A Review of the Clinical Significance of the Occlusal Plane: Its Variation and Effect on Head Posture

Head posture is a resultant response of environmental influences on the growth and development of the cranio-mandibular complex. A review of the literature substantiates the importance of a proper occlusal plane orientation and how it plays a major role in postural stability. Failure to recognize and treat cranio-mandibular dysfunctions without an understanding of the importance of head posture and proper occlusal plane orientation during the diagnostic and laboratory phase can often result in relapse of the "rehabilitated" cranio-mandibular dysfunction (CMD) patient. The importance of optimal head positioning is significant relative to many areas of dentistry such as bite registration, occlusal plane determination and occlusal management for fixed reconstruction, full denture, and orthodontic diagnosis and treatment. A physiologic level head position with an accompanying average 6-10 degree anterior sloping occlusal plane has been confirmed in literature. This paper discusses how these neuromuscular principles have effected the orientation of the occlusal plane as it relates to head positioning, the cervical neck alignment, and how the neuromuscular trajectory can affect head posture. Computerized mandibular scanning (CMS) and electromyography (EMG) objectively substantiates these findings. Boney and soft tissue reference planes are discussed to help give the clinician a practical way to mount the maxillary cast using the Fox occlusal plane analyzer in a modified manner. Recent research data comparing two methods using a modified Fox occlusal plane method and the classic HIP (hamular notch and incisive papilla) reference method to mount the maxillary cast is presented and compared. Discussion as to these findings and clinical relevance are also presented showing the importance of a proper occlusal plane reference which impacts the diagnosis and treatment of phase II therapy of the comprehensive restorative/orthodontic case. Head posture and the clinical significance of the occlusal plane orientation must be considered if the clinician desires to bring stability and health to the stomatognathic cervical system.