RESUMO
Abstract Objective To compare the effect of two therapeutic ultrasound protocols, with different times of exposure in the regeneration of critical bone defect. Methods Forty-five male rats were distributed among three experimental groups: therapeutic ultrasound group 5 minutes (TUG 5); therapeutic ultrasound group 10 minutes (TUG 10); and control group (CG). In all groups, a critical bone defect of 8.5 mm diameter was made in the calvaria region. The protocol was initiated on the 1st postoperative day in TUGs 5 and 10, with therapeutic ultrasound at the frequency of 1.0 MHz, pulsed mode, five times a week, at periods of 15, 30, and 60 days. Results Among the experimental groups, the highest volume of neoformation of osteoid matrix took place in the TUG 10 group followed by TUG 5, when compared with the CG group, in which the neoformation was restricted to the border region. The use of ultrasound promoted an increase in the thickness of the conjunctive matrix, proliferation of capillaries, alignment of the collagen fibers, reduction of edema and inflammatory process, being more significant in the 10-minutes time period. Conclusion Therapeutic ultrasound stimulated the repair of a critical bone defect, and the longer exposure time promoted greater osteogenic stimulation.
Resumo Objetivo Comparar o efeito de dois protocolos de ultrassom terapêutico com diferentes tempos de exposição para regeneração de defeito ósseo crítico. Métodos Foram utilizados 45 ratos, machos, distribuídos em três grupos: grupo ultrassom terapêutico 5 minutos (GUS 5); grupo ultrassom terapêutico 10 minutos (GUS 10); e grupo controle (GC). Em todos os grupos, confeccionou-se um defeito ósseo crítico, com 8,5 mm de diâmetro, na região da calvária. O protocolo foi iniciado no 1º dia do pós-operatório, no GUS 5 e no GUS 10, com ultrassom terapêutico na frequência de 1,0 MHz, modo pulsado, 5 vezes por semana, nos períodos de 15, 30, e 60 dias. Resultados Dentre os grupos experimentais, houve maior neoformação de matriz osteoide no GUS 10, seguido do GUS 5 quando comparados ao GC, no qual a neoformação foi restrita à região de borda. O uso do ultrassom promoveu aumento na espessura da matriz conjuntiva, proliferação de capilares, alinhamento das fibras colágenas, redução do edema e do processo inflamatório, tendo sido mais significativo no tempo de 10 minutos. Conclusão O ultrassom terapêutico estimulou o reparo do defeito ósseo crítico, e o maior tempo de exposição promoveu maior estímulo osteogênico.
Assuntos
Animais , Ratos , Crânio , Terapia por Ultrassom , Osso e Ossos , Regeneração Óssea , Morbidade , ColágenoRESUMO
Abstract Purpose: To analyze, histomorphologically, the influence of the geometry of nanostructured hydroxyapatite and alginate (HAn/Alg) composites in the initial phase of the bone repair. Methods: Fifteen rats were distributed to three groups: MiHA - bone defect filled with HAn/Alg microspheres; GrHA - bone defect filled with HAn/Alg granules; and DV - empty bone defect; evaluated after 15 days postoperatively. The experimental surgical model was the critical bone defect, ≅8.5 mm, in rat calvaria. After euthanasia the specimens were embedded in paraffin and stained with hematoxylin and eosin, picrosirius and Masson-Goldner's trichrome. Results: The histomorphologic analysis showed, in the MiHA, deposition of osteoid matrix within some microspheres and circumjacent to the others, near the bone edges. In GrHA, the deposition of this matrix was scarce inside and adjacent to the granules. In these two groups, chronic granulomatous inflammation was noted, more evident in GrHA. In the DV, it was observed bone neoformation restricted to the bone edges and formation of connective tissue with reduced thickness in relation to the bone edges, throughout the defect. Conclusion: The geometry of the biomaterials was determinant in the tissue response, since the microspheres showed more favorable to the bone regeneration in relation to the granules.