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

I think there are slight variations to inject the masseter muscles. I typically recommend as low as possible on the jawline and with a conservative number if units. I suggest you review your injections when you follow up with your injector. Best wishes, Dr. ALDO 

The reason your nurse asked you to clench your teeth was to locate your massester muscle.  Botox is injected right into the bulk of the muscle. It does not matter if injected at rest or clenched as long as it is injected into the correct muscle. 
Regards Anil Shah 

There are several different techniques to inject botox and every injector is little different. I ask the client to clinch to feel the muscle boundary and then inject while the muscle is relaxed. Bottom line is follow up with the injector where you got the best result. 

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.

Many practitioners will have you clench your jaw to locate the muscle, some will have you relax after they locate it and others will inject with the muscle clenched, either is correct. Good luck. 

There is no right or wrong way to inject the masseters other than getting the bulk of the muscle treated.  I often have patients clench to locate the muscle and then subsequently inject while the patient is relaxed.  

It's normal for injection technique and preferences to vary by injector. I prefer the muscle to be relaxed prior to injection because it find it reduces patient discomfort. I would discuss your concerns with your injector at your followup appointment.

Botox injected into the masseter muscles can be a highly effective treatment for people who grind their teeth and/or clench their jaws.  A nice side effect is that it usually produces some slimming in the lower face.  Many injectors have patients clench during the treatment so that they can feel and see exactly where the masseter is.  This should not influence the results of the treatment.  You can take Tylenol or Ibuprofen if you are experiencing some aching or tenderness.