RESUMO
The present study aimed to analyze the effect of LED phototherapy on the presence of hyalinization and root resorption during orthodontic tooth movement (OTM) in rats and to measure the amount of tooth movement. Eighty rats were allocated into two groups: LED and control (CON), where the LED rats were irradiated with infrared LED (850 nm, 30 mW) for 5 min during the first five days of OTM and where controls were not irradiated. Both groups were subdivided into four subgroups (n=10) according to the date of euthanasia (4, 7, 14 and 21 days). Five out of ten LED21 and five of ten CON21 rats were submitted to micro-computed tomography (µCT); µCT scans were taken on days 0, 7, 14 and 21. For histological study, maxillae were processed to light microscopy using Hematoxylin-Eosin (HE) and Tartrate-Resistant Acid Phosphatase (TRAP) histochemistry. The amount of tooth movement did not differ between LED and CON. Hyalinization was observed at the pressure areas in both groups, and it did not show a statistically significant difference between the groups. Root resorption was also observed in both groups after 7 days and it did not represent any differences between the two groups. LED phototherapy was not able to increase the amount of OTM. Similar characteristics of hyalinization and root resorption were observed in both groups.
Assuntos
Reabsorção da Raiz , Técnicas de Movimentação Dentária , Animais , Ratos , Ratos Wistar , Fosfatase Ácida Resistente a Tartarato , Microtomografia por Raio-XRESUMO
O objetivo deste estudo foi observar, ao microscópio eletrônico de varredura (MEV), a micromorfologia do esmalte de dentes decíduos intacto ou desgastado após condicionamento com ácido fosfórico a 37% ou com sistemas adesivos autocondicionantes de uma ou duas etapas. Foram selecionados 15 dentes decíduos, que foram divididos em três grupos, com 5 dentes em cada, de acordo com o agente condicionador e dentre eles, sub-divididos mantendo-se a superfície do esmalte intacta ou desgastada. G1: ácido fosfórico a 37% (Condicionador Dental Gel - Dentsply). G1A: esmalte intacto. G1B: esmalte desgastado. G2: condicionamento com primer do sistema adesivo autocondicionante de duas etapas (Adhese - Ivoclar Vivadent). G2A: esmalte intacto. G2B: esmalte desgastado. G3: condicionamento com sistema adesivo autocondicionante de etapa única (Xeno III Dentsply). G3A: esmalte intacto. G3B: esmalte desgastado. Após os tratamentos propostos, todas as amostras foram desidratadas, montadas em bases metálicas e observadas ao MEV quanto ao padrão de condicionamento ácido. As amostras do G1A revelaram um padrão não homogêneo de condicionamento (áreas de esmalte condicionado e outras não condicionadas). No G1B foi observado um padrão homogêneo de condicionamento, prevalecendo o padrão Tipo 2 de Silverstone et al.(1975). As amostras dos G2A e G2B não revelaram um padrão homogêneo de condicionamento, tanto no esmalte íntegro como no desgastado. Concluiu-se que o uso do ácido fosfórico parece ser mais favorável para a formação de uma superfície micro retentiva, notadamente no esmalte desgastado. O uso de sistemas adesivos autocondicionantes, tanto no esmalte intacto como no desgastado não propiciou a formação de uma superfície do esmalte micro retentiva.
The aim of this study was to examinate under scanning electron microscopy (SEM) the micromorphology of grounded and ungrounded primary enamel after conditioning with 37% phosphoric acid, single or two-step self etching adhesive systems. Fiftheen primary teeth were selected and divided into three groups (n=5), according to the etchant and then sub-divided maintaining the enamel surface ungrounded or grounded. G1: 37% phosphoric acid (Condicionador Dental Gel Dentsply). G1A: ungrounded enamel. G1B; grounded enamel. G2: etching with primer of a two-step adhesive system Adhese (Ivoclar Vivadent). G2A: ungrounded enamel. G2B: grounded enamel.G3: etching with a single-step adhesive system (Xeno III Dentsply). G3A: ungrounded enamel. G3B: grounded enamel. After enamel etching, all the samples were dehydrated, mounted on metal stubs and observed by SEM for etching pattern. G1A samples showed a non-uniform pattern of enamel etching (with etched and unetched areas). In G1B samples it was observed an uniform Type 2 etching pattern, according Silverstone et al. (1975). G2A and G2B samples did not reveal an uniform etching pattern, for both grounded and ungrounded enamel. It was concluded that the use of phosphoric acid seems to be more suitable to create a micro retentive surface, specially when enamel surface was grounded. Use of a self etching adhesive system on grounded or ungrounded primary enamel did not propitiate the formation of a microretentive enamel pattern.