Botulinum toxin slims face without affecting chewing

Dental Tribune International

Tue. 28. October 2025

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BANGKOK, Thailand: Given the growing demand for non-surgical facial contouring and ongoing debate about the functional effects of muscle-relaxing procedures such as botulinum toxin injection, a recent study in Bangkok has investigated whether botulinum toxin Type A (BTX-A) injected into the masseter muscles can reduce lower face volume without adversely affecting masticatory function. Its findings suggest that BTX-A masseter injections may provide effective cosmetic improvements without perceptible loss of oral function in healthy adults.

While BTX-A is known for delivering aesthetic results, little evidence exists about its effects on masticatory function when used for cosmetic purposes. By combining advanced 3D facial imaging with validated patient-reported outcome measures, the researchers sought to provide an assessment of both the aesthetic and functional effects of this increasingly popular treatment.

The clinical trial involved 24 healthy adult participants, who each received standardised injections of 25 units of BTX-A into the masseter muscles bilaterally. Changes in lower facial volume were assessed at baseline and at four, eight and 12 weeks using 3D stereophotogrammetry. Importantly, the study evaluated patient satisfaction with the treatment and participants’ perceived masticatory function through validated instruments.

The results showed statistically significant reductions in lower face volume at every follow-up, and the most prominent changes were observed by the final follow-up. Patient satisfaction scores with facial appearance and treatment outcome rose dramatically over the study period. Importantly, the participants consistently indicated that they had no functional masticatory limitations despite noticeable changes in facial contour.

The study offers preliminary reassurance for the use of BTX-A for facial contouring for clinicians. However, the researchers noted that further studies with larger samples and longer-term follow-up are needed to establish the effects in a broader group of patients, such as those undergoing prosthodontic treatment or bruxism management.

The study, titled “Facial volume reduction and masticatory function after masseter botulinum toxin injection: A prospective study”, was published online on 10 October 2025 in BMC Oral Health.