Abraham Lincoln Calixto

Regional bond strengths to root canal dentin of fiber posts luted with three cementation systems

This study evaluated the influence of the cementation system on the regional push-out bond strength and failure pattern of fiber posts to radicular dentin. The roots of 48 extracted human incisors were prepared and divided into 3 groups (n = 16), according to the cementation system: AdperScotchbond Multi-Purpose + resin cement RelyX ARC (SBMP+ARC); Adper SingleBond 2 + RelyX ARC (SB+ARC) and; RelyX U100 self-adhesive resin cement (U100). The posts were cemented as per manufacturers instructions for each cementation system. After 1 week, the roots were sectioned transversely into 6 discs. Two discs were obtained from the cervical, middle and apical thirds and the push-out test was carried out. The failure pattern was examined on all debonded specimens. The data were analyzed by two-way repeated measures ANOVA and Tukeys test. When U100 was used, no statistically significant difference (p>0.05) was observed among the different root regions. Statistically higher push-out bond strength values were detected in the cervical third for SBMP+ARC and SB+ARC (p<0.05). The U100 showed significantly more mixed failures than SBMP+ARC in the apical third (p<0.05). In conclusion, the self-adhesive cement RelyX U100 was the only cement not sensitive to the root canal region.

Hardness of a bleaching-shade resin composite polymerized with different light-curing sources

The microhardness of a bleaching-shade resin composite polymerized with different light-curing units was evaluated. Composite samples (3M ESPE Filtek Supreme) were applied to brass rings (2 mm in thickness, 5 mm in diameter). Three commercial LED lights were used to polymerize the specimens and the results were compared to those of a conventional halogen light. The light sources used in the present study were: Demetron Optilux 401 (QTH), 3M ESPE Elipar FreeLight (LED 1); Kerr L.E. Demetron I (LED 2), and ColtoluxLED lights (LED 3). The microhardness of the top and bottom surfaces was assessed with a digital Vickers hardness-measuring instrument, under load. At the bottom surface, no significant difference among the light sources was observed (two-way ANOVA). At the top surface, the QTH light source presented significantly higher hardness values compared to the values observed when LED 1 and LED 3 were used. There were no significant differences between the QTH and LED 2 light sources. Significantly higher hardness values were also found at the top surface when compared to the values observed at the bottom surface. The power density of the polymerization light sources seemed to be responsible for the observed resin composite hardness, not their irradiance.

Análise da capacidade de remoção de pigmentos da resina composta pelo peróxido de hidrogênio 35

Objetivo Avaliar in vitro a capacidade de remocao de pigmentos ocasionados em resina composta apos aplicacao de peroxido de hidrogenio 35%. Material e metodo Confeccionaram-se 20 amostras de resina composta Opallis (FGM), cor A1, em matriz metalica circular. As amostras foram divididas em quatro grupos (n=5) dos seguintes agentes corantes: agua destilada (controle), cafe, vinho tinto e Coca-Cola®. No manchamento, as amostras ficaram imersas nas solucoes durante 72 horas, com troca diaria das bebidas. Procedeu-se a aplicacao do gel de peroxido de hidrogenio 35% (Whiteness HP Blue Calcium, FGM) em tres sessoes, sendo uma aplicacao do gel por sessao, o qual permaneceu nas amostras durante 40 minutos. Medidas de cor foram feitas inicialmente, apos manchamento, apos aplicacao do peroxido e por mais 21 dias, usando espectrofotometro Vita Easyshade. Os dados foram submetidos a analise de variância de dois fatores (tempo vs. corante) e ao teste de Tukey, para o contraste das medias (α=0,05). Resultado Apresentaram alteracao de cor (ΔE - media/desvio padrao de L*) o cafe (15,7 ± 2,0) e o vinho (15,2 ± 4,6), quando comparados a Coca-Cola® (4,8 ± 1,9). O peroxido de hidrogenio removeu a pigmentacao das amostras, porem, para nenhum dos corantes, houve retorno a coloracao inicial, principalmente no grupo manchado por cafe (12,9 ± 1,5); este mostrou diferenca significativa quando comparado ao controle (1,6 ± 0,6), diferentemente do vinho (3,3 ± 0,6) e da Coca-Cola® (2,1 ± 0,9), que se aproximaram do grupo controle. Conclusao As solucoes corantes pigmentaram a resina composta, principalmente o cafe. A aplicacao do peroxido de hidrogenio 35% foi eficaz na remocao de pigmentos das amostras, porem, em nenhum dos grupos, com diferentes corantes, houve retorno a coloracao inicial (p>0,005).