25 units of Botox injected in each masseter muscle but see no difference. Do I need more?

Botox can be used to decrease the bulk of the masseter muscle and therefore narrow the lower face around the corner of the mandible . In order to do that the muscle hast to shrink (become atrophic)  dude to decrease activity secondary to Botox treatment. This doesn't happen overnight. Therefore, in order to see the effect of Botox in masseter: 1) time has to pass and 2) very likely several serial treatments of Botox might be necessary 

Hello,
Thank you
for your question.
It
appears that you may require a larger dose. I'd recommend speaking with your
qualified injector to discuss your concerns and to determine your options.
All the
best.

Botox can be a great option for decreasing the size of the masseter muscle and in patients who grind their teeth.  Generally, dosages range from 20-40 units per side.  It is important to know that the best results from treatment of this muscle will take time unlike treating movement lines.   Over time, due to muscle inactivity, the muscle will shrink with a peak at 4-6 months; repeated treatments are usually necessary to further improvement.