To the Editor, We read with great interest the study by Faria et al. evaluating calcium hydroxyapatite (CaHA) combined with a polymicronutrient (PMN) solution for hand rejuvenation [1]. The authors are to be commended for conducting a randomized, double-blind, split-hand clinical trial together with complementary in vitro experiments. Nevertheless, several methodological considerations warrant attention when interpreting the comparative clinical findings and the proposed biological mechanisms.
