will spread less than about 30 cm in human obicularis oculi in accordance with the invention the toxin may be prepared in dosage form in conventional biologic standardizations such as ld 50 but most importantly in terms of a unit dose of the toxin 39 s spread capability this involves nomagram preparation as outlined above and labeling the pharmaceutical agent with the information to provide the physician with the capability of placing injection sites at preselected intervals on the muscle selectively to denervate the muscle and to limit toxin spread in contiguous muscles this permits expansion of use of the preparations into procedures such as those described below the involuntary grinding of teetch characteristic of true bruxism is caused by involuntary contractions of the masseter temporalis and pterygoid muscles the masseter and temporalis usually are targeted as the muscles which will undergo chemodenervation they are injected so as to limit the penetration of the toxin to the volume and body of the muscles diffusion should be limited to a distance of no more than 25 to 35 mms a unit dose injection is given at the surface of each of these muscles at multiple points percutaneously or permucosally of course appropriate dental evaluation to assess the degree of damage or potential damage to the teeth should be conducted prior to application of the toxin the treatment is repeated periodically e g.