Avaliação comparativa em mandíbulas e tíbias de ratos submetidos à terapia com bisfosfonatos nitrogenados e não nitrogenados: análise imaginológica e histomorfométrica

Abstract

Bisphosphonates (BPs) are synthetic analogs of the inorganic pyrophosphate, used for prevention and treatment of diseases with excessive bone resorption. The medication-related osteonecrosis of the jaw (MRONJ) is a condition characterized by persistent bone exposure in the maxillofacial region of patients exposed to this class of drugs, with no history of head and neck radiotherapy. The objective of the present study was to compare, histologically and imagiologically, the bone structure of mandibles and tibiae of rats that were treated with BPs and rats that did not received BPs. Thirty-four rat especimens (Rattus novergicus, Wistar strain) were divided in 3 groups: (1) 12 mandibles and tibiae of rats treated with zoledronic acid; (2) 12 mandibles and tibiae of rats treated with clodronate; (3) control group, containing 10 mandibles and tibiae of rats that received saline solution. All individuals were exposed to cone beam computed tomography (CBCT). The images were processed and analised to obtain the bone density (BD) in Hounsfield Units (HU), using the software OsiriX 7.0. Sixty-eight histological slides were obtained from the mandibles and 34 from the tibiae, stained with hematoxilin and eosin (HE). The histological sections were scanned, and using the software Adobe Photoshop CC, the proportion of bone volume (BV) was quantified. The statistical analysis was made using ANOVA and Student’s t-test, performed by the software Stata 15.0. There was no statistically significant difference comparing the BD neither among the drug groups, nor between mandible and tibia. The comparison of BV among BPs and control group was not significant different. However, comparing the two bones, the mandibles in control group presented higher BV than tibiae of the same group. Based on the results, it is possible to conclude that (1) BD is not altered by bone type, neither by the kind of drug administered, and (2) the therapy with zoledronic acid and clodronate did not affect the BV in mandibles and tibias of tests groups.