The purpose of this study was to investigate the effects of occlusal trauma on periodontal tissues when different degrees of inflammation were combined with traumatic force applied in 1- or 2-directions. Two adult monkeys were used, and inflammation was provoked by silk ligature insertion around the necks of the teeth. The durations of silk insertion were 10 and 20 weeks for the mild (Group A) and the severe group (Group B) periodontitis groups, respectively. After the development of experimental periodontitis, the ligatures were removed. Groups A and B were further devided into 3 groups according to the intensity of traumatic forces. Lateral force was applied from one direction in Groups A I and B I at one week intervals for 5 weeks. In Groups A II and B II, elastics were inserted for one week alternately at the mesial and distal surfaces of the experimental teeth for 5 weeks. In the control groups (Groups Ac and Bc), no traumatic forces were applied. The monkeys were then sacrificed. The data obtained were evaluated clinically, radiographically and pathologically, and histometric analysis was also performed. The results were as follows: 1) P1 I, GI, and PD showed minimal differences among the groups. The clinical attachment level was unchanged in Groups A I and All, but was increased in Groups B I and B II. 2) Based on the radiographic examinations, bone loss was more severe in Groups B I and B II than in Groups A I and A II. No significant radiographic difference was noted in relation to the severity of the occlusal trauma. 3) The pathological observation revealed that Groups B I and B II had significantly more attachment loss, bone loss and destruction of transseptal fibers around the bony crest than Groups A I, A II, and Ac. The intensity of occlusal force produced no significant differences. It was thus concluded that, when the applied force exceeds a certain level, tissue with preexisting severe periodontitis will undergo a similar destructive process. Further studies are under way aimed at fully elucidating the role of occlusal trauma in periodontal destruction.

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This study was designed to evaluate the effect of the glycemic control on the periodontal condition of streptozotocin-induced diabetic rats (STZ rats) with experimental periodontitis. Sixty-three conventional (CV) rats were divided into normal control rats (N-DM), STZ rats (DM), and insulintreated STZ rats (DM-I). On Day 0, an elastic ring was placed around the right mandibular 1 st molar (experimental side). On Day 7, STZ (40 mg/kg) was administered to both the DM and the DM-I groups to induce experimental diabetes. The animals were given daily intra-peritoneal injections of either 0.9% NaCl (N-DM and DM), or 10 I.U. of insulin (DM-I) from Day 10 to Day 28. The evaluation of the periodontal condition was made on Days 14 and 28. Blood glucose levels, the extent of the inflammatory change, and the quantitative measurement of the alveolar bone area were recorded.
Results obtained were as follows;
1. Insulin administration was effective in controlling the hyperglycemia in STZ rats.
2. The blood glucose levels were 134 ±10 (mg/dl) in the N-DM group, 544 ±50 (mg/dl) in the DM group and 130±44 (mg/dl) in the DM-I group.
3. The insertion of an elastic ring in the periodontal crevice induced attachment loss and alveolar bone resorption.
4. The most severe inflammatory changes at the experimental side in the DM group were observed on Day 14. The changes in both the N-DM and the DM-I groups were milder than those in the DM group on Days 14 and 28.
5. The alveolar bone area of the experimental side in the N-DM and DM-I groups were significantly larger than those in the DM group on Days 14 and 28.
These results suggested that insulin prevented periodontal destruction caused both by mechanical and oral microbial stimulation in diabetic rats.

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In part one of this report (Kato, 1996), it was suggested that insulin prevented experimental periodontitis in streptozotocin-induced diabetic rats (STZ rats).
This study was designed to evaluate the effect of the glycemic control on the periodontal destruction in germfree (GF) and STZ rats. Thirty-nine GF rats were divided into normal control rats (N-DM), STZ rats (DM), and insulin-treated STZ rats (DM -I). On Day 0, an elastic ring was applied to the right mandibular 1 st molar (experimental side). On Day 7, STZ (40mg/kg) was administered to the DM and DM-I groups to induce experimental diabetes. The rats were given daily intraperitoneal injections of either 0.9% NaCl (N-DM and DM), or 10 I. U. of insulin (DM-I) from Day 10 to Day 28. The periodontal condition was evaluated on Days 14 and 28. Blood glucose levels, the extent of inflammatory change, and quantitative measurement of the alveolar bone area were recorded.
Results obtained were as follows;
1. Insulin administration was effective in controlling hyperglycemia in GF STZ rats.
2. The blood glucose levels assessed by the glucose hexokinase method were 131±18 (mg/dl) in the N-DM group, 506±89 (mg/dl) in the DM group, and 109±40 (mg/dl) in the DM-I group.
3. The elastic ring insertion induced attachment loss and alveolar bone resorption in GF rats:
4. Inflammatory change was severe in the DM group on Day 14. The inflammatory change in the N-DM and the DM-I groups on Day 14 were mild. On Day 28, there were no differences in the inflammatory changes among the three groups.
5. The alveolar bone area in the N-DM and DM -I groups was significantly larger than that in the DM group on Day 14.
Administration of insulin prevented periodontal destruction caused by mechanical stimulation in diabetic rats, even in the absence of oral microorganisms.

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The purpose of this study was to evaluate the effectiveness of bone morphogenetic protein (BMP), which was combined with improved fibrous collagen membrane No_ 1 (FCM 1), for using in periodontal regenerative therapy of furcation involvement.
In experiment 1, an artificial class III furcation bony defect at molars of a monkey was prepared and cementum was removed. Then the highly concentrated partially purified BMP (1.0mg) combined with improved FCM 1 was implanted. Histopathological observation after 12 weeks showed bone regeneration at the furcation site was accompanied with ankylosis to the root surface. However, regeneration of cementum and periodontal ligament without ankylosis was observed at the notch of the root surface. This finding was considered to be caused by a space between the root surface and the implant carrier. This result suggested that alveolar bone, cementum and periodontal ligament might be regenerated with BMP combined with the biodegradable membrane as a spacer.
In experiment 2, several implants were tried to compensate the artificial furcation bony defects prepared at molars of monkeys. The results were clinically and histopathologically assessed after 6 and 12 weeks. Group F, solely implanted with an improved FCM 1 showed insufficient bone regeneration. Group BF, implanted with the BMP combined with improved FCM 1, showed almost complete regeneration of bone but ankylosis occured in some areas of the root surface. Group FBF, implanted with two improved FCM 1, one for BMP carrier and the other for a spacer, showed almost complete regeneration of alveolar bone, cementum and periodontal ligament without any ankylosis.
Thus, the implantation of BMP with another degradable membrane such as collagen membrane as a spacer may be a new treatment method for the successful regeneration of alveolar bone, cementum and periodontal ligament without ankylosis.

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This study evaluated a new regenerative approach for the periodontal ligament and cementum by implantation of cultured periodontal ligament cells.
The study was performed with syngeneic rats divided into the following three groups. In the experimental group, dentin blocks with cultured periodontal ligament cells were transplanted to the cranial bone defect. In the control group, dentin blocks without cells were transplanted. In the tooth root transplantation group, extracted teeth with fresh periodontal ligament from other rats were transplanted. In all groups, the cranial tissues were routinely prepared for the histological analyses at 2, 4 and 6 weeks after transplantation.
In the experimental group, formation of cementum-like tissue was observed on 1 of 6 blocks at 2 weeks and 4 of 10 blocks at 4 weeks and dentin blocks showed ankylosis at 6 weeks after transplantation. In the control group, dentin blocks partly exhibited ankylosis at 2 weeks and all blocks exhibited ankylosis at 4 and 6 weeks after transplantation. In the tooth root transplantation group, periodontal ligament had established at 2 weeks, partial root resorption was observed at 4 weeks and dentin blocks exhibited obvious ankylosis at 6 weeks after transplantation.
These results suggested that the implantation of cultured periodontal ligament cells had the regenerative potential of the periodontal ligament and cementum. But even in the experimental group, dentin blocks exhibited ankylosis in all cases at six weeks after transplantation, that was similar to the tooth root transplantation group. This suggests that an occlusal function or similar kinds of function may be involved in the process of regeneration after implantation.

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The aim of this study was to assess the response of peri-implant and periodontal tissues to accumulated plaque in dogs. Six mongrel dogs were used in this study. The mandibular premolars were extracted on both sides in each dog. Three months later, either four Brånemark System® (fixture, n=12) or Integral® (implant body, n=12) were placed in the edentulous area of each dog and after another 12 weeks, abutment connection was performed. The mandibular first molars were used as controls (n=12). A plaque control regimen was main tained for 30 days until superstructure was placed. Then it was terminated to allow gross plaque accumulation. The dogs were allowed to accumulated plaque during a period of 6 months after the termination of the plaque control. Biopsies from the teeth and implant sites were harvested and processed for histological evaluation. The results from histological examination revealed that all implants were characterized by the presence of a large infiltrated connective tissue in the peri-implant mucosa, and loss of alveolar bone. Although the natural teeth had accumulated plaque, no significant histologic change could be found in the periodontal tissues. These results indicate that plaque may be a tissue-destruction factor against periimplant tissues.

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The cytotoxicity of tetracyclines and pyridonecarboxylic acids was examined with cultured human keratinocytes from gingival tissues by the uptake of neutral red (NR) assay. The NR assay is a quantitative in vitro assay that distinguishes between viable cells and damaged or dead cells. Cultures from different individuals were established, and secondary cultures in serum-free medium were used. The cytotoxicity of tetracyclines and pyridonecarboxylic acids was determined from the dose-response curves of inhibition of NR uptake in cells treated with the drugs for 2 days. As a quantitative measure of cytotoxicity, NR 50, the concentration of the drugs that resulted in a 50% decrease in NR uptake relative to untreated controls, was extrapolated from dose-response curves. The rank-order of cytotoxicities (NR 50) of tetracyclines was demeclocycline > minocycline> tetracycline > chlortetracycline. The cytotoxicity of demeclocycline, minocycline or tetracycline was 378-, 23.0- or 12.1- fold that of chlortetracycline, respectively. The rank-order of cytotoxicities of pyridonecarboxylic acids was tosufloxacin tosilate> lomefloxacin ≈ enoxacin ≈ sparfloxacin> ofloxacin. Tosufloxacin tosilate was 17. 3 times more cytotoxic than ofloxacin. Lomefloxacin, enoxacin or sparfloxacin were 3.8-5.1 times more cytotoxic than ofloxacin. Little cytotoxicity was observed when the cells were treated with either>10μg/ml of tetracyclines or>6μg/ml of pyridonecarboxylic acids.

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The purpose of this study was to establish polishing methods, with a rubber cup or a polishing brush in combination with various polishing pastes, pumice powders and water, to remove plaque on titanium surfaces. The material used in the present study was a titanium plate with 99.5% titanium. A titanium surface was painted with Magic Ink. After the paint was removed with various polishing methods, the roughness of the surface was measured according to JIS, surface roughness. Titanium plates were set in the retainers which were placed on both maxillary buccal sites. After dental plaque formation, the plates were carefully removed from the retainers and were polished by various methods. Titanium surface and plaque removal were observed by scanning electron microscope, and then given a Plaque Score. No difference in titanium surface roughness was observed between the various polishing methods (p<0.05). Statistically significant differences in titanium surface properties and plaque removal conditions were found between controls and each polishing method (p<0.05).
There various polishing methods were shown to remove dental plaque by in a short time, and produced no major titanium surface alterations. Polishing with a polishing brush was more effective than polishing with a rubber cup.

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Prostaglandin (PG) E₂ is known to play significant roles in the local control of bone metabolism and to stimulate both formation and resorption of bone in vivo and in vitro. We previously reported a stimulatory effect of PGE₂ on the formation of bone nodules (BNs) in cultures of fetal rat calvaria RC) cells and we clarified that PGE₂ at 3× 10^-8M markedly promoted the differentiation of osteoprogenitor cells in cultures of RC cells. In this study, we investigated the action of PGE₂ on BN formation by mature osteoblasts using an RC cell culture system. Treatment with PGE₂ at 3×10^-8M resulted in an increase in the ratio of BN mineralization which was initiated by organic phosphate. However, PGE₂ did not affect alkaline phosphatase activity during the whole experimental period. SDS-PAGE profiles showed that PGE₂ at 3×10^-8M increased the content of Ca²⁺-binding proteins (58 and 62 kDa) in mineralized BN matrix. Western blot analysis revealed that the increased proteins were osteopontin. These data suggest that PGE₂ increased mineralization by stimulating the cellular function of mature osteoblasts in cultures of RC cells.

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We examined the incidence of fibrotic gingival hyperplasia in 42 cardiac patients treated with nifedipine (Adalat ®) during a period of 3 years or more (average: 6.5±2.5y). The mean age of patients (23 males and 19 females) was 65.8±10.0 years. Periodontal examinations were comprised of recording the probing depth, plaque control record, number of remaining teeth and color photograph of gingiva.
Only 2 patients revealed characteristic gingival hyperplasia. The degree of periodontal parameters examined, probing depth, plaque control record and number of remaining teeth, in addition to accumulated dose of drug, were not strongly associated with the appearance of gingival hyperplasia induced by nifedpine.

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The purpose of this study was to establish a new measurement system using a unit pulse technique which could evaluate tooth mobility objectively and conveniently. Periotest ® was used as a percussion instrument. A light-weight accelerometer (0.15g) was used for detection of the resonance frequency from a tooth and associated periodontal tissue. Analysis of data was performed by FFT (fast Fourier transform).
The resonance frequency, Periotest value and tooth displacement by 250gf were measured in an experinental model with an artificial tooth and periodontal tissues. The resonance frequency was also measured in 7 maxillary central incisors of 6 male adult volunteers with healthy periodontal tissues, 25 to 35 years of age (mean: 29.8 years).
In the experimental model, the resonance frequency obtained by this system showed a high correlation with the height of the artificial supporting bone, with the width of the artificial periodontal ligament and with the elasticity of the artificial periodontal ligament. The displacement of the tooth showed similar results. The periotest value did not correlate with the width of the artificial periodontal ligament when the height of the artificial supporting bone was high. In vivo the average resonance frequencies F1 and F2 were 1, 300±207 Hz and 2, 805±366 Hz, respectively. The reproducibility of the resonance frequency obtained by the system was high. From above results, the measurement system used in this study was useful for the objective evaluation of tooth mobility.

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The purpose of this study was to evaluate whether our new measurement system for tooth mobility using unit pulse technique was effective for clinical use. In the previous basic study, our unit pulse technique used a light-weight accelerometer and Periotest ® for objective evaluation of tooth mobility. In the present study, the clinical values of this measurement system were examined.
The resonance frequency was measured in 15 maxillary central incisors of 9 adult volunteers with periodontitis, 31 to 76 years of age (mean: 52.9 years). The resonance frequency was also measured in 7 maxillary central incisors of the 6 adult volunteers with healthy periodontal tissues, 25 to 35 years of age (mean: 29.8 years) after a jiggling force was applied to teeth.
In subjects with periodontitis, the resonance frequency F 1 obtained by our system showed a high correlation with the degree of alveolar bone resorption and the width of the periodontal ligament. In subjects with healthy periodontal tissues, the resonance frequency F 2 shifted significantly to the low frequency range with an extended period of jiggling force. These results suggested that the system used in our study is useful for the clinical examination of periodontitis and can evaluate slight changes in periodontal tissues with occlusal trauma.

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The purpose of this study was to establish a preventive program for periodontal disease associated with adult mass dental examination. Periodontal status was surveyed by using CPITN among 900 employees (mean age: 41.2) in Hokkaido. A questionnaire was given to 411 of the subjects. The questionnaire included smoking habits, personal awareness of periodontal disease, history of periodontal treatments and habits of oral hygiene. The influence of these factors, PH. and C. I. on CPITN was analyzed by using Hayashi's Quantification to determine the essential factors of the preventive program and to evaluate the possibility of selecting a high risk group from the questionnaire, who may require intensive preventive measures. The following results were obtained. The prevalence of periodontal disease was 84.5%. 82.2% of subjects showed a CPITN of more than 2. Therefore it was suggested that oral hygiene instruction alone was ineffective and that scaling was neccesary for the prevention of periodontal disease. A significant correlation was found between CPITN and oral hygiene index, while smoking habits and other factors had little influence. Selection of a high risk group from the quesionnaire was not possible. These results suggested that a preventive program of periodontal disease combined with adult mass dental examination should be performed in all subjects irrespective of other factors (ie., awareness of periodontal disease and oral hygiene habits) and preventive measures (ie., oral hygiene instruction, scaling and recommendation to a dental office) should be taken according to periodontal status.

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In order to establish a preventive program for periodontal disease in association with adult mass dental examination, we surveyed the employees of 14 companies in Hokkaido from the previous study. According to the CPITN-Max value, the preventive measures for periodontal disease were recorded including oral hygiene instruction, scaling and recommendation to a dental office.
The purpose of this study was to evaluate the effectiveness of our preventive program for periodontal disease by using Hayashi's Quantification type II. This preventive program was performed during and after mass dental examination. The same subjects were re-examined after 1.5 to 2 years in a follow-up examination.
The results were as follows:
1. At the first examination, 187 out of 225 subjects were found to require preventive measures, but only 111 subjects (59.4%) received them.
2. Our preventive measures should be adopted during mass dental examination, because some subjects who were contacted subsequently failed to come to receive our preventive measures.
3. CPITN was significantly improved by this preventive program for periodontal disease.
4. Hayashi's Quantification analysis indicated that scaling was the most effective factor in improving the CPITN value.
5. One time oral hygiene instruction alone at the first examination had little effect.
6. Recommendation to visiting a dental office had little effect.

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The present case report describes the outcome of collapsed bite with advanced periodontitis. A 47-year-old male with a noncontributory medical history was referred to our hospital in August of 1984, with a chief complaint of gingival swelling of the maxillary molars. A complete oral examination revealed the pronounced loss of periodontal attachment in most parts of the dentition, anterior spacing and crowding with the collapsed bite and the development of reduced height of the bite. Initial therapy was started with diagnosis of advanced adult periodontitis. Following completion of the initial therapy, periodontal surgeries for the deep pockets were performed on the most teeth. The number 2, 3, 4, 13, 14, 15 and 20 teeth were extracted during the periodontal surgical phase. After healing of the periodontal tissue, orthodontic treatment based on edgewise technique including bite opening, correction of crowding and space closure, was applied to reestablish esthetic and physiologic occlusion. After 1 year of orthodontic treatment, a maxillary lingual plate and a mandibular adhesion bridge were cemented. Following reevaluation of both the periodontal condition and craniomandibular status, the patient was recalled for maintenance care for about 12 years from an initial visit. In the maintenance phase, only 2 teeth were extracted and the prosthetic reconstruction was done. Mean probing depth and alveolar bone loss were improved from 4.1 mm and 63.8% to 2.6 mm and 45.9%, respectively. An attachment level of 6 mm has been maintained since 1989. As shown in this treatment procedure, we suggest that the comprehensive approaches to bite collapse with advanced periodontal breakdown may inhibit the progression of periodontal disease.

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