The purpose of this study was to ascertain that local application of prostaglandin E₂ (PGE₂) produced some effects on the proliferative activity of the cell and collagen synthesis in rat periodontal membrane during tooth movement. According to Waldo’s description, an orthodontic elastic band was inserted between the upper first and second molar of 7 to 9 week-old male wister rats. After insertion of the elastic band experimental group,10μg/50μl of PGE₂ was injected locally into the mucogingival around the first molar. The control group was injected with 50μl of saline for 3,7, and 14 days. Twenty minutes before sacrifice, each animal received an intraperitoneal injection of 74 kBq/g of ³H-proline. After the sacrifice, teeth and supporting tissue of the upper molar were decalcified, embedded, sectioned, and autoradiographed to observe staining of hematoxylin-eosin,the silver staining of nucleolar organizer regions (Ag-NORs). On the 3rd day’s pressure side after tooth movement, the control group had about twice as many cells with one and more Ag-NORs as the experimental group. Both on pressure side and tension side on the 3rd day after experimental tooth movement, silver grain labelled ³H-proline specifically increased compared with that of the control group. As to the number of osteoclast, the experimental group specifically increased compared with that on the pressure side of the control group on the 3rd and 7th days.

All the above findings demonstrated that treatment with PGE₂ inhibited the proliferation of periodontal fibroblasts and activated collagen synthesis concerning the remodeling by the activated osteoclast in the begining of tooth movement in rats.

This study was aimed to clarify the hypothesis that the reduction of masseter muscle activity induces insufficient growth of the jaw bones. From this viewpoint, relationship between the skeletal structure on roentgenographic cephalograms and both the thickness of the masseter muscle and electromyograms were investigated.

Subjects and methods: Subjects were 74 children (39 males and 35 females) aged from 4 years 9 months to 6 years 7 months, who live in Aomori prefecture. The analysis of 311inear and 23 angular items of dentofacial structure was made on the traces from lateral roentgenographic cephalograms.The masseter muscle thickness was measured from the image obtained from an ultrasonic scanner (Aloka: Echo Camera SSD 500, Probe: 7.5 MHz), and electromyograms of the masseter muscle were analyzed. The dental diseases were also examined and recorded.

Results:

1. The incidence of normal occlusion in these children was 66.2%, and malocclusion was classified into 3 types (crowding 18.9%, anterior cross bite 8.1%, and maxillary protrusion 6.8%). The prevalence of the dental caries was 95.9%, and the gingivitis was 62.2%.

2. Electromyogram indicated that the dentofacial morphology was related to the muscle activity based on electromyograms. Especially the size and shape of maxillofacial structure, such as measured items of Y-axis, mandibular plane angle, superficial masseter muscle insertion width,ramus height and inclination of masseter muscle axis in male, the gonial angle, mandibular plane angle and masseter muscle length in female were significantly correlated.

3. The masseter muscle thickness was related to some morphological characteristics, such as well as masseter insertion width, masseter length, gonial angle, ramus angle, mandibular plane angle and alveolar bone height in both male and female.

4. The maximum bite force was 20.1kg in male and 25.9kg in female. Their bite force was related to the skeletal structure, such as masseter insertion width in male, and ramus height, gonial angle and mandibular body length in female.

These results indicated that the muscle thickness, electromyogram and bite force had significant correlation with the maxillofacial skeleton. Hence, it was suggested that the masseter muscle shape was one of the indicators of masticatory capability related closely to the size and shape of mandibular bone.

Basic fibroblast growth factor (bFGF) promotes dermal wound healing, bone fracture healing, and angiogenesis in vivo. However, the effects of bFGF local administration on the periodontal ligaments after experimental tooth movement remain to be fully elucidated. The present study was carreid out to determine the effects of bFGF on the periodontal ligaments from the viewpoint of cell kinetics. Wistar strain male rats were used, and tooth movements were performed under ether anesthesia according to the technique of Waldo. Orthodontic elastics were inserted between both the upper lst and 2nd nlolars for 3,7, and l4 days. Each animal in the experimental group (n=15) was injected with a single dose of bFGF (10μg/50μℓ) into the palatal submucosa of the interradicular septa of both Ist molars 0,4,7, and 11 days from the beginning of the tooth movement. Saline solution was administered to the control group (n=15). A dose of 74 kBq/g of ³H-proline was injected interperitoneally into the animals of both groups 20 minutes before sacrifice. After the experiments, paraffin sections of the specimens were examined histomorphometrically by means of a silver stain (which reacted with the argyrophilic nucleolar organizer regions (AgNORs) -associated protein) and an autoradiographic technique. These results suggested that bFGF enhanced the cell proliferative activity and collagen synthetic activity of periodontal ligament predominantly on the tension side. Consequently, bFGF seems to be valuable for retention following tooth movement.

Carcinoma of the buccal mucosa is likely to metastasize to cervical lymph nodes if it has developed to surrounding tissues, and prognosis is poor. In the VX2 carcinoma transplanted to the buccal mucosa in the rabbit, lymphatic architecture due to proliferation of the tumor, the routes to regional lymph nodes and metastatic lymph nodes were examined. VX2 carcinoma, subcultured in the rabbit femoral region, was transplanted to the right buccal mucosa near the occlusal line. The architecture of collecting lymphatic vessels in the surrounding tissues of the tumor and metastasis to the regional lymph nodes were histologically examined by intravascular injection of India ink and impregnation with silver nitrate solution, 3, 7 and 14 days after the tumor transplantation, and routes to the regional lymph nodes were traced by the stick injection of India ink.At 3 days after tumor transplantation, diameters of collecting lymphatic vessels were markedly dilated in the nearby carcinomatous area, and lymphatic vessels showed a tendency of tortuousness 7 days after tumor transplantation. At 14 days after tumor transplantation, formation of new lymphatic vessels was noted in the pericarcinomatous area, and these lymphatic vessels running adjacent to each other formed a network. The routes to the regional lymph nodes in the tumor transplanted side were clearly detected, and no lymphatic routes to the opposite side were seen. Fourteen days after tumor transplantation, the metastasis in cervical lymph nodes was observed in peripheral sinuses near afferent lymphatic vessels.Thus, it was suggested in this study that there were changes of lymphatic architectures, due to proliferation of the VX2 carcinoma transplanted into the buccal mucosa, and metastatic routes to the regional lymph nodes in rabbits.

Nasalization of vowels is observed frequently in the post-palatoplasty cleft plate patients. Velopharyngeal incompetence is known as the main cause of this speech disorder. The correlation between the maxillofacial structures of cleft palate patients and the formant analysis of their nasalized vowels was investigated. The following results were obtained.Subjects were 45 cleft palate patients (23 male patients and 22 female patients) and 18 female adults as the controL Lateral cephalograms of the occlusal position and speech position of vowels were taken and measured by the cephalometric procedure. The shape of the soft palate was measured as to the thickness and the length from the cephalograms. Formant frequencies of isolated vowels were analyzed with a SH-10 speech analyzer (RION company, Japan). Subjects were classified into 6 groups by their degree of velopharyngeal incompetence and sex. All variables were compared and examined statistically.1. Skeletal class Ⅲ tendency was related to the severity of the nasalized vowel.2. Various irregularities of the spectral analysis were observed in most of the cleft palate patients’ speech;the descending of /i / 2nd formant frequency, abnormal formants, hoarseness, instability of fundamental frequency, and the probability of anti-formants.3. An inverse correlation between the upper facial height and 2nd formant frequency of /i / was observed in the female mild incompetent group.

Twelve cases of mucoepidermoid carcinoma histologically diagnosed at the, 2nd Department of Oral and Maxillofacial Surgery, School of Dentistry, Iwate Medical University during the period of April 1975 to March l995 were reviwed and clinically studiedFrom this study,we obtained the following results: (1) According to the TNM classification (UICC 1987), the 12 cases of mucoepidermoid carcinoma were classified into 1 case of T1, 5 cases of T2, 5 cases of T3 and l case of T4. In stage grouping, 1 case was in stage I, 5 cases in stage Ⅱ, 4 cases in stageⅢ, and 2 cases in stage IV.

(2) The histological malignancies by g cases were low, and 3 cases were high on the W. H. O. standard.

(3) Five cases were treated by surgery alone, and 7 cases by surgery with chemo-radiotherapy.

(4) Metastases of cervical lymph node were observed in one of the cases of low grade malignancy, and in two of the cases of high grade malignancy. Distant metastasis was observed in one of the cases of low grade malignancy.

(5) The five years and ten years survival rate were both 81.8%.