Participants will be subjected to injection of cross-linked hyaluronic acid fillers on both sides of the face in 3 different regions: temples, cheeks and chins.~Each female will undergo:~Before injection:~Aesthetic facial clinical analysis.~Baseline quantitative surface electromyography.~Baseline digital photography.~Injection:~Each female will receive the injection in the particular facial region at superficial level to the muscle (subcutaneous) on one side and the same amount at deep level to the muscle (supraperiosteal) on the other side.~One week after injection:~Follow up quantitative surface electromyography.~Follow up digital photography.
assess electrophysiological changes in some facial muscle dynamics following hyaluronic acid filler injection in superficial versus deep level of injection.