RESUMEN
INTRODUCTION: Biostimulation properties of diluted and hyperdiluted calcium hydroxylapatite (CaHA) injections have become increasingly popular. However, the existing data are insufficient to certify a particular dose-response pattern. OBJECTIVE: To assess and compare the dermal stimulation potentials of different concentrations of CaHA injections. MATERIALS AND METHODS: Two independent experiments (Experiment-1: constant injection volume vs Experiment-2: constant CaHA amount) included 4 study groups each, and these experimental groups were placed consecutively on the abdominal skin of a juvenile Yorkshire pig. Histopathological and immunohistochemical stainings were performed on punch biopsy materials collected 4 months after the injection day. RESULTS: The fibroblast count significantly decreased upon dilution from 1:3 to 1:19 in experiment 1 ( p = .000) but still higher than the control group. In experiment 1, the collagen density of the concentrated form was more elevated than the 1:19 dilution and the negative control groups ( p = .034 and .000, respectively) but similar to the 1:3 dilution ( p = .123). No significant difference was observed between the groups regarding collagen density with a standard amount of CaHA (0.2 mL, 30%) ( p > .05). CONCLUSION: Despite the efficacy being more pronounced till 1:3 dilution, hyperdiluted CaHA at any dilution ratio up to 1:19 can provide a higher fibroblast count than the negative control group.
