Age-Related Changes in the Orbicularis Oris Muscle and Their Implications on Aesthetic Lip Rejuvenation

BACKGROUND: Aging leads to noticeable changes in lip volume, definition, and projection largely due to alterations in the orbicularis oris muscle. Although superficial signs of aging are well-documented, deeper muscular changes remain underexplored. These anatomical shifts can influence both lip aesthetics and the effectiveness of interventions such as dermal fillers and botulinum toxin. OBJECTIVE: This study aimed to evaluate age-related changes in the angle of the orbicularis oris muscle and to examine potential sex-based differences. MATERIALS AND METHODS: Thirty healthy participants (17 women and 13 men), aged 20 to 60 years, with normal body mass index (18.5-24.9), were enrolled. None of the patients had any history of lip surgery or injections. Using high-resolution ultrasonography, the angle of the orbicularis oris muscle was measured at 5 standardized anatomical points on both the upper and lower lips. RESULTS: A significant decrease in the muscle angle was observed with age, particularly in female participants. These changes were most pronounced in the upper lip and associated with a more inverted lip shape. CONCLUSION: Age-related changes in the orbicularis oris muscle, especially in female participants, contribute to altered lip morphology. Understanding these changes can help develop more effective and natural rejuvenation strategies using injectables.