Kimie Okimoto

Clinical Study of Root Caps. The Influence to the Periodontal Tissue of Root Caps and Overdenture.

The morphological changes in periodontal tissues around root caps, anchor teeth, and dentures were examined in 24 denture wearer with root caps (mean age: 63.4 years) to study the influence of root caps on tooth preservation and protection of the residual ridge and denture conditions. Sixty-two root caps were morphologically classified into five types. The root caps of long square type were frequently worn on premolar teeth, while those of short dome type were worn on the incisor and canine teeth. The mobility of tooth was significantly largest in the group with the short dome type and in the subjects wearing denture for 4-10 years, while it was lowest in those wearing denture for 10 years. The periotron value, which reflects periodontal inflammation, was significantly smallest in the group with the long square type. These results suggested that the shape of root caps might relate to the prognosis. The major mastication is more likely to be done on the same side as in the root cap in full overdenture wearer with root caps.

The Relation between Intraoral Environmental Change and Taste. Part 1. Clinical Examination of Partial Denture Wearer's Consciousness.

The purpose of this study was to investigate the relation between wearing a partial denture and taste. Denture and intraoral conditions of 44 partial denture wearers, 31 females and 13 males, aged 35 to 80 years, were examined by questionnaire on food, taste, and seasoning preferencesand taste perceptions.The results were as follows:1. Twenty-three subjects (group Y) showed the changes of food preferences as compared with those in their youth. However, these changes were not revealed in twenty subjects (group N). Nine of twenty-three thought that these changes may be due to wearing partial dentures.2. Most of the upper dentures in group Y revealed the form similar to full denture. It was suggested that extensive covering of the soft palate by denture base influenced the taste.3. The score of satisfaction and mastication of denture in group Y were significantly lower than that in group N. In addition, the degree of denture retention and fitting in group Y was less than that in group N. These may suggest that many denture problems were closely related with taste and/or food preference and perception.

The Statistical Study of Relation between TMJ Dysfunctions and Tooth Contacts Pattern on Lateral Mandibular Movements in Twenties.

The effect of occlusal factors, especially balancing contact in stomatognathic dysfunction, was studied by statistical analysis. Then, in order to study the relationship between the canine contact and the molar contact on working side during lateral movement, the subjects were divided into three groups.U test was used to analyze statistical difference in the incidence of TMJ symptoms between the groups. The results were as follows:1. The molar contact on the working side may have unfavorable effects on TMJ functions.2. The tooth contact on the balancing side, excluding the molar, may suppress the effecst due to the molar contact on the working side on TMJ functions.3. As to the incidence of TMJ symptoms, the group, in which tooth contact includes bilateral canine teeth but excludes the molar, was significantly lower than that in the other groups.

Dynamic Analysis of Implant Bridge. with Special Reference to the Need of Stress Relaxation Mechanism and the Influence of the Connection.

Using two-dimensional finite element method, stress analysis was made of a molar bridge with supposed 6 7 defect. Examinations were also made of the need of stress relaxation mechanism for upper structures and the influence of mechanical properties of the implant material in a free-standing position on the stress distribution in bone interfaces. The following information was obtained: The existence of the fibrous connective tissue around the implant body had no influence on the stress relaxation onto the base thereof, but acted as a stress breaker on the periphery thereof. In case of free-standing, either existence or otherwise of the stress breaker scarcely had influence on the stress distribution of the implant. In case of the connection of the implant with natural abutment tooth, stress relaxation in the presence of the stress breaker may lead to a decrease in the stress around the implant, but excess stress relaxation may do damage to natural abutment tooth, making it necessary to take countermeasures thereto.

Statistical Observation on Stomatognathic Function in the Twenties.

A number of clinico-statistical observation on temporomandibular arthrosis reported that the incidence was the highest in the adults in the twenties. This lead us to pinpoint to the age of twenties and observe the status of stomatognathic system to examine the way temporomandibular arthrosis had developed.The adults concerened the study were 75 for male and 45 for female in the twenties, each of whom was questioned and tested. Sirognathograph Analysing System was used to the analysis of chewing movements. It resulted in discovering symptoms of temporomandibular arthrosis in 61.2% male and 55.6% female. Clinically, patients presented with the noise in general and the pain especially among female. The patients with symptoms of temporomandibular arthrosis had the normal maximum opening volume, the slightly increased index of DMFT, the reduced Type I pattern in the pattern classification (Kuwahara classification) of frontal projection of chewing movements. The incidence of reverse pattern, crossover pattern or both was high in male patients. Furthermore, the male patients with symptoms of temporomandibular arthrosis had the reduced maximum opening and closing velocity and occlusal phase period, while they gave the increase in the cycle, opening phase period, closing phase period and each coefficient of varia-tion.

Stress analysis of posterior bridge. Case of abutment teeth with reduced periodontal supporting tissue. (Part II). Stress distribution of 3-dimensional finite element model and 2-Demensional finite element model on the single rooted tooth.

In the first report, the two dimensional finite element analysis was performed on the bridge model through a computer in order to learn the effect of such two factors as the resorption of the alveolar bone and the number of abutment teeth against the stress distribution of the supporting tissue of the brige whitch is subject to the occlusal force. Furthermore, the results of the finite element analysis under vertical load were compared between the three and the two dimensional models of single rooted tooth in order to study the relation between the threedimensional resorption state of the alveolar bone and the two dimensional model.The models used in study, however, were extremely simplified. Moreover, the periodontal membrane was not modeled and the influence of the lateral load was not considered. Based on these background, in this report, more practical three dimensional model was created including the periodontal membrane. In addition, two two-dimensional models of bucco-lingual and mesiodistal cross sections of three dimentional one were created.The loading direction and the degree of alveolarbone defect were varied by each model. The load was given vertically, bucco-laterally and lingual-laterally. Alveolar bone defect were three cases of 0, 1/3 and2/3 defect of the root length. The comparison of the results of the finite element analysis performed on the total of 18 cases and those of first report resulted in as follows.1. The periodontal membrane has stress breaking effect on the alveolar bone surrounding teeth.2. In the extremely-stressed part, the three dimensional model tends to show higher stress value than the two dimensional one.3. In the laterally loaded case, the load part generates tensile stress and opposite side, compressive stress around the ceavical part. Around the apical part, the two stresses are reversed.4. As bone defect progresses, the stress to be generated increases. For exsample, equivalent stresses generated atthe periodontal membrane in the vertically-loaded three dimensional model were 1.0, about 1.5 and about 2.3 in terms of 0, 1/3 and 2/3 defect respectively.