松山市の中学校生徒783名 (男383名, 女400名) を対象として, CPITNによる歯周組織評価を行なった。この調査に用いたCPITNの診査法は, 先に報告した小学生に対して用いた方法に, Code3, Code4を追加したものである。すなわち, CPITN原法の診査規準と異なる部分は, fals epocketを要治療として検出する危険性を排除するために代表歯から第2大臼歯を除外したこと, professional careが必要であるという観点から歯石沈着に加えて不良充填物もCode2に分類したことである。調査結果は, 歯周組織に病的徴候を認めなかった者の比率は14-18%, 歯肉出血のみは17-26%, 歯石沈着 (不良充填物) は約60%, 浅いポケットは4%であった。この年代では急激な変化を認めないが, 先に報告した小学生より, さらに高い有病率を示した。成人に対する歯周疾患予防のための歯科保健指導が必要であることは論をまたないが, それは第2次予防としての性格が強い。従って, 第1次予防を鑑み, 小学生から中学生を通じ一貫した歯周疾患予防計画とその実行の必要性が痛感され, その一手段として, 学校歯科健康診断にCPITNの導入が望まれる。

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Dental laboratory work includes frequent cutting and polishing, which are always accompanied by scattering of dust. It is well known that microscopic particles are deposited in lung alveoli when inhalated for long periods, so that dentists and dental technicians may have their health affected by inhalation of dust.
In a preliminary measurement of cutting dust from various laboratory procedures, I found that polishing cast framework for dentures caused the highest concentration of dust.
Chromium-cobalt alloy is commonly used in denture framework. Cobalt exposure can cause interstitial pulmonary fibrosis, and chromium has cell toxicity and exerts corrosive action on mucous membranes.
Therefore, I investigated dust from framework polishing from the viewpoint of occupational hygiene.
Air samplings during work were performed with a low volume air sampler (flow rate 15 l/min.) at 7 dental laboratories in the Tokyo area, and personal exposure was measured with a size-selective personal dust sampler (flow rate 1.4-1.5 l/min.) which sorted dust particles 7 μm increments.
Dust collected by both atmospheric air sampling and personal sampling was measured as dust concentration, and cobalt and chromium concentrations were measured with atomic absoption analysis and neutron activation analysis.
The free silica and chromium content of the polishing materials were also analyzed.
The following results were obtained:
1. The atmospheric dust concentration in polishing workplaces was 0.07-0.26 mg/m³.
2. Although a low atmospheric dust concentration was maintained in the workplaces, personaldust exposure was several times higher than the atmospheric dust concentration. The average dust exposure of dental technicians differed greatly according to working conditions, such as the type of work, working posture of the technician, and the use of a local exauster. In 13 cases of dental technicians who polished framework under the condition using local exaust systems, the average concentration of dust did not exceed the threshold limit value (JAIH) in any case, but 8 of 11 cases without local exaust systems exceeded the threshold limit value.
3. The atmospheric cobalt concentration in polishing workplaces was from 0.001 to 0.016 mg/m³. Chromium concentration was from 0.001 to 0.008mg/m³.
4. The average cobalt exposure of dental technicians was 0.1mg/m³, which ACGIH indicated as the TLV·TWA for cobalt, in 1 of 14 cases with local exaust systems, and more than 0.1mg/m³ in 3 of 10 cases without local exaust systems. Therefore, I suggest that cobalt exposure is hazardous to the health of dental technicians under some polishing conditions.
5. The average chromium exposure of dental technicians was less than 0.5mg/m³, which ACGIH indicated as the TLV·TWA for chromium, independently of the use of a local exaust system.
6. Free silica content was 11.3% in abrasive for sandblasting, and less than 5% in the other polishimg materials for cast framework.
7. Cr₂O₃ was confirmed as a main component of“green polishing agents”by X-ray diffraction analysis, and buffing with“green polishing agents”caused a high degree of chromium exposure.

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The salivary IgA antibodies to the extracts of Bacteroides gingivalis and Actinobacillus actinomycetemcomitans were measured with an enzyme-linked immunosorbent assay (ELISA) in 45 subjects with adult type of marginal periodontitis.
The reference curve for the binding of salivary IgA to the bacterial antigens was established by testing serial dilutions of the standard saliva. The curve for each bacterial antigen was converted to the regression line using an equation for log-logit transformation with a high correlation coefficient of more than 97 percent. Antibody activity in each saliva sample was estimated from the line for the respective antigen and was expressed as ELISA units (EU).
When subjects were divided into two groups in reference to the periodontal pocket depth of 4mm, salivary IgA levels to both B. gingivalis and A. actinomycetemcomitans were significantly higher in subjects with deeper pocket depth. But when they were divided in reference to the periodontal pocket depth of 5mm, the subjects with deeper pocket depth had significantly elevated IgA levels to only B. gingivalis.
The results indicated that the increase of salivary IgA level to these bacteria, especially to B. gingivalis, was associated with severity of periodontitis.

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Since the occlusal contour correction proposed in a previous paper did not significantly reduce dental plaque on the occlusal surface, this study was performed to find the effect on the occlusal plaque and dental caries by a modified method using smaller abrasive and polishing points.
One hundred and forty pairs of sound first molars of both sides in the same jaws were selected from 2nd grade school-children in 4 elememtary schools of Koromogawa Village, Iwate Prefecture, in Japan. The occlusal surface of one side of the experimental group was operated on as shown in Fig. 2 with the smaller instruments shown in Fig. 1, and the other side of the control group was not operated on.
The differences in occlusal plaque index values after 12 to 48 months between the experimental and control groups were large and statistically significant, and the caries reduction rated of the experimental group were raised 65.1% to 76.0% over the control group in each experimental period, and the differences were also highly significant.
Therefore, the modified occlusal contour correction with smaller instruments than the previous method produced lower caries incidence with less occlusal dental plaque.

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歯根膜のアルカリホスファターゼは歯周疾患における骨代謝に重要な役割を演じていると考えられる。しかし, 本酵素の生理的機能については不明な点が多く, 生理的基質の同定すら行われていない。
今回我々は, 歯根膜のアルカリホスファターゼをノイラミニダーゼで処理し, その前後の各種リン酸エステルに対する基質特異性の変化を調べた。また, 歯根膜のアルカリホスファターゼと同じユニバーサル型のアイソザイムであり, 糖鎖部分の構造だけが異なる腎臓のアルカリホスファターゼについても同様に基質特異性の変化を調べ, 歯根膜のアルカリホスファターゼの結果と比較した。
この結果, ノイラミニターゼにより酵素の糖鎖部分からシアル酸を除去しても, いずれのアルカリホスファターゼの基質特異性にも著明な変化は認められなかった。このことから, アルカリホスファターゼの糖鎖中のシァル酸は酵素の基質に対する親和性に特に重要な役割は演じていないものと考えられる。

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In this study the factors of daily habits which have an influence on the dental caries of 3-year-old children were investigated. In addition the effectiveness of a guidance for mother on children's dental health at 1.5-year-old health examination was evaluated.
The 3-year-old dental examination was carried out at a Community Health Center in Niigata City from August 1979 to June 1980. At the same time the mothers of the children were asked about the following factors by the dental hygienist: i. e., the identity of the guardian, the order of birth, whether they had a 1.5-year-old health examination, tooth brushing habits (frequency/ day, brushing assisted by the mother, brushing just before sleeping), sweets and beverages (frequency/ day), use of a nursing bottle (period, sugar content, use at the sleeping time) and topical fluoride application.
Subjects selected for analysis were 1, 638 3-year-old children who had lived in the region handled by the East Health Center in Niigata city, a non-fluoridated area.
The factors which have an influence on the dmfs number were analyzed by means of the theory (1) ', that is a series of multivariate analysis. The partial correlation coefficient of frequency of sweets and beverages per day was the highest coefficient (=0.222 p<0.001), The second was the guardian factor (p<0.001), followed by the order of birth (p<0.05) and topical fluoride application (p<0.05).
The factors of the 1.5-year-old examination, frequency of tooth brushing per day and period of use of a nursing bottle were not significant. All the mothers whose children had received a 1.5-year-old health examination had been given instruction in dental health by the dental hygienist at the examination. The elements of this instruction included the following: 1) tooth brushing just before sleeping, 2) tooth brushing assisted by the mother, 3) frequency of sweets and beverages, 4) period of use of a nursing bottle, 5) recommendation of topical fluoride application. The rate of practice of these five items was compared between the group which received the 1.5-year-old examination and the group which did not receive it. There was no significant difference between the two group in daily habits but there was a significant difference in the rate of topical fluoride application.

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Community differences in caries prevalence in deciduous teeth were investigated. The Community Organization Data Base System (CODB) includes the data of 3-year-old children's dental examinations from 112 communities (cities, towns and villages) in Niigata prefecture in 1983, 1984 and 1985. This CODB also includes the data of 141 items concerned with community characteristics. Multiple regression analysis was used to find the factors that have an influence on the caries prevalence in deciduous teeth in each community.
The dmft indices on an average for these 3 years were distributed from 1.32 to 7.06 in 111 communities, ignoring one community in which the number of 3-year-old children was less than 10. There was a fivefold difference between the maximum value and the minimum. The pattern of caries prevalence was similar in each community belonging to the same county. It appears that the county has a homogeneous life environment that affected the caries of deciduous teeth.
Community characteristics were closely related to the caries prevalence (multiple correlation coefficient=0.51, p<0.01). Five items from these community characteristics were highly correlated to the caries prevalence. These were percentage of children receiving 1.5-year-old dental examination, degree of self-sufficiency for medical care in a community, numerical rating of the health insurance for dental treatment, annual family income and mean dmft index of 3-year-old children in the county exclusive of the subject community
It appeared that the lower caries prevalence of deciduous teeth in a community had close relationship to urbanization of the community.

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Since Stern et al. (1964) found an incremental effect against acid decalcification of human enamel with an irradiation of ruby laser, many investigations have been carried out with different types of lasers, such as ruby, CO₂, and Nd-YAG, for dental caries prevention.
Ar laser is widely used in clinics of ophthalmology or plastic surgery. In this experiment, we investigated the possibility of using an Ar laser to increase the acid resistance of human enamel.
Significantly less calcium ion was dissolved into lactate buffer solution from the surface of lased enamel than from that of unlased control. Scanning electron microscopy confirmed that an irradiated area of enamel surface was more acid-resistant after acid etching. An energy density of 67 J/cm² was the optimum intensity for acquirement of acid resistance, as judged from the inhibition of calcium dissolution from the surface zone of irradiated enamel and from scanning electron microscopy of the irradiated area of enamel surface.
The application of an absorptive agent to the enamel surface is essential to increasing acid resistance, because the absorption of human enamel for the Ar laser beam is very low. Chinese ink for brush-writing was most effective and waterproof black and red inks, dental plaque disclosing solutoin with red color, and 5% fuchsin solution were also effective.
The thickness of enamel from surface to inner part which possessed an acquired acid resistance was calculated by the total amount of calcium ion released from lased enamel into lactate buffer solution. A zone of acid resistance of 144μm was obtained by using black ink and one of 59μm by using red ink.

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We studied the colonial morphology and some characteristics of phase variants of Actinomyces viscosus, in order to clarify factors of its virulence.
All of A. viscosus examined spontaneously presented three types (P₁-P₃) of colonies on TYC agar, which contained 5% sucrose. These morphological differences of colonies seemed to be due to the difference of their ability to produce extracellular polysaccharide. The strain which produced the largest amount of extracellular polysaccharide was designated P₁, the strain which was designated P₃ lacked or had little ability to produce it, and P₂ possessed an intermediate.
Although both P₁ and P₃ strains showed similar characteristics in many biochemical tests, P₁ adhered well to the glass wall when cultivated in sucrose-containing medium, whereas adherence of P₃ was negligible. Electron microscopic examination of cell walls revealed longer fibrils on P₁ cell walls than on P₃ cell walls. P₁ was virulent for infected golden hamsters, causing periodontal disease, bone loss and root surface caries, but P₃ was avirulent.
These data suggest that the ability to produce extracellular polysaccharide and the presence of fibrils on cell surfaces are important factors in making A. viscosus successful members of plaque community and oral pathogens. The phase variation which occurred spontaneously during sub-culturing of A. viscosus should be given attention because it might influence the pathogenicity of the organism.

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福岡市立心身障害福祉センターを訪れた器質的構音障害例58例のうち, 口蓋裂の一次手術の術後例42例を調査した結果, 十分な鼻咽腔閉鎖機能を得ていたものが21例 (50%) 認められた。また, 42例中一次手術を行った病院に専門の言語治療士がいたのは15例 (36%) であった。42例中, 系統的構音訓練を行った13例について, 正しく構音できる段階に達した症例は3例 (23%) にすぎなかった。なお, 異常構音では口蓋化構音が最も多かった。鼻咽腔閉鎖機能の良否と構音訓練成績の関係を調べた結果, 鼻咽腔閉鎖機能が良好であれば構音訓練の成績が良い傾向はあったが, 統計学的には有意な差がなく, 複雑な要因の存在が示唆された。以上の所見は, 当福祉センターで行った構音訓練の成果が満足できるものではなかったことを示していた。この原因の一つには, 言語治療士と手術側との連携がよくとれていなかったことが挙げられ, 口蓋裂手術を行なう病院のスタッフに言語治療士が加わる必要性が示唆された。

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Bacteroides gingivalis possesses adhesive properties enabling it to bind to sulcular epithelium and saliva-coated hydroxyapatite and to aggregate oral gram-positive organisms. This study deals with the isolation and some properties of adhesin aggregating Streptococcus mitis ATCC 9811 from culture medium of B. gingivalis 381. The inhibitory effect of various compounds on the aggregation was also studied.
B. gingivalis 381 was anaerobically grown in trypticase soy broth supplemented with yeast extract, hemin and menadion at 37°C. The bacterial binding adhesin (BBA) was isolated from the culture fluid by ultracentrifugation followed by gel filtration on Sepharose CL-4B and by affinity chromatography on arginine agarose. Through these procedures, the BBA was purified about 5800 times from culture fluid based on the specific aggregating activity assayed by serial dilution using a microtiter plate. By electron micrographs of negatively stained BBA preparations, the structures resembling fimbriae were never observed. To screen sugars, amino acids and other substances for inhibition of aggregation of the BBA, the aggregation-inhibition test was performed by turbidimetric assay. The activity of BBA was inhibited by L-arginine and arginine-containing peptides although the activity was unaffected by the sugars tested. These results suggest that arginine may function as contact residue between the BBA and S. mitis ATCC 9811 during the aggregation.

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The purpose of this study was to investigate the effect of immunization with the cell surface antigen extracted from Actinomyces viscosus on periodontal disease of hamsters, which was induced by inoculation with A. viscosus K-TL ⁺.
Cell surface substances were released from A. viscosus K-TL⁺ cells by stirring them in 0.05M Tris-HCl buffer, pH 7.4, containing 1M NaCl. These were purified by ammonium sulfate precipitations, gel filtration and ion-exchange chromatography, and fibril-rich substance was obtained. This prepaation was used as an immunogen.
Golden hamsters were divided into three groups, immunized, shamimmunized and diet-control groups, and they were immunized in their pouches at 4 and 5 weeks of age. At six weeks of age, they were infected with A. viscosus K-TL⁺, and the establishment of the strain was examined during the experiment. At the end of the experiment, 8 weeks after the last immunization, the hamsters were killed after sampling their saliva and sera, and the mandibulars were evaluated for their alveoral bone loss and root surface caries.
In the immunized group, the mean recovery of A. viscosus K-TL⁺ was less, and the occurrence of alveolar bone loss and root surface caries considerbly decreased comparing with the sham-immunized group. Both saliva and sera obtained from hamsters in the immunized group also showed more elevated levels of antibody against cell surface antigens than in the sham-immunized group.
The results suggested that immunization with the cell surface antigen might be effective in prevening periodontal diseases induced by A. viscosus.

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The purpose of this study was to compare the cariostatic effect of the daily use of three concentrations of fluoride mouth rinse. The subjects of this study were 487 (257 boys and 230 girls) school children at 6 years of age, who practiced mouth-rinsing with acid-acidified NaF solution containing 500ppm of F (pH 5.0), 250ppm of F (pH 5.0) and 100ppm F (pH 5.0) 5 times a week for 5 years. The experimental periods and number of subjects were as follows: 500ppm group: 1979-1984, 146 school children (76 boys and 70 girls) 250ppm group: 1981-1986, 166 school children (91 boys and 75 girls) 100ppm group: 1980-1985, 175 school children (90 boys and 85 girls) control group: 1984, 1985, 946 school children (470 boys and 476 girls). DMFT index and DMFT rate for each tooth type were calculated using cohort analysis for 5 years in the fluoride groups and a cross-sectional study in the control group.
The three fluoride groups showed higher DMFT indexes than the control group at the start of the treatment. However, since the increment of DMFT indexes in the fluoride groups was reduced, a signi ficantly high cariostatic effect was obtained in the 6th grade. The 100ppm and 250ppm groups showed a tendency toward more effective caries prevention than the 500ppm group; girls especially showed a statistically significant difference in the DMFT index in the 4th, 5th, and 6th grades. The eru pted tooth rate was similar in each group and there was significant difference between the fluoride groups and the control group in the DMFT rate in 1, 2, 4, 6, and T.
These facts indicate that three applications result an effective caries prevention and fluoride mouth rinses of 100ppmF and 250ppmF give the same or higher cariostatic effect as the use of 500ppmF mouth rinse.

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Fluoride varnish (F-varnish) has been already used for treatment of hypersensitive dentin in clinic. In this study, F-varnish was examined in vitro the possibility of application for caries inhibition. Experiments were made in vitro of applications of F-varnish, containing 5% NaF or placebo-varnish with the intact enamel surface and fissure, for two weeks at 37°C twice a week, followed by 1, 2 or 3 weeks of washing with distilled water. Fluoride uptake and release, morphological observation, and acid solubility test on enamel blocks following treatment with F-varnish, or after washing were studied by means of electron probe microanalysis (EPMA), chemical analysis and sacanning electron microscopy (SEM).
The fluoride uptake of F-varnish-treated enamel surface and fissure were increased, especially a large amount of CaF₂ deposited on the outer surface layer and fissure of enamel. Although, CaF₂ was released after washing for three weeks, fluoride was taken up at the depth of approximately 40μm. The acid solubility test proved that the acquisition of acid resistance was greater in F-varnish-treated enamel than in the control even after washing for three weeks. SEM of enamel surface showed that CaF₂ was formed in the F-varnish-treated enamel, and clearly showed that there was an acid-resistant picture after perchloric acid-etching.
Therefore, we suggest that F-varnish which applied to treat hypersensitive dentin may be effective in clinical use for caries inhibition, because the treatment time of enamel can be extended.

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This study deals with a noninvasive method for estimating hemoglobin concentration and oxygen saturation from reflectance spectra of a gingival model and dog gingiva by tissue reflectance spectrophotometry. The index of hemoglobin concentration (Hb index) and the index of oxygen saturation (HbSO₂ index) were measured from the spectra of the gingival model and dog gingiva. In both the in vitro and in vivo experiments, the Hb index was positively correlated with hemoglobin concentration, and the relationship between HbSO₂ index and PO₂ appeared as a sigmoid curve resembling hemoglobin oxygen dissociation curve. These results suggest that the tissue reflectance spectrophotometry could be applied to the gingiva in vivo to estimate hemodynamics and oxygen sufficiency in gingiva.

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An acute toxicity test for a new gallium alloy was carried out by supplying orally a test solution of gallium alloy to rats and mice. The medium lethal dose (LD₅₀) was estimated and histopathological observations were made.
The results obtained were as follows:
1. The LD₅₀ values obtained by probit method were 580mg/kg for male rats, 493mg/kg for female rats, 377mg/kg for male mice and 430mg/kg for female mice. These values indicate that the gallium alloy has low toxicity and pertains to the category of“common materials”described in the pharmaceutical law of Japan.
2. Major signs of acute toxicity, which were observed in all rats and mice except in the lowest dose group, were loss of spontaneous activity and cyanotic appearance. Some individuals also showed symptoms of diarrhea and hematocyturia.
3. In autopsy and histopathological examinations, various degrees of congestion were observed in organs of rats which died during test period, and in rats which survived the acute episode, tubular damage in the kidneys or signs of recovery from inflammatory lesions in the kidneys and other organs wers observed.
4. It appears, from analyis of the data obtained, that the toxicity of the gallium alloy is due first to the copper contained in the alloy, and then to the gallium.

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A new gallium alloy for dental restoration was subjected to a subacute toxicity test using rats for twenty-eight days. S.D. rats were orally administered the test solution of gallium alloy at the doses of 0.04 mg and 0.4 mg/kg/day, which were determined according to the dose preparation method for short-time toxicity test of dental filling materials.
The results were as follows:
1. No symptoms or deaths were observed in either test group and body weight gain of the test groups was as good as the control group.
2. Every hematological and serological value for both groups was within the range of normal physiological values.
3. Appearance, size, and color of various organs observed by autopsy of test rats were normal and the organ weights did not differ from those of control rats.
4. In the histopathological findings for both test groups, no toxic signs were observed in any tissue or organ examined.
These results suggest that the dose of 0.4 mg/kg/day of the gallium alloy will be safe even if applied clinically.

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