Kanagawa shigaku. The Journal of the Kanagawa Odontological Society最新文献

The parietal bone fragment (1.5 mm square) extracted from murine fetal calvaria (periosteum was removed) in the latter stage of gestation was cultured in alpha-MEM containing 10% fetal bovine serum over 10-day period, and the initial calcification site was subsequently examined utilizing both electron microscopy and histochemical methods. At the initial calcification site, the so-called "matrix vesicle" (width 100 nm), derived from osteoblasts which induce matrix formation, and the larger vesicular structures (width 100-600 nm) which originated from degenerated or dead cells were observed. Additionally dead osteoblast-like cells phagocytosing bone crystals participated in bone nodul formation. In the border region between the degenerated or disrupted cells and the functioning cells, multilamellar structures (mainly composed of phospholipids) were frequently observed. Concurrently it was concluded that there is a possibility of partial deposition of calcium salts on the surface of the above mentioned cells under some circumstances. Through selective decalcification, it was determined that bone trabecule was formed by fusion of respective bone noduli and degraded collagen fibrils which filled the intervening spaces. From the above results, it was evident that both the matrix vesicles derived from functioning osteoblast, and the vesicular structures derived from the degenerated or dead cells concurrently phagocytosing spicules and collagen fibrils were involved in the initial calcification process of the membranous bone in vitro.

The purpose of this study was to analyze the relationship between the caries incidence, oral environment at the age of 1.5 years and the prevalence of the caries at the age of 3.5 years in order to establish the methods of dental health surveys on infants and to prevent dental caries. Oral health examination and caries activity (Cariostat) test were performed on 436 children successively undergoing dental health examinations of 1.5-year-old and 3-year-old children, and the following results were obtained: 1. Concerning the condition of dental caries prevalence, percentages of children with dental caries, mean deft and mean defs were 10.6%, 0.36 and 0.68 at the age of 1.5 years and 67.2% 4.43 and 8.41 at the age of 3.5 years, respectively. 2. According to dental surfaces, the mesial proximal surface and lingual surface of primary central incisor in the upper jaw showed a high defs rate of 4.6% at the age of 1.5 years. At the age of 3.5 years, the occlusal surface of primary second molar in the lower jaw, the mesial proximal surface of primary central incisor in the upper jaw and the occlusal surface of primary second molar in the upper jaw had defs rates as high as over 35%. 3. Concerning the condition of occlusion, normal occlusions and deep overbites appeared at almost the same frequencies occupying about 70% of overall occlusions. 4. A risk of dental caries became higher when the body weight at birth was higher, eruption occurred earlier, a fissure in the enamel of primary was deeper, Cariostat pH was lower, and/or no interdental spaces between primary incisors in the upper jaw; therefore the author recognized the necessity of individual health guidance and aftercare.

When designing a prosthesis in a clinical setting that takes into consideration the protection of the abutment teeth and alveolar ridge, it remains difficult to carry out a method of connecting the abutment tooth and prosthesis based on objective grounds. This is because there are still many matters that remain unclear about dynamics of the stomatognathic system, including the prosthesis, when attached in the oral cavity. The author created the following three prostheses on a stimulation model of a tooth bone saddle that included an artificial mucous membrane and periodontal membrane: (1) A fixed bridge, (2) A telescopic denture (Konuskronen Telescope), (3) An Akers clasp denture. Following this, flat-controlled random noise was applied to each denture to create a dynamic load that exhibits a state closer to a clinical situation. Modal analysis was carried out with a laser doppler vibrometer and observations were made of the prosthesis and the abutment tooth apex to obtain visual clarification of dynamics, The following results were obtained. 1. As far modal resonant frequency, in mode #1, the bridge measured at 483 Hz and 561 Hz, the Telescope at 452 Hz and 600 Hz and the clasp at 581 Hz and 596 Hz. In mode #2 the bridge measured at 1,355 Hz and 1,370 Hz, the Telescope at 1,343 and 1,040 Hz and the clasp at 1,114 Hz and 1,079 Hz. In mode #3, only the bridge was detected and the recorded values 1,906 Hz and 2,026 Hz. 2. The influence on the modal resonant frequency due to the difference in abutment devices was limited. 3. Observation of animation indicated that the tendency for lateral movement of the abutment teeth increased going from the bridge to the Telescope to the clasp. 4. Displacement of the abutment tooth root apex decreased in reverse proportion to the strength of the connection between the abutment tooth and the abutment device.

In order to study the preservation of phospholipids in specimens for electron microscopic study, two procedures were compared; routine double fixation with glutaraldehyde followed-by osmium tetroxide and fixation with a mixture of tannic acid-glutaraldehyde followed by osmium tetroxide, utilizing both glass slide smear and ultrathin section methods, using artificial lung surfactant (mainly composing of phospholipids). The following results were obtained. (1) In routine double fixation with glutaraldehyde-osmium tetroxide, although the lamellar structure, mainly composed of phospholipids, was often visualized, prefixation with mixed tannic acid-glutaraldehyde always resulted in a lamellar structure with a regular periodicity and good contrast. (2) The saturated phospholipid was better preserved with acetone dehydration than with alcohol dehydration. (3) Depending on the outcome of the first fixation, there was extensive loss of phospholipids during the process due to alcohol dehydration and propylene infiltration. (4) When the specimens were fixed with osmium tetroxide prior to tannic acid treatment, the multilamellar structure of the bilayer was usually irregular. Moreover, if the specimens were fixed with osmium tetroxide without tannic acid, phospholipid preservation was not good. From the above results, it became, apparent that prefixation by a mixture of tannic acid-glutaraldehyde followed by osmium tetroxide postfixation and dehydration by acetone was the most appropriate method for preserving saturated phospholipids and thus a stable ultrastructure of phospholipids an lamellar will obtained.

Recently, many studies have demonstrated the superiority of the ultrasonic devices in endodontic treatment, while other reports did not recognize the advantage of the ultrasonic instrumentation over hand instrumentation. This disagreement in opinion might be due to the fact that the mechanical characteristics of ultrasonic devices have not been clarified. Therefore, some factors which might contribute to the mechanical characteristics of ultrasonic device for root canal treatment were examined. These factors were: (a) applied force on file; (b) angle of connector; (c) position of substrate material being cut; (d) filing speed; and (e) resonance of file. These factors were examined by measuring the cutting depth on acrylic wafer using the cutting efficiency testing apparatus. This apparatus with a push-pull stroke approximately 4 mm in length, was propelled the root canal instruments in linear motion. The filing speed was adjusted to 100 strokes per minute. The results were as follows: 1. The greater load was given to the file, the higher was the cutting ability of ultrasonic device. But cutting efficiency of #15, #25 and #35 files were inhibited over the load of 50, 60 and 70g each. It was considered that the adequate load for filing utilized ultrasonic device was #15:50g, #25:60g and #35:70g. 2. The file attached to the angled connector had a cantilevered vibration. And the cutting ability was effected by connector angle. The 120 degree-type connector was more effective than straight type (180 degree-type connector). 3. Substrate materials were made deeper cut when it was applied against the vibrating direction of the file than were applied at right angle to vibrating direction of the file. 4. Cutting efficacy of ultrasonic device was evaluated under the conditions as filing speed of 25, 50 and 100 strokes/min by comparing each ratio of cutting depth per total number of filing strokes after 20 minutes. The ultrasonic vibration showed tighter cutting ability when this ultrasonic device was operated 25 strokes/min. 5. Cutting efficiency of two methods was examined under the same amplitude. One was to set up the file length slightly shifted from the resonance point and to give the amplitude to file using resonance phenomenon. The other was to set up the file length of nonresonance condition and to give the amplitude by power supplying from the device. The latter showed higher cutting ability without the risk of the file fracture.(ABSTRACT TRUNCATED AT 400 WORDS)

To elucidate the relationship between trigeminal stimulation and vagal ambiguus nucleus, effects of trigeminal stimulation on the changes infiring pattern of neurons in the ambiguus nucleus were examined. Unit discharges from the ambiguus nucleus in cats were recorded using a glass micropipette containing fast green FCF, and the microelectrode position was assertained histologically after the experiment. The analysis of unit discharges was performed with an ATAC-450 microcomputer. There were three types of neurons in the ambiguus nucleus from the view-point of effect of trigeminal stimulation: neurons for which firing was accelerated by trigeminal stimulation, neurons for which firing was decreased by trigeminal stimulation and neurons indifferent to trigeminal stimulation. These findings suggest that trigeminal stimulation modifies the neuronal firing pattern and consequently causes changes in vagal outflow, finally evoking the Reilly phenomenon in oral medicine.

The purpose of this study was to find the characteristic nursing environments of children in order to confirm the methods of the dental health examination in infancy and early childhood. So questionnaires were performed. The subjects were 436 children, 218 boys and 218 girls, who had undergone successively both dental healthy examinations at the age of 1.5 and 3 years. The following results were obtained: 1. Concerning occupation, 63% of their fathers were office workers, and 75% of their mothers had no occupation. More than 90% of parents were both at the age of 20's or 30's. 2. Eighty percent of the children was nursed by their mothers in the daytime at the age of both 1.5 years and 3.5 years. 3. Abnormalities during the gestational period were present in about 1/3 pregnant women, but were mild in most cases. About 20% had abnormalities at the time of deliver; however, less than 5% showed abnormal courses thereafter. The mean birth weight was 3,104.6 g, which is lower than that in Japan. 4. Breast feeding was most highly observed at the age of 3 months; 80% took baby food at the age of 6 months; milk intake was markedly increased at the age of 12 months. 5. Concerning kinds of all between-meal snacks, sweet snacks were slightly increased, showing more variety in food. However, a consciousness of oral hygiene in parents seemed to show a favorable tendency on the data on regularity, number and place of eating snacks. 6. Although a majority of the children used a toothbrush after the age of 1.5 years, 50% and 25% of the children did not brush teeth every day at the age of 1.5 years and 3.5 years, respectively. Therefore the author recognized the necessity of health guidance and aftercare.