Is there a right or wrong way to insert Botox in masseter?

When treating the masseter muscles with Botox, some injectors will ask patients to clench because this shows them exactly where the muscle is located.  Whether you were injected while relaxed or clenching should not make a difference in your results.  

Thank you for your question. After proper evaluation of each patient and properly understanding the indications for treatment of masseter hypertrophy, either reducing facial discomfort or lower 1/3 facial reduction, my method is: (1) pre-injection photos, (2) with patient's mouth clenched, make 4-5 marks of the "bulging muscle" depending on the extent of hypertrophy, (3) apply topical numbing cream, (4) inject approximately 20-25 units of Botox per side for a total of 40-50 units per session. This should be performed by a board certified Plastic Surgeon who is familiar with the entire facial anatomy.