A Study to Assess the Effectiveness of BOTOX (Botulinum Toxin Type A) Injections for the Change of Masseter Muscle Prominence in Adult Participants

Inclusion Criteria:

• Body mass index < 30 kg/m^2 using the calculation: BMI = weight (kg)/height (m)^2,rounded to the nearest whole number.

• Participants meets the following criteria:

• Bilateral Grade 4 or Grade 5 MMP (identical grades for left and right side ofthe face), as determined at screening and at the Day 1 visit by theinvestigator using the MMPS.

• Bilateral Grade 4 or Grade 5 MMP (identical grades for left and right sides ofthe face), as determined at the Day 1 visit by the participant using theMMPS-P.

• MMP grades, as assessed by investigator and participant, do not need to beidentical but have to be a minimum of Grade 4 with bilateral symmetry at Day 1.

• Participants who responded "A lot" or "Extremely" bothered by the appearance oftheir MMP as measured by the Bother Impact Assessment for Masseter Muscle Prominence (BIA-MMP) and attain a total score of ≥ 15 on the Lower Facial Shape Questionnaire -Impact Assessment (LFSQ-IA), determined at the Day 1 visit.

Exclusion Criteria:

• Has current intraoral infection, including infection of the mouth or gums, or facialskin infection requiring medical treatment in the opinion of the investigator.

• Has weakness of the masseter, pterygoid, or temporalis muscles due to trauma, facialnerve injury, or other condition that could interfere with normal chewing and jawclenching, as determined by the investigator.

• Excess lower facial fat, jowling, loose or lax skin in lower face, or parotid glandprominence that could interfere with MMPS or MMPS-P grading, as determined by theinvestigator.

• Has medical condition that may put the participant at increased medical risk withexposure to BOTOX, including diagnosed myasthenia gravis, Eaton-Lambert syndrome,amyotrophic lateral sclerosis, or any other condition that might interfere withneuromuscular function.

• History of dental or surgical procedure for lower facial shaping or masseter musclereduction.

• History of any soft tissue fillers in the jawline.

• Has prior exposure to botulinum toxin of any serotype to any part of the body (notincluding masseter muscle) within the 3 months prior to Day 1.

• History of or current TMJD, or presence of signs/symptoms of possible TMJD in theopinion of the investigator.