Inhibitory effects of YM175, a bisphosphonate, on the progression of experimental periodontitis in beagle dogs.

This study examined the efficacy of YM175 [disodium dihydrogen (cycloheptylamino) methylene-1, 1-bisphosphonate] in reducing alveolar bone loss caused by experimental periodontitis in beagle dogs. Thirty-six dogs were used and divided into 6 groups. Periodontitis was induced in 30 dogs (groups 2-6) by ligating the bilateral mandibular third and fourth premolar teeth with silk ligatures and by feeding a soft diet. Six dogs were sham-operated (group 1). Saline (placebo), flurbiprofen (0.02 mg/kg) and YM175 (0.01, 0.1 and 1.0 mg/kg) were administered to the dogs (groups 2-6) 5 d/wk for 25 wk. Radiographic and morphometric analyses were performed. In placebo-treated animals (group 2), the ligation caused a significant decrease in the alveolar bone height by 0.57 and 1.91 mm at 2 and 25 wk, respectively. YM175 (1.0 mg/kg) prevented the decrease in bone height by 47 and 31% at 2 and 25 wk. YM175 (0.1 mg/kg) and flurbiprofen tended to prevent bone loss after 15 wk. Although the ligation elicited no significant change in bone mineral density, it significantly decreased bone volume. YM175 (1.0 mg/kg) and flurbiprofen tended to increase the bone volume. The number of formative or resorptive Haversian canals and the bone turnover through the periosteal bone surface were increased by the ligation, indicating the increased turnover of the cortical bone. YM175 (1.0 mg/kg) reduced the increased bone turnover. The gingival index was maximally increased at 2 wk and was suppressed by YM175. These results suggest that YM175 prevents alveolar bone loss by reducing the increased alveolar bone turnover in dogs with periodontitis.

[Microbiological study in clinically characterized rapidly progressive periodontal disease].

Samples of subgingival bacteria were collected from two sites of offanteriors with greater than or equal to 6 mm deep pockets in each ten patients in a clinically characterized rapidly progressive periodontal disease. The purpose of this investigation was to study the predominant cultivable microflora at pre- and post-periodontal treatment stages, in order to monitor the clinical effects of periodontal treatment and possibly to determine the presence or absence of active disease. "Non effective site" was defined as little elimination of periodontal pocket. Some patients responded remarkably well to root curettage. However the subgingival flora of effective sites, which had been successfully treated and maintained over a period of three weeks, was still significantly different from the subgingival floras of people with healthy gingiva. The predominant cultivable microflora of diseased lesions at the pre-treatment stage, in which a similar proportion of microbiota were detected on both sites in each patient, were significantly increased proportions of Bacteroides sp., B. intermedius and B. gingivalis. Although B. gingivalis has been implicated as the etiologic agent of the disease, to which marked antibody response has been found in periodontal pockets, there were decreased proportions of B. intermedius and B. gingivalis after treatment, compared to pre-treatment stage. The results showed that non-effective lesions were associated with subgingival microflora which were populated by higher proportions of B. intermedius and E. corrodens. H. actinomycetemcomitans were detectable during the experimental periods in all sites. It was possible to indicate progressing periodontitis by examining these microflora at the pre-treatment stage. However active or progressing disease in young adults might represent not only an overgrowth of existing organisms but also an abnormality in host resistance.

[The clinical and etiological study on juvenile periodontal disease].

Seven juvenile periodontally diseased patients were evaluated for clinical, microbiologic and local or systemic host factors. Three patients showed the localized from of periodontitis clinically and radiographically and by deep periodontal pockets associated with the molars and incisors. Four were in the generalized froms, in which in most cases all teeth were affected. The results in both diseased froms on the predominant cultivable subgingival microflora, the composition of which was not different from that in adult periodontitis, consisted of significantly increased proportions of Gram-negative anaerobic rods, Bacteroides sp. and B. gingivalis, Haemophilus sp. and H. actinomycetemcomitans were detected in 1/3 of the localized and 2/4 of the generalized periodontitis. They were of no value in distinguishing activity that enhanced disease in the generalized from. Elevated serum IgG responses were noted with B. gingivalis. No markedly functional abnormalities of neutrophils from peripheral blood have been demonstrated, however it might function with systemic factors, like an insulin-dependent diabetes. Morphologic characteristics of the oral and periodontal tissue in localized periodontitis were that the pattern of destruction was confined to specific teeth groups characterized by extensive the bucco-lingual width ratio of the dental crown to alveolar bone width. These observations indicate that the generalized form of juvenile periodontitis lesions were associated not only with the presence of subgingival bacteria, but also with conditions such as local morphologic and systemic or constitutional factors, individual variation in relation to destructive and protective aspects of the defense mechanisms.

[Effects on repaired bone with hydroxyapatite by the changes of dynamics in the alveolar bone].

Hydroxyapatite (HAP) is regarded as a useful material for grafting in procedure aimed at bone replacement. The purpose of this investigation, as a basic experiment, was to demonstrate bone formation in the dental extraction sockets during orthodontic movement of the neighboring teeth in the initial wound healing phase, and to clarify effects of indirect forces through alveolar bone on repairing bone in extraction sockets. Secondary we examined changes in the bone formation in the sockets during the tooth movement which were plugged with HAP granules and compared with the repairing bone without HAP. For this study seven dogs were used and were scarificed according to a schedule yielding observation periods up to 6 weeks. The animals were injected continuously with tetracycline during the experimental period. Undecalcified mesio-distal specimens 65-100 microns of thickness were prepared at first for microradiogram and then subjected to fluorescence microscopy. The observations indicated that the bone formation seemed to be accelerated with HAP implantation, however the alveolar trabeculae around HAP were developed during the tooth movement less than the control. The tooth movement in implanted sites was faster than in the sites without HAP implantation. The decreased response on alveolar bone formation, incident to experimental tooth movement into extraction sockets, was found in the pressure area, mesial part of socketswall. It might be induced by excessive stress during the tooth movement, amplified by the change of bone repairing due to the HAP implantation.

[Effects of composite resin materials on gingiva and pulp].

Composite resin materials are now widely used for dental therapy. The purpose of this study was to clarify the effect of composite resins on gingiva and pulp in case of application of them for temporally splint in periodontal treatment. 60 teeth in 6 female dogs ranging between 1 and 2 years of age with healty teeth and gingiva were divieded to 4 groups; (1) 12 teeth, controls; (2) 12 teeth, self-cured composite resin (Clearfil F II, CF II); (3) 18 teeth, light-cured resin (Belfel LX, BLX), curing time 20 sec. and (4) 18 teeth, BLX, 40 sec., and then 48 class V composite resins were restored supragingivally. The experimental procedure were carried out for 5 days and 30 days. Histopathological observations of 60 teeth inclusive of controls were made by applying to specimens with Hematoxylin eosin staining. For the materials and time periods in this study it was found that; 1. Light-cured composite resin was superior to self-cured composite resin on handlings. 2. There were no significant differences in periodontium between the experimentals (BLX, CF II) and controls in 5 days. At the 30 days the histologic score showed more gingivitis for the experimental teeth than for the controls (BLX-40 greater than BLX-20 greater than CF II greater than Cont.). 3. At 5 days hyperemia occurred in some cases of experimentals (both BLX and CF II). The appearance of predentin and changes of odontblastic layer were observed slightly in 30 days. But there were no significant differences between BLX and CF II. 4. The result suggested that applying to composite resin materials for temporally splint, both gingiva and pulp have to be protected.

[Group therapy for periodontal disease. 1. Practical application of CPITN and the effects of group therapy].

The purpose of this study was to determine the oral conditions in bakery workers (473 subjects) in addition to the screening system of O'Leary and CPITN, designed for rapid recording of the level of periodontal treatment needs, and to evaluate the periodontal treatments, managed by professional cleaning (scaling) and oral hygiene instruction. The assessment of the prevalence and severity of periodontal disease and resultant treatment needs in this group showed the characteristics of chronic periodontal disease in an advanced stage in persons aged 25-29 and 50-54. 228 patients were selected for treatment for nine months and examined accurately for their periodontal condition. 137 patients continued the following group therapy three times and were reevaluated. Following the group therapy, the oral hygiene status and subjective symptoms of bleeding were improved in all groups, the effectiveness of the treatment on sextants, scoring cord three, four, showed markedly high. To achieve the treatment with few individual appointments, it is necessary to increase our knowledge of how these groups live, depending on the diversity of life style and the differences in ethnic consciousness.

[Morphological study of periodontal tissues in the initial stage of periodontal disease. Part 1. Application of a morphological measurement and a system for evaluating the periodontal status].

The functional aberration of occlusion, based on the morphology of the alveolar process, causes chronic irritation of the periodontium in addition to the concomitant effect of other local environment factors. This investigation was designed to study the role of morphological characteristics in the periodontal disease process. The periodontal health of 22 subjects was recorded by clinical and roentgenological measurements of the loss of periodontal tissue. The criteria for this selection were no loss of or a crowding of adjoining teeth and no disharmony in occlusal contact. Morphological data were measured around the premolars and molars of lower jaws on the study models individuals, in bucco-lingual width of the alveolar bone in relationship to the width of the crown and the sagittal figure of the Spee curve etc. by using a three-dimensional analyzer. The subjects were categorized as Type II when the records indicated a ratio of the crown width/bone width of 1/1.2. Types I and III, depended on a greater and smaller ratio, respectively. Type W symbolized the alveolar process, of which the interproximal bone showed a considerable curvature mediodistally. Type F showed a flat pattern. The sagittal figure of the Spee curve was divided into four patterns: Pattern A or B, when the cusp of the canine and first premolar leveled over or on the occlusal plane; Pattern C, when the cusp of the canine leveled over and the first premolar under the occlusal plane, and Pattern D, when all cusps, canine, premolar and molar, were under the occlusal plane. The distance from the occlusal plane to the deepest point of the Spee curve was divided into four groups: Pattern a, when the distance was 0-1.0 mm, Pattern b, 1.1-2.0 mm, Pattern c, 2.1-3.0 mm and Pattern d, 3.1-4.0 mm. These results suggest that the morphological evaluation is a useful diagnostic indicators on a rational basis. The morphological characteristics might be related to the presence of periodontal disease and allowed to speculate the pathological changes in established stage, and also to the response to periodontal treatment in the initial stage of periodontal disease.

[Morphological study of periodontal tissues in the initial stage of periodontal disease. Part 2. Analysis of morphological measurement and status of periodontal disease].

The morphological characteristics of periodontal tissue in periodontal disease have been interpreted differently by a number of clinical observers. Many have reported that the malposition and functional malocclusion of teeth is injurious to the periodontium. We reported in Part I that a system for evaluating periodontal status was developed for the diagnosis and management of the interproximal area at the initial stage of bone resorption. The patient group consisted of 36 adults, from 21 to 55 years of age. The severity score represented the calculated loss of periodontal support tissues: loss of alveolar bone, evaluated roentgenologically, bone level and pattern in vertical and horizontal form, periodontal pocket and gingival inflammation. Because poor oral hygiene and other factors caused swelling by gingival inflammation, we obtained study specimens from patients with chronic periodontal disease after a few tooth brushing instructions, and scalings during initial therapy in order to detect initial and established pathological changes in periodontal tissue. The purpose of this study was to clarify the relationship between periodontal disease status and morphological diagnostic indicators and different degrees of harmony and disharmony in the lower jaw. In all age groups the average percentage of bone loss and intraosseous defects tended to be higher in the groups categorized as Type III and Type F, and in the area that showed a very deep concave Spee curve to the occlusal plane in Pattern D. We considered that these morphological characteristics might be of secondary importance for diagnosis. Oral local factors were the primary extrinsic factor in the pathogenesis of horizontal and vertical interproximal bone absorption in the area of the premolars and molars.

The inhibitory effect of chlorhexidine digluconate on dental plaque formation. A scanning and transmission electron microscope study.

The purpose of this study was to determine the effect of chlorhexidine digluconate mouthrinses on the development of dental plaque in man. The dental plaques were formed on strips of triacetylcellulose film (TAC), which were attached to the lingual surfaces of the mandibular incisors by silk suture thread on 20 human volunteers. Differences in the degree of plaque formation on TAC films after 2, 4 and 24 hours were observed in placebo vs. chlorhexidine treated samples using both scanning and transmission electron microscopy. It was found that (1) solutions containing chlorhexidine digluconate and lactic aluminum have an inhibitory effect of the development of dental plaque on the TAC film as evaluated by electron microscopy, (2) the TAC film was a convenient model for the study of early dental plaque formation by electron microscopy, (3) the three types of pellicle reported by Tryggve Lie (1977) were also observed, (4) the method enabled evaluation of the bacterial accumulation of TAC films. After 2 hours, there was no visible difference in the bacterial accumulations on placebo or chlorhexidine treated films. After 4 and 24 hours considerable differences were observed.