• The Journal of the Korean dental association
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• v.48 no.7
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• pp.522-530
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• 2010

Temporomandibular disorders(TMD) have been defined as a collective term embracing a number of clinical problems that involve the temporomandibular joint, the masticatory muscles, and associated structures. Since Dr. James Costen has mentioned about the relationship between TMD and posterior bite collapse, there have been many controversies about the etiology and comorbidities of TMD. The purpose of this study was to investigate the relationship between TMD and hearing acuity in 158 volunteers with or without TMD symptoms. The subjects were examined clinically about TMJ sound, missing teeth, tinnitus, TMJ pain and masticatory muscle pain and the hearing acuity were measured by Audiometer(ITO AE-1000, Japan). The result of this study indicated that there was no significant differences between TMD symptoms and hearing acuity relatively.

• Journal of Dental Rehabilitation and Applied Science
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• v.23 no.3
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• pp.187-195
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• 2007

Temporomandibular disorders have been defined as a collective term embracing a number of clinical problems that involve the temporomandibular joint, the masticatory muscles, and associated structures. Since Dr. James Costen has mentioned about the relationship between TMD and posterior bite collapse, there have been many controversies about the etiology and comorbidities of TMD. The purpose of this study was to investigate the relationship between TMD and hearing acuity in 158 volunteers with or without TMD symptoms. The subjects were examined clinically about TMJ sound, missing teeth, tinnitus, TMJ pain and masticatory muscle pain and the hearing acuity were measured by Audiometer(ITO AE-1000, Japan). The result of this study indicated that there was no significant differences between TMD symptoms and hearing acuity relatively.

• Journal of Oral Medicine and Pain
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• v.31 no.3
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• pp.255-263
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• 2006

Objectives: This article reported three patients developed anterior open bite seemed to be related to TMJ anterior disc dislocation without reduction(ADD WO R), but no evidence of condylar destructive or collapse and analyzed the craniofacial skeletal structure by means of cephalometric analysis. Results: All patients suddenly developed a centric relation/centric occlusion discrepancy, an increased overjet and an anterior open bite following ADD WO R. All patients had Angle's Class I occlusion and shallow bite, but they had skeletally Class III and Class II pattern and all were vertically significant hyperdivergent type. Conclusions: These 3 patients had characteristics of common facial morphology including:(1)Angle classification Class I and shallow bite,(2)high mandibular plane angle,(3)high gonial angle. Developed anterior open bite resulted from clockwise rotation of the mandible related TMJ ADD WO R, rather than a result from the eruption of posterior teeth. We hypothesize rotation may relate to attached direction of masticatory muscle.

• Journal of Dental Rehabilitation and Applied Science
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• v.32 no.1
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• pp.70-79
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• 2016

Patients who lost posterior teeth due to periodontitis or dental caries have collapsed vertical dimension, unstable occlusion and change of the mandibular position. In particular, patients in orthognathic surgery, clinician should re-establish the pre-operative stable position of mandibular condyle in articular fossa and favorable vertical dimension for high post-operative stability of mandible. Therefore, interdisciplinary approach and co-operation, including prosthetics, orthodontics, oral and maxillofacial surgeon, from diagnosis and treatment plan is important to get a good outcome. This case report was patients who had collapsed occlusal plane due to severe dental caries on maxillary molars with skeletal Class III malocclusion. Before orthognathic surgery, resetting of maxillary occlusal plane with temporary removable denture was performed. Then successful multidisciplinary approach was done and lead to acceptable clinical outcome.

• Journal of Dental Rehabilitation and Applied Science
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• v.17 no.4
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• pp.245-256
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• 2001

The purpose of this study is to analyze the mechanical stress and displacement on the jaws during the simulated bilateral clenching task on the three-dimensional finite element model of the dentated skull with unilateral molar loss. For this study, the computed tomography(G.E.8800 Quick, USA) was used to scan the total length of human skull in the frontal plane at 2.0mm intervals. The fully assembled finite element model consists of the articular disc, maxilla, mandible, teeth, periodontal ligament and cranium. The FE model was used to simulate the bilateral clenching in intercuspal position. The loading condition was the force of the masseter muscle exerted on the mandible as reported by Korioth et al. degrees of freedom of the zygomatic region where the masseter muscle is attached were fixed as restraints. In order to reflect the actual action of the muscles force, the displacement of the region was attached where the muscle is connected to the temporal bone and restraint conditions were given values identical to values at the attachment region of the masticatory muscle but with the opposite direction of the reaction from when the muscle force is acted on the mandible. Although the mandible generally has higher displacement and von Mises stress than the maxilla, its mandibular corpus on the molar-loss side has a higher stress and displacement than the molar-presence side. Because the displacement and von Mises Stress was the highest on the lateral surface of mandibular corpus with molar loss, the stress level of the condyle on the molar-loss side is greater than that of the molar-presence side, which in turn caused the symphysis of the mandible to bend. In conclusion, the unilateral posterior bite collapse with molar loss under para-functional activities such as bruxism and clenching can affect the stress concentration on the condyle and mandibular corpus. It is therefore necessary to consider the biomechanical function of dento-skeleton under masticatory force while designing the occlusal scheme of restoration on alveolar bone with the posterior collapse.