Incoordinated, hyperactive mus- culature can, over time, displace the disk from a condyle and cause a variety of structural deformations to the temporo- mandibular joints (TMJs). Muscle is the primary focus in vertical dimension, the neutral zone, arch form, occlusal dis- ease, orofacial pain, and even smile design. If muscle is not a prime consideration in treatment planning for prosthodon- tics, restorative dentistry, implants, orthodontics, or maxillo- facial surgery, predictability of treatment results will be re- duced to guessing.Research into how the masticatory musculature functions and dysfunctions has clarified much of our clinical think- ing.2-5 Sophisticated EMG studies have expanded our knowledge from gross muscle activity all the way down to the function of single motor units within different sections of individual muscles.6,7 These elegant muscle studies have been further enhanced by research into the neuro part of the neuromusculature8,9 to expand our understanding of the ex- quisite influence of mechanoreceptors within the periodon- tal ligaments, and the even more sensitive odontoblastic sen- sory units within the teeth.10What we know today is that communication between the teeth and the musculature is far more exquisite in its sensi- tivity than was realized in the past. By matching this infor- mation up with extensive clinical observations, it explains why there has been so much controversy regarding the many different approaches to treatment of occlusal problems and TMJ-related disorders. The good news is that there are solid, dependable answers. Today there is little reason for confu- sion about diagnosis or treatment of occlusal problems, TMJ disorders, or pain within the masticatory system.Let’s start with a basic understanding of what is meant by coordinated muscle activity, because it is an essential goal for all occlusal treatment.