Evaluation of the comparative effects of infrared and red laser photobiomodulation therapy on skeletal muscle atrophy in an immobilization model in rats / Avaliação comparativa dos efeitos da terapia de fotobiomodulação com laser infravermelho e vermelho na atrofia muscular esquelética em modelo de imobilização em ratos

INTRODUCTION: Skeletal muscle atrophy leads to a reduction in muscle strength, functionality, and the quality of life of individuals. OBJECTIVE: To explore the effects of two different wavelengths (red and infrared) of laser PBMT on muscle atrophy and its active ingredients on skeletal muscle atrophy using an in vivo model of muscle atrophy. METHODS: Thirty-two Wistar rats were randomly divided into four experimental groups: control (CG) animals were not immobilized and did not receive any type of treatment; immobilized animals with no treatment (ImC); immobilized animals submitted to red laser with wavelength of 660 nm (ImR) and near-infrared laser with wavelength of 808 nm (ImIR) treatments. The treatments were applied daily, at 2 points in the right gastrocnemius muscle (cranial and caudal), through the punctual contact technique, for 9 sessions, with the first application immediately after removing the cast. RESULTS: The histological results demonstrated that in both treated groups (red and infrared wavelengths) a reduction of the inflammatory infiltrate and less connective tissue thickening when compared to the ImC. However, only infrared light was observed regenerating muscle fibers and an increase in the number of oxidative fibers (type I). CONCLUSION: These results suggest that red and infrared wavelength laser PBMT were able to promote changes in the morphology of the gastrocnemius muscle submitted to atrophy in an experimental immobilization model, reducing the inflammatory infiltrate and the formation of intramuscular connective tissue. However, infrared laser PBMT promoted more evident positive effects by increasing regenerating muscle fibers and the number of oxidative fibers.

Análise da força de tração necessária para a remoção de cimento resinoso fixado em raízes preparadas com diferentes substâncias químicas / Analysis of the force required to remove resin cement from roots prepared with different chemicals

OBJETIVO: Avaliar in vitro, a influência das substâncias químicas utilizadas durante o preparo endodôntico na força de tração do cimento resinoso Rely-X (3M, Sumaré, Brasil) na dentina radicular bovina. MÉTODOS: Utilizou-se 72 dentes bovinos que tiveram suas coroas seccionadas e raízes padronizadas. A seguir, os espécimes foram incluídos em blocos de resina e receberam tratamento químico por 10 minutos com hipoclorito de sódio nas concentrações de 0,5 por cento, 1 por cento, 2,5 por cento, 5,25 por cento ou gel de clorexidina a 2 por cento, além do grupo-controle que recebeu água destilada. Em seguida os espécimes foram imersos em solução de EDTA a 17 por cento por 3 minutos. Dois espécimes de cada grupo foram submetidos à microscopia eletrônica de varredura para avaliação da superfície. Os espécimes para o ensaio de teste de tração receberam condicionamento com ácido fosfórico a 37 por cento por 15 segundos, sistema adesivo Single-Bond (3M, Sumaré, Brasil) e sobre este aplicado o cimento resinoso Rely-X (3M, Sumaré, Brasil). RESULTADOS: Os resultados em Kgf foram: GClorex (2,26); GNaOCl-0,5 por cento (7,92); GNaOCl-1 por cento (9,70); GNaOCl-2,5 por cento (9,05); GNaOCl-5,25 por cento (8,91); GA (0,61). CONCLUSÃO: O hipoclorito de sódio nas concentrações testadas aumentou a força de adesão do cimento resinoso na dentina de forma significativa frente água destilada e gel de clorexidina a 2 por cento. A observação na microscopia eletrônica de varredura mostrou que a estrutura de dentina radicular que fora tratada com hipoclorito de sódio apresentava túbulos dentinários com diâmetros aumentados, menor quantidade de dentina intertubular, além de áreas de depressões, diferentemente dos grupos-controle e gel de clorexidina a 2 por cento.

OBJECTIVE: This study assessed in vitro how the chemicals used in the preparation of root canals affected the force required to remove the resin cement Rely-X (3M, Sumaré, Brazil) from bovine root dentin. METHODS: The crowns of 72 bovine teeth were sectioned and the roots were standardized. The specimens were then placed in resin blocks and treated for 10 minutes with sodium hypochlorite at 0.5 percent, 1 percent, 2.5 percent or 5.25 percent or chlorhexidine gel at 2 percent. The control group was treated with distilled water. Next, the specimens were soaked in 17 percent EDTA for 3 minutes. The surfaces of two specimens from each group were assessed by electron scanning microscopy. The tested specimens were then treated with 37 percent phosphoric acid for 15 minutes, adhesive system Single-Bond (3M, Sumaré, Brazil) and the resin cement Rely-X (3M, Sumaré, Brazil) was applied over it. RESULTS: The results in Kgf were: GChlorhex (2.26); GNaOCl-0.5 percent (7.92); GNaOCl-1 percent (9.70); GNaOCl-2.5 percent (9.05); GNaOCl-5.25 percent (8.91); GA (0.61). CONCLUSION: Sodium hypochlorite in the tested concentrations increased the adhesion of the resin cement to the dentin significantly when compared with water and 2 percent chlorhexidine. Electron scanning microscopy showed that the structure of the root dentin treated with sodium hypochlorite presented widened dentinal tubules, less intertubular dentin and depression areas, all of which were not observed in the roots treated with water and 2 percent chlorhexidine gel.