Utilizing the mathematical method for experimental analysis on occlusal curves, which is based on three-dimensional analytical geometry. and using the data measured by Nodauna et al of three-dimensional positions on maxillary dental casts of twenty-two male and female young Japanese having clear cusps, Experimental analysis of curve of Spee, curve of Wilson, and sphere of Monson have been performed.
As the result, the most probable position of the center of the curve of Spee existed in between 110-130mm superior to the incisal point and in between 0.6-4.4mm posterior to the incisal point. and further the most probable radius of the curve of Spee existed in 108.6-129.0mm within 0.27% of accuracy.
Each radius of the curves of Wilson corresponding to each buccal and lingual cusps of Ist molar, and each buccal and lingual cusps of 2nd molar are separately determined definitely, and calculated. They are, 482.6mm, 363.4mm. 397.0mm, 297.8mm, respectively.
The most probable position of the center of the sphere of Monson existed in between 110-130 mm superior to the incisal point, in between 8.5-4.7mm posterior to the incisal point, and the most probable radius of Monson existed in between 109.7-129.3mm within 0.22mm of accuracy.

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[in Japanese]

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In powerful grinding movements of the mandible like bruxism, disocclusion of the posterior teeth is important to prevent the hyperbalance of masticatory muscle activity. Although disocclusion is established on the articulator, the cusp contacts of posterior molars in the mouth is sometime recog-nized due to retrusive condylar movement on the laterotrusive side. We have investigated the relationship between the inclination of the occlusal plane, posterior disocclusion during retrusive condylar movement, and the degree of the curve of Spee. Results have indicated that increasing the inclination of the occlusal plane provides posterior interference during protrusive mandibular movement, while posterior disocclusion is obtained during retrusive movement. Accentuation of the curve of Spec provides elimination of posterior contact during retrusive condylar movements.

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Periodontal disease is infection disease by periodontopathic bacteria. Periodontitis were induced by host factor (general condition, smoking, and mental stress) and local factor (bruxism and occlusal trauma) . Most important and harmful influence factor was inflammation and occlusal force. Unnoticed in progression of periodontal disease is“Time-axis”is the theory based on this viewpoint. On this report, we discuss about application of the theory and practice of periodontal-occlusal complex (POC) for Periodontitis patients.

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Continuous occlusal force in a reduced periodontium causes progressive periodontal destruction, which leads posterior bite collapse and flare out of anterior teeth in patients with advanced periodon-titis. We propose new concept “periodontal-occlusal complex (POC) ”for this process. It is important to remove excessive occlusal force in POC in treatment of aggressive and severe periodontitis such as early-onset periodontitis (EOP) . In this study, we present a new treatment strategy for EOP patients. At first, we performed orthodontic therapy and splinting to restore vertical stop and anterior guidance in occlusion. Then, we regenerated periodontal tissue by periodontal surgery.

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[in Japanese]

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