Occlusal contacts of edentulous patients with mandibular hybrid dentures opposing maxillary complete dentures.

The purpose of this study was to evaluate differences between the occlusal contacts of edentulous patients with mandibular implant-supported hybrid dentures opposing maxillary complete dentures and those of patients with conventional maxillary and mandibular complete dentures. Six parameters related to occlusion were measured in the 2 groups (n = 40 for each group) using pressure-sensitive film. The mean values generated by each test group for each parameter were compared using a t test. Pearson's correlation coefficients between occlusal force, age, and time in function were examined. Occlusal force and area in the implant denture wearers were larger than those in the conventional denture wearers. No significant difference was seen in occlusal force balance between the left and right sides. The center of occlusal load in the implant denture wearers was more anterior. The maxillary denture may become more unstable in implant denture wearers. It is suggested that the stability and retention of a maxillary denture be checked and the occlusion be adjusted more frequently in the hybrid denture wearer than in the conventional denture wearer.

[Anterior occlusal contact of complete denture during mastication].

The purpose of this study was to measure the actual anterior occlusal contacts in complete denture during mastication and discuss the relation between anterior occlusal contacts and masticatory movements. The actual anterior occlusal contacts were measured electrically with metal occlusal surfaces in five edentulous patients. These metal occlusal surfaces could be removed and changed into two types of occlusion. The masticatory movements were measured by Sirognathograph for seven edentulous patients. The types of anterior and posterior occlusions were changed, and the masticatory movements were analyzed for each of the four types of occlusion. The results were as follows: 1. Anterior occlusal contacts were found during mastication, but not during tapping, in bilateral balanced occlusion. 2. The frequency of anterior occlusal contacts during mastication was increased in non-balanced occlusion. 3. The frequency of occlusal contacts at the canine on the chewing side was increased by continuing of mastication, but was not increased at the canine on non-chewing side. 4. The stability of the denture tended to be lost by eliminating the anterior occlusal contact, judging from the rhythm of masticatory movements. This study suggested that anterior occlusal contacts are necessary for the functional harmony of complete denture during mastication.

[Clinical evaluation of measuring system of occlusal force].

An occlusal diagnostic system was evaluated for clinical applications. This system consists of pressure sensitive sheets (DENTAL PRESCALE, Fuji Photo Film Co.) and analyzing computer (OCCLUZER FPD703, Fuji Photo Film Co.). The clinical efficiency of this system was evaluated in aged dentates, aged complete denture wearers and an aged patient suffered from periodontitis. The results were as follows: 1. There was a positive correlation between the masticatory efficiency and maximum occlusal force. 2. In the complete denture wearers, the distances from the medial line to the center of the occlusal load were statistically greater in the adjustment needed cases than in the control group. 3. In a case of periodontitis, the full arch fixed splint was adjusted using this system. After adjustment, the maximum occlusal force and contact area increased, and the maximum and medial pressure of the occlusal contact force decreased. 4. It was suggested that this system would be available for the examination of masticatory efficiency and diagnosis of various types of occlusions.