Uma nova estratégia para PDT antimicrobiana em Endodontia / A new approach for antimicrobial Endodontic PDT

O presente estudo avaliou diferentes parâmetros como concentração do fotossensibilizador,tempo/energia de irradiação e uso de fibras ópticas, na a PDT para redução bacteriana intracanal.Avaliou-se, in vitro, em cubetas de quartzo contendo concentrações de 50, 100, 150 e 300μM de solução aquosa de Azul de Metileno (AM) a produção de espécies reativas de oxigênio (EROs) em irradiações adicionais de 30s com um laser de diodo emitindo em 660nm. Utilizando-se a mesma metodologia, foi avaliado os efeitos na produção de EROs com e sem o uso de fibra óptica. Concentrações de 50, 150 e 300μM de AM e análise por imagens, avaliaram a formação do fenômeno escudo óptico. Dez incisivos contaminados com P. Aeruginosas bioluminescentes, foram utilizados para analisar as energias/tempo para redução bacteriana intracanal. Imagens obtidas nos dentes avaliaram a contaminação inicial. Os canais foram preenchidos com o fotossensibilizador (PS) eirradiações de 2,4J foram realizadas. A cada irradiação, imagens foram obtidas e a redução bacteriana avaliada. A formação de EROs é maior em concentrações menores do PS, assim como a formação de escudo óptico. O uso de fibra aumenta a formação de ERO quando comparado a irradiação sem fibra. Irradiação com 7J impossibilitou a detecção de biofilme intracanal. A concentração do PS em que há maior eficiência na formação de EROs e menor formação de escudo óptico se encontra entre 50 a 100μM. O uso de fibras ópticas contribui para maior formação de EROs. Energia de irradiação mínima de 7J promove significativa redução bacteriana intracanal.

This study evaluates different approach such as photos sensitizer (PS) concentration, irradiation time/energy, and the use of optical fiber for intracanal microbial reduction. In a quartzcurvet, aqueous solution of Methylene blue at 50, 100, 150 and 300μM was tested for reactive oxygen species production (ROS) after successive irradiations of 30s with a diode laser (660nm,100mW). Using the same methodology, the ROS production was tested using an optical fiber. Image analyses evaluated the presence of optical shield in 3 different concentration of PS. Tencentral incisors were contaminated with bioluminescent P. aeruginosas to test the ideal energy/time for endodontic microbial reduction. Initial contamination was recorded by image after biofilm grown. The root canals were ful filled with Ps and irradiated with successive energiesof 2.4J. After every irradiation new images were recorded to compare the microbial reduction. ROS formation was improved using low concentration of PS, such as optical shield formation. The use of optical fiber did enhance the ROS formation when compared to irradiation with thelaser tip. Energy of 7J was the minimal energy to achieve lost of bioluminescent signal. For more efficient ROS production and minor optical shield presence, a concentration between 50 and 100μM seams to be ideal. The use of an optical fiber improves ROS production. Energy of 7J promotes significative intracanal de contamination.

Evaluation of stiffness and plastic deformation of active ceramic self-ligating bracket clips after repetitive opening and closure movements.

OBJECTIVE: The aim of this study was to assess whether repetitive opening and closure of self-ligating bracket clips can cause plastic deformation of the clip. METHODS: Three types of active/interactive ceramic self-ligating brackets (n = 20) were tested: In-Ovation C, Quicklear and WOW. A standardized controlled device performed 500 cycles of opening and closure movements of the bracket clip with proper instruments and techniques adapted as recommended by the manufacturer of each bracket type. Two tensile tests, one before and one after the repetitive cycles, were performed to assess the stiffness of the clips. To this end, a custom-made stainless steel 0.40 x 0.40 mm wire was inserted into the bracket slot and adapted to the universal testing machine (EMIC DL2000), after which measurements were recorded. On the loading portion of the loading-unloading curve of clips, the slope fitted a first-degree equation curve to determine the stiffness/deflection rate of the clip. RESULTS: The results of plastic deformation showed no significant difference among bracket types before and after the 500 cycles of opening and closure (p = 0.811). There were significant differences on stiffness among the three types of brackets (p = 0.005). The WOW bracket had higher mean values, whereas Quicklear bracket had lower values, regardless of the opening/closure cycle. CONCLUSION: Repetitive controlled opening and closure movements of the clip did not alter stiffness or cause plastic deformation.

Evaluation of stiffness and plastic deformation of active ceramic self-ligating bracket clips after repetitive opening and closure movements

OBJECTIVE: The aim of this study was to assess whether repetitive opening and closure of self-ligating bracket clips can cause plastic deformation of the clip.METHODS: Three types of active/interactive ceramic self-ligating brackets (n = 20) were tested: In-Ovation C, Quicklear and WOW. A standardized controlled device performed 500 cycles of opening and closure movements of the bracket clip with proper instruments and techniques adapted as recommended by the manufacturer of each bracket type. Two tensile tests, one before and one after the repetitive cycles, were performed to assess the stiffness of the clips. To this end, a custom-made stainless steel 0.40 x 0.40 mm wire was inserted into the bracket slot and adapted to the universal testing machine (EMIC DL2000), after which measurements were recorded. On the loading portion of the loading-unloading curve of clips, the slope fitted a first-degree equation curve to determine the stiffness/deflection rate of the clip.RESULTS: The results of plastic deformation showed no significant difference among bracket types before and after the 500 cycles of opening and closure (p = 0.811). There were significant differences on stiffness among the three types of brackets (p = 0.005). The WOW bracket had higher mean values, whereas Quicklear bracket had lower values, regardless of the opening/closure cycle.CONCLUSION: Repetitive controlled opening and closure movements of the clip did not alter stiffness or cause plastic deformation.

OBJETIVO: o objetivo deste estudo foi avaliar se a abertura e o fechamento repetitivo do clipe de braquetes autoligáveis podem causar deformação plástica do clipe.MÉTODOS: três tipos de braquetes autoligáveis ativos/interativos estéticos (n = 20) foram testados: In-Ovation C, Quicklear e WOW. Um dispositivo realizou, de forma controlada e padronizada, 500 ciclos de abertura e de fechamento do clipe, com instrumentos e técnicas adequadas, tal como recomendado pelo fabricante de cada tipo de braquete. Dois ensaios de tração, um antes e um depois dos ciclos repetitivos, foram realizados para se avaliar a rigidez dos clipes. Para o ensaio de tração, um fio de 0,40 x 0,40mm de aço inoxidável foi inserido no slot do braquete e adaptado em uma máquina universal de ensaios (EMIC DL2000), sendo as medições registradas. Na porção retilínea da curva de carregamento dos clipes, a inclinação é definida por uma equação de primeiro grau, determinando o coeficiente de elasticidade (rigidez) do clipe.RESULTADOS: os resultados quanto à deformação plástica não mostraram nenhuma diferença significativa entre os tipos de braquetes, antes e depois dos 500 ciclos de abertura e de fechamento (p = 0,811). Foram encontradas diferenças significativas na rigidez entre os três tipos de braquetes (p = 0,005): o braquete WOW demonstrou valores médios mais elevados, e o braquete Quicklear demonstrou valores mais baixos, independentemente do ciclo de abertura e fechamento.CONCLUSÃO: movimentos repetitivos controlados de abertura e de fechamento do clipe não alteraram a rigidez ou causaram deformação plástica.