Botulinum Toxin Type A Versus Cross-Linked Hyaluronic Acid Filler Myomodulation for Non-Surgical Management of Excessive Gingival Display: A Randomized Controlled Trial

This randomized controlled trial compared the clinical efficacy and patient satisfaction of two non-surgical treatments for excessive gingival display (gummy smile): botulinum toxin type A (BTX-A) and cross-linked hyaluronic acid (HA) filler myomodulation. Excessive gingival display is defined as exposure of 3 mm or more of gingival tissue during maximal smiling. It affects approximately 14% of women and 7% of men and is associated with reduced self-confidence, smile suppression in social settings, and impaired quality of life. When caused by hyperactivity of the upper lip elevator muscles, it can be treated without surgery using injectable therapies. Twenty patients (18 females, 2 males; age 18-45 years) with excessive gingival display greater than 3 mm were randomly allocated 1:1 to one of two groups. Group A (n=10) received bilateral injections of botulinum toxin type A (Refinex; 5 IU per side) at the Yonsei point. Group B (n=10) received cross-linked hyaluronic acid filler (Juvederm Voluma with lidocaine; 1.0 mL total) injected at six periosteal sites around the nose and upper lip using a myomodulation technique. Participants were assessed at baseline and at 1, 3, and 6 months after treatment. The primary outcome was maximum gingival display measured in millimeters using a calibrated periodontal probe. Secondary outcomes included patient satisfaction measured by Visual Analog Scale and a 12-item questionnaire, and adverse event monitoring. Both treatments produced equivalent gingival display reductions at one month (BTX-A: 69.6%; HA: 63.0%). At six months, the HA group maintained a statistically significant 26.4% improvement while the BTX-A group showed near-complete relapse. Despite this, BTX-A patients reported higher categorical satisfaction. Both treatments had excellent safety profiles.

Inclusion Criteria: 1. Excessive gingival display \>3 mm during maximal smiling (measured by UNC-15 periodontal probe) 2. Age 18-45 years 3. Either sex 4. Ability to provide written informed consent 5. Availability for all follow-up visits at 1, 3, and 6 months post-treatment Exclusion Criteria: 1. Chronic neurological diseases or blood coagulation disorders 2. Pregnancy or lactation 3. Immunological disease or current immunosuppressive drug therapy 4. Known sensitivity or allergy to botulinum toxin or hyaluronic acid products 5. Previous treatment for gummy smile within 12 months 6. Extreme age (outside 18-45 range) or pediatric patients