by Clayton A. Chan, D.D.S.
The concept that the stomatognathic muscle system is subject to constant interaction between the soft functional in motion tissues and their influences upon the forming skeletal structures has been well documented by Van Der Klaauw and Moss (1-3). These concepts have help clarify the role of the tongue and mandibular posture in the development or morphogenesis of the surrounding intra oral and extra oral facial structures. Many investigators (4) have shown that head posture is effects oral respiration as well as mandibular positioning. As the infrahyoid muscles and suprahyoid muscles pull the mandible posteriorly and inferiorly musculoskeletal dysfunction of the head and neck occurs along with a corresponding abnormal intra oral forces further strained by suboccipital muscles behind the head and neck region. Shortened sternocleidomastoids can also extend the occiput to the extend that spinous process of C1 (Atlas) closely approximating the occiput which can create compressive pathology in the upper cervical region.
These strains can further pain in the suboccipital muscles radiating down from the vertex of the head to the back and contribute to retractive mandibular positioning. As the muscles slowly over time strain the teeth and surrounding intra oral structures of the mouth, a slow morphologic changes occur to the shape of the dental arches and supporting boney structures. The tongue begins to swallow abnormally as a result of narrowing dental arches trying to maintain sufficient intra oral volume during the swallowing movements. Instead, the tongue begins to vertically and laterally displace the occlusion as a compensation to maintain the loss of vertical dimension of the intruding posterior teeth as well as shrinking posterior oral pharyngeal space (the back of the mouth and throat). With a decreased posterior and tongue space (narrowing of the arches), the tongue in some circumstances will escape and exert forward tongue thrusting forces contributing to abnormal splaying of the anterior incisors, termed “anterior open bite”.
CASE 1: 38 year old male with chronic craniofacial musculoskeletal pain symptoms and previous orthodontics. Low frequency TENS (J5 Myomonitor and the K7 Kineseograph (Myotronics – Noramed, Inc.) aids the clinician to relax the spastic musculature and objectively locate the physiologic and Optimal Bite position in 6 dimensions.
Lower frequency TENS helps relax the muscles and improves posterior vertical tongue and jaw space during bite registration. Optimized bite techniques are implemented to determine the most physiologic relationship.
To Read More on the Relaxing the muscles with the J5 Myomonitor TENS
The K7 is a computerized mandibular scanning unit that allows the dentist to visualize within 0.1-0.3 mm an accurate and precise mandibular to maxillary jaw relationship without manual manipulation techniques.
For more information on the Bite Recording with the K7 Kineseograph
It is my belief, understanding and clinical observations that as the lower jaw is positioning slightly more forward (anterior) and downward (vertical) that the back part of the oral cavity also increases in intra oral volume. When this occurs, there is more room for the tongue both vertically and AP wise in the back of the mouth even if the arches are narrower. Narrow arches no doubt can constrict and displace the tongue laterally over the posterior teeth and in some more V shaped narrow arches the tongue is displaced even forward (contributing to anterior open bite tongue thrust problems). When the trained dentist optimizes the mandible to maxillary jaw relationship, there is an increased posterior intra oral tongue volume space that allows for an improved tongue position. When doing measured CMS swallowing tests using the K7 one can observe even with an intra oral orthotic that even narrower arch forms can have improved normal swallowing patterns (upper teeth braces against lower orthotic occlusion) compared to the before decreased vertical and narrow or less intra oral volume with an aberrant tongue swallow pattern (that is tongue positions between teeth during swallow). I am not a believer that the orthotic has to be so big that it creates abnormal tongue swallowing patterns. If so then that to me is not proper NM (neuromuscular) bite positioning neither complete NM thinking and or adequate orthotic designing and understanding. I don’t buy into the perpetuated concept that a lower orthotic is too bulky on the inside so one has to go fixed orthotic…some rare occassions yes, but not for those particular reasons. The tongue will position itself in any manner to escape out of the confines of the dental arches as long as the dental arches are trying to invade on normalized tongue space.
Lesson to Learn: Create adequate tongue space intra orally even with an orthotic and the tongue will not fight against an Optimized orthotic. This is GNM thinking…a step beyond standard NM orthotic intra oral thinking.
- Van Der Klaauw: Size and position of functional components of the skull. Arch Germany, Neerl Journal 1948-1952;9:1-559.
- Moss ML: Vertical growth of the human face. Am J Orthod 1964;50(5):359-376.
- Moss ML: The Functional Matrix. In: Kraus BS, Reidel RA, eds. Vistas in Orthodontics. Philadelphia:Lea and Febiger; 1962;85-98.
- Olmstead JM: Francois Magendi. New York: Shuman’s, 1829.
© 2009 Clayton A. Chan, DDS. All Rights Reserved.