes sem preparo cavitário (controle), 2-Inlays e 3-Overlays. O preparo para as inlays apresentava uma cavidade de Classe II MOD tendo caixa oclusal com largura de metade da distância intercuspídica. O preparo para as overlays era semelhante ao das inlays; porém com cobertura das cúspides vestibular e palatina. Os grupos 2 e 3 foram restaurados com porcelanas feldspáticas fixadas com cimento resinoso. As amostras foram submetidas à compressão até a fratura. Os valores médios de fratura (KN) foram: grupo 1 = 1,17, grupo 2 = 1,17 e grupo 3 = 1,14. O teste de Kruskal-Wallis não revelou diferença estatisticamente significante entre os 3 grupos (p>0,05). Para as inlays e overlays, a predominância das fraturas envolveu fragmentos de uma das cúspides (70% de fraturas simples). Concluiu-se que os dentes restaurados com inlays e overlays apresentaram resistência da cúspide comparável aos dentes intactos

Evaluation of the Possibility of Removing Staining by Repolishing Composite Resins Submitted to Artificial Aging

This in vitro research verified the possibility of eliminating staining caused by coffee and red wine in five composite resins, after being submitted to thermal cycling. Thirty-six specimens were prepared and immersed in water at 37 degrees C for 24 hours. After polishing, specimen color was measured in a spectrophotometer Cintra 10 UV (Visible Spectrometer, GBC, Braeside, VIC, Australia). All specimens were submitted to thermal cycling at temperatures of 5 and 55 degrees C with a dwell time of 1 minute, for 1,000 cycles in a 75% ethanol/water solution. After thermal cycling, the specimens were immersed in water at 37 degrees C until 7 days had elapsed from the time the specimens were prepared. All specimens were then taken to the spectrophotometer for color measurement. The specimens were divided into three groups (N = 12): distilled water (control), coffee, and red wine. For the staining process to occur on only one surface, all the sides, except one, of the surfaces were isolated with white wax. The specimens were immersed in one of the solutions at 37 degrees C for 14 days. The specimens were dried and taken to the spectrophotometer for color measurement. After this, the specimens were submitted to 20 mu m wear three times, and the color was measured after each one of the wear procedures. Calculation of the color difference was made using CIEDE2000 formula. According to the methodology used in this research, it was concluded that the staining caused by coffee and red wine was superficial and one wear of 20 mu m was sufficient to remove the discoloration