## 3 Discussion  
TMD is characterized by the presence of symptoms including pain, TMJ noises and restricted mandibular movement. The etiology of TMD is known to be multifactorial and includes biological, environmental, and psychosocial factors [11]. Conventional treatment for TMD includes conservative therapies such as behavioral modification, physical therapy, pharmacotherapy, and oral appliances [9]. Previous studies sometimes provide conflicting results regarding their effectiveness according to the treatment approach and investigation methodology. A previous meta-analysis reported that occlusal appliance, certain pharmacologic agents, behavioral therapy, jaw exercises and postural training are effective in alleviating TMD pain [12] and such approaches also efficiently improved sleep quality and quality of life [13]. However, a recent review does not show sufficient evidence to support the usage of topical medication for TMD treatment [14]. A previous meta-analysis concluded that splint therapy can reduce pain related to TMD [15], however another randomized controlled trial did not support its effectiveness in reducing subjective pain [16]. A recent systematic review suggests the possibility of myofunctional therapy as a cost-effective TMD treatment [17]. Unfortunately, there are no well-designed investigations on the effect of masseteric nervectomy with radiofrequency on TMD signs and symptoms. Radiofrequency has been applied in various muscle areas. Calf reduction is the most commonly conducted procedure and is generally performed in the field of plastic surgery. Radiofrequency based gastrocnemius muscle reduction brought esthetically satisfactory results [18; 19]. However, muscle contracture due to excessive muscle fibrosis was reported as a side-effect [20]. Another procedure done with radiofrequency is flagellar frowning reduction by ablation of efferent branches of the temporal and angular nerves; the procedure efficiently eliminates corrugator and procerus muscle contraction [21; 22]. Radiofrequency ablation has also been applied for the reduction of pain. Ablation targeting preaglionic fibers of the Gasserian ganglion has been done to treat trigeminal neuralgia [3; 4]. A study based on 1600 trigeminal neuralgia patients showed pain relief in 92% of the patients 5 years after the first ablation was performed. Side-effects included diminished corneal reflex, masseter muscle weakness and paralysis, dysesthesia, anesthesia  
Figure 6: Occlusion status. dolorosa, keratitis, and transient paralysis of the third and fourth cranial nerves [23]. In case of complications related to direct nerve injury, type I collagen-based devices may be considered as an alternative to conventional microsurgery with autologous grafts [24]. Reports related to the masseter muscle area are relatively sparse. Masseter muscle reduction using radiofrequency coagulation has been generally conducted with the objective of reducing masseter muscle hypertrophy. The procedure resulted in a 10-60% (mean 27%) reduction in muscle volume at 6-month post-operative follow-up, with most patients satisfied with the esthetic improvement [25]. Another study also reported pronounced reduction of masseter muscle volume [26]. The reported side-effects included mucosaperous fluid collection, persistent mouth opening limitation, delayed bleeding, infection, long-lasting pain, facial nerve injury, and parotid gland injury. Mouth opening limitation subsided in most cases with time except for 1 case that presented with symptoms lasting even after 10 months [25]. In a study based on 19 female patients whose chief complaint was masseter muscle hypertrophy and who received masseter nerve neurotomy, post-operative swelling or pain was found in all patients but the degree was mild and the symptoms resolved within 1-2 weeks in most cases. A decrease in masticatory function was observed after the procedure in all patients, but there were no patient complaints related to it. Pain on mouth opening was observed in 3 patients but resolved within 1 week.