HISTOMORPHOMETRIC ANALYSIS OF BIOLOGICAL RESPONSES FOLLOWING THE USE OF PURE HYDROXYAPATITE AND HYDROXYAPATITE WITH COLLAGEN: A STUDY IN DORSAL SUBCUTANEOUS TISSUE OF RATS / ANÁLISE HISTOMORFOMÉTRICA DAS RESPOSTAS BIOLÓGICAS APÓS A UTILIZAÇÃO DE HIDROXIAPATITE PURA E HIDROXIAPATITE COM COLAGÉNIO: UM ESTUDO NO TECIDO SUBCUTÂNEO DORSAL DE RATOS

Purpose: The aim of this study was to evaluate the biological responses resulting from the implantation of two types of experimental hydroxyapatite – Pure Ha (HaP) and Ha with collagen (HaCol) and compare them with a third type HaAlobone (commercial) – on dorsal subcutaneous tissue of female rats. Methods: Forty-five animals were used (15 in each group), which were sacrificed 7, 15, and 30 days after operation. The specimens were fixed, stained with hematoxylin and eosin, and then evaluated for inflammatory reactions with a light microscope. Results: The three experimental groups showed a high inflammatory response after 7 days. The inflammatory response was seen to decrease sharply after 15 days. After 30 days, the foreign body reactions were seen to reduce significantly, and an organized collagen tissue was observed. The results showed that the types of hydroxyapatite tested – HaP and HaCol – are biocompatible. When compared with the commercially available hydroxyapatite, these new biomaterials showed similar biocompatibility performance. CLINICAL SIGNIFICANCE: The new hydroxyapatite tested are considered biocompatible.