Clinical and Histological Effects of Calcium Hydroxyapatite Filler in the Orofacial Region: A Study in Rats

BACKGROUND Calcium hydroxyapatite (CaHA) dermal filler has been increasingly used in facial aesthetic procedures. OBJECTIVE To investigate clinical and histological changes associated with calcium hydroxyapatite (CaHA) dermal filler in the orofacial region. MATERIALS AND METHODS Forty-eight female Wistar rats were divided into CaHA and control groups. The material was applied in the ventral tongue and the submandibular region; the animals were euthanized after 7, 30, and 90 days. RESULTS After 7 days, yellowish nodules with a firm consistency were observed on the tongue. In 2 animals, the material migrated to the base of the tongue. Histopathological examination revealed CaHA spheres surrounded by an infiltrate, predominantly composed of macrophages. In the CaHA group, the percentage of collagen in the tongue and dermis was higher compared with the control group ( p < .05) at both 30 and 90 days. The thickness of the epidermis/dermis was also higher in the CaHA group ( p < .05). In 5 submandibular glands containing material, areas of edema and hyperemia were observed, along with infiltrates of neutrophils, lymphocytes, and plasma cells. Changes in the morphology of ducts and acini in adjacent regions were evident. CONCLUSION CaHA exhibits satisfactory properties for filling and collagen biostimulation in the tested regions. Further studies are required to explore the potential for migration and the glandular alterations.