Abstract
Dental instrumentation has long provided insight into the mechanism of musculo-skeletal function of the gnathic system. While large population studies associate dental arch displacement (DAD), especially laterally, with symptoms, mandibular condyle displacement (CD) resulting from DAD has not been targeted as possibly etiologic in the production of common muscle contraction headache (CMCH) and temporo-mandibular dysfunction (TMD). The objective was to evaluate the three-dimensional nature of DAD and CD between the seated condylar position (SCP) and the intercuspal position (ICP) and to compare results derived from large deprogrammed asymptomatic and symptomatic populations. A total of 1 192 sets of dental casts collected from asymptomatic and symptomatic populations were articulated in the SCP. The initial occlusal contact, DAD, and condylar displacement were evaluated for frequency, direction, and magnitude of displacement between the SCP and ICP. The data revealed significant displacement between the SCP and ICP of the condyles (displaced most frequently inferior (down) and posterior (distal)) and substantially increased frequency and magnitude of displacement of the dental arches (with posterior premature occlusal contacts, increased overjet, decreased overbite, midline differences, and occlusal classification changes) in symptomatic subjects. These discrepancies were statistically significant and clinically significant. The data support the concept of increased DAD and CD with dysfunction. Transverse condylar displacement, commonly presenting with dental cross bite, may be associated with CMCH and TMD. Displacement of the mandibular condyle may be an etiologic factor in CMCH and dysfunction of the temporo-mandibular joint.
Highlights
Upon concluding his 1973 investigation comparing mandibular condyle position in the seated position (SCP) and the intercuspal position (ICP), Hoffman states: “When suitable studies are performed in the future, it will be interesting to learn whether the (ICP-seated condylar position (SCP)) distance is statistically different in healthy individuals and in those with pathology of the temporo-mandibular (TM) joint, periodontium, or occlusal surfaces of the teeth.[1]
Are the condyles displaced as the teeth are brought into the ICP? Is there a difference in dental inter-arch displacement and condylar displacement for asymptomatic and symptomatic populations? If so, what is the significance of this difference? These are central questions that must be addressed when determining whether occlusion may be associated with production of symptomatology, common muscle contraction headache (CMCH) and TM dysfunction (TMD), in susceptible subjects
The 95% confidence level was used to test for statistical significance (Confidence intervals are given as CI LCB.[95], UCB.95.) The Wilcoxon signed-ranks test was used to determine statistical significance between measures in the ICP and the SCP
Summary
Upon concluding his 1973 investigation comparing mandibular condyle position in the seated position (SCP) and the intercuspal position (ICP), Hoffman states: “When suitable studies are performed in the future, it will be interesting to learn whether the (ICP-SCP) distance is statistically different in healthy individuals and in those with pathology of the temporo-mandibular (TM) joint, periodontium, or occlusal surfaces of the teeth.[1]. The positional difference of the mandibular condyle between the SCP and ICP is a source of contention and conflicting judgments by those who rehabilitate dental occlusions. The difference is associated with contradictory theories of jaw movement, jaw recordings of positional and dynamic states, and the selection of dental instrumentation (articulators) for diagnosis and dental rehabilitation. It is, an important topic for further study and greater understanding. Is there a difference in dental inter-arch displacement (for example, the bite or the occlusion) and condylar displacement for asymptomatic and symptomatic populations? Are the condyles displaced as the teeth are brought into the ICP? Is there a difference in dental inter-arch displacement (for example, the bite or the occlusion) and condylar displacement for asymptomatic and symptomatic populations? If so, what is the significance of this difference? These are central questions that must be addressed when determining whether occlusion may be associated with production of symptomatology, common muscle contraction headache (CMCH) and TM dysfunction (TMD), in susceptible subjects
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