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子供たちの「う蝕」はどのように減っているだろうか?
Get PDFapplication/pdfIt has been about 20 years since many dentists have realized that there is a declining of number of Japanese children with tooth decay. Some reports dealing with recent survey of dental health were investigated to show new findings about tooth decay rates of 3 year olds, schoolchildren and young adults. The results of the surveys show that there certainly is a continuing decline in the rate of tooth decay in all age groups from infants to young adults. However this decline has not occurred at same rate across Japan, it is quite different in respect to the kind of teeth, ages and living locations. At the time the prevalence of tuberculosis decreased, it was thought that this was because of the introduction of anti-tuberclosis medicines. It is now believed, however, that the trends of the natural history of tuberculosis had a much greater effect than those anti-tuberculosis medicines. For the same reason it can be said that tooth decay prevalence is decreasing itself now. The changes of eating habits of aged society, the spread of tooth cleaning habits and topical fluoride applications are being touted as the reasons for this decrease in the rate of tooth decay. However, it is dificult to precisely say what the exact causes of this decrease in Japan are. In Japan there is no community that has implemented water fluoridation and the average Japaneses does not use fluoride, so it is not clear if the decrease in tooth decay will continue in the future.journal articl
歯科用X線フィルムの電子保管のための画像評価 第2報 根尖病単におけるデンタルX線フィルムとCRT画像との画像評価
Get PDFapplication/pdfElectronic image-reading and storing of radiographs obtained in the field of stomatology is a goal in dental radiology. Using a popular-type image scanner with an 8-bit intensity level, original dental radiographs and images on a CRT monitor have been compared and evaluated visually. To make this evaluating method more concrete, the optimal conditions for image scanning were obtained, then, using actual images on apical periodontitis and the receiver operating characteristics (ROC) analysis, more objective evaluation of the original radiographs and CRT images was attempted. The dental radiographs were converted to electronic signals, and images on CRT were evaluated by the ROC analysis. The evaluations were similar to those obtained with the dental radiographs. In the examination of apical periodontitis, image-reading and diagnosis on CRT is feasible. It appears to be important for the observer to have sufficient priorunderstanding of the characteristics of the scanner and that the radiographic imaging be performed with an adequate X-ray dose.journal articl
有害金属の生体影響(ヒ素に関連して)および有害金属拮抗薬DMSA, DMPSについて
Get PDFapplication/pdfGreat concerns of investigators engaging in studies of toxicology of arsenic have been focused on the biotransformation of inorganic arsenic. The first in the world, Aposhian's group purified partially the enzyme(s), arsenite methyltransferase and also monomethylarsonate methyltransferase in rabbit livers. Methyltransferase is considered a key enzyme related to arsenic detoxification, because methylated arsenic species (organic arsenic) are much less toxic than inorganic arsenic. In a recent discovery, some animals such as marmosets, guinea pigs and chimpanzees were found not to have the enzyme and therefore are unable to detoxify the toxic inorganic arsenic compounds. Aposhian speculated the reason for deficiency of this enzyme in these animals from a view point of revolutionary natural selection. Among similar heavy metal antagonists, DMSA has been already approved as a drug of choice in the US for children suffering from heavy lead poisoning. On the other hand, DMPS has not yet been approved. Aposhian's group adopted DMPS as a chemical of a challenge test for the evaluation of toxic metal loads on the human body. They evaluated mercury loads on the subjects with amalgam in their teeth and another groups of subjects consisting of dentists and dental technicians dealing with mercury at one particular dental clinic. These subjects responded well to the challenge test, showing a substantial amount of mercury excreted in urine as compared with the respective control. However, in the case of arsenic after the challenge dose of DMPS, subjects highly exposed to arsenic in drinking water excreted high concentrations of total arsenic in urine, but a different rate was observed among amounts of detected metabolites of arsenic from that of control group.journal articl
第1大臼歯のフィッシャーシーラントの予後について
Get PDFapplication/pdfSince Buonocore initially introduced the use of pit and fissure sealant to clinical dental practice, sealant has been used as an effective prophylactic system due to advances in high molecular weight materials. We examined the percentage of patients undergoing other repair treatments after a procedure using the sealant and the duration between this procedure and other repair treatments to investigate prophylaxis of the first molar in patients in whom the oral cavity was controlled on periodic examinations at 3-month intervals. The first molars of patients were divided into those treated and untreated with the sealant. The clinical course was compared between the two groups to examine the effectiveness of the sealant. 1) The percentage of the first molars that underwent repair treatment with the sealant was 64.2%, while that of first molars that underwent repair treatment without this procedure was 85.1%. The percentage of first mandibular molars of girls undergoing repair treatment was 74.4%, which was the highest percentage among the groups examined. 2) The mean duration between eruption and repair treatment was 37.7 months for the first molars treated with the sealant and 16.6 months for the untreated first molars. In the first mandibular molars of girls, the mean duration between eruption and repair treatment was 35.4 months, representing the lowest value. These results suggest that the sealant inhibits dental caries development in juvenile permanent teeth with immature enamel.journal articl
軟質裏装材の変色と劣化について
Get PDFapplication/pdfThe success of complete and partial dentures depends on comfort, esthetics, and function. One of the fundamental principles of these prosthesis is the prevention of undue movement of the denture during function; in an effort to reduce movement it is generally recognized that a rigid denture base is desirable. There are, however, cases when the denture-bearing area is of such a nature as to make coverage by a rigid denture intolerable to the patient. Many patients experience pain and difficulty using dentures constructed with hard denture bases. The soft denture-bearing mucosa is confined between the hard denture base and the bone, and during normal function damage can be done to the tissues, resulting in chronic soreness. This problem is even more pronounced for those patients who have diabetes or other debilitating diseases or for geriatric patients. Dental soft lining materials are widely used as aids for the treatment and prevention of localized areas of painful tissue irritation under dentures. These materials provide a cushion for the denture-bearing mucosa, and this provides comfort for patients. Soft denture liners also valuable when treating patients with (1) ridge atrophy or resorption, (2) bony undercut, (3) bruxing tendencies, (4) congenital or acquired oral defects requiring obturation, (5) xerostomia, and (6) dentures opposing natural dentition. A number of different types of materials have been tried for these application, but none has proved fully satisfactory. Commonly observed deficiencies include poor adhesion to the denture base, poor tear resistance, difficult finishing and polishing, excessive hardness, gradual hardening with time, and excessive fluid absorption with resultant distortion and fouling. The desirable properties, and certain clinical requirements, of a resilient denture base materials have been suggested: (1) non-irritant and non-toxic to the oral tissue, odorless and tasteless, (2) dimensionally stable during processing and in use, (3) low water sorption, (4) high abrasion resistance, (5) permanent resilience, (6) color stability, (7) adequate bond strength to the rigid denture base resin, (8) no adverse effects on the denture base such as distortion, loss of strength, crazing, or blanching, (9) ease of processing, finishing and polishing and (10) ease of repair. However, such an excellent material can not be found in clinics. Most soft lining materials can be classified broadly into two types, namely silicone elastomers and plasticized soft acrylics. The properties and selects together with chemical structure of these materials have been well documented. While acrylic materials have excellent adhesion to poly (methyl methacrylate), they have poor elastic properties and harden gradually due to leaching out of plasticizers. Although silicone soft liners have excellent elastic properties, they have great susceptible to deterioration in the oral enviroment. In particular, depending on their detailed chemical composition may support the growth of Candida albicans. The success or failure of a soft denture liner is not only determined by the physical properties but also other properties sucu as bond strength, creep compliance, dynamic modulus and resilience, water sorption, and stain resistance should be considered. It is also apparent from the results of many studies that the dental profession needs to develop specific performance properties for these materials. Additionaly, future studies should be undertaken to evaluate how the physical/mechanical properties of soft denture liners relate to patient comfort and tissue health.journal articl
下顎前突にチンキャップを使用した2症例
Get PDFapplication/pdfThe head-chin cup, widely used and regarded as an effective appliance for treatment of Class III malocclusion, was used to treat skeletal Class III malocclusion in two male patients. The effect of the head-chin cup was evaluated by comparison of the pre-treatment and post-treatment lateral roentgenocephalograms. The resits of treatment suggested that the head-chin cup therapy contributed to resolving the posterior displacement of the glenoid fossa by correction of the skeletal Class III malocclusion.journal articl
