What is Involuntary Arc of Closure

Masticatory muscle hyperactivity has been considered a significant factor in promoting and perpetuating dysfunctional symptoms observed in temporomandibular disorder patients. Many therapeutic modalities have evolved within dental medicine that attempt to lessen or resolve the varying symptoms frequently reported by dysfunctional patients. One such method, known as ultra-low frequency (ULF) transcutaneous electrical neural stimulation (TENS), has been used to relax the masticatory musculature by applying an electrical stimulus to the efferent motor fibers of the fifth and seventh cranial nerves, such that TENS can result in pain analgesia and patient sedation, restore compromised muscle physiology and increase muscle resting length. TENS also aids in establishing a neuromuscular maxillomandibular relationship by inducing a muscularly contracted involuntary arc of closure. This chapter will discuss TENS as a treatment modality for temporomandibular disorders (TMD), explain how to employ TENS to obtain a neuromuscular maxillomandibular relationship, and illustrate in a clinical case report the use of TENS in combination with the T-Scan Computerized Occlusal Analysis System to measurably and physiologically balance, a removable overlay anatomical acetyl resin orthotic prosthesis. This chapter will also detail the interrelationships between TMD musculoskeletal problems and posturo-occlusal disorders, and how disclusion time reduction therapy (DTR) with occlusal rebalancing, performed with the T-Scan 9/BioEMG synchronization, can improve whole body alignment. The chapter concludes with discussions about the problems with direct anatomic relationships, and the three problems of occlusion.