Características clínicas e histopatológicas associadas ao uso do preenchedor dérmico hidroxiapatita de cálcio na região orofacial : um estudo experimental em ratos

Abstract

The increasing use of calcium hydroxyapatite (CaHA) for facial aesthetic procedures has raised questions about safety and possible complications. The present study aimed to evaluate the clinical and histological effect of the subcutaneous and submucosal application of CaHA in the orofacial region of rats. The sample consisted of 48 female Wistar rats, which were distributed into CaHA and control groups. The material was injected into the middle third of the ventral tongue (0.07 mL) and into the submandibular region (0,1 mL). In the control group, saline solution was injected in the same amounts. The animals were euthanized after seven, 30 and 90 days. The tongue and skin of the submandibular region were dissected, prepared and stained with HE and Masson's trichrome for analysis of the inflammatory process and the collagen percentage, respectively. In the histological sections of the skin, the thickness of the epidermis/dermis was also measured. Histological alterations in the submandibular glands were also analyzed in animals euthanized in seven days. The main clinical alteration was the formation of nodules on the tongue of the animals within seven days. In two animals, migration of the material to the base of the tongue was observed. Upon histopathological examination, an abundant amount of CaHA spheres surrounded by a circumscribed inflammatory infiltrate, composed predominantly of macrophages, was the most evident alteration. In the experimental group (CaHA), the collagen percentage in the tongue and in the dermis was significantly higher compared to the control (p<0.05) in the periods of 30 and 90 days. Epidermis/dermis thickness was also higher in the CaHA group in both periods (p<0.05). In the submandibular glands, in which the material was present, CaHA spheres were observed. Areas of edema and hyperemia were present, in addition to an infiltrate composed of neutrophils, lymphocytes and plasmocytes. Alterations in the glandular architecture in the regions adjacent to the material were observed, with damage to the ductal and acinar morphology. This study demonstrated the expressive volumizing capacity of the material, the surrounding inflammatory response to the CaHA particles, the increase in collagen density and in the thickness of the epidermis/dermis. Other important findings were material migration in two samples and morphological changes in the salivary gland. CaHA has several positive properties for facial filling and collagen biostimulation. More studies are needed to investigate the possibility of migration and the glandular changes.