Dr. L. Wayne Halstrom DDS
An unwelcome but common occurrence in patients undergoing oral appliance therapy for management of sleep disordered breathing is a change in the occlusion.
Research at the University of British Columbia suggests that bite changes may be expected to occur in 14% of patients (ref). 25% of these changes may be positive while the balance present management issues and threat of litigation to the attending dentists. Such changes are largely impossible to predict and sometimes impossible to correct without giving up the appliance and resorting to dental procedures to re-establish the patients’ customary occlusion.
Why?
Condylar angle of the fossa of the TMJ?
Condylar angles:
– vary widely from patient to patient and from side to side in individual patients.
– Without expensive radiological examination these angles are impossible to establish. Routine Cephalometric radiology offers insufficient information to be diagnostic.
Muscular responses:
– During the initial stages of therapy muscular responses may result in the development of TMJ issues. Patients who exhibit Bruxism will be more likely to experience some TMJ response that may include some negative occlusal outcomes.
Hard tissue changes:
– There is no body of evidence that confirms that occlusal changes are a result of hard tissue changes in the TMJ that lead to irreversible changes in occlusion.
Soft tissue changes:
– The conventional wisdom for management of jaw position in treatment of SDB has been to begin therapy at 50% of the range of motion and then titrate the appliance forward until the symptoms are resolved. This technique may present significant threat to occlusion by stretching the ligaments that govern the positioning of the condyle of the TMJ. In patients with a steep condylar angle a continuance of advancement of the mandible beyond the tolerance of the spacing allowed within the joint itself may result in a stretching of the ligaments. In the authors’ experience this occurrence may be mitigated by increasing the vertical positioning of the appliance while continuing to advance the mandible. By changing the vertical angle of advancement it has been possible to bring patients into a greater advancement both from the comfort as well as the possible mandibular extension perspective.
Tooth movement?
There is no doubt that tooth movement occurs in some cases. There are enormous forces that may be applied by the bruxing patients which may result in some changes. In addition the selection of materials for the appliance may play a roll. The use of Thermoplastic materials in appliance construction will have a tendency to have the material at the back of the mouth at one temperature while at the opening of the mouth another temperature. This would be of greater significance in patients who are subject to mouth breathing. It may be preferable to use a fabrication technique that involves the use of hard acrylic to cover the teeth to the height of contour and an elastic material for the balance of the appliance.
DEFENCE MECHANISMS:
Informed consent?
It has been demonstrated over and over again that in spite of well documented informed consent documents the courts have maintained that a patient is not competent to understand the implications as described.
Records?
– The only protection against legal implications of negative occlusal change challenges comes in the form of adequate records. These records must include accurate measurements of mandibular range of motion capability as well as radiological support to treatment decisions.
– In the authors’ opinion the only way to establish the specifics of mandibular range of motion and be able at the same time to identify existing but nonsymptomatic TMJ issues is with the use of a gothic arch tracing.
– The use of a gothic arch tracing technique that offers the advantages of specific measurements and inclusion of an actual hard copy tracing entered into the patients’ permanent health history can be very advantageous when confronted by an unhappy patient. Such patients are often “egged on” by a dentist unfamiliar with, unhappy with and unfriendly to the issues involved in treatment of the medical condition of sleep disordered breathing with a dental approach.
– A gothic arch tracing that results in a competent bite registration is, in the authors’ opinion, imperative in the management of patients with SDB.
In summary, the advantage of the gothic arch tracing technique may be found in a technique that involves not only the specific forward positioning of the mandible but also a registration of Centric Relation for the patient. By keeping the actual gothic arch tracing generated by the bite registration it is possible to at any time recreate the occlusion of a given patient. Many patients have no real idea of what their occlusion was like prior to treatment and the resulting
change. Often it is the uninformed general dentist who initiates the patient awareness of the existence of bite change and its’ negative consequences. This opinion in combination with an aggressive tort lawyer in the background is enough to present significant financial threat and a mountain of unwelcome irritative narrative. By being able to specifically recreate, with the aid of a gothic arch tracing generated bite registration, the existing occlusion the treating dentist may be able to overcome the threat engendered by an unwelcome and unforeseen event.
– Dr Halstrom has been practicing dentistry in Canada since 1960. In addition to his position as chief executive of Dr. Halstrom Sleep Apnea and Snoring Clinics; he is also Adjunct Professor of Respiratory Therapy, Faculty of Science – Sleep Program, Thompson Rivers University. Contact Dr Halstrom at dhalstrom@drhalstrom.com
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