The Frankfurt plane is most used for the horizontal basal plane of the cranio-facial measurments. In the dentistry, the occlusal plane is important on the clinical medicine. This plane has been studied on the dentulous jaw. The most of these reports were regarding on the permanent dentitions. However, the determination of the occlusal plane in the deciduous and mixed dentitions is so difficult that the reports on those dentions are little. Therefore, This study examined the relationship between the occlusal plane, Frankfurt plane and Camper’s plane at the each stage of dentitions.

The Frankfurt plane and the Camper’s plane were recorded on the basal plane of maxillary models, and the occlusal plane was recorded on mandibular models. The both models were fixed on the centric occlusion with the adhensive agents. These models were cut in the sagital plane and then the frontal plane. Each plane was made photograph with standardized method. The angles between each plane were measured on those standardized photographs.

Results were as follows:

1. In the sagital sectional plane, the angle between the occlusal and the Frankfurt plane on the decidus dentition, mixed dentition and permanent dentition were each 15.85°, 12.28° and 7.73°. These angles decreased about 4°-5° along with increasing in age. On the other hand, the angles between the Camper’s plane and the Frankfurt plane were 3.67°, 4.58° and 5.43°. At the each dentition, the rate of increased angles was one degree, With increasing ages, the occlusal plane became more pallarel to the Camper’s plane.

2. In the frontal sectional plane, the angle of the right and left inclination between the Frankfurt plane and the Camper’s plane were almost regarded as zero degree at the each dentition.

3. No correlation was found between the occlusal plane and the Camper’s plane at the deciduous dentition and mixed dentition. However, in the permanent dentition, high correlation was found between the occlusal plane and Camper’s plane.

By means of an apparatus designed by MITA, the electrical impedance and reactance factor to sinusoidal alternating current were determined at 16 regions of the soft tissue in human oral cavity, especially including the normal gingiva. The frequency of current was mainly fixed at 3Hz and a cotton-wick (φ=5mm) was employed as a different electrode. The results obtained in this paper were as follows:

1)Within the oral cavity, it was indicaled that impedance value for 3Hz varied depending on the local characteristics of the mucous membrane and showed highest (17.4KΩ) at the surface of the hard palate and lowest (5KΩ) at the tongue root. This local dependency of the impedance was clearly observed in all subjects. 2)When the frequency of the current was varied from 3Hz to 30kHz, the impedance value determined at a given mucous membrane was decreased with increase in frequency. 3Hz alternating current was found as a most adequate frequency for detection of the local dependency. 3)The mean values of gingival impedance determined in 10 healthy subjects, 5 male and 5 female students, were about 7KΩ for male and 9.3KΩ for female indicating that the gingival impedance of the female was higher than that of the male. 4)Daily variations of the gingival impedance observed in interdental papilla showed a typical changes which indicated the highest value in early morning and became stable at low value in later afternoon. The diminutive effect on the daily variations was produced by eating, speaking and tooth. brushing, while the augmentative effect induced by sleeping. 5)The regional differences in impedance value were observed between the two symmetrical part of attached gingiva. The differences were always below 20%, however, the differences between the lingual and buccal gingiva were remarkably observed in maxilla. 6)Developmental change of the gingival impedance was determined during the tooth crown emerge through fusion of oral and enamel epithelium into the oral cavity. The gingival impedance increased gradually before erution of the tooth and then decreased abruptly at an early stage of tooth eruption. 7)Finally, the relationship between the impedance changes and the pathologic tooth mobility was studied in several patient with periodontal diseases. When the tooth mobility was increased, the impedance value of its surrounding gingiva was proportionally decreased.

In our previous report (1976), caries prevalences of schoolchildren (6-11yr.) in the rural area of the northern Japan, showed no significant difference compared with the data of the National Survey (Report on the survey of dental diseases, 1975), except for a fluoride area investigated in our studies.

The purpose of this study was to figure out the up-to-date target of caries prevention program for schoolchildren by means of cross-sectional analysis on the dentition. The erupted permanent teeth per 100 children, DMF per 100 erupted teeth and the treated teeth per 100 DMF teeth were evaluated respectively.

A characteristic trend of dental caries prevalence in children was observed in the upper central and lateral incisor. DMF per 100 erupted teeth of the upper incisors group showed 2.0% for central and 2.4% for lateral incisor in the 2nd grade (Mean: 7yrs old) children. However, the increment of caries prevalence of this tooth group was recognized remarkably from 4th and 5th grade children (Mean: 9 and 10 yrs old) and the prevalence attained 23.2% for central and 26.2% for lateral incisor in the 6th grade (Mean: 11 yrs old). These values are considerably higher than those of previous investigations in this country.

The results of this study suggest that an important task for caries prevention of schoolchildren should be emphasized to maintain cariesfree of the upper incisors teeth group because of the difficulty of adequate treatments for these teeth, especially in the time of schoolchildren (6-11 yrs old).

Acase report was made of anomalous case of the upper second premolar with two paramolar tubercles in a 29-years old male. The Carabelli’s tubercle and the protostylid were found in the upper and lower first molars bil- aterally. As the result of stastic investigations of previous authors, the incidence frequency of the param.olar tubercle in the premolar region is assumed to be one anomalous tooth among four to five lhousand people. It appeares far more frequently in the upper than in the lower jaw, and in the second than’.in the first upper premolar. There is no comparable recognizable between the left and right sides of the jaw. It is found to be true that this tubercle originate from cingulum.

Authors reported two cases of the mandibular protrusion treated by light wire edgewise technique. One of these cases was treated following the extraction of upper first premolars and lower first molars, and the other case, the lower first molars were extracted.Inboth cases, chin cap appliance was utllized to control the growth increments of tlle mandible. Those treatment results suggested to following conclusions:The clinical application of the extraction of first molars were effective in the treatment of the severe discrepancy cases and steep mandibular plane cases with skeletal class III malocclusion.

Twenty cases of inflammatory complication extraction of teeth referred to the Depart-ment of Oral Surgery II, Iwate Medical University for treatment during 2 years and 6 months. The complication was found to have slight sex predilection(8males and 12females)and was most frequentry seen at the 3 rd decade. Clinical findings were spontanous pain, trismus, swelling and pus discharge, and these were revealed in 3 days after extraction of teeth. Nineteen patients were treated with antibiotic therapy in combination with surgical procedure.Clinical course was favourable.

In the modern world of buslness stress and soclal obllgatlon, many patlents who must become edentulous can no longer submlt to the custom of waltlng 6 to 10 weeks or longer wllhout teelh whlle thelr heallng surglcal procedure. Modern denustry should accept the challe-nge of provldlng a replacement servlce wlth less tlme and less dlscomfort.

Transitional denture ls a complete denture which is made before preextractlon of teeth and ls lnserted to the patlent moulh lmmedlately after the al|remalnlng teeth are relnoved Thls den-ture is little dlfferent than that of so called "immedlate denture".

There are many advantages ln the use of transltlonal dentureb They are ldeal and compulsory for patients with severe periodontal disease. However, transitional dentures have not frequently been apPlied in the daily dental practice because of the difficulty of their construction procedures and the lack of understanding of their advantages.

We have been developed newly silnple procedures constructing transitional dentures and obtai-ned successful result to make patient’s satisfaction.