This paper is a record of my final lectures which detail my 33 years of teaching, researching and practicing orthodontics at the School of Dentistry, Iwate Medical University, the first school of dentistry established north of Tokyo. I was among the first group of professors who started from scratch.

The lectures touched on:

(1) New approaches to teaching

(2) Dealing with postgraduate training

(3) Relations with the various scientific societies

(4) My personal achievements in research

(5) The actual practice of orthodontics

Atotal of 161 inpatients, 90 males and 71 females, aged 12-80 years, were seen at the Department of Periodontology upon referral from Iwate Medical University Hospital and the following information was obtained from each patient’s medical conditions based on the interview with inpatients and the data from physicians at first visit: (1) age, (2) sex, (3) medical problems. The medical problems were divided into following categories; cardiovascular, respiratory, neuropsychiatric, digestive, genitourinary, metabolic disease, muscle, joint, and bone, endocrine,hematologic, dermatologic and eye, ear, nose, and throat problems. The age was also divided into four groups: 10-20, 21-40, 41-60 and 61-80. The number of cardiovascular disorder was reported by 51,lin the age group of 21-40,28 in the age group of 41-60 and 22 in the age group of 61-80. Neuropsychiatric disorder was next in reported frequency (31), followed by digestive and metabolic disorders (29 respectively). Other disorders were reported by less than 20 for each condition. Four diseases above mentioned were reported in 63.1% of all medical problems. Hypertension was reported in 27.5% (14 of 51) in cardiovascular disorder, and hepatitis was in 31.0% (9 of 29) in digestive disorder. Diabetes mellitus was represented in 68.9% (20 of 29) in metabolic disorder, and cerebral infarction was 22.6% (7 of 31) and schizophrenia was 32.3% (10 of 31) in neuropsychiatric disorder.

The malority of the types of systemic conditions were in 41-60 age group with the highest incidence of all age groups. The highest incidence of inpatients with single and two medical problems among in patients was in 41-60 age group (59.5% and 58.8%), but the incidence of inpatients with three and over medical problems among inpatients was the same in both 41-60 age group and 61-80age group (43.8% respectively).

In this study, the information obtained from medical conditions for inpatients based on the interview with inpatients and on the data from physicians seems to be valid for every specific condition rather than that information obtained from a ”patient-provided” history.

To develop the cariogenicity test for sugar substitutes and foods in vitro, the growing system of mutans streptococci was examined in this study. Four strains of mutans streptococci were cultured under aerobic or anaerobic conditions, and the time course of changes in pH value, cell growth and insoluble glucan synthesis were analysed. In all bacterial strains, either pH decrement, cell growth and insoluble glucan synthesis showed slightly higher values under anaerobic conditions compared with those under aerobic conditions after 5 to 7 hours of incubation. However, a difference of oxygen conditions did not have remarkable effects on data after a long incubations over g hours. After 23 hours of incubation, sorbitol was fermented by all strains of mutans streptococci used in this study, especially by Streptococcus mutans. Yet, after 9 hours of incubation, the fermentation was not very notable, but the difference in fermentability from sucrose was shown clearly. These results suggest that the optimal incubation time for evaluation might be approximately g hours under the conditions used in this study.

The time course of changes in pH and cell growth showed a similar pattern, so the capacity to grow mutans streptococci in sugar substitutes and foods were evaluated directly and indirectly. In addition, we analysed insoluble glucan synthesis in this test system. The capacity of sugar substitutes and foods to form dental plaque were assessed by the integration of data from the three ways of analysis in this test system.

Maltitol, xylitol and a food sample were tested by this system､ The results suggested that either two sugar substitutes or a food sample were non-cariogenic.

The upward curving of the inferior border of the mandible anterior to the mandibular angle is known as the antegonial notch. Previous studies suggest that antegonial notch development is dependent on the growth of the mandibular condyle and the mandibular ramus, and the mandibular angle’s attachment to the superficial layer of masseter muscle and medial pterygiod muscle.

The functions of the muscle group of the upper hyoid bone for opening movement are known to influence maxillofacial growth which is also affected by the position of the hyoid bone group and the mandibular shape. We assume that antegonial notch variables relate to the variance in the position of the hyoid bone. The aim of this paper is to determine possible associations between the antegonial notch’s depth and maxillofacial morphology which includes the mandible and the position of the hyoid bone.

This study was based on 31 adult female subjects with a mean age of 23 years and 5 months (S. D., 1 year,2 months). Lateral roentgenocephalograms were taken to study the depth of the antegonial notch, facial shape, and the position of the hyoid bone. Simple correlation analysis was used to assess the cephalometric variables.

In subjects with a deep antegonial notch, point B was significantly positioned to the posterior position (p<0.05), the ramus height was shorter (p<0.05), the mandibular plane angle was larger (p<0.05), the lower facial height was longer (p<0.01), and the angle between the mandibular plane and the hyoid bone was larger (p<0.01).

This suggests that the depth of the antegonial notch was affected not only by mandibular shape and size but also by the position of the hyoid bone.

It is well-known that the bone shape and its internal structure will be affected by the functional activity of associated muscles. As to the masticatory organ, many researchers have suggested that masticatory muscles, especially the masseter muscle and lateral and medial pterygoid muscles affects the formation of the dentofacial skeleton. This study was performed to verify the hypothesis by means of morphometric analyses using CT scanned images,ultrasonography and roentgenograph cephalometry.

Sublects and method: The subjects of this study were 61 adult volunteers. Their mean age was 24years for male, and 23 years for female. All the subjects participated after giving their informed consent. CT image in each subject was scanned from the region of mandibular condyle to mandibular border according at the interval of 2 to 5 mm. The masseter superficial muscle thickness was observed at the middle region by ultrasonograph, using a 7.5MHz scanning probe.24 evaluation items were measured for analysis of dentofacial pattern using lateral roentgenographic cephalogram.

Results: Mean values of all measurements for evaluation items showed light sexual differences except for the case of masseter muscle thickness.

According to correlation coefficients analysis, volume of the medial pterygoid muscle was observed to be correlate with mandibular sizes, such as the mandibular length, mandibular body length and mandibular ramus height. This muscle also showed to have a high level correlation coefficient with the distance between mandibular backside and coronoid process or zygomatic bone that represent the facial depth.

Otherwise, the masseter muscle thickness showed a correlation with the mandibular ramus height as well as molar height, and also relate to both the inclination and the length of masseter muscle that represent the axis and distance between zygomatic processes and point gonion, respectively.

Thus, it seems true that masticatory muscles affect the development and formation of the mandibular posterior area, where is the attachment region of these muscles, via the stress of muscle activity.

Pathological examinations diagnosed in the Department of Oral Pathology of Iwate Medical University in 1997, were statistically reviewed.Atotal of 638 biopsies was discovered among 562 cases (Male:266, Female:296). The cases were found most frequently in the seventh decade. In histological classifications of the lesions, odontogenic benign lesions consisted of five ameloblastomas, three odontomas, and one cementoma. The non-odontogenic benign lesions were 30 fibrous hyperplasias, 20 hyperkeratoses (leukoplakia),16 hemangiomas and 11 papillomas. Non’odontogenic malignant lesions consisted of 42 squamous cell carcinomas, 3 malignant lymphomas and 2 malignant melanomas. Odontogenic cysts consisted of 31 radicular cysts, 20 primordial cysts and 13 dentigerous cysts. The non-odontogenic cysts consisted of 39 mucoceles, 25 post-operative maxillary cysts and 5 incisive canal cysts. In addition, 27 Sj6gren syndromes, 16 lichen planuses, 13 epulides and 46 chronic inflammatory granulation tissues were found.

Since a large number of elderly patients suffer from some kind of systemic disease,careful attention should be given in treating such patients. We report a patient with cancer of the mandibular gingiva complicated by postoperative acute renal failure. The patient had been treated with combination therapy of chemotherapy, radiotherapy and surgery at another medical institution before being transferred to our department. Tumor resection and reconstruction with the pectoral major myocutaneous flap and the delto-pectoral flap were performed under general anesthesia in our department. The patient developed postoperative acute renal failure four weeks later and was started on hemodialysis. Hemodialysis was performed nine times before being discontinued. When her general condition became stable, the patient returned to her former hospital. Next, she received hemodialysis two times prior to surgery, and her delto-pectoral flap was divided under general anesthesia at the hospital. Then, the patient showed oliguria and postperative hemorrhaging five days Iater. Thereafter, the patient developed disseminated intravascular coagulation (DIC) syndrome and died.