Local and systemic administrations of tetracycline have been used in human periodontal treatment for conditions including juvenile periodontitis and rapidly progressive periodontitis, although microbiological effects of the treatment have not been clear.
The effect of systemic oral administration of tetracycline on subgingival bacteria in experimental periodontal disease in hamsters as an animal model has not yet been reported.
The aim of this study was to investigate changes in subgingival bacteria and bone resorption at the lower left first moii, and supragingival plaque formation on the lower right first molar in animals with TC group) or without (Diet-2000 group) systemic oral administration of tetracycline hydrochloride 25 mg/kg/day in 20-day-old golden hamsters that mere fed a high sucrose diet (Diet-2000). Experimental periods were established as 15, 29, 43, 57, and 71 days.
Supragingival plaque formation on the lingual surface on the lower right first molar in the Diet-2000 group gradually increased with time; that in the TC group was scarce and was not increased with time.
Bone resorption at the lower left first molar in the Diet-2000 group proceeded rapidly with time, while that in the TC group was scarce.
Total number of bacteria from subgingival plaque on the lower left first molar in the Diet-2000 group increased rapidly with time, but that in the TC group did not vary at all with time. Actinomyces (Actinomyces naeslundii and Actinomyces viscosus) and Bacteroides (Bacteroides capillosus and Bacteroides ruminicola subsp. ruminicola) in the Diet-2000 group increased with time; those in the TC group decreased with time.
A remarkable difference in IgG titers to Bacteroides asaccharolyticus was not observed in the Diet-2000 and the TC groups.
These results suggest that systemic oral administration of tetracycline hydrochloride on experimental gingivitis in golden hamsters causes the total number of subgingival bacteria to be confined, and to be decreased species of Actinomyces (Actinomyces naeslundii and Acinomyces viscosus) and Bacteroides (Bacteroides capillosus and Bacteroides ruminicola subsp. ruminicola), leading to the inhibition of bone res-orption and supragingival plaque formation.
It is suggested that Bacteroides asaccharolyticus is not a pathogen concerned in experimental periodontal disease in hamsters, because the antibody titer was not elevated in the Diet-2000 group.

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In order to investigate biocompatibility of pure metals, which are widely used, the gingival tissues were brought into contact with pure metals. Nine kinds of pure metals, such as gold, platinum, silver, palladium, copper, nickel, zinc, indium and tin were used in the analysis of biocompatibility. With a No. 1/2 round bar, a stadardized small cavity was prepared in the mesiolingual cervical portion of the upper first molar. Nine kinds of pure metals powder were inserted into the small cavity of the maxillary root surface in rats. Post operative changes of the gingival tissue were studied histopathologically.
The results were as follows:
1. Gold, palladium and indium powder were observed in the lamina propria of the gingiva. Infiltration of cells was not observed around these pure metal powders. Gold, palladium and indium powders showed little cytotoxicity.
2. Zinc powders were not associated with chronic inflammatory charges. Zinc powders were surrounded by an abundance of connective tissue substances. The fragments were surrounded by collagen fibers, but no inflammatory cells were present. Zinc powders showed little cytotoxicity.
3. Platinum and tin powders were not associated with chronic inflammatory changes. These pure metal powders were surrounded by macrophages, but no other mononuclear inflammatory cells were present.
4. Clumps and granules of silver powder were not associated with chronic inflammatory changes. Multinucleate giant cells were shown surrounding silver powders. Silver powders were observed to have been taken into the multinucleate giant cells. Many of these cells also contained fine dark granules in their cytoplasm, and a few contained small pieces of silver. The tissue reaction to silver showed little cytotoxicity.
5. Copper and nickel powders were associated with chronic inflammatory cells. Moderate chronic inflammation and occasional neutrophils leucocytes and lymphocytes were shown to be associated with these pure metal powders. Copper and nickel caused extensive damage to the gingival tissues.

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Damage to periodontal tissues caused by dental materials (silver alloy powder) was examined by histopathological observation. Three kinds of silver alloy powder containing copper of various contents, such as that used in the first group : Ag-Cu (25% Cu), second group: Ag-In (5% Cu), and third group: Ag-Sn-Zn (0% Cu), were used to analyze damage to periodontal tissues caused by silver alloy powder.
With No. 1/2 round bar, standardized small cavities were prepared in the mesiolingual cervical portion of the upper first molars of rats. Three kinds of silver alloy powder were then inserted into the small cavities. Postoperative changes in the gingival tissues were studied histopathologically.
The results were as follows:
1. Under the light microscope, all three groups showed similar tissue reaction. Many dark deposit (metal) were observed in the lamina propria of the gingiva. These dark deposits had been taken into the histiocyte-like cells and multinucleate giant cells. Infiltration of cells was not observed around these dark deposits. Findings among the metals in three groups were of specific structures, which displayed black and dark-brown stained deposits in surrounding silver alloy powder.
2. Under the electron microscope, the first, second and third groups showed similar tissue reactions. Dark deposits (metal) had been taken into the multinucleate giant cells. These cells contained many lysosomes, vacuoles, and endocytosed materials. The deposits consisted of a dence central core of silver alloy powder surrounded by fine needle-like components and filaments of lower electron density. Extremely fine particles were also observed around the basal lamina of capillary vessels and along collagen fibers.
3. By AEM, components of the lower electron density material were identified as silver, copper and sulfur in the first and second group, and silver and sulfur in the third group. The elements in the fine particles were silver and sulfur.
4. Using scanning electron microscope, the micrograph indicated that a barnacle-like structure was formed on the surface of the silver alloy in the gingival tissue. A phenomenon of solubility appeared as stacks of granules firmly attached to the silver alloy surface.
5. The silver element of the silver alloy powder damaged the gingival tissues slightly, resulting in minor tissue reactions. When the range of copper content was from 0% to 25%, the alloys caused no damage to gingival tissue.

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The aim of this study is to determine the process of periodontal tissue regeneration and the metabolic activity of osteoblasts after implantation of bone ceramic and collagen gel compound materials (BC).
Bone defects were artificially prepared in the alveolar septa of the bilateral upper first and second molars of Wistar rats. Subsequently, BC were implanted into the defective sites on the left side, and the gingival flaps were closed. At the defective sites on the right side, as a control, gingival flaps were closed without implantation.
Rats were sacrificed 1, 3, 5, 7 or 14 weeks after implantation, and prepared tissue sections were observed both pathologically and autoradiographically using ³H-Proline.
The results obtained were as follows:
Pathological Findings
One week after BC implantation, inflammatory cellular infiltration of the surrounding gingival connective tissue was relatively mild. Three weeks after implantation, BC were present in fibrous connective tissues, and some directly bound to the marices of regenerated bone. Observation 5 weeks after implantation revealed that BC had become embedded in the regenerated bone matrices and that there was giant cell reaction to foreign bodies at the margin of BC located in connective tissue. BC were directly bound to the regenerated bone matrices without intermediary fibrous tissues 7 and 14 weeks after implantation. Connective tissues showed high grade regeneration of collagen fiber bundles, in an arrangement that tended to be fixed in mesial and distal directions.
Autoradiographic Findings
There was no uptake of ³H-Proline into the regenerated bone matrices or the gingival connective tissue surrounding BC, while uptake of ³H-Proline into the entire area around the root apex and in the vicinity of the alveolar septum was observed with time (weeks) after BC implantation.
These results suggest that BC provide nuclei for bone regeneration through inclusion in newly-generated periodontal bone tissue, although it is difficult to produce definite induction of bone tissue by BC alone. It is also apparent that these are useful bone implantation materials for restoration of the physiological morphology of alveolar bone in periodontal surgical treatment.

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Since endotoxin may be absorbed only in the superficial layer of cementum leaving the deep cementum unchanged morphologically, the cementum of teeth with periodontal involvement was examined. The author considered that the application of citric acid after curetting of only the superficial cementum was better root treatment than complete removal of the cementum. The aim of this study was to examine histological events during the formation of new fibrous attachment to demineralized cementum after flap surgery following citric acid treatment in fifteen dogs. The demineralized cementum prevented the apical proliferation of junctional epithelium. The fibroblasts apposed to the exposed cemental collagen produced numerous new fibrils. Furthermore, the newly-formed collagen fibrils appeared to link with the exposed ones. These findings suggest that this root treatment would facilitate the formation of new fibrous attachment.

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We have previously reported that the sonicate extrast from Actinomyces viscosus T 14 V (Av. sup) causes polyclonal B cell activation (PBA) in murine splenic B cells without any T cell assistance. However, there are some reports describing T cell dependency of PBA induced by A. viscosus in human peripheral blood B cells, and it is still controversial whether or not A. viscosus has the capability of exhibiting PBA without the help of T cells.
In this report, we examined PBA in human peripheral blood B cells using the same Av. sup which induced T cell independent PBA in murine splenic B cells. The PBA was evaluated in terms of immunoglobulin (Ig) production by means of micro-ELISA method and cell proliferation by incorporation of ³H-TdR after incubation of cells for 5 or 7 days with Av. sup. Human peripheral blood B cells were highly purified by the following methods; The peripheral blood was collected by venipuncture and the peripheral blood mononuclear cells were harvested using gradient centrifugations. These cells were passed through a Sephadex G-10 column, and T cells were eliminated by rosette formation with sheep red blood cells. B cells were highly purified from these T celldepleted cell populations by panning method with anti-human Ig antibody coated dishes followed by complement-dependent cytotoxisity using monoclonal antibody cocktails consisting of OKT 3, OKT 4 and OKT 8.
These highly purified B cells could not respond to T cell mitogens such as PHA. The Av. sup did induce both cell proliferation and Ig production both in human peripheral blood mononuclear cells and peripheral blood lymphocytes, while it did not induce PBA in highly purified human peripheral blood B cells without the participation of T cells. However, reintroduction of T cells into B cell cultures restored significant PBA by Av. sup. Moreover the addition of macrophage fractions allowed further PBA by Av. sup.
These results indicate that the presence of T cells may be necessary for A. viscosus-induced PBA in human peripheral blood B cells (i.e. T cell-dependent PBA). It also suggested that the interactions of immunocompetent cells influenced the A. viscosus-induced PBA in human peripheral blood B cells.

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Interleukin-6 (IL-6) is involved in the final differentiation of B cells into antibody-producing cells. Recent studies reveal that IL-6 plays an important role in inflammation. Histopathological studies showed that a large number of plasma cells in periodontitis is usually seen in the apical parts of cellular infiltrates beneath the periodontal conective tissues. This evidence suggests that IL-6 may play a critical role in the development of periodontitis. Therefore, we examined IL-6 production in the gingival tissues.
Twelve periodontitis patients and five gingivitis patients were included in this study. Nine individuals with healthy periodontium acted as control subjects. Biopsy specimens were dissected into fragments 3 mm in diameter and plated onto 24-well culture plates with RPMI 1640 medium. IL-6 activity in the culture supernatants was measured by IgM production assay using the cell line SKW6-CL4.
IL-6 activity was detected at significantly higher levels (P<0.001) in culture supernatants from the gingival tissues in periodontitis (23.2±14.4units/ ml) and gingivititis (12.5±3.4units/ml) than in control tissues (2.3±1.2units/ml). Subsequently, the relationship between IL-6 activity and, clinical stages was examined. The IL-6 levels before initial preparation (23.2±14.4units/ml) were significantly higher (P<0.001) than those after initial preparation (1.4±1.8units/ml), but were not associated with either periodontal pocket depth or the extent of alveolar bone resorption in periodontitis. Further-more, IL-6 activity was detected at significantly higher levels (P<0.01) from gingival tissues in experimental gingivitis (5 .6±0.8units/ml) than in control tissues (1.1±1.2units/ml).
These results suggest that IL-6 may play a pathogenic role in periodontal diseases.

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The purpose of this study was to evaluate histological regeneration of epithelial and connective tissue attachment to the denuded dentin surface after hydroxyapatite ceramic granule (HAP) implantation.
HAP (particle size 100-300 μm, burn temperature 900..) were implanted into dehiscent defects of alveolar bone which eliminated about a 1.1mm area at mesial and palatal sites of the upper 1st molar in 20 male Wistar rats. Subsequently the root cementum was removed totally and dentin was denuded. Same osseous defects were formed but HAP was not implanted at any contralateral site for the purpose of control. Results of 8-week examination using light and electron microscopy were as follows:
1. In the HAP group junctional epithelium was regenerated on the denuded dentin surface 2 weeks after implantation and epithelial down growth was less than at the control site.
2. In the HAP group connective tissue reattachment with new cementum formation was observed at 2 to 4 weeks after implantation, the healing period tended to be shorter than at the control site and the connective tissue reattachment level was located more coronally.
3. In ultrastructural findings collagen fiber bundles attached to the denuded dentin surface had fibers continuing around HAP granules.

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The purpose of this study was to investigate the effects of hybrid material compounded with periodontal ligament cells on human teeth and porous hydroxyapatite.
As the first step, we tried to produce hybrid materials compounded with periodontal ligament cells and porous hydroxyapatite, and to observ3 the attachment and invasion of periodontal ligament cells porous hydroxyapatite.
Human periodontal ligament cells which had been scraped off the root with a disposable blade were cultured at 37°C in α-MEM plus 10% fetal calf serum. The cultuae cells were attached to the porous hydroxyapatite in vitro.
After 3 and 14 days of incubation, the specimens were fixed in gluteraldehyde and examined using SEM. Other specimens were embedded in paraffin and successive specimens were prepared for to remodelling of the attachment and invasion. Many cells attached to the P-HAP granules, and some cells invaded the P-HAP granules.
The results suggest that when these hybrid materials are implanted in bone defects, the cells remain in the defect for a certain period, and exhibit the functions and characteristics of itself.

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This study was carried out in order to determine the efficacy of CaO-P₂O₅-MgO-SiO₂-CaF system glass ceramics, which are made as implant materials, for treatment of furcation lesions. Glass ceramic granules were implanted in artificial class II furcation bony defects in monkeys. As controls, non-implanted sites were preserved. Radiographic and various clinical examinations were performed before surgery and at 0, 2, 4 and 8 weeks after implantation. Two, 4 and 8 weeks after implantation, two monkeys were sacrificed and the mandibles were sectioned for histopathological observation.
The results obtained were as follows;
1. During the experiment, no clinical problems or abnormal response at the sites of glass ceramic implantation were observed.
2. In clinical observation, no remarkable differences were obtained between control sites and implanted sites.
3. Two and 4 weeks after surgery, remarkable regeneration of bone was shown in the implanted sites. However 8 weeks after surgery, the difference between implanted and control sites was not so cicar.

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The present study was undertaken to determine the biocompatibility of a newly-developed CaO-P₂O₅-MgO-SiO₂-CaF system glass ceramic tooth implant. Two adult male monkeys were selected and 12 weeks after extraction of M₁ and P₁, 8 glass ceramic teeth were implanted into alveolar bone. At 1 week after implantation, 6 teeth were allowed occlusal function, and 2 teeth were left free from occlusion as control teeth. The implants were observed for 4-12 weeks and examined histopathologically.
The results were as follows:
1. Seven implanted teeth were well maintained clinically, and only one tooth was lost after 5 weeks.
2. In histopathological observation, implanted teeth were surrounded by bone, and connected by bonyankylosis. At cervix of dental implant, connective tissue as also attached firmly to implanted tooth surfaces and epithelial attachment was observed.
3. Although these implants were allowed occlusal function at an early stage (1 week after implantation), osteogenesis around implants was not disturbed.
These results suggest that the new glass ceramic implant has good biocompatibility and is useful as an implant tooth.

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This study was designed to examine the relationship between frequency of silent period and initial occlusal sliding time. The subjects consisted of three volunteers with normal occlusal contacts and three patients with premature contacts.
Electromyograms of the bilateral masseter muscles, initial occlusal contacts and jaw movements during the habitual tapping (20-25) were synchronously recorded and replayed using TAKAMATSU's technique.
Results were as follows:
1. The frequency of silent period in the bilateral masseter muscles was 95-100% in subjects with normal occlusal contacts and 34-53% in patients with premature contacts.
2. The silent period latency in three normal subjects was 8.9±1.3 msec in the left masseter and 13.9±2.2msec in the right masseter. The silent period latency in three patients with premature contacts was 12.4±2.6 msec in the left masseter and 13.9±8.2 msec in the right masseter.
3. The duration of silent period in three normal subjects was 12.4±2.6 msec in the left masseter and 11.1±3.7 msec in the right masseter. The duration of silent period in three patients with premature contacts was 9.1±1.7 msec in the left masseter and 11.1±5.6 msec in the right masseter.
4. Initial occlusal sliding time in three subjects with normal occlusal contacts was less than 30 msec, and 98% of all slidings lasted for less than 15 msec. Initial occlusal sliding times in patients with premature contacts were distributed between 6 and 80 msec (40%: 6 to 15 msec, 60%: >15 to 80 msec).
This data may be basic for diagnosis and treatment of patients with premature contacts.

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Bruxism has been considered to be one of the most important factors in accelerating the progression of established periodontal lesions. However the objective diagnostic method has not yet been established. At present, diagnosing bruxism might mainly be dependent on interview.
The purpose of this study was to compare and analyze the differences in frequency and duration of bruxism between a group of patients conscious of the problem and a group not conscious of bruxism. After interviewing, the subjects were divided into two groups; 1) group A consisted of 8 subjects who were conscious of bruxism and 2) group B of 8 subjects who were not conscious of bruxism. The frequencies and durations of muscle activity during sleep at night were compared between groups A and B using EMG with a telemetric method.
In the one-night observation, muscle activity supposed to be bruxism was observed in both groups. Significant differences in frequencies of muscle activity were not found between the two groups. A similar result was obtained in the durations of muscle activity.
In a seven-day observation, muscle activity was seen in all three volunteers, although marked differences were not found among them. A long duration of muscle activity was found under conditions of physical or mental stress.
The results of this study showed the difficulty of diagnosing bruxism by interview and the necessity of an objective method.

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The purpose of this study was to make an objective diagnosis of bruxism using a new recording system by observation during sleeping at home. The system was composed of a portable recorder for monitoring bruxism at home and an analyzing device for recalling the data later in laboratory. Muscle activity as recorded by EMG, occlusal tooth contacts were monitored by microvibration pick-up, and grinding sounds were recorded by a small microphone, simultaneously. These were printed on the one recording paper by playing back the tape.
Six subjects were selected and were monitored individually for five nights with this new system at home. Records were transcribed and analyzed in the laboratory.
As a result, nocturnal muscle activity, occlusal tooth contacts, and grinding sounds were recorded and analyzed efficiemtly with system.
This new system is considered in useful for the investigation and diagnosis of bruxism in periodontal disease.

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The present study involved cultural and microscopic characterization of the subgingival microorganisms of pubertal children with gingivitis. Samples were obtained from eight children 12-14 years of age. Gram-positive organisms made up 56% of the isolates and included mainly Actinomyces israelii, Actinomyces naeslundii. Gram-negative anaerobic rods constituted 25% of the isolates and Bacteroides intermedius (9.7%) was most predominant species. The selective media permitted significantly lower recovery of Actinomyces spp. and Capnocytophaga spp. than nonselective blood agar medium. However, sixty-nine percents of isolates were cultured on the selective media employed in the present study. These results suggest that the subgingival microflora of gingivitis in pubertal children may be similar to those of adult gingivitis and that the use of these six selective media makes it possible to enumerate predominant cultivable microorganisms in subgingival area of pubertal children with gingivitis.

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The purpose of this study was to examine the relationship between clinical findings and subgingival microbial flora in periodontitis at the first medical examination and after initial preparation.
The results obtained were as follows:
1. Clinical findings with the exception of plaque index showed improvement after initial preparation in comparison with the first medical examination.
2. In phase contrast microscopy, both total bacteria and incidence of spirochetes and motile rods decreased after initial preparation in comparison with the first medical examination.
3. Clinical findings with the exception of plaque index were related to the toal bacteria and proportional distribution of spirochetes and motile rods in periodontal pockets, observed in phase contrast microscopy.
4. Total bacteria and proportional distribution of black-pigmented Bacteroides in periodontal pockets decreased after initial preparation in comparison with the first medical examination.

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The purpose of this study was to evaluate the clinical application of strips containing 10% Tetracycline (TC) in periodontal disease. In this double blind study, placebo strips, which did not contain TC, were also prepared.
Ninety-two sites in 46 cases with greater than a 4 mm periodontal pocket were randomly assigned to experimental and control study groups.
The following clinical parameters at each site were recorded at Weeks 0, 1, 2 and 3 after insertion of the LSD or placebo strip: plaque and calculus score, probing depth, gingival inflamation (redness, swelling, bleeding on probing, pus discharge), mobility of the tooth, pain on insertion of strip and pain after the procedure.
The residual quantity of TC in the periodontal pocket was also determined at 1, 2 and 7 days after inserting the LSD. All clinical data was evaluated using 3 types of statistical test (X² test, Mann-Whitney's U test and Wilcoxon's test).
Thus, the following results were obtained:
1. The LSD group showed much improvement in clinical condition compared with the placebo group.
2. The conditions of bleeding, redness or swelling of gingival tissue were much improved in the LSD group, even after data evaluation with all 3 types of statistical test.
3. The residual quantity of TC was decreased day by day until finally it was not recognized in the 7 day samples.
4. This study suggested that the application of LSD in the periodontal pocket could be effective in periodontal treatment.

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The purpose of this study is to examine the relation ship between residual plaque score at an individual tooth surface during initial treatment and the pocket reduction rate at the evaluation time. Thirty-nine adult periodontal patients (mean age 39.2 years) whose O'Leary plaque control record (PCR) reached a level of 10% PCR, were selected for this study. A total of 5638 surfaces were monitored by recording probing pocket depths at the disto-buccal (a), midbuccal (b), mesio-buccal (c), disto-lingual (d), midlingual and (e), mesio-lingual (f) regions, and by examining ' Leary plaque control records. The results were as follows:
1) The residual plaque score at all teeth surfaces was 14.7419.21%.
2) The lowest plaque score were seen at 54 45, and 2 1 12.
3) The highest plaque score were seen at 7 7, and 76 67.
4) Well-responding sites that showed a hign residual plaque score and a good pocket reduction rate, were 5 5 (initial probing pocket depth 3.03.5mm, a), and 4 4 (initial probing pocket depth 3.03.5 mm, f; 5.05.5mm, f).
5) 7 7 (initial probing pocket depth 3.0mm a, b, d), and 7 7 (initial probing pocket depth 3.0 3.5mm, f) showed a high residual plaque score and a low pocket reduction rate.
6) The normal pocket response occurred at a level of residual plaque score of less than 25%. In order to gain good pocket response, it is important to keep the level of residual plaque score at less than 25% rather than to keep the level of PCR at 10% or 20% (as several authors have previously stated).
7) A low residual plaque score during treatment is therefore more important than a low PCR.

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The purpose of this study (Report 5) was to investigate the effect of difference in the length of toothbrush shank and type of tip of toothbrush bristle on toothbrushing pressure and plaque removal in the scrubbing method.
Four kinds of toothbrushes which were different in length of shank (30mm, 40mm) and type of bristle tip (round type, tapered type respectively) were used in this study. Referring to the results of our previous reports (1-4), the dimension of new toothbrushes were determined as follows. nylon bristles: 10 mm long and 0.20 mm in diameter, brushing surface: 30 mm long, bristles: 3 rows with 26 tufts, and a straight handle. Twelve subjects participated in this experiment. Plaque scores were measured before and after toothbrushing. Then plaque removal rates were calculated. Toothbrushing pressure was determined using Watanabe's method.
The average toothbrushing pressure of the toothbrush with a 40 mm long shank 301.6±84.1 g/cm² was higher than that with a 30 mm long shank 294.7±74.8 g/cm², and that with a tapered bristle type 316.7±90.4 g/cm² was higher than that with a rou nd type bristle 279.6±61.7 g/cm². However statistically significant differences were not found among the four toothbrushes in brushing pressure and in plaque removal on total teeth surfaces and on distal way ANOVA . surfaces of the most posterior teeth (P<0 .05; two-way ANOVA).

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In order to assess by periodontal evaluation the changes that might occur with time in the abutment teeth and periodontal tissues when Konus-Telescope dentures are used as that final treatment of periodontal disease, the dentures (15 units) were placed in 13 patients with missing tooth and periodontal disease and findings at the time of denture placement and 30 months after the placement were compared.
The number of cases that exhibited significant changes in hygiene level, tissue inflammation and periodontal pocket depth of the abutment teeth after 30 months was very small, while as many as 85.2% of the abutment teeth showed decrease in tooth mobility. Increase in tooth mobility was not detected in any of the cases. In addition, X-ray examination revealed tendencies toward improvement of the periodontal ligament and remission of alveolar bone resorption in many of the cases.
These results suggest that Konus-Telescope denture is highly offers protection of the residual periodontal tissues through its secondary splint action.

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The purpose of this study was to determine the prevalence of periodontal disease and the relationship between the results of questionnaire concerning periodontal disease and the actual periodontal condition in youth.
The examination was carried out in three parts. In the first part, a questionnaire was conducted on 3, 886 junior and senior high school students (12 to 18 years of age) living in Kawagoe, Japan. The questionnaire was composed by of items concerning habits of oral hygiene, periodontal symptoms, understanding of periodontal disease and history of diagnosis by dentist of periodontal disease.
Secondary, mass intraoral examination was carried out on all objects. The examination covered gingival inflammation, periodontal probing depth, calculus, dental plaque, dental caris and malalignment. Lastly, we examined the relationship between the results of periodontal examination and questionnaire with the original periodontal classification.
The following results were obtained:
1. As an example of items in questionnaire, 83.1% brushed their teeth more than two times daily. The understanding of oral hygiene concerning dental caries was improved, but concerning periodontal disease was still poor.
2. The symptom most frequently reported was gingival bleeding during tooth brushing (18.4%).
3. The percentage of persons with periodontal disease (moderate gingival inflammation and periodontal pocket 4mm or deeper) was of the highest frequency at 13 years old. The proportion of males increased with the advanced state of periodontal disease.
4. A significant correlation was found (X²-test: a< 0.001) between advanced state of periodontal disease and a decrease in tooth brushing time per day.
5. A significant correlation was found between the advance of periodontal disease and gingival bleeding on tooth brushing (X²-test: a<0.001). Similarly, a correlation was found between the advance of periodontal disease and gingival swelling (X²-test: a<0.001).
6. A significant correlation was found (X²-test: a< 0.001) between the advance of periodontal disease and aggravation of condition of dental plaque, calculus, dental caries and malalignment.

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A case of periodic neutropenia with specific symptoms of gingiva and alveolar bone loss in primary dentition is reported. The patient was a boy, and it was followed between the ages of 3- and 9 years-old. At the period of neutropenia he was suffered from recurrent redness, swelling and bleeding of the gingiva, and also with cold-like symptoms with fever. Although the cause of these symptoms was not definite at first, even in medical exploration, we could diagnose this disease as periodic neutropenia by the process of dental therapy.
By alveolar bone resorption, pocket formation and severe tooth mobility, the patient had lost more than half of his primary teeth at the end of 2 years after the initial examination. However throughout this period we motivated and instructed the patient and his mother how to brush his teeth. His oral hygiene was improvd in the mixed and permanent dentition stages. Then there was no evidence of bone resorption around the teeth of the permanent dentition stage, but recurrent gingival symptoms are continuing now.
The specific feature of this case is found in the gingival findings. There was no ulceration of the oral mucosa, but a bright red jelly-like appearance was found periodically in the area of the marginal and attached gingiva. The junction between the reddened attached gingiva and the alveolar mucosa was well-defined.
The serial examination of peripheral blood in this case revealed the cycle of neutropenia as 16 to 21 days. During this examination, and at the almost time of neutropenia of this patient, hyperplasia of monocytes and lymphocytes occurred. In this situation there was no clinical signs except for gingival redness. However at other times, generally marked signs were recurrent. This may have occurred due to the lack of both neutrophils and monocytes.
From the above results we think that periodic neutropenia may be diagnosed first in the dental clinic by the distinctive redness in the gingival area as one specific sign of this disease. We also think that plaque control procedures may retain the teeth.

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