The Effects Of Intraoral Appliances On Respiration: A Pilot Stud

The purpose of this study is to investigate whether autonomic nervous system activity can be reliably altered through the immediate experimental manipulation of tongue position and its presumed effects on airway. Tongue position is inevitably affected by most types of intra-oral appliances used for the treatment of temporomandibular disorder (TMD) symptoms associated with sleep bruxism, yet the role of tongue-space and airway is seldom considered as a possible mechanism of action in resolving these symptoms. There is an ongoing debate regarding the indications of intra-oral appliances for sleep bruxism in the literature. Although there is no consensus regarding possible supporting evidence for the mechanism whereby they might be effective, intra-oral appliances are nevertheless universally prescribed for individuals with sleep bruxism.;Preliminary evidence supports at least a modest co-morbidity of sleep bruxism and sleep disordered breathing, suggesting that both conditions may share common mechanism. Centrally, both conditions share certain physiological changes (e.g. sleep micro-arousals), but whether these shared mechanisms are only central (e.g. brain centers underlying sleep disorders) or also peripheral (e.g. altered airway dynamics) is not currently established. In contrast to intra-oral appliances used for sleep bruxism, appliances for sleep apnea explicitly include consideration for posterior airway space via mandibular advancement and a protruded tongue position.;Building on the observation of how intra-oral appliances affect sleep apnea, the study's hypothesis is that one mechanism by which intra-oral appliances affect central function for treatment of TMD symptoms induced by sleep bruxism is via their direct effect on airway, and that such airway changes necessarily alter heart rate variability as a surrogate index of an altered autonomic nervous system activity.;Objectives: 1. To analyze heart rate variability (HRV) while the posterior airway space is manipulated by changing the tongue position with three intra-oral appliances' designs: a. A George gauge, which is widely used in the construction of sleep apnea appliances. The George gauge significantly increases the posterior airway space by holding the mandible and the base of the tongue with it in a protruded (anterior) position. b. A traditional mandibular full coverage appliance that is often a part of TMD standard treatment. With this appliance, a moderate effect of increasing posterior airway space is hypothesized via increasing the occlusal vertical dimension and moving the tongue position anteriorly as compared to occluding on the natural dentition. c. A comparable appliance with customized components that partially occupy naturally existing tongue-space, and thus pushing the tongue posteriorly to experimentally compromise posterior airway space. 2. To explore whether the experimental manipulation of tongue position and posterior airway space will affect the autonomic nervous system in healthy individuals to the same degree it does in individuals with TMD symptoms associated with parafunctional activities (sleep bruxism). 3. To provide preliminary evidence for a postulated mechanism of intra-oral appliances, where their possible efficacy in reducing TMD symptoms associated with parafunctional activities (sleep bruxism) is associated with the promotion of breathing and a re-balanced autonomic nervous system activity. 4. To explore whether an instructed attention resting baseline method shown to stabilize heart rate activity will be effective at the shorter recording periods designed in the study.;Results: The reliability of the instructed attention rest baseline method was statistically significant for the 5 minutes and 2 minutes recording periods (Intraclass Correlation Coefficient = 0.85, 0.9) respectively. The analysis of variance failed to show any statistical significance for the effect of tongue position or the presence of pain on HRV.;Conclusion: The use of the instructed attention resting baseline method was successful at consistently restoring heart activity to basal levels in the shorter periods designed in the study. The analysis of HRV was carried out using RMSSD (root mean square of successive R-R differences) as the primary dependent variable. As a future recommendation, the exploration of other HRV indices in response to baseline methodology and the current independent variables (tongue position manipulation and the presence of pain) is suggested.