Does the temporal region truly induce facial tissue displacement? - A quantitative randomized split-face clinical trial.

BACKGROUND: Posterior temporal region has been proposed as a key vector for facial lifting, yet its isolated contribution remains unclear. Objectives: Quantitatively evaluate the effects of high G-prime hyaluronic acid (HA) and poly-L-lactic acid (PLLA-SCA) injected into the posterior temporal region on soft tissue displacement and aesthetic outcomes. METHODS: In this randomized, split-face trial, 17 participants received 0.5 mL of HA on the right side and 4.5 mL of PLLA-SCA on the left side, injected in the posterior temporal region. Soft tissue displacement was assessed using 3D stereophotogrammetry at baseline, 30, 90, and 180 days. Perceived outcomes were evaluated by Global Aesthetic Improvement Scale (GAIS). RESULTS: Both groups produced minimal soft tissue displacement, with consistent but clinically insignificant lateral and cranial tendencies. No significant differences were observed over time (p > 0.05) or between treatments. GAIS at 90 and 180 days showed no relevant aesthetic improvements. No serious adverse events were reported. CONCLUSION: This is the first split-face trial to objectively assess the posterior temporal region's role in facial lifting. The findings suggest that injections in this area, whether with HA or PLLA-SCA, are insufficient to produce clinically meaningful lifting effects when applied in volumes consistent with routine practice.