In order to minimize undesirable factors to the abutment teeth affected by retainers of removable partial prostheses, several experiments on the retainer designs including Konus-type telescope crowns have been made in our department. As a part of the experimental program, the abutment movements of unilateral distal-extended removable partial dentures with four clasp assemblies, a cast Aker's, a back-action, a double Aker's, and an extended arm, were observed by using two digital type of laser displacement sensors and they were reciprocally compared through the statistical analyses. The obtained results were as follows : 1. In all of the abutment teeth with four clasp assemblies were recognized the following movements ; the parallel ones of the long axes of the abutment teeth, the inclination, the twist-like, and the vertical ones during the crush of the test food. 2. On the mesiodistal displacements : 1) On the mesiodistal parallel movements of the long axes of the abutment teeth ; (1) The displacement of the abutment teeth (〓) with designs D and E has a tendency to become larger than those with designs A and B. (2) The displacement of the abutment teeth (〓) during the crush of the short test food tended to be significantly larger than those during the long one. 2) On the mesiodistal inclinations : (1) In contrast with the mesiodistal parallel movements, the abutment tooth (〓) with design A showed greater displacements than that with design E significantly. (2) The mesial abutments (〓) with the splinting clasp assemblies showed prominent displacements, which were greater than those of the distal abutments (〓). (3) Displacements when crushing the long type of test food were greater than those when crushing the short one in contrast with those of the above mentioned parallel movements. 3. On the buccolingual displacements : 1) Generally greater inclinations and smaller parallel movements were recognized on the buccolingual behaviors, too. 2) On the buccolingual inclinations ; (1) Different behaviors were clearly noticed on the whole between designs B, D, E, and design A : a buccal or a lingual tipping arose in the abutement teeth (〓) with the former designs (B, D, and E) according to types of the test food. On the contrary, the abutment tooth (〓) with design A arose always to buccal tipping regardless of the type of the test food. (2) The abutment tooth (〓) with the former designs tipped toward buccal side when crushing the long test food, and the amount of displacements were decreased gradually as the load increased. On the other hand, they had a tendency to tip toward lingual side when crushing the short test food. However, the mesial abutment teeth (〓) were little affected. (3) The directions of the inclinations of the distal abutment teeth (〓) with design D were completely contrary to those with one. 4. On the vertical displacements : (1) The abutment teeth (〓) with splinting designs had a tendency to be more depressed than those with single designs. (2) Large displacements were recognized in the mesial abutment teeth (〓), too, although they were somewhat smaller compared with the distal ones (〓). 5. On the twist-like movements : (1) Amount of the twist-like movements of the abutment teeth (〓) were larger in the splinting designs than in the single ones. (2) Prominent twist-like movements were recognized in the mesial abutment teeth (〓).

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It has been shown that there is a groove on the mesial or buccal root surface of the mandibular premolar in human. When the groove is formed deep, the root bifurcates or trifurcates and presents complicated morphology. There have been many studies done on racial variations in the frequency of appearance of this groove. The morphology and location of this groove therefore were studied to obtain information for dental treatment. Of a total of 2, 557 mandibular premolars used, 226 teeth (108 first premolars and 118 second premolars) classified by Okumura's (1914) into 4 types, Aa1, Aa2, Ab1 and Ab2, with deep grooves on the mesio-lingual surface of their roots were examined. The results were as follows. 1. The average length of the lingual groove is 10.63 mm in the first premolar and 10.53 mm in the second premolar. They are 80.0% and 77.8% of their root length. 2. The lingual groove is located 2.26 mm from the lingual edge in the first premolar and 2.24 mm in the second premolar. They are 32.4% and 31.4% of the bucco-lingual diameter. 3. The buccal grooves appear in 81.5% of the first premolar and in 47.5% of the second premolar. The average length of the grooves is 7.55 mm in the first premolar and 7.25 mm in the second premolar. They are 57.8% and 53.5% of their root length. 4. The distal grooves appear in 25.0% of the first premolar and 19.5% of the second premolar. The average length of the grooves is 7.88 mm in the first premolar and 7.61 mm in the second premolar. They are 60.0% and 56.1% of their root length. 5. The buccal grooves were observed in 3.7% of the first premolar and 5.9% of the second premolar. The average length of that groove is 9.70 mm in the first premolar and 8.89 mm in the second premolar. They are 73.9% and 66.2% of the root length. 6. Many of the first premolars have two grooves on their mesial surface (55.5%), as in the second premolars (47.5%). 7. The root ridges were observed on the mesial surface in the first premolar (94.5%) and in the second premolar (91.3%). They were also observed on the distal surface in the first premolar (38.8%) and the second premolar (22.8%). The tooth that has deep grooves on the mesial surface has distal ridges as well as mesial ridges. 8. There is a significant relationship between the length of the mesio-lingual groove and root length. There is also relationship between the bucco-lingual diameter and the distance from the lingual edge.

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An investigation of dental diseases in the highlands of Nepal was carried out in Langtang village (3, 500m elevation) from the middle to the end of March of 1992. The people of Langtang village were mostly of the Tamang tribe of Tibetan. This report is related to an epidemiorogical study of this particular tribe. The purpose of this investigation is to understand the dental diseases of Nepali people better. The results obtained were as follows : 1. As for the DMFT of permanent teeth, the DT increased from about 13 years old. Then at the age of over 60 years, it becomes 17.7. The MT is under 1.0 until 50 years old, but it increased dramatically at the age of over 50 years. The incidence of caries affection increased dramatically from about 13 years old and at this age the rate was over 60%. At the age of over 50 years, the incidence became 100%. The FT couldn't be observed. In comparison with the Japanese, the DMFT was very low and its progress was slow. Prior to this survey they received no dental treatments. 2. As for the attrition, attrition score 1 is observed at the ages of 10 to 12 years. According to the aging, number and degree of attrition increased dramatically. 3. The incidence of TMJ is very low in comparison with the people of Thecho village or the Japanese. 4. Few diseases of the soft tissue, except periodontal disease, could be observed. 5. Dental treatments in Langtang village conducted by us were mostly scalling and teeth extraction. We couldn't conduct other treatments, because we didn't have enough equipment and medical staff in there.

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Hyperalgesia following peripheral nociception may be mediated by up-regulated synaptic transmission of spinal cord. N-type Ca channel, which is ω-Conotoxin (ω-CgTx) sensitive, and the protein kinase C (PKC) localized at presynaptic terminal are possibly concerned in pain modulation. However, role of these synaptic regulation exerted by concurrent amino acids release and pain response is not fully understood. The purpose of the present study was to investigate whether manipulation by inhibitors for PKC and N-type Ca channel modulate similar pain-related response in relation to CSF amino acids following formalin-induced nociception in rats. In addition, we compared characteristics with morphine well-known as a potent pre-and post synaptic inhibitor in modulating hyperalgesia. Three days after intrathecal implantation of PE-10 catheter along with loop - type microdialysis probe in male Sprague-Dawley rats, 50 μl of 5% formalin was subcutaneously injected into left hind paw. Thereafter, simultaneous determinations of microdialysis at 10 min. -intervals for glutamate by HPLC-ECD and observation of flinches were performed for 60 min after intrathecal administration of either drugs (saline for control, the N-type Ca channel blocker ω-CgTx, the PKC inhibitor staurosporine (STU), STU combined with the PKC activator PDBu, the opioid receptor agonist morphine). Biphasic increases of flinches after injection of formalin were observed ; phase 1 (max. 13 flinches/min. at 1 min.) and phase 2 (max. 22 flinches/min. at 30-45 min.). ω-CgTx attenuated flinches during both phase 1 and 2 periods. STU attenuated flinches during phase 2 period and this inhibition was reversed by combined use of PDBu. CSF glutamate in saline group was transiently increased by 149±12% during first 10 min but this increase of glutamate was supressed by ω-CgTx and STU. With morphine, both increased CSF glutamate release and biphase of finchings after formalin injection were completely supressed. The present results clearly demonstrated that ω-CgTx inhibits the both phases of flinchings as shown with morphine, associated with supressed glutamate release, suggesting Ntype Ca channel may regulate neurotransmitter release evoked by C fiber activation. In contrast, the significant inhibition of second phase of flinches (hyperalgesia) with supression of glutamate release by PKC inhibitor, staurosporine, was reversed by combined use of PKC activator, suggesting possible contribution in developing hyperalgesia through the mechanism that PKC evokes both pre synaptic neurotransmitter release and activation of NMDA receptor at post synaptic event.

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A clinical study on immediate reconstructions of mandibular defect with reconstruction plate following mandibular resection were carried out in case of both benign tumor (male : 9 cases, female : 11cases) and malignant tumor (male : 32cases, female : 20cases) during the past 14 years from 1980 to 1994. 1. Resection area was classified 4 area, the resection area distribution is body resection (17 cases), median and body (11 cases), body and angle (37 cases), hemisection (4 cases). 2. In cases of benign tumor, its our principle that combined reconstruction of the mandibular bone by reconstruction plate and iliac bone graft, whereas malignant tumor cases were reconstructed immediately by using reconstruction plate singly. The case number of the former was 16 cases and that of the latter was 50 cases. 3. Postoperative complication included infections (9 cases), exposed plate (8 cases) and broken plate (6 cases) ; other complication were 3 cases of loosen screw and 1 case of broken screw.

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Dental radiographic and other imaging examinations have been taken at the Department of Dental Radiology, Kyushu Dental College Hospital. Plain radiography was found to be taken most frequently in the radiological examination. Not only tomography and contrast radiography but also ultrasonography and computed tomography could be carried out recently. The aim of this survey on the imaging examinations is to clear the role and characteristics of our department at the Kyushu Dental College Hospital. Two hundred and seven thousand eight hundred and eighty-five imaging examinations, which were taken at our department from April 1, 1985 to March 31, 1995 was analyzed mainly on the examination numbers and methods. The results were as follows : 1. The number of annual patients, who visited our department during the past 10 years, increased yearly. The number of the annual imaging examinations during the same period also increased. The results obtained suggest that there was relationship between the number of outpatients and the number of imaging examinations. Examination numbers in spring and summer were larger than those of the other seasons. 2. The periapical dental radiographs were taken most frequently, and their number occupied a half of all radiographs taken in our department. 3. Modified schuller and orbito-ramus radiographies have been carried out significantly. This phenomenon illustrates that patients who suffered from temporomandibular joint disorders are increasing. 4. Due to the beginning ultrasonography examination in our department in February 1990, contrast radiography for the diagnosis of soft tissue diseases decreased especially in 1992. 5. To evaluate the imaging examinations in our department, the examination number was compared with that of imaging examinations in the Departments of Dental Radiology, at Niigata University and at Hiroshima University. The examination number at either Dental Hospital was predominantly larger than that of our Dental Hospital. However, it was interesting that panoramic and occlusal radiographies were taken more frequently in our department than in either Dental Hospital.

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[in Japanese]

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The purposes of this laboratory experiment were to observe the movements of abutment teeth with the Konus-type telescope attachments by utilizing two digital type of laser displacement sensors, and to evaluate their movements through the statistical analysis. Furthermore, another purpose was to examine thoroughly by comparing with the movements of abutment teeth with clasps which had been obtained from the same condition. The results are summerized as follows : 1. On the amount of mesiodistal parallel movements to the long axes of abutment teeth : a) Displacements of design K2 (〓) were significantly greater than those of K1 (〓) and moved towards the mesial direction. b) The amount of displacements when crushing the short type of test food were always four to five times greater than those of when crushing the long type. Little influence of food type, however, could be recognized at 〓 in design K2. 2. On the degree of mesiodistal inclinations of the abutment teeth : Contrary to above mentioned parallel movements, displacements of design K2 (〓) were significantly smaller than those of K1 (〓) and inclined towards the distal direction. 3. On the amount of buccolingual parallel movements to the long axes of abutment teeth, those were the smallest of the whole displacements. In addition, little influence could be recognized concerning amount of loads and food shapes included in K2 (〓). 4. On the degree of buccolingual inclinations : The largest degree of inclination was detected in K1, and it inclined towards the lingual side. 5. On the amount of vertical movements, little difference was recognized between designs K1 and K2 by appearance. but the movement of K2 was greater than that of K1 at highly significant under almost all loads. 6. On the twist-like movements : a) Different directions and amount of the abutment teeth movements were observed due to the food shape. b) Counterclockwise movements were recognized in both designs when crushing the short type of food, and the amount of them increased as loads increases from 3 kg to 7 kg. Clockwise movements arose when crushing the long type of food. Also there was no significant increase in the displacement of the whole abutment teeth. 7. In the displacements in K1, inclinations were occupied about 50%. When connecting the outer crowns to each other (K2), displacements decreased by about 30% and some 34% of the inclinations were also observed in 〓. 8. When comparing the displacements of abutment teeth with these Konus-type retainers to that with clasp accemblies under the same conditions, the degree of inclination in design K1 was almost equal to that in design A. In addition, the degree of inclination in design K2 was almost the same as in designs B, D, and E, but greater than those in designs Aw, Ca, Ct, Rk, and Ik. It may be said in this connection that abbreviated words in the writings represent A : Akers, B : Back-action, Aw : Wrought wire Akers, Ca : Combination with cast and wrought wire Akers, Ct : Combination with T-bar and cast Akers, Rk : Krol's retainer, Ik : Kratochvil's I-bar, and D : Double Akers, E : Extended arm clasp accemblies respectively. The above mentioned results indicate that ideas free from preconceived concepts should be entertained about splinting of abutment teeth. In order to do so, accumulation of still more data about the various cases is necessary.

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The Dental Aesthetic Index (DAI) is an orthodontic index based on socially defined aesthetic standards. As no epidemiological studies are available on malocclusion in Bali, Indonesia, it was decided to study the prevalence of malocclusion among Balinese and compare with other groups using the DAI. The sample consisted of 173 randomly selected dental casts (85 males and 88 females) ranging in age from 18 to 38 years old from Bali, and malocclusion in this group was evaluated using the DAI. The mean DAI scores of male and female of the Balinese were 31.2 and 30.5 respectively, and there was no significant difference of mean DAI scores between both sexes. Therefore, the data of both sexes were combined and presented as the DAI scores of the Balinese, and was compared with those of 1, 129 Japanese, 176 Chinese in Taiwan, 485 Native American and 1, 337 Caucasian American students. The mean DAI scores of the Balinese was 30.8, and it is not significantly different from those of the Japanese and Native Americans, but significantly higher than those of the Taiwanese and Caucasian Americans. On the other hand, characteristics of malocclusion of Balinese were evaluated by analysis for each DAI component (the DAI is composed of ten components). The Balinese have the highest prevalence of the largest anterior irregularity in mandible and the anterior maxillary overjet in all groups. Then, the distribution of each component score of DAI in all groups was compared with the Caucasian American group as a standard. The distribution of each component score of DAI in Balinese approximates Native Americans. The findings in this study indicate that the Balinese have higher prevalence of malocclusion than Chinese in Taiwan and Caucasian Americans using the DAI. The Balinese are greatly inferior to the Caucasian American group in four components of the DAI : crowding in the incisal segments, largest anterior irregularity (maxilla), largest anterior irregularity (mandible), and anteroposterior molar relation. The results revealed common characteristics of malocclusion in the Balinese, Japanese, Chinese in Taiwan and Native Americans as compared with the Caucasian American group as a standard.

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Once the periodontal treatment was called "radical treatment". There is a long history before it was considered as a main part of periodontal treatment. However, it also can be considered as a history of periodontal treatment failure. Today, it is clear that the main purpose of the periodontal treatment is to remove the disease factors. Therefore, in the periodontal treatment, the importance of initial therapy was widely noticed. Consequently, periodontal surgery can be supposed to be one selection in the periodontal treatment. As the result, the rate of success in using the periodontal surgery is largely increased. The focus of this report is to explain the proper indication of periodontal surgery and to find where its position it should be in the periodontal treatment.

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