Shigaku = Odontology; journal of Nihon Dental College最新文献

The new ceramics material (OCC) was developed for the purpose of aesthetic restration which can be fabricated by an usual lost wax process and it produces accurate marginal fit. OCC possesses mechanical, chemical, and physical properties. This article is discussed utility and security of OCC complete crown on the clinical application from Dec, 1986 to Jun, 1989. The results may be summarized as follows: 1) 2 of 69 cases were broken down in the period from Dec, 1986 to Jun, 1989. These reasons are caused by the lack of occlusal thickness and unsuitable fit of crown. 2) Although 4 of 69 cases are stained by tobacco tar and 5 of 69 cases are suffered from plaque accumulation, these staining and plaque accumulation are improved by plaque control. 3) An allergic reaction or an abnormality of oral tissues haven't been recognized during test period of clinical use. Consequently OCC crown showed itself about safety and usefulness.

Di(2-ethylhexyl)phthalate (DEHP), a commonly used plasticizer, induces peroxisome proliferation in liver cells and hepatocellular carcinomas in rodents. To study possible mechanisms for DEHP-associated cancer, we have measured induction of morphological transformation, chromosome aberrations, and peroxisome proliferation of cultured Syrian hamster embryo (SHE) cells. Molphological transformation was weakly induced by treatment with DEHP. The transformation frequency of DEHP was enhanced in the presence of rat liver postmitochondrial supernatant. DEHP induced chromosome aberrations in the cells only in the presence of exogenous metabolic activation. Clofibrate, a widely used hypolipidemic drug, failed to induce morphological transformation or chromosome aberrations. Treatment with [4-chloro-6-(2, 3-xylidino)-2-pyrimidinylthio]acetic acid (Wy-14, 643), which is a more potent carcinogen than DEHP or clofibrate, elicited a lower frequency of morphological transformation than DEHP in the presence of exogenous metabolic activation. Similar levels of peroxisome proliferation, as determined by an intensity of diaminobenzidine (DAB) staining, were observed in cultures treated for 2 hr with DEHP, clofibrate or Wy-14, 643. The results suggest a possible involvement of genetic damage by DEHP metabolites in induction of transformation of SHE cells. No clear relationship between inductions of peroxisome proliferation and cell transformation was observed.

As a means of studies of securing freeze-drying method by application of tray for prevention of white spots, decalcification and secondary caries of enamel, which may develop during and after orthodontic treatment, comparison and review were made on physico-chemical properties of fluoride gel to be used for gelatin gel method and freeze-drying gelatin gel method (control group gel and experimental group gel), and the following results were obtained: 1. Physical properties As the results of naked-eye observations, morphological observations through scanning electron microscope and measurements of gelly strength and viscosity, no distinct difference between control and experimental group gel was noted. 2. Chemical properties The qualitative analyses of fluoride ion with ion chromatogram and pH measurement were carried out, and consequently experimental group gel indicated similar values to control group gel. From the foregoing results, it was learned that no significant difference in their physico-chemical properties was clearly confirmed between control and experimental group gel, and it was suggested that similarly to control group gel, experimental group gel would be an effective gel substance as gel media for the formation process of fluorapatite or the reinforcement method of tooth enamel.

In the present study, the effect of dexamethasone on MC3T3-E1 cells, a strain of osteoblasts derived from mouse cranial bone, was determined. The following results were obtained. 1) Dexamethasone showed dose-dependent suppression of the growth of MC3T3-E1 cells at concentration of 1 microgram/ml or more. 2) The alkaline phosphatase activity was increased 12, 24, and 48 hours after treatment with dexamethasone at 1, 10 or 30 micrograms/ml. The activity was highest at 48 hours, the level being 311% of the control value at a dose of 10 micrograms/ml. When dexamethasone at a dose of 60 micrograms/ml or more was used, the activity was increased at 12 hours, but was lower than the control at 48 hours. 3) Synthesis of collagenous protein was facilitated after 24-hour treatment with dexamethasone at 1, 10 or 30 micrograms/ml. In particular, the level of synthesis was highest, 232% of the control value, at 10 micrograms/ml. Such synthesis, however, was suppressed at a dose of 60 micrograms/ml or more. 4) Synthesis of collagenous protein was facilitated by 48-hour treatment with dexamethasone at a dose of 1 or 10 micrograms/ml and suppressed at a dose of 30 micrograms/ml or more. 5) Microscopic observation of stained preparations revealed that dexamethasone caused vacuolar degeneration, deep staining of the nucleus, and pyknosis at 60, 150, and 200 micrograms/ml, respectively.

We have adopted a behavior-modifying method in the medical care system for children with psychosomatic disorder, using the developmental screening table and the first training check list to make the method effective. Also in order to know the effect of training, patients were classified into 4 groups (A, B-1, B-2, C). We have recently made a comparative examination of both the developmental screening table and the first training check list between B-1 and B-2 groups out of these 4 groups. [Method] Subject for investigation are 32 patients belonging to B-1 and B-2 groups out of those patients who have received medical examination in the Dental Center for the Handicapped Children in our Hospital. Developmental ages and proportions permitting each behavior were determined from the table for the developmental screening table and the first training check list, respectively. On the basis of the about the developmental screening table and the first training check list, behaviors between at the consultation room and at home were compared for 2 items of greeting and gargling and the condition of applying these items was also examined. [Results] 1) The B-1 group had well-matched 5 items compared with the developmental age for the B-2 group and was easier in communication with the operator because of its high cognitive ability. 2) The B-2 group, whose speaking and sociality were low, was more difficult in communication with the operator in the practice of dental treatment, and was evident from the first training check list. 3) Lack of patient's adaptability and communication with the operator often represented patient's capability of greeting and gargling at home but not at the consultation room. 4) Some need for improvement occurred in non-answering the developmental screening table and non-entering some items of the first training check list.

With a view to modifying the respective behaviors of patient, protector and operator so that a relationship of reliability can be established among them, we have adopted the training for dental treatment in the medical care system for handicapped children. We took this opportunity to classify the present handling methods at the practice of medical care into 4 groups (A, B-1, B-2, C) and to examine the training effect in each group and its features. [Method] On 145 patients having received treatment in the Dental Center for the Handicapped Children in our Hospital, number of patients by group, average age at the first examination, average training frequencies before and after treatment, average treating frequency, behavior in the training and relationship between each group and the disorder were examined for the card. [Results] 1) About 40% of the subjects for examination became capable of receiving treatment without any controlling appliance before the final treatment. 2) Average training frequency and average treating frequency had higher values of B-1 group than for other groups. 3) Behavioral estimation during the training revealed that A and B-1 groups showed better performance in mouth washing, brushing and cleaning by brushing than B-2 group, but the case was the contrary with oral use of three-way syringe and the vacuum. [Conclusion] Application of various behavior-modifying techniques to the training for dental treatment in children with psychosomatic disorder made its effect and features.

The dynamic analyses of bone scintigraphy were performed in 30 cases of hemodialysed patients. The regression analyses between biochemical data or duration and K indexes obtained from the 2-compartment model analysis in the maxillofacial region were carried out. The obtained results were as follows. 1) The duration and K indexes were significantly correlated with 1 or 2% of significance level in the parietal bone and the zygomatic bone. 2) Serum Ca and K indexes were highly correlated in every settled ROI. The correlation coefficients were distributed from 0.58 to 0.79. In the cranial bone the correlation were more higher than in maxilla and mandibular bone. 3) Serum ALP and K indexes have more higher significant level of correlation than the results of Ca. The correlation coefficients were distributed from 0.48 to 0.83. The level of significance were changed by location. The highest correlation coefficient was 0.83 in the parietal bone. 4) Serum c-PTH and K indexes have significant correlation in every settled ROI with the correlation coefficient from 0.59 to 0.69. The significance level were nearly equal in every location. 5) In the case of subtotal parathyroidoectomy the K indexes which were abnormally high in preoperation showed the tendancy to decrease toward normal range in postoperation. These results indicated that K indexes reflected the bone change caused by renal osteodystrophy. And the K indexes considered to be usefull to estimate the bone improvement.

The purpose of this study is to investigate features and histological structures of the microdontic wisdom tooth. Materials investigated in this study deal with a very small upper right microdontic wisdom tooth of a male patient aged thirty-six. It was observed with binocular microscopy and under X-ray. Horizontal ground sections of it were prepared and observed with polarizing microscopy, phase microscopy, microradiograph, and scanning electron microscopy. Total length of this specimen was about 1/2 of the average measurement in Japanese upper third molars, breadth of the crown about 1/3, thickness of the crown about 1/4. It had one cusp and one root. It is considered that one cusp was formed by fusing of the mesiolingual cusp and mesiobuccal one because fundamental features of the buccal and lingual surfaces of upper molars were preserved in this specimen. It is thought that dental tubules in this specimen were formed more densely than those in the common wisdom tooth because the space of retreating odontoblasts of this specimen was limited but that enamel rods in this specimen were formed more thickly than those in the common wisdom tooth because the space of retreating ameloblasts of this specimen was wide. It is considered that the degeneration in this specimen came up to not only the dental form, but also the histological structure of the enamel because the surface layer of the enamel of this specimen was composed of the laminal structure.

The aim of this study is to determine the method of maintenance care for support the functional condition during long period. The present paper reports on the result of osseointegrated titanium fixture in four complete denture patients. The marginal soft tissue reactions were investigated at the 1st, 3rd, 6th, 12th and 18th month after prothetic restrations by clinical examination and microbiological observations. All abutments were surrounded by clinically in healthy gingiva, however most individuals with the implant fixture had used as a complete denture for many years, without oral hygiene. For a favorable prognosis of the implant-recipients, self plaque control should be acquired for the patients shortly after prothetic restration. Before the healing phase, it is necessary to recall frequently for maintenance marginal soft tissue and prothetic restoration. After healing and remodeling phase, the interval of maintenance care was decided on each 3rd months. The interval seemed practically reasonable because the 18th month later the prognosis was satisfactory. This report presents two cases of complications during the maintenance phase of osseointegrated implants. Case I: A 72-year-old female patient presented gingival hyperplasia formation around the abutment after 19th months on abutment setting. We performed excision of the hyperplastic gingiva and apically positioned flap. Probing depth (PD) could not be determined because of gingival hyperplasia formation before operation, but there was marking reduction of probing depth after operation. The gingival bleeding index (GBI) was improved and the amount of gingival crevicular fluid (GCF) was reduced after operation. In pre-operative anaerobic culture, the proportions of Capnocytophaga species and Haemophilus actinomycetemcomitans were found. Post-operatively, Capnocytophaga sp. was not found, but H. actinomycetemcomitans was unchanged. Case II: A 47-year-old male patient presented gingivitis around the abutment after 13th months on abutment setting. We performed cleaning of the abutment surface with the flap procedure. Furthermore, a joint screw between the fixture and abutment was adapted due to loosening after operation, PD was unchanged, GBI was improved and GCF was slightly reduced. In pre-operative anaerobic culture, Bacteroides intermedius was rich. Post-operatively, B. intermedius was not found. In conclusion, we advocate that maintenance care of osseointegrated implants is the most important factor in the procedure.

The influences of differing strains levels of impression materials in compression and impression techniques on the distortion of working models were examined. The working models, which differed in the size of cervical spillway (2mm and 9mm) and the impression techniques applied (the two-phase technique and the wash technique), were produced by using putty-type impression materials with three different strain levels (Reprosil, Express and Exaflex) following the metal master model of mandibular denture in an abutment form. Distortion of the working models was then measured by a three-dimensional measuring system. The results were as follows. 1) The models produced through the impression technique using hard impression materials with low strain levels displayed decreases both in the degree of inclination to the X axis of the abutment tooth variations distance between the left and right abutment teeth. This procedure was found to yield a model which was proximate to the master model. 2) The impression technique incorporating a small cervical spillway resulted in decreases in variations in the distance between the right and left abutment teeth and the diameter of the molar part of the abutment tooth, and the horizontal distortion of the alveolar ridge; the model thus produced was found to be proximate to the master model. 3) Application of the two-phase technique reduced variations in height of the abutment tooth, and the use of the wash technique led to decreased variations in the distance between the right and left abutment teeth and diameter of the molar cervix of the abutment tooth. 4) Differences in strain levels of putty-type impression materials, the size of cervical spillway and the impression technique used did not influence deviation of the model toward the Y axis (vertical direction). 5) The models with least distortion of the abutment tooth were obtained by the two-phase technique using hard impression materials with lower strain levels or by the wash technique using soft materials with higher strain levels.