Optical density evaluation around the zirconia granules used as graft in rat calvaria/Avaliacao da densidade optica ao redor dos granulos de zirconia usados como enxerto na calvaria de ratos

The aim of this study was to evaluate the optical density of the zirconia granules used as a graft in a rat calvarium model. Forty animals (Rattus Novergicus, albinus, Wistar) were divided into control and experimental groups and submitted to bone detects in the cranial cap using a trephine type burr 6 mm in diameter. The control group had the defect filled with blood coagulum, and the experimental group was filled with zirconia granules of 300 to 850 µm. The animals were sacrificed at intervals of 7, 14, 30, and 60 days. Digital images were obtained from the bone defect region, and optical density of the zirconia granules was measured using the Image Tool® 3.0. software (UTHSCSA, San Antonio, EUA). The histological analysis of the specimens was also evaluated. The values obtained were analyzed by statistical methods: Analysis of Variance, Welch's Anova, and F Test. It was verified that the mean optical density of the bone repair process differs in all analyzed regions, irrespective of time (p < 0.0001). In the region with the zirconia graft, the mean density was always higher than the other regions analyzed, and the control group showed the same behavior of the experimental groups, but for the region with zirconia graft, the average density is always greater. Keywords: digital radiography, bone density, zirconia, biomaterials, histology. O objetivo deste estudo foi avaliar, comparativamente, a densidade optica no processo de reparacao ossea utilizando enxertos com granulos de zirconia em calvaria de ratos. Foram utilizados 40 animais (Rattus Novergicus, albinus, Wistar), divididos em grupo controle e experimental, os quais foram submetidos a defeitos osseos na calota craniana com broca do tipo trefina de 6 mm de diAmetro. Os animais do grupo controle tiveram o defeito preenchido com coagulo e os do grupo experimental com grAnulos de zirconia de 300 a 850 µm. Os animais foram sacrificados nos periodos de 7, 14, 30 e 60 dias. Foram obtidas imagens digitais da regiao do defeito osseo e a densidade optica foi mensurada no programa Image Tool® 3.0 (UTHSCSA, San Antonio, EUA). A analise histologica das amostras tambem foi avaliada. Os valores obtidos foram analisados pelos metodos estatisticos Analise de VariAncia Welch's Anova e Teste F. Verificou-se que a media da densidade optica do processo de reparacao ossea difere-se em todas as regioes analisadas, independente do tempo, ou seja, apresenta diferenca estatisticamente significante (p < 0,0001), entretanto p