Fototerapia com luz azul combinada à aplicação de clorexidina 0,12% em um modelo ortodôntico com biofilme cariogênico
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Data
2020-04-03
Autores
Cavichioli, Eder Augusto Mastropietro
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
Aparelhos ortodônticos fixos criam áreas de estagnação para biofilmes dentários e dificultam a limpeza dos dentes; portanto, existe o risco de desenvolver lesões incipientes de cárie durante o tratamento ortodôntico. O objetivo deste estudo é verificar se a aplicação de luz azul antes da clorexidina 0,12% no esmalte, bráquete e elástico ortodôntico reduziria ou inibiria os biofilmes maduros de Streptococcus mutans e seu crescimento nesses substratos 24 horas após a aplicação dos tratamentos; e se esse tratamento interfere na adesão do bráquete ao esmalte. Biofilmes de S. mutans UA159 foram formados por 5 dias sobre amostras compostas por esmalte bovino, bráquete ortodôntico e elástico ortodôntico. Em seguida, as amostras foram tratadas com NaCl 0,89% por 1 minuto (NaCl), luz azul por 12 minutos (BL), clorexidina 0,12% por 1 minuto (CHX) e luz azul por 12 minutos seguido da aplicação de clorexidina 0,12% por 1 minuto (BL+CHX). O acúmulo de biofilme imediatamente após os tratamentos e 24 horas após os tratamentos foram avaliados por unidades formadoras de colônias (CFU) e peso seco (DW). O pH do meio foi medido no quinto dia e sexto dia. A formação de biofilme nas amostras após os tratamentos (Imediato) e no recrescimento (Regrowth) foi avaliada visualmente por microscopia confocal de varredura a laser (CLSM). O teste de adesão (SBS) entre o bráquete e o esmalte foi feito após as amostras serem termocicladas por 500 ciclos (5°C e 55°C), tratadas e termocicladas novamente nas mesmas condições. O teste de adesão (N/mm²) foi feito com uma máquina de teste universal com uma velocidade de 1 mm/min. Após 5 dias de formação do biofilme, o tratamento com BL+CHX reduziu significativamente a viabilidade bacteriana no esmalte em comparação com o NaCl (p = 0,004) e BL (p = 0,014). Para o bráquete e o elástico, todos os tratamentos resultaram em viabilidade bacteriana semelhante (p≥0,081). No recrescimento, CHX e BL+CHX reduziram significativamente a viabilidade bacteriana no esmalte em comparação com o NaCl (p≤0,015) e BL (p≤0,013). Para o bráquete, BL+CHX reduziu significativamente a viabilidade bacteriana em comparação com NaCl (p = 0,008) e BL (p = 0,009). Para o elástico, BL+CHX eliminou o biofilme do substrato. CHX e BL+CHX reduziram significativamente a viabilidade bacteriana 24 horas após o tratamento para todos os substratos (p≤0,05). O pH do meio aumentou significativamente quando as amostras foram tratadas com CHX e BL+CHX (p≤0,001). Imagens da CLSM mostraram maior quantidade de células mortas nas amostras tratadas com BL+CHX. Não houve diferença no SBS entre os tratamentos (p≥0,932). A associação entre BL+CHX reduziu o biofilme de S. mutans e seu recrescimento em um modelo ortodôntico in vitro e não influenciou na resistência de adesão entre bráquete e esmalte.
Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient lesions of caries during the orthodontic treatment. The objective of this study is to verify if the application of blue light prior to 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets and elastics would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 h after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel. Biofilms of S. mutans UA159 were formed for 5-days over samples composed by a bovine enamel, an orthodontic bracket and an orthodontic elastic. Then, the samples were treated with 0.89% NaCl for 1 minute (NaCl), blue light for 12 minutes (BL), 0.12% chlorhexidine for 1 minute (CHX) and BL for 12 min + 0.12% CHX for 1 min (BL+CHX). Biofilm accumulation immediately after treatments and 24-h after treatments (regrowth) were evaluated by colonies forming units (CFU) and dry weight (DW). The pH of the spent media was measured on the 5th and 6th day. Biofilm formation on the samples after the treatments and on the regrowth was visually evaluated by confocal laser scanning microscopy (CLSM). Shear bond strength (SBS) between bracket and enamel was evaluated after specimens were thermocycled for 500 cycles (5° and 55 °C), treated and thermocycled again in the same conditions. Shear forces (N/mm2 ) were applied to the specimens with a universal testing machine at a crosshead speed of 1 mm/min. After 5 days of biofilm formation BL+CHX significantly reduced the bacterial viability on Enamel compared to NaCl (p=0.004) and BL (p=0.014). For Bracket and Elastic, all the treatments resulted in similar bacterial viability (p≥0.081). In the regrowth, CHX and BL+CHX significantly reduced the bacterial viability in the Enamel compared to the NaCl (p≤0.015) and BL (p≤0.013). For Bracket, BL+CHX significantly reduced the bacterial viability compared to NaCl (p=0.008) and BL (p=0.009). For the Elastic, BL+CHX eliminated the biofilms from the substrate. CHX and BL+CHX significantly reduced the bacterial viability 24 h after treatment for all substrates (p≤0.05). The media pH significantly increased when samples were treated with CHX and BL+CHX (p≤0.001). CLSM images showed greater amount of dead cells in the samples treated with BL+CHX. There was no difference on the SBS between the treatments (p≥0.932). The association between BL and CHX reduced S. mutans biofilm and its regrowth on an in vitro orthodontic model and did not influence on the bonding strength between bracket and enamel.
Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient lesions of caries during the orthodontic treatment. The objective of this study is to verify if the application of blue light prior to 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets and elastics would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 h after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel. Biofilms of S. mutans UA159 were formed for 5-days over samples composed by a bovine enamel, an orthodontic bracket and an orthodontic elastic. Then, the samples were treated with 0.89% NaCl for 1 minute (NaCl), blue light for 12 minutes (BL), 0.12% chlorhexidine for 1 minute (CHX) and BL for 12 min + 0.12% CHX for 1 min (BL+CHX). Biofilm accumulation immediately after treatments and 24-h after treatments (regrowth) were evaluated by colonies forming units (CFU) and dry weight (DW). The pH of the spent media was measured on the 5th and 6th day. Biofilm formation on the samples after the treatments and on the regrowth was visually evaluated by confocal laser scanning microscopy (CLSM). Shear bond strength (SBS) between bracket and enamel was evaluated after specimens were thermocycled for 500 cycles (5° and 55 °C), treated and thermocycled again in the same conditions. Shear forces (N/mm2 ) were applied to the specimens with a universal testing machine at a crosshead speed of 1 mm/min. After 5 days of biofilm formation BL+CHX significantly reduced the bacterial viability on Enamel compared to NaCl (p=0.004) and BL (p=0.014). For Bracket and Elastic, all the treatments resulted in similar bacterial viability (p≥0.081). In the regrowth, CHX and BL+CHX significantly reduced the bacterial viability in the Enamel compared to the NaCl (p≤0.015) and BL (p≤0.013). For Bracket, BL+CHX significantly reduced the bacterial viability compared to NaCl (p=0.008) and BL (p=0.009). For the Elastic, BL+CHX eliminated the biofilms from the substrate. CHX and BL+CHX significantly reduced the bacterial viability 24 h after treatment for all substrates (p≤0.05). The media pH significantly increased when samples were treated with CHX and BL+CHX (p≤0.001). CLSM images showed greater amount of dead cells in the samples treated with BL+CHX. There was no difference on the SBS between the treatments (p≥0.932). The association between BL and CHX reduced S. mutans biofilm and its regrowth on an in vitro orthodontic model and did not influence on the bonding strength between bracket and enamel.
Descrição
Palavras-chave
Ortodontia, Fototerapia, Streptococcus mutans., Orthodontics, Phototherapy, Streptococcus mutans.