Histological evaluation of critical size bone repair treated with xenogen graft in rats induced to hypothyroidism

Almiro de Almeida Vasconcelos Neto, Maria Isabel Pereira Vianna, Luciana Maria Pereira Ramalho, Gardênia Matos Paraguassu, Dario Augusto Oliveira Miranda

This study aimed at assessing bone repair of critical-size defects by comparing normal animals with hypothyroid animals, with or without bone graft (Bio-Oss® Geistlich Pharma AG, Wolhusen, Switzerland) at two times of evaluation (30 and 60 days). Forty-two Wistar rats were used and divided into two major groups, namely: Group 1: Euthyroid, without graft, 30 days (G1E30); euthyroid, without graft, 60 days (G1E60); hypothyroid, without graft, 30 days (G1H30) and hypothyroid, without graft 60 days (G1H60). Group 2: Euthyroid, grafted, 30 days (G2E30); euthyroid, grafted, 60 days (G2E60); hypothyroid, grafted, 30 days (G2H30) and hypothyroid, grafted, 60 days (G2H60). The animals were induced to hypothyroidism by propylthiouracil (PTU) diluted with drinking water. Critical-size defects were created by trephine burs in the rats’ calvarium. Treatment was performed to prepare histological slides and analysis as well as to carry out statistical tests. 95% confidence interval (P < 0.05) was employed. Results revealed no statistically significant differences in cortical repair between hypothyroid and euthyroid animals at both times of evaluation. However, statistically significant differences were found in comparing 30 x 60 days (G1E60> G1E30, p = 0.01 G1H60> G1H30 and p = 0.01 G2h60> G2H30). Bone formation around graft particles was not statistically different when groups with the same time of evaluation were compared. Nevertheless, animals with hypothyroidism had bone formation associated with graft particles statistically greater 60 days after repair (G2H60> G2H30 P = 0.03). Based on the results of this study it is reasonable to conclude that the systemic condition did not significantly affect bone repair. Additionally, graft seemed to positively contribute to bone formation in induced animals.

Keywords: Bone repair. Hypothyroidism. Biomaterial.

How to cite: Vasconcelos Neto AA, Vianna MIP, Ramalho LMP, Paraguassu GM, Miranda DAO. Histological evaluation of critical size bone repair treated with xenogen graft in rats induced to hypothyroidism. Dental Press Implantol. 2013 Oct-Dec;7(4):75-84.

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