STOMATOLOGY EDU JOURNAL 2017, Volume 4, Issue 3 SEJ_3-2017_Online - Page 51

Surgery and Dentistry. We have few publications in this area but many clinical possibilities which are tested by some authors. Some clinical applications target rare diseases, some address very frequent and challenging problems like bruxism. The aim of this paper is to present current possibilities with little evidence-based literature which we have now and to inspire systematic research. 2. The principle of the method and its history Botulinum toxin causes presynaptic blockade at the neuromuscular junction, which has the anatomically permanent character but due to the growth of new connections the effect is clinically reversible. 3 The blockade prevents the transmission of the signal and the muscle cannot be activated until after three to four months 3 by which time the sufficient amount of new synapses has been created to restore the function of the affected muscle. This formation mechanism of new synapses connections has not been exhausted even after a few decades of repeated treatment on long-term treated patients. (Fig. 1) Figure 1. Action of botulinumtoxin (Rowland LP, N Eng J Med. 2002;347(6):382-383). Originally it was thought that the mechanism influences the motor function selectively, but now it is considered proven that the botulinum toxin reduces the sensitive nerve function as well. 4 Botulinum toxin is supplied to the market by several manufacturers, however the product molecule differs fundamentally so that the units of each product do not interconvert. Therefore different brands can not be interchanged arbitrarily as appropriate dosage to potency ratios varies. The history of the botulinum toxin application in medicine is quite short. In ophthalmology, the first patient with strabismus was injected in 1997 by Alan B Scott (San Francisco, CA, USA), who subsequently also reported the clinical utility. 5 In plastic surgery, it was used to treat facial asymmetry by Richard Clark (Sacramento, CA, USA) in 1989. 6 Three years later it was further successfully elaborated in a study published by the Canadian couple, ophthalmologist Jean Carruthers and dermatologist Alistar Carruthers, who observed that blepharospasm patients after injections around their eyes and upper face enjoyed diminished facial glabellar lines. 7 Today the interdisciplinary knowledge is essential for most applications, and the subject is thus an example of the necessity of broader medical education in dentistry to be able to deploy its full potential. (Table 1) The precautionary principle, however, is a must due to the short history of indications alongside the lack of studies and binding recommendations. Doctors shall adhere to the principle of prudence to enhance the safety and satisfaction of patients and reduce the risk of complications. Effective applications of botulinum toxin in dentistry and in head and neck surgery 3. Contraindications and systemic complications The application of botulinum toxin has contraindications, which are often overlooked. They include neuromuscular diseases (eg. Myasthenia gravis), pregnancy, infection at the site Table 1. Therapeutic uses of botulinum toxin. Indication Effectiveness First line treatment medium No low high Possibly high medium Possibly low low-medium No low low No low medium-high Possibly Tinnitus low No Decreased or increased position of the upper lip high very likely medium-high Application into Orbicularis oris muscle high very likely medium-high Elevation of the mouth corners medium-high very likely medium Applications to the mimic m. of the lower facial third medium-high Very likely medium-high Headaches in region m. Occipitofrontalis BTX for facial asymmetry Applications to the m. Masseter (mostly bruxism) Syndrome of temporomandibular joint Trigeminal neuralgy Sialorrhoea Stomatology Edu Journal Risk of complications low-medium low 201