What is the best treatment for a 'snarl' facial expression? (photo)

Your question raises some important issues--the qualifications, experience and expertise of the injector and the significant impact of these factors on the outcome of nonsurgical facial rejuvenation techniques and the critical importance for the treating physician to tailor treatments to the specific needs of the individual patient, rather than using a "one size fits all approach." The deep smile line (laugh line) folds, as seem to be the case here, that are giving rise to the "snarl" look require the use of an volumizing agent intended for supplying greater re-inflation and durability. The tiny drops of Botox (using more than small droplets risks negatively impacting the ability to smile normally) that are sometimes used to the sides of the nose to help improve smile lines, would be unlikely to make much of an impact on these relatively deep "snarl" lines. Likewise, a filler, like ordinary Juvederm, which is appropriate for treating fine lines and wrinkles, would also be unlikely to yield more than a short-term gratifying response when used for deeper folds.The good news here, however, is that the Juvederm worked (albeit for only two days), which means that a properly chosen volumizing agent would be likely not only to obtain the result you are looking for, but also to last considerably longer. In my Upper East Side Manhattan practice, I would opt for a combination of Radiesse and Perlane L for this purpose. In my Israel satellite facility, where a far greater number of regulatory agency approved fillers and volumizers are available, I would opt for Radiesse combined with Restylane SQ, Emervel Volume, or Stylage XXL, a decision I would make after an in-the-flesh examination and palpation of the treatment site.

Please consult a dermatologist or plastic surgeon who is experienced with Botox/Dysport/Xeomin for off-label use.  You need to be examined carefully to see which muscles are being used and address them specifically. Treating your forehead will not help.