The main occluding area in normal occlusion and mandibular prognathism

Abstract

Objective: To clarify whether the concept of main occluding area, where hard food is initially crushed, exists in patients who have a jaw deformity. Materials and Methods: Nineteen subjects with normal occlusion, 18 patients with mandibular prognathism, and 11 patients with mandibular prognathism who had undergone orthognathic surgery participated in this study. The main occluding area was identified by clenching Temporary Stopping. The coincidence, location of the main occluding area, and distance from the first molars to main occluding area were examined. Results: High coincidence of the main occluding area was obtained in all groups, signifying that the main occluding area exists even in these patients. Mandibular main occluding area was located on the first molar in all groups. Maxillary main occluding area in subjects with normal occlusion was located on the first molar. However, it was located on the second premolar and first molar in patients with mandibular prognathism, and on the first and second molars in patients with mandibular prognathism who had undergone orthognathic surgery. There was a statistically significant difference in distance from the maxillary first molar to the main occluding area among groups, but there was no difference in the distance from the mandibular first molar among groups. Conclusion: The main occluding area is more stable on the mandibular first molar than the maxilla in all groups. (Angle Orthod. 2016;86:87-93.)

Somatosensory evoked magnetic fields caused by mechanical stimulation of the periodontal ligaments

“…Investigation of the main occlusion area by biting a small piece of dental putty identified three main groups: normal occlusion, mandibular prognathism, and mandibular prognathism corrected by orthodontic surgery [ 41 ], and was reported that the mandibular first molar is more important in the main occlusion area than the maxillary first molar, and even the anteroposterior jaw relationship is different. The reports using Electromyography (EMG) showed the mandibular periodontal ligament was more important than the maxillary periodontal ligament for adjusting jaw position during exertion of relatively weak occlusal force [ 42 ], and the unit EMG activities were smaller in the muscle of mastication under anesthesia of the mandibular periodontal ligament than under no anesthesia and anesthesia of the maxillary periodontal ligaments [ 43 ].…”

Finite element analysis on tooth and periodontal stress under simulated occlusal loads

“…The mandibular first molar is the earliest permanent tooth appearing in the mouth and guides the development of the jaw . Analysis of its biomechanics provides understanding about tooth and periodontal functional patterns during chewing, and thus the evaluation of masticatory functions . To precisely define the stress/strain field of a molar during clenching, it is critical to build a model that incorporates the structure geometry, tissue properties and the acting forces on the mandibular system .…”

The base of the tongue regulates the main occluding area in the patients with mandibular prognathism

“…The main occluding area in the subjects with normal occlusion are located distobuccal cusp tip of the mandibular first molar [3,16]. In addition, the main occluding area in the patients with MP is stable on the mandibular first molar after orthognathic surgery [4].…”

“…Kato et al reported that the main occluding areas in the subjects with normal occlusion are located within 5mm of range between the mesiolingual ridge of the maxillary first molar and distobuccal cusp tip of the mandibular first molar [3]. Regarding the main occluding area in the patients with mandibular prognathism (MP), we reported that the main occluding area also exist in these patients, and it was stable on the first molar even after orthognathic surgery in the mandible, though it was changed from the second premolar to the first molar in the maxilla [4]. We had presumed that the main occluding area is preferentially determined in the mandible rather than in the maxilla in the patients with MP.…”