Test-retest and accuracy of measuring the position and orientation of the human mandible via magnetic sensors: A pilot study

Obstructive sleep apnea is a common type of sleep-disordered breathing, often treated with an oral appliance that protrudes the mandible. This therapy widens the upper airway thereby eliminating and/or preventing collapses and/or obstructions of the upper airway during sleep. Up till now, monitoring of the actual position of the mandible during therapy was not available — although this should be considered a prerequisite in the process of judging treatment efficacy — thus impeding therapy compliance monitoring. To optimize therapy, patient-based data need to be collected during the device's use. At present, electronic sensors attached to the oral appliance monitoring the temperature in the oral cavity are used to objectify therapy compliance as a simple time-logged binary signal: wearing-not wearing. The current paper presents an in-vitro set-up for monitoring both position and protrusion of the mandible relative to the upper jaw. Two magnetic sensors are attached to the upper maxillary part of an oral appliance in combination with two magnets affixed to the lower mandible part of the oral appliance. The mandibular position relative to the maxilla was measured with an accuracy of 0.5 mm for a range of 17.5 mm in the protruding direction.