What is the Correct Way to Inject Botox for Jaw/masseter Contouring?

I use a 1/2" needle for treating wrinkles along the forehead, Crow's feet and glabella.  The masseter is a far bulkier muscle than the muscles in those areas, so as you can imagine the needle must deliver the Botox deeper in order to achieve the optimal effect.  I use a 1" needle for masseter injections and inject within the body of the muscle just above the bone.  The muscle is covered with a dense fascial layer, so if the injections are placed superficial to this any diffusion of the Botox will be limited by this layer.  The needle must penetrate this fascia and deliver the Botox within the body of the muscle.  

Especially with 20 units per side, additional units may need to administered to achieve maximal effect.  This is common for an initial treatment, and your physician will be able to titrate the appropriate dosage better with future treatments based on your response to this initial treatment.  

I think you're main concern is that you don't see results in 2 weeks.  I think the sequence is the following:1) botox injection (20 units per side is an okay starting point)2) within 2 weeks, you should feel that your muscles can't clench down as hard (you will not notice this if you are eating a salad, but if you try eating a bagel or a steak, you will notice that you're muscles are weaker than usual).  Any change in the width of the face at this point is due to the botox lessening the resting tension in the muscle.3) Over the course of the next many weeks, the masters will slowly shrink and your face will slowly slim.  This is due to the muscle atrophying as a result of not working as hard (analogy: if you have your arm in a cast for a few weeks, it will be smaller than the other arm when the cast comes off).  The changes are gradual.  I wouldn't worry about not seeing dramatic results just yet.  But, if your masseter muscle doesn't feel weak, that may be a sign that the botox was not injected properly.

Thank you for your question. Botox in the masseter region usually takes longer than in the standard areas to take effect. I tend to use anywhere from 15 units (conservative treatment) to 50 units (for someone with really strong masseters) on each side to get the desired result. It may start within the first week but I tell my patients to wait three weeks before doing a more thorough evaluation. The treatment typically lasts longer than the forehead/crows feet/frown regions. It is also a gradual onset of the return of masseter function. I have tried the masseter injections myself and space the treatments around 4 months apart, but use smaller doses to maintain the effect. I normally know the effects are wearing down when I start to clench my teeth more heavily at night when asleep. Once you stop using Botox, the masseter muscles will return to their original baseline when the effects of Botox wears off completely.As far as depth, the masseter muscle is a much bigger and deeper muscle than the frown, crows feet or forehead muscles.  I would make sure that your injector is well experienced with this region as it is considered a more advanced technique.