Three-dimensional occlusal examination of the contacts of maxillary premolars and molars in three different age groups

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We attempted to determine whether occlusal contacts of the maxillary premolars and molars changed with age. Silicone occlusal registration was taken for five subjects each in three age groups, young, middle-aged and elderly. The subjects had no restorations with full occlusal coverage. All readings were taken at 30% of maximum voluntary clenching in the intercuspal position. A non-contact three-dimensional form measuring device (Surflacer VMS-250R, Unisn Inc., Osaka Japan) digitized the silicone occlusal registration. The three-dimensional data were analyzed by CAD software (Surfacer, Imageware Inc., Michigan USA) with a personal computer. The occlusal surface of the maxillary premolars were divided into four regions: the buccal cusp, lingual cusp, mesial marginal ridge, and distal marginal ridge. The occlusal surface of maxillary molars were divided into six regions: the mesial buccal cusp, distal buccal cusp, mesial lingual cusp, distal lingual cusp, mesial marginal ridge, and distal … More marginal ridge. We evaluated the occlusal contacts, which were defined as less than 60 μm of silicone thickness between opposing teeth, and analyzed their number, rate, area, and orientation. We found that occlusal contacts on the functional cusps were significantly different between the young and middle-aged, and between the young and elderly.The purpose of this study was to clarify the differences in amount and direction of mandibular displacement from habitual occlusal position to intercuspal position, between normal adults and volunteers with temporomandibular joint (TMJ) noise. The mandibular displacement in the volunteers with TMJ noise was larger than that in the normal adults. The direction of MOD (movement of dentition) was superior, and the direction of MOC (movement of condyle) was posterior, in all of the volunteers with TMJ noise. These results suggested that the mandibular displacement from habitual occlusal position to intercuspal position was associated with noise in the joint. Less