The purpose of this study is to establish a reliable method to evaluate the change of alveolar bone and to correlate the roentgenographic estimation with various clinical indices.
Using a collimating device reported by Kawasaki which consisted of a individual film holder and a pointer, intraoral roentgenographs were taken and microdensitometric measurements were undertaken on the proximal alveolar crest area on the films. A cupper stepwedge placed at the outer margin of the film was used as the densitometric scale.
The spot diameter of 0.6mm was chosen as the size for the microdensitometric sweep. The key point to obtain topographic relationship among films was found in the superposition according to the shadow of the traveculae at the cervical area on the films. In the case of anterior teeth, the avoidance of lip and cheek between the stepwedge and the focus enhanced the accuracy of the gray scale but this was not possible in posterior teeth.
Fifteen patients with the diagnosis of chronic marginal periodontitis were selected and the effect of plaque control and scaling on the alveolar radiopacity, probing pocket depth (PD), gingival index (GI), bleeding index (BI), plaque index (Pl. I) and calculus Index (CI) were examined. The initial diagnostic procedures were carried out on the first visit of the patient. The follow-up examinations were made at 3 months and 6 months after the end of initial preparation.
The average increase of alveolar crest height was 0.2mm and the average increase of radiopacity at alveolar crest area was 1.3×10^-2mmCu equivalent at 6 months after the end of initial preparation. When the patients were divided into two groups, i. e. the group who had equal to or more and the group who had less than the average opacity at the alveolar crest area, more increase in radiopacity was observed in the latter group. The group of patints who had smaller Pl. I value than the average showed better clinical improvement, but it was not possible to prove statistical significancy in the change of radiopacity.
The procedure described here is a reliable method to evaluate the state of proximal alveolar crest area in periodontal patients.

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Assessment of the physicochemical conditions of the gingival sulci and periodontal pockets was made by measuring the pH and pO₂ in 47 sites of 5 patients.
The HIS-FET (Hydrogen Ion Sensitive-Field Effect Transistor), developed by M. Esashi and T. Matsuo, and a Ag/AgCl reference electrode were used to measure the pH. Prior to the measurements, the drift, pH sensitivity, and linearity of the system were examined by standard solutions.
A platinum electrode, covered with celluloseacetate, and a Ag/AgCl electrode were adopted to measure the pO₂ of the sulci and pockets. The Pt-electrode was connected to the negative terminal and the reference electrode to the positive terminal of the current source. The pO₂ was estimated from the current observed during the reduction process at the tip of the Pt-electrode. The sensitivity and the linearity of the measuring system were also calibrated before the measurements.
The pH was measured at depth of 1mm from the gingival margin and the pO₂ measurements were made at the bottom of sulci or pockets.
The results were as follows:
1. The range of pH sensitivity of the HIS-FET electrode was distributed between 44.5 and 51.8mV/pH, and the maximum drift was 0.03pH/min.
2. When the HIS-FET electrode and the Ag/AgCl electrode were repeatedly immersed in the solution, the maximum drift was 1.4mV/90s.
3. Three kinds of buffer solution (i. e. mixture of 0.1N-NaOH and 0.1M-KH₂PO₄, 1/15 M-KH₂PO₄ and 1/15M-Na₂HPO₄, and 0.1M-citric acid and 0.2M-Na₂HPO₄ respectively) were used to examine pH-linearity. The average sensitivity of the electrode was 51.6mV/pH.
4. The pO₂ was recorded by the method based on the polarographic principle. Three kinds of buffer solutions and a solution that contained 5 kinds of salt (MgSO₄: 0.06g/l, MgCl₂: 0.10g/l, K₂HPO₄: 0.27g/l, NaHCO₃: 2.60g/l, NaCl: 5.80g/l) were examined. A plateau of the reduction current was obtained between -0.55V and -0.75V in those solutions.
5. A linear relationship was obtained between the pO₂ concentration and the reduction current. The sensitivity of pO₂ was 64.0×10^-12A/mmHg (35.0°C).
6. The average pH and the pO₂ of the periodontal pockets in patients were 6.35 (S.D.=0.149) and 24.9mmHg (S.D.=17.7mmHg) respectively, and those of the sulci in normal adults were 6.59 (S.D.=0.174) and 36.4mmHg (S.D.=17.1mmHg) respectively. The difference between the average pH value in periodontal pockets and in sulci was significant (p<5%).

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The purpose of this study was to show whether rabbit anti-collagen antiserum could induce gingivitis and to show what kind of host responses would be, if occurred.
Two mongrel dogs were toothbrushed for about 2 months to establish healthy gingiva. Rabbit antisera against dog skin acid soluble collagen (anti-collagen) and against dog skin collagen digested by collagenase (anti-d-collagen) were injected topically into the gingivae. Physiological saline (S) and normal rabbit serum (NRS) were used as the controls. Three days and 4 weeks after each injection the gingival strips were taken. Alterations in the gingiva were examined histopathologically and by fluorescent antibody techniques. The dogs were then sensitized with NRS γ-globulin fraction and the same procedure described above was done. Toothbrushing was carried out throughout the experiment.
The following findings were obtained:
1) Total number of cells in perivascular connective tissue (TNC) at injection sites increased 3 days after the injection of anti-collagen and anti-d-collagen as compared with S and NRS significantly (P<0.01). Four weeks after the injection the inflammation was reduced.
2) Three days and 4 weeks after the injection of anti-collagen, IgG, IgM and C3 were stained a little stronger as compared with S and NRS. T-and B-cells were observed 3 days after the injection but almost disappeared 4 weeks later.
3) After sensitization with NRS γ-globulin fraction one dog had the same tendency in TNC as before sensitization and the other dog showed no changes 3 days and 4 weeks after the injection.
4) Three days after the injection of anti-collagen and anti-d-collagen in the sensitized dogs, IgG, IgM and C3 were stained obviously more intensive than the controls. A few T-and B-cells were observed 3 days after the injection, but disappeared 4 weeks after the injection.
These findings indicate that gingivitis could be induced by injection of anti-collagen and anti-d-collagen in a short duration.

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The present investigation was designed to study the histopathological features following gingivectomies or flap surgerys in two monkeys with healthy periodontium.
Gingivectomy was carried out on labial or buccal aspects of each sextant at intervals of 3 days and 1, 2, 3 and 4 weeks. On the other hand flap surgery was undertaken at 3 days and 1, 2, 4 and 12 weeks. During experiments toothbrushing and mouthwashing by 0.2% CHX were continued. At the end of experiment the block tissues were taken, prefixed, demineralized, post-fixed and embedded in Epon 812.
Fourty serial bucco-lingual sections of 1μm thickness prepared were stained with toluidine blue and observed for measurement of numerical density of various cell types (fibroblast, leukocyte, lymphocyte, plasma cell and mast cell) in the connective tissue adjacent to sulcular epithelium, junctional epithelium and central part of connective tissue.
The number of fibroblasts related to the wound healing following operations was small after 1 week in both operations, but increased significantly after 4 weeks in gingivectomy and 12 weeks in flap surgery (P<0.01). The differences in the number of fibroblasts were highly significant in almost experimental periods between gingivectomy and flap surgery (P<0.01). The number of fibroblasts correlated significantly with that of leukocytes and lymphocytes (P<0.01).

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The kinins, a group of biologically active polypeptides, are generally considered as important chemcal mediators in the inflammatory process. However, the role of these mediators in peridontal disease still rmain unknown.
To make these points clear, the present study was performed to assay bradykinin in saliva from patients with periodontal disease, and to correlate these data with various clinical observations such as GI, DI-S, CI-S, Pocket depth, GBI, Tooth mobility and Bone loss.
Whole saliva was collected into ice-cold plastic tube and filtered through ultrafiltration membrance [IMMERSIBLE CX-10] at 0°C. Filtered saliva was applied on a SEP-PAK C-18 column, and bradykinin was extracted by 80% ethanol containing 1% acetic acid afer washing out other components. The extract was used sample for HPLC assay.
The bradykinin level of samples was assayed by HPLC method of Omori et al.. Minimum detectable amount of bradykinin by this method was about 2ng per injection. However, there is no difficulty to determine a bradykinin level of 0.5ng per ml of filtered saliva or less when the sample was taken enough in volume, because the peptide can be concentrated at the prepreparation step.
The results were as following;
1. The saliva bradykinin level in periodontal diseased group and clinical healthy one were 10.36±6.70ng/ml of filtered saliva and 3.82±2.72ng/ml of filtered saliva respectively.
2. The clinical observations, such as GI, DI-S, CI-S, Pocket depth, GBI, Tooth mobility and Bone loss, were significantly correlated with saliva bradykinin level.
3. The saliva brandykinin level of bleeding samples [12.58±7.52ng/ml of filtered saliva] was significantly higher than non-bleeding ones [5.37±2.92ng/ml of filtered saliva].

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The purpose of the present study was to investigate macroscopically and histologically the effect of feces or sterilized feces in the powder diet (a normal laboratory) or high carbohydrate diet (Keyes No. 2000) on the periodontal tissues of golden hamsters. The experimental animals were divided into the following seven groups: K group recieved a solid diet, F group a powder diet, f group a high carbohydrate diet, G group a powder diet with feces, g group a high carbohydrate diet, M group a powder diet with sterilized feces and m group a high cabohydrate diet with sterilized feces. The experimental animals were killed at intervals of 4, 6, 8, 12 and 16 weeks, and the periodontal tissues of first and second molars of these animals were examined macroscopically and histologically.
The results were as following;
1. In K and F groups, there were no apparent changes in the periodontal tissues during the entire experimental period.
2. In f group, the plaque accumulated slightly more than that in M group. There were inflammetory cell infiltration and partial resoption of the alveolar bone at 16 weeks.
3. In G group, the plaque accumulated moderately. Histologically, there were irreqular proliferation of the gingival epithelium and resorption of the alveolar bone at 16 weeks.
4. In g group, the plaque accumulated slightly more than that in G group. Histologically, at 12 weeks, the epithelium of the gingiva was thin, and inflammetory cell infilitration was sever. The alveolar bone was resorbed by osteoclasts. At 16 weeks, these changes became more conspicuous than those at 12 weeks.
5. In M group, the plaque accumulated a slightly and histologically there were no evident changes during the entire experimental period.
6. In m group, the periodontal tissues were almost the same as those in f group.

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The normal and alloxan diabetic rats received either excessive amalgam filling in the maxillary first molar or elimination of the crowns of the mandibular second and third molars. After the treatments, these animals were fed on the powder diet (a normal laboratory diet) or the powder diet containing their feces. The animals were killed at intervals of 1, 3, 5, 7, 10, 14, 17 and 21 days. The histologically observations were performed on the periodontal tissues in the root bifurcation area of the mandibular first molar.
The results were as follows;
1. Excessive amalgam filling group
1) In both normal and alloxan diabetic rats on the powder diet, the resorption of the cementum and alveolar bone and the necrosis of the periodontal ligament were observed at 7 days. These injuries in normal and alloxan diabetic rats were repaired at 14 days and 21 days, respectively, but the osteopotic change was seened in alloxan diadetic rats at 21 days.
2) In normal rats on the powder diet with feces (C group), histological observations were similar to those seen in A group.
3) In alloxan diabetic rats on the powder diet with feces (c group), the resorption of the alveolar bone and the necrosis of the periodontal ligament were found at 7 days. These changes become severer by the inflammation after 7 days, and the injury was not repaired even at 21 days.
2. Elimination of the crowns group
1) In normal and alloxan diabetic rats on the powder diet, (B and b groups, respectively), the changes were less severe than those seen in A group.
2) In normal and alloxan diabetic rats on the powder diet with feces (D and d groups, respectively), the changes were less severe than those seen in A group.

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Restorative materials for root caries were investigated on adhering plaque bacteria on them. Tested materials were five products of composite resin and a product of glass ionomer cement.
In vitro, these materials were incubated and shaked with phosphate saline solution of three stains of plaque bacteria (Actinomyces viscosus, Streptococcus mutans, Streptococcus sanguis) under the conditions of 37°C and 3cm/70st/min. In addition, these materials were also done the same method after treated with human saliva.
In vivo, palaffin plates each mounted with two products of composite resin and a product of glass ionomer cement were set up into the vestibule of mouth adjacent right, left molars and incisors.
Attached bacteria were stained, after five hours, by acridinorange solution and counted with a microscope under incident fluorescent lump.
Concerning with both in vitro and in vivo, the most bacteria adhering material was composite resin which made from Bis-GMA base resin, the second was glass ionomer cement and the least bacteria adhering material was composite resin which made from polyurethane base resin. Also adhering number of plaque bacteria decreased after treated with human saliva in vitro study.
The results indicated that polyurethane base resin composite was the best material for filling of root caries from the point of view of adhering plaque bacteria to material surface.

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The purpose of this study is to investigate cell attachment in vitro to the exposed root surfaces of periodontally involved teeth. Extracted human teeth were split longitudinally into four pieces. The root segments of one group were untreated. Those of the other groups were root-planed or underwent application of either citric acid (pH 1.0) or sodium deoxycholate (NaD) and human serum after being root-planed. These samples were autoclaved and incubated with cultured fibroblast-like cells derived from the human gingiva. After being fixed and stained, the number of attached cells on each sample was calculated using a light microscope. A few samples were prepared for scanning electron microscopic study. The following results were obtained.
1. Untreated root surfaces allowed little or no cell attachment.
2. On the root surfaces of the citric-acid-treated group, denuded fibers were observed and attached cells were the most numerous; this was followed by the NaD-treated group and root-planed group, in that order.
3. The differences of the mean cell counts of the untreated group and the others were significant (p≤0.001). The root surfaces of the citric-acid-treated group and the NaD-treated group allowed a significantly higher degree of cell attachment than those of the root-planed group.

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To decide the application of hydroxyapatite to periodontal therapy, following fundamental studies on hydroxyapatite were performed.
Materials used were six kinds of hydroxyapatites of which firing temperature were 900°C (LT) and 1, 400°C (HT), and diameter were less than 100μm (size S), 200-300μm (size M) and 500-1, 000μm (size L).
To investigate the surface ultrastructure of the hydroxyapatites with different firing temperature, LT-size M and HT-size M were coated with gold and observed scanning electron microscopically.
Dissolving each hydroxyapatite in pure water and 0.1% hydrochloric acid, specific electron conductivity test was carried out to compare the solubilities.
Each hydroxyapatite was implanted in M. rectus femoris of rats, and in artificial bone defect cavity (measuring 1×3×1mm) on maxillas and mandibles of dogs. These animals were sacrified two or four weeks after implantation. Then tissue response against hydroxyapatite and osteogenic activity of hydroxyapatite were examined histopathologically.
The results obtained were as follows.
1) On scanning electron microscope, LT showed fine granular surface, but on the other hand, HT showed smooth surface.
2) Specific electron conductivity test presented higher solubilities in LT than HT.
3) At two and four weeks after implantation in muscles, all hydroxyapatites were enclosed with fibrous capsules involving foreign body giant cells and isolated from surrounding muscular tissues.
4) At two weeks after implantation in artificial bone defect cavity, foreign body response was not seen. Bone repairs in both case-LT and case-HT were more delayed than in control case, but that in case-LT was more prompt. Osteblastic cells coexisted with fibrobrasts in the connective tissue filling the artificial bone defect cavity and were in immediate contact with hydroxyapatite.
At four weeks after implantation, bone repairs had almost already completed in control and all hydroxyapatite.
At two and four weeks, there was no foreign body response and inflammatory cell infiltration.
Considering above results, hydroxyapatites were non-inflammatory and non-stimulative, and had good tissue tolerance and some kind of osteogenic activity.

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The individual differences in toothbrushing was investigated in a single blind cross-over trial.
The dentists with a normal dentition and clinically healthy periodontal tissue volunteered for this experiment. Percentage of plaque removal on the upper central incisors and the Plaque Control Record (O'Leary et al., 1972) were obtained after the use of five different types of toothbrushes used by the scrub method.
The percentage of plaque removal varied in a wide range between the subjects. The similar difference between the subjects was demonstrated by an analysis of the Plaque Control Record. These differences were statistically significant at the 0.05 level. The subjects of high percentage of plaque removal showed low S. D. value between used toothbrushes and those of low percentage of plaque removal, high S. D. value. It is considered from these results that the toothbrush managing ability varies between individuals and this ability affects the plaque removal.

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On previous studies, we have shown that osteoclast activating factor (OAF) is released from human peripheral blood leukocytes (PBL) which have been stimulated by phytohemagglutinin (PHA).
In this study, OAF-producing cells were investigated.
PBL were isolated by differential centrifugation using sodium metrizoate-Ficoll, and monocytes, T and non-T lymphocytes were then separated using the methods of plastic adherence and E rosette formation. Each fraction was cultured in RPMI 1640 medium with PHA. The supernatants from the cultures were assayed for bone resorption activity by measuring the release of ⁴⁵Ca from fetal rat calvaria in vitro, and their prostaglandin contents were also determined.
Consequently, it was suggested that both T and B lymphocytes produce OAF and its production was enhanced by the addition of monocytes, particularly with regarded to the T lymphocyte population. The results of experiments in which double culture chambers were used indicated that probably an intimate T lymphocyte-monocyte contact was required for the production of OAF.

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The purpose of this study was to investigate the relationship between plaque index and some clinical parameters on experimental gingivitis in man. The subjects were ten clinical students. Gingivitis was produced in students with healthy gingivae by withdrawing all active efforts directed toward oral cleanliness for 19 days. Gingival index, gingival bleeding index and gingival crevicular fluid flow were measured as periodontal parameters.
A significant correlation was observed between plaque index and other clinical parameters in the order bleeding index>gingival index>crevicular fluid flow. In the healing stage of gingivitis after reinstitution of oral hygiene, the plaque index and bleeding index were highly correlated.
It is concluded that the bleeding index is a useful parameter for evaluating inflammatory state in the plaque accumulating and removing stage.

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This investigation was to examine the age-related changes of pyridinoline which was non-reduced and matured crosslink of collagen. The subjects were alveolar bones and femoral bones of 2, 4, 10, 20, 40, 60, 70, 90 week-old and mandibular bones of 10, 40, 90 week-old Wistar rats. These bones were ground, decalcified and hydrolyzed in a sealed tube with 6N HCl at 110°C for 24 hours. The hydrolysate was applied to a SP-Sephadex C-25 column. Fractions were pooled and the fluorecence at 395nm was measured with excitation at 295nm.
Experimental results were as follows:
1) Pyridinoline contents in collagen from rat alveolar bone showed little change from 4 to 40 week-old, then continued to in crease gradually up to 90 week-old.
2) Pyridinoline contents in femoral bone showed similar changes, but significant difference at 4 week-old in comparison with that of alveolar bone.
3) Pyridinoline contents in mandibular bone were much than that of alveolar and femoral bone at 10, 40, 90 week-old.

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In Nagasaki Prefecture there are fifty-three islands, the population of which is less than one thousand. It is difficult to have their own doctor or dentist in such areas. Therefore medical service for such an island is an important problem by which Nagasaki Prefecture confronted.
We participated in the medical examination held in Enoshima, one of such small islands in Nagasaki Prefecture, to investigate the oral state. The purpose of this study was to obtain the basic data of their oral condition in such a small island.
Oral survey on 313 inhabitants were carried out by two examiners. One of them examined dental caries and the other periodontal disease.
The results were as follows:
1. The average number of missing teeth in middle and upper age bracket in inhabitants in Enoshima increased rapidly with age and was much higher than the mean value of the Japanese.
2. Mean G. I. and P. I. of both men and women between the age of 10 and 19 showed minimum value. Mean G. I. increased with age and showed the highest value in women aged from 70 to 79.
3. Mean values of the pocket depth of each subject in the younger generation were nearly less than 2 millimeter. The values increased with age. In the middle and upper age bracket the proportion of the subject with the pocket depth from 2 to 4 millimeter was the largest.

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The purpose of this study was to investigate the effect of chewing-gum for halitosis.
Volatile sulphur compounds (V. S. C.) produced during the mouth air and the incubation of whole saliva were analyzed by gas chromatograph.
The following conclusions were obtained as the result of chewing-gum by its experimental use of the saliva and the mouth air of periodontal patients having halitosis.
1. By chewing of gum V. S. C. were reduced significantly.
2. By adding Chn. V. S. C. were not detected. However 60 minutes after a small amount of V. S. C. was detected.
3. By adding F. V. S. C. were not detected or reduced to lower level.
4. By adding and incubating 100mg, 50mg, 10mg, 5mg, Chn, and 10mg, 5mg F. respectively into 1ml saliva, V. S. C. were reduced to low level.
From this study significant effect for halitosis was observed by chewing of gum.

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The purpose of this study was to classify factors on which effect the change of plaque control level. 81 patients involved with periodontal disease who were treated by senior students were observed their PCR changing during the active treatment. According to the PCR changing pattern, participants were classified into three groups: well group, average group, poor group. To deal with patients directly, following factors were recorded: sex, age, occupation, the reason come to the hospital, chief complaint, the history of periodontal treatment, TBI have or haven't, the change of subjective symptoms during the process of PCR reached about 10% level, recognization of plaque and psychological tests. The senior students were asked the detail of their motivation to patients and their reliabilities were measured by instructors. Patient's Malalignment Index was scored from study cast. Pocket depth and the degree of bone absorption were measured. And each factor compared statistically among three groups.
The results indicate that factors as follows effect the PCR changing: chief complaint, change of subjective symptoms, pocket depth, degree of bone absorption; and the occupation, TBI, Malalignment Index and student's reliability may have some effect on the PCR changing. Student's motivations to the patients were almost equivalent in the contents and the emphasis. Consequently, the factors given above may effect on the motivation itself.

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We investigated morphologically and biochemically the effect of epidermal growth factor (EGF) on newborn mouse calvaria in vitro. EGF at concentrations of 2-50ng/ml increased protein content but decreased alkaline phosphatase activity in calvaria of tissue culture. EGF at concentrations of 2-50ng/ml significantly decreased collagen synthesis in the tissues, whereas protein synthesis was rather stimulated. Thus, the proportion of collagen to total protein synthesized decreased with increasing concentration of EGF. Bone resorption was not observed in the tissues cultured with medium containing and lacking EGF. EGF also did not affect acid phosphatase activity in the tissues. These results indicate that EGF inhibits bone formation but does not affect bone resorption.

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For prevention or cure of periodontal disease, effective plaque control methods should be popularized. Löe and co-workers described that about 70% of the total plaque on the teeth were found for the interproximal area, and that the interdental area were most affected by the inflammation. In order to clean between the teeth, one-row brush as an applicator of chlorhexidine paste has been devised. And so, the subjects with periodontal disease were directed to put 0.05% of chlorhexidine paste between the teeth with the applicator, once a day for two weeks. Sixty subjects were devided into three groups; I. placebo paste without the applicator, II. 0.05% of chlorhexidine paste without the applicator and III. 0.05% of chlorhexidine paste with the applicator. The plaque accumulation was disclosed with a solution once a week, and all the subjects removed plaque by their own brushing method.
Significant improvements were observed in obvious swelling of gingiva and the pus discharge in the chlorhexidine group without the applicator (χ²-test). In the chlorhexidine group with the applicator, the redness, the bleeding, the plaque accumulation and the depth of periodontal pockets were significantly improved. It suggests the practical use of the method is acceptable in the community.

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The purpose of this report was to evaluate the effect of topical anesthesia. With the application of benzocaine (Hurricaine Gel and Liquid), 143 cases (112 males and 31 females) were studied on the relief of the pain on scaling, root planing and 57 patients were investigated of the relief of the pain at the insert of needle for local anesthesia. Results were as follows: 1) Effects of Hurricaine Gel observed in 22 cases (53.8%), Hurricaine Liquid relieved 80 cases (55.9%) from the pain on scaling. 2) Relief of the pain at the insert of needle for local anesthesia were observed in 24 patients (85.7%) with Hurricaine Gel and 26 patients (89.7%) with Hurricaine Liquid.

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The purpose of this study was to determine the prevalence of juvenile periodontitis and periodontal disease in high school students. The survey was conducted on 12, 723 students aged from 15 to 18 years, living in Sapporo, Japan.
The examination was carried out in three stages. The first stage, probing depth was measured at six teeth, maxillary and mandibular first molars and mandibular central incisors on mesial surface. The second stage, bite-wing radiographs were taken on the individuals who had one or more periodontal pockets (probing depth≥4mm). The third stage, all individuals who had clear signs of marginal bone destruction on bite-wing radiographs, were invited to our hospital for thorough clinical and radiographic examinations.
The results of the first and second stage were as follows;
1) Periodontal pocket (probing depth≥4mm) was detected in 2.1% of the teeth examined. Probing depth≥5mm was detected in 0.3%. About 7.3% of the individuals had periodontal pocket on at least one teeth.
2) The mean of probing depth and prevalence of deepend periodontal pocket was higher in following order, mandibular central incisor<mandibular first molar<maxillary first molar.
3) There was no significant difference between sexes or ages from 15 to 18, with regard to probing depth.
4) The mean of probing depth was significantly high on the teeth with proximal restorations.
5) About 0.4% of the individuals had bone loss≥3mm from cemento-enamel junction, on at least one first molar. About 0.1% had bone loss≥4mm.

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The purpose of this study was to determine the prevalence of juvenile periodontitis in high school students. The survey was conducted on 12, 723 students aged from 15 to 18 years, living in Sapporo, Japan.
The examination was carried out in three stages. The first stage, probing depth was measured at six teeth, maxillary and mandibular first molars and mandibular central incisors on mesial surface. The second stage, bite-wing radiographs were taken on 447 individuals who had one or more periodontal pockets (probing depth≥4mm). The third stage, 40 individuals who had clear signs of marginal bone destruction on bite-wing radiographs, were invited to our hospital for thorough clinical and radiographic examination.
For the diagnosis of juvenile periodontitis, the following criteria were used:
i) The patient must be in good general health.
ii) Angular bone loss of 3mm or more from cemento-enamel junction must be radiographically detectable around more than one tooth.
iii) The amount of subgingival calculus must not be comensurate with the bone loss.
Four cases among 12, 723 students fulfilled these criteria. The prevalence of juvenile periodontitis in high school students in Japan was about 0.03%.

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The efficacy of photographic subtraction radiography in detecting the proximal bony lesion has been studied using human dry mandibles.
The standardized x-ray projection has been used to assure geometrically identical radiographs. Reference radiographs of the molar areas of seven mandibles were obtained. Bone defects were produced artificially in the proximal areas between molars. After the defect had been made, the subsequent radiographs were obtained using the same exposure conditions. The subsequent radiographs reversed photographically using Kodak masking film, were superimosed on the reference radiographs in order to get subtraction images. The images were then registered on Kodak duplicating film to be served for the observer performance study. The conventional radiographs obtained before and after defects had been made were mounted, and presented to each of ten periodontists. The were asked to compare the images and decide whether or not a bone defect was present. The subtraction images with and without lesions were presented and asked in the same fashion.
The results showed that the diagnostic accuracy defined as the present correct diagnoses of true positives was significantly higher in subtraction images than conventional images. However, once the lesion was big enough, the lesion width of 3/10 of madible, no significant differences were not observed. The true negative data did not show the differences between two systems. The subthaction images made from two conventional radiographs obtained from patient with periodontitis showed successful results of surgical theraphy with regeneration of bone, in shape and pattern.
It is concluded that photographic subtraction radiography is one of the promising method to evaluate the minute change and its architectural pattern of alveolar bone in the longitudinal periodontal study.

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The purpose of the present study was to investigate both the clinical and associated histologic responses of periodontal tissue to Hydroxyapatite ceramic (H. A. C.) which were implanted into artificially created 3-walls periodontal defects in monkeys.
8 weeks after implantation of three sizes (more than 600μ, 100 to 400μ, 10μ) of H. A. C. particles, monkeys were killed, for histological evaluation.
The results are as follows:
1. Clinical response: At eight weeks postoperatively, gingival inflammation could not be observed both in control (without H. A. C.) and experimental sites. Standardized radiograph showed no evidence of exfoliation of H. A. C.
2. Histologic response: The junctional epithelium had not migrated apically. At eight weeks postoperatively, almost all H. A. C. particles could be observed in the connective tissue over the defect.
Osteogenesis was present around the particles adjacent to the bottom of defect, but some particles were encapsulated by fibrous connective tissue.
From these results, H. A. C. seemed to have excellent tissue biocompatibility, and it could be used as a bone substitute. But further investigation is needed for use in the treatment of human periodontal defects.

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Eleven outpatients (twelve cases) associated with vertical bone defects bilaterally were selected for this study.
After treatment of initial preparation, the one bone defect lesion was received flap-operation with bone grafts “Synthograft^®” (test) and the another was treated only flap-operation (control) in one of the patients.
Pocket depth, attachment level and roentgenographic bone loss which was the area of the vertical bone defect surrounded by CEJ of aproximate teeth coronally were employed for the pre-and post-operative examination. And the treatment effects were evaluated between the preoperative and three and six postoperative months periods.
Results revealed that
1. In the experimental groups, the mean values for decrease of pocket depth, gain of attachment level and roentgenographic bone formation were respectively 3.5mm, 2.5mm and 6.3mm² at three months, 2.6mm, 1.4mm and 5.0mm² at six months postoperatively.
2. In control groups, the mean values for decrease of pocket depth, gain of attachment level and roentgenographic bone formation were 3.3mm, 2.3mm and -0.2mm² at postoperative three months, and 2.4mm, 1.4mm and 2.1mm² at postoperative six months respectively.
3. There was a significant difference in roentgenographic bone formation at three months postoperatively between experimental and control groups.

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For the micro-morphological study of diseased root surface in situ, the use of an accurate and reproducible replica techniques is essential if the object under study cannot be observed directly.
Before taking the impression, the surface was irrigated with saline solution, dried with air jet. Primary replica is taken by application of silicone rubber impression material into periodontal pocket.
Epoxy resin is poured into hardened impression material to obtain secondary replica, and this secondary replica plated with platinum was used for the observation with scanning electron microscope (S. E. M.). The replica surface reproduced accurately the tooth surface except in the areas near the bottom of poeket, where the close proximity of epithelium and cementum hindered the insertion of impression material making observation impossible.
This technique offers possibilities of the micro-morphological study of diseased root surface in situ.

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In the experiment conducted this time, an efficacy of a tooth paste containing chlorhexidine-gluconate was evaluated in 24 patients of periodontal disease by the double blind cross-over method as compared with Active control.
Scaling was performed just before a medicament was used and at the time a medicament was replaced to new one 2 weeks later in order to evaluate inhibition of plaque and prevention of gingival inflammation.
While, a bracket for bacterial testing was installed on the front maxillary teeth when a medicament was used and when a medicament was replaced. As a result,
1. There was no difference in an inhibition efficacy of plaque between the two medicaments in the maxillary. However, significant difference was observed in the mandible at the time two weeks passed, and an inhibition efficacy was remarkable in LS-5 group in comparison with OTCAC group.
2. In the experiments on an efficacy for prevention of gingival inflammation normal accounting rate with less 3mm, any difference was not observed between the two medicaments in the maxillary.
In the mandible, however, LS-5 group showed significant efficacy with respect to improvement of gingival inflammation and periodontal normal accounting rate in comparison with OTCAC group.
3. As to the number of bacteria deposited in a piece of TAC film, there was no difference between the two medicaments in an anaerobic bacteria. However, in an inhibition efficacy for proloferation against aeromcrobe, LS-5 group was considered effective in comparison with OTCAC group.
4. As a result that scanning electron micro scope was photographed, it was concluded that there was no difference between the two medicaments.
5. Evaluation on availability concluded that 75.0 was available in LS-5 group and 50.0% was available in OTCAC group. The comparison between the two medicaments showed significant difference at p=0.041.
6. No side effect was observed in each case.

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