Efeito do campo eletromagnético pulsado na reparação de defeito ósseo crítico na calota de ratos / Effect of the Pulsed Electromagnetic Field in the repair of a calvaria critical bone defect in rats

O reparo de defeitos ósseos críticos representa um grande desafio clínico, dentre as terapias adjuvantes que apresentam um potencial benefício na aceleração do reparo ósseo destaca-se o CEMP, o qual por meio da sua estimulação biofísica é capaz de modular parâmetros fisiológicos de diferenciação, proliferação e mineralização das células ósseas. Sendo assim, o presente estudo teve como objetivo avaliar o efeito de dois protocolos de terapia com CEMP na neoformação óssea em defeitos críticos nas calotas de ratos. Noventa e seis ratos machos adultos foram divididos aleatoriamente em 3 grupos experimentais GC: (n= 32), GT1h: (n= 32) e GT3h: (n= 32). Os animais foram submetidos à cirurgia para a confecção de defeito crítico na calota craniana e à terapia com CEMP seguindo os seguintes parâmetros fixos: 25 ciclos de -1 mTesla a + 1 mTesla em 200 microssegundos que se repetiram à taxa de 15 Hz. O tempo de duração da exposição ao CEMP nos grupos testes foram de 1 hora (GT1h) e de 3 horas (GT3h), ambos durante 5 dias por semana. Os animais foram submetidos à eutanásia nos períodos 14, 21, 45 e 60 dias. Os espécimes foram processados para análise histológica, histomorfométrica e para análises de textura e volume, obtidas por meio de TCFC. As análises histomorfométrica e de volume revelaram que não houve diferença estaticamente significante no reparo dos defeitos ósseos entre os grupos que receberam a terapia com CEMP e o GC. A análise de textura revelou que houve diferença estatisticamente significante entre os grupos somente para o parâmetro entropia, no qual o grupo GT1h apresentou um maior valor comparado ao GC, ambos no período de 21 dias. Conclusão: não foi possível neste estudo mostrar um potencial benefício da utilização do CEMP na cicatrização óssea do DOC na calota de ratos. Dessa forma, esta região deve ser melhor explorada em estudos futuros, assim como a busca pelos parâmetros ideais relacionados ao gerador do CEMP de forma a maximizar os efeitos no reparo ósseo. (AU)

The repair of critical bone defects represents a major clinical challenge, among the adjuvant therapies that have a potential benefit in accelerating bone repair, PEMF stands out, which through its biophysical stimulation can modulate physiological parameters of differentiation, proliferation and mineralization of bone cells. Therefore, the present study aimed to evaluate the effect of two protocols of therapy with PEMF on bone neoformation on calvaria critical defects in rats. Ninety-six adult male rats were randomly divided into 3 experimental groups CG: (n=32), GT1h: (n=32) and GT3h: (n=32). The animals were submitted to surgery for the creation of a critical defect in the skull and to therapy with PEMF following the following fixed parameters: 25 cycles of -1 mTesla to + 1 mTesla in 200 microseconds that were repeated at a rate of 15 Hz. The duration of exposure to PEMF in the test groups was 1 hour (GT1h) and 3 hours (GT3h), both for 5 days a week. The animals were euthanized at 14, 21, 45 and 60 days. The specimens were processed for histological, histomorphometric and texture and volume analysis, obtained by CBCT. Histomorphometric and volume analyzes revealed that there was no statistically significant difference in the repair of bone defects between both groups receiving PEMF therapy and GC. The texture analysis revealed that there was a statistically significant difference between the groups, except for the entropy parameter, in which the GT1h group presented a higher value compared to CG, both in the period of 21 days. Conclusion: it was not possible in this study to show a potential benefit of using PEMF on bone healing of calvaria critical defects. Therefore, this region should be better explored in future studies, as well as seeking the ideal parameters related to the PEMF generator in order to maximize effects on bone repair (AU)

Macroscopic and radiographic aspects of orthodontic movement associated with corticotomy: animal study.

INTRODUCTION: To quantify the rate of tooth movement in two corticotomy protocols in an experimental model in rats through macroscopic and radiographic analysis. METHODS: The animals were divided into three groups: orthodontic movement (CO), orthodontic movement plus corticotomy surgery (G2), and orthodontic movement and corticotomy surgery with decorticalization (G3).The euthanasia occurred in 7 and 14 days. The data were statistically analyzed (p < 0.05). RESULTS: The CO presented lower distance between the mesial surface of the first molar and the distal surface of the third molar when compared to the G2 (6.96 ± 0.24, p = 0.009) and G3 (6.93 ± 0.18, p = 0.016) in the macroscopic analysis. In the 7 days, there was no statistically significant radiographic difference between the three groups: CO(0.94 ± 0.21 mm2), G2(1.05 ± 0,27 mm2), and G3(1.08 ± 0.27 mm2).There was a statistically significant difference between CO (0.87 ± 0.12 mm2), G2 (1.00 ± 0.12 mm2), and G3 (1.11 ± 0.14 mm2) at 14 days. There was a statistically significant linear difference between the groups in all periods. CONCLUSION: Tooth movement and the region of interest were influenced by corticotomy, regardless of the surgical technique in the 14 days.