Histological examination suggests a cycle in which the highest deposition of new collagen and elastin occurs around four months after injection, with stability achieved by nine months. In patients younger than 40 years old, the neocollagenesis and neoelastogenesis is so strong, that one single treatment results in a significant clinical improvement within four months. In patients older than 40 years, where neocollagenesis is a slower process, retreatment is proposed after four months to enhance dermal remodeling. When injected in retrograde fashion, using cannulas with the described dilutions, it is extremely unlikely to experience adverse events. Make markings with the patient in upright position. Mark the area of concern, as well as visible superficial veins that should be avoided during the procedure. In the neck, the superficial jugular vein is at risk. Calcium hydroxylapatite has been extensively used for facial rejuvenation and HIV-associated lipoatrophy with few complications.