In an attempt to promote periodontal tissue regeneration following periodontal surgery, an experimental study was conducted by applying the guided tissue regeneration (GTR) technique to a cross-linked atelocollagen membrane. The palatal gingiva of maxillary first molars of rats were dissected and the cementum was removed by curettage. An atelocollagen membrane was implanted into the site of dissection in the experimental group, while the control group received no implant. The wound healing processes in two groups were examined by histopathological methods, including histometric analysis of the cells and histological measurement of the regenerated periodontal tissue, 1, 3, 5, 7, 14 and 21 days, and 1, 2, 3 and 4 months after the implantation. The results were as follows.
1) Implantation of the atelocollagen membrane did not enhance or prolong the inflammatory reaction, indicating possible involvement of inflammatory cells and macrophages in the membrane absorption. 2) In the experimental group, epithelial downgrowth was markedly inhibited and fiber bundles of the gingival connective tissue were clearly arranged vetical to the root surface. 3) The experimental group showed a significant increase in new cementum formation 2 months after surgery compared with the control group. Root resorption was seldom observed in either group during the study period. The above results indicate that the GTR technique using an atelocollagen membrane may provide an effective method to promote periodontal tissue regeneration after periodontal surgery.

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The purpose of this study was to examine the process of bone destruction and also to examine the ultrastructural features of the cells and the resorbed sites of bone matrix in experimental periodontitis.
To induce the periodontitis, a defect was prepared with a endodontic reamer in the proximal surfaces of the upper 1st and 2nd molars of rats.
The process of the bone resorption was examined histopathologically once a week for 3 week. Transmission Electron Microscopy (TEM) and Scanning Electron Microscopy (SEM) were used to examine the cells and the bone matrix using the specimens taken 2 or 3 weeks after the start of the experiment.
The alveolar bone resorptions of interdental areas were observed 2 weeks after starting the experiment and it continued to progress longitudinally. After 3 weeks, concave bone loss appeared on the buccal surfaces of the bone. The resorbed bone surface revealed by TEM typical osteoclasts, macrophages and mononuclear cells resorbing collagen fibrils. These cells resorbing collagen fibrils which worked with the osteoclasts appeared frequently in resorbed sites. Numerous osteoblasts appeared on the resorbed area. However, judging from their undeveloped organelles, their function seemed to remain inactive and unproductive. SEM showed many resorbed lacunae in the alveolar bone in interdental areas and the differences in the ultrastructural features of the resorption lacunae were distinctive. These finidings suggest that the massive and rapid bone resorption in experimental periodontitis is the result of increased osteoclastic activity and depressed osteoblastic activity. The different ultrastructual features of each lacunae were results of the resorbing stage.

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The purpose of the present studies was to examine the healing process following the free gingival autograft placed on the recipient bed either with or without periosteum in 54 adult mongrel dogs with healthy periodontium. A recipient bed was prepared on denuded alveolar bone in a definite portion of the attached gingiva of the right maxillary canine tooth, and the graft was taken from the attached gingiva of the left maxillary canine and transplanted in the recipient bed. Morphological changes were observed by means of vascular corrosion casts on the postoperatively 3rd, 5th, 14th, 21th, 28th, 42nd, 56th and 84th day. The healing process following the free gingival autograft on the denuded alveolar bone showed that this graft survived in its margin by recirculation from the cut margin of the recipient bed, and in its center the necrotic tissue changed to granulation tissue, which gradually cicatrized. This was different from the healing process following the free gingival autograft on periosteum, in which the graft was survived entirely by recirculation from the vascular plexus of the periosteum on the recipient bed. This may help to restore the function proper.

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The purpose of this study was to analyze antigens of Actinobacillus actinomycetemcomitans. Fifteen hybridomas producing monoclonal antibodies (MAbs) against A. actinomycetemcomitans strain Y 4 were obtained. These hybridomas were divided into three groups (Group 1, Group 2 and Group 3) on their MAbs' specificity. The MAbs (MAb Sl-S8) produced by Group 1 hybridomas reacted with serotype b-specific antigen of A. actinomycetemcomitans. The MAbs (MAb L1-L3) produced by Group 2 hybridomas reacted with lipopolysaccharides (LPSs) of all serotypes of A. actinomycetemcomitans.
The high-molecular-weight peak (peak A) and the low-molecular-weight peak (peak B) were separated by gel-filtration of the phenol-water extract (PWE) of strain Y 4. MAb S 5 reacted with peak A, and MAb L 2 reacted with peak B. Peak B bound to a polymyxin affinity column, but peak A did not. These findings indicate that peak A was serotypespecific antigen and peak B was LPS.
MAbs P 1, P 2, P 3 and P 4 produced by Group 3 hybridomas reacted with 81 kDa, 64 kDa, 64 kDa and 40 kDa protein antigens, respectively. Preincubation of strain Y 4 whole cells with MAb P 3 inhibited significantly the adherence of the tells to human buccal epithelium cells (HBECs). These findings suggest that the 64 kDa protein antigen might participate in the adherence of A. actinomycetemcomitans to HBECs.

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The therapeutic effect of superoxide dismutase SOD) and the role of O₂^- were assesed on 3 groups of Wistar rats (total 115). Fifty-four received injections of gingival bacteria or of anaerobically cultured rat dental plaque in their peritoneum, then received both intravenous (i. v.) and intraperitoneal (i. p.) injection of SOD. The rats were killed 48 hours later to collect their peritoneal exudate for cell count and for acid phosphatase activity assessment. Twenty-six received injections of bacteria in their footpads, after which SOD was administered intravenously. These rats were killed at 6 hours, 48 hours and 1 week respectively for histological examination. The gingiva of 26 rats were incised to create artificial lesions. The rats were killed at 24 or 48 hours and examined histologically. The nine remaining rats were used as controls (untreated) for the 3 experiments.
The results of the 3 experiments showed that: Injection of SOD reduced exudation and acid phosphatase activity enhanced by the injection of B. gingivalis, at dosages of 1, 5 mg/kg i. p. and 5 mg/kg i. v., but 10 mg/kg i. p. had no apparent effect; i. v. injection of SOD had inhibitory effects on cell infiltration of B. gingivalis into the footpad, and the increase in fibrin and fibroblast formation through time was greater in SOD-administered rats; a decreased cell infiltration rate and increased fibrin network, fibroblast proliferation and gingival tissue regeneration occurred in specimens with artificial lesions given SOD.
Apparently SOD has a curative effect on both inflammatory reaction induced by B. gingivalis and periodontal wound healing.

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It has been supposed that lipopolysaccharide (LPS) derived from the gram negative bacteria of subgingival plaque is one of the important etiologic factors in periodontal disease.
The purpose of this study was to detect specifically the LPS from Bacteroides gingivalis (Bg) and to determine the effects of gram-positive bacteria on LPS in culture supernatant of Bg.
Enzyme-linked immunosorbent assay was used for specific detection of LPS from Bg. LPS of Bg could be measured in concentrations as low as 4 μg/ml.
LPS of Bg was not detected in gingival crevicular fluid from periodontal disease patients.
There were no significant differences in the concentration of LPS between the culture supernatant of Bg and co-cultivation of Bg and gram-positive bacteria.
In this stuay, gram-positive bactria had no effects on release and degradation of LPS in the culture supernatant of Bg.

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We examined PGE₂ synthesis using inflamed and non-inflamed GCF PMNs and PB PMNs in the presence and absence of certain stimulators. The basal levels of PGE₂ release from GCF PMNs isolated from ligature-induced gingival sulcus with a GI value over 2.2 were significantly lower than those from GCF PMNs isolated from sham operated sites with a GI value below 2.1 Levels were comparable to those from PB PMNs isolated at each experimental period, indicating that the amount of PGE₂ synthesized by GCF PMNs is not correlated exactly with the severity of periodontitis.
Calcium ionophore A 23187 stimulated PGE₂ synthesis by all PMN preparations. When compared to those with inflamed and non-inflamed GCF PMNs, stimulation was higher with PB PMNs. However, the chemotactic factor fMLP inhibited the synthesis by inflamed and non-inflamed GCF PMNs. PGE₂ synthesis by PB PMNs isolated after periodontal operation was stimulated by the drug, but those cells isolated before the operation did not respond.

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Root planing is one of the most important procedures in periodontal treatment. However, there are no objective clinical signs to indicate completion of this procedure. The purpose of this study was to examine the friction sound produced by curettes and root surfaces during root planing and to test the possibility of utilizing the sound changes as an objective parameter for evaluating completion of the procedure. The study consisted of a clinical and laboratory experiment.
Seven periodontally diseased teeth were utilized in the clinical trial. During scaling and root planing with the Gracey curette, the friction sound was clinically analyzed with a sound spectrograph. The root surface, in situ, was observed by scanning electron microscopy (SEM) with the replica technique.
Twenty-one periodontally diseased teeth were used in the laboratory study. Root planed surfaces were classified as pre-root planed and post-root planed according to their friction sounds during root planing. Each surface was examined by the following methods: 1) measuring root surface roughness 2) SEM observations 3) determination of number of adherent cells by the cultured fibroblast technique.
As a result, post-root planed surfaces were well root planed as evaluated by SEM observations and the profilometer. Similarly, adherent cell counts were increased on post-root planed surfaces.
These results indicated the possible usefulness of friction sound analysis to judge the completion of root planing.

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The purpose of this study was to clarify the relationship between the lamellar structure and the fibrous components of cementum. Freeze-fracture specimens and ground sections of the human molar cementum were treated with acid-and/or alkalinesolutions, then examined by scanning electron microscopy. Both of the layers of Sharpey (extrinsic) fiber and matrix (intrinsic) fiber were distinguished in freeze-fracture specimens and ground sections, but no lamellar structures appeared. For the first time, the lamellae isolated with narrow grooves were clearly observed on the ground sections that were treated with 5% sodium hypochlorite for 60min followed by 0.5-1.0 M hydrochloric acid for 30-60 sec. In addition to the two fiber-layer types, the mixed fiber layer containing both components of matrix and Sharpey's fibers was classified, and the lamellar arrangement of matrix fibers was also revealed. When the hypochlorite treatment time was prolonged for 120min, the lamellar structures were evident.
Our results show that those treatments may resolve the regions of physiological hypomineralization related to the incremental lines running parallel to the cemento dentinal junction and the lines of discontinuity of the fibrous components.

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The regenerating process in tissue around periodontally diseased teeth (PDTs) and non-diseased teeth (NDTs) was studied with clinical and histological analysis following flap surgery .
PDTs were prepared in the premolars of 7 beagle dogs by which surgically denuding the root surfaces by removing the alveolar bone. The denuded sites were covered with gutta-percha plates and gingival epithelial tissues and exposed to the oral environment for 4 weeks. Then flap surgery was performed on the PDTs. As control sites: the root surfaces of the NDTs were denuded by removing the alveolar bone at the time of flap surgery. The root surfaces of the PDTs and NDTs were planed with curette scalers at one root site but not at the other site . Clinical and histopathological findings were evaluated at fixed intervals for 32 weeks after surgery. Results of observation were as follows.
1. In the clinical evaluations: the gingival inflammation index: probing depth and attachment level were improved in the root plaining (PR) group of both the PDTs and the NDTs: but in the non RP group of PDTs there was no improvement.
2. In the histologic observation: the position of the gingival margin: length of regenerated junctional epithelium: depth of gingival sulcus and the level of connective tissue attachment in the RP groups recovered in both the PDTs and the NDTs but not in the non RP groups.

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Two established osteogenic cell lines (NY, MC3T3-E1) were used in vitro to determine the biocompatibility of glass ceramics and their effect on initial calcification of osteogenic cells. Morphological study of the cell under the phase-contrast microscopy and histochemical staining were applied as follows. First, glass ceramic granules were placed in 60mm dishes, and cells were suspended in the dishes in α-MEM supplemented with 10% FBS (basic medium) or medium with 50μg/ml of L-ascorbic acid added. After 8 or 14 day of culturing, calcium formation was tested by von-Kossa's staining. Also, alkaline phosphatase staining was performed by the azo-dye method. As controls, cultures in dishes without glass ceramic granules were stained at the same time. The results obtained in the experimental culture were as follows.
1. Phase contrast microscopy showed that contacts with glass ceramics did not cause cellular death or degeneration.
2. In both cell cultures with the glass ceramics the von-Kossa reaction was positive as early as the 8th day.
3. The alkaline phosphatase reaction on the 8th day occurred only in MC3T3-E1. The reaction was localized on fibroblastic cells which proliferated three-dimentionally around glass ceramics, and on small polyhedral cells situated relatively for apart from the ceramics.
4. On the 14th day, the MC3T3-E1 formed large nodules around the glass ceramics, and they were stained uniformly positive by von-Kossa's method. The alkaline phosphatase-positive cells extended spoke-like forms.
5. In medium with L-ascorbic acid, growth of NY was inhibited, After being cultured for 14 days, abundunt von-Kossa positive reaction was found around glass ceramics in both cells. In MC3T3-E1 on the 8th days, the alkaline phosphatase reaction was stronger with glass ceramics than with basic medium only.
On the contrary, in the control cultures of both cells there was negative von-Kossa reaction during the culture period. The above results showed that glass ceramic granules have the biocompatibility needed for bone grafts, and they facillitated calcification of MC3T3-E1 in culture.

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As mononuclear phagocytes have been implicated as important cellular elements in the process of bone resorption, we decided to study the relevancy of macrophage (Mφ) activities to bone resorption.
In this study, we investigated the phagocytic activity and activities of lysosomal enzymes of peritoneal resident Mφ from rats fed a high-sucrose diet (Diet 2000) to appreciate the effects of Diet 2000 on systemic and local factors. Minkin et al. have postulated that bone-derived chemotactic factors were released from foci undergoing resorption. And so, we examined the effects of the supernatant from alveolar bone cultures (Bone-sup) prepared from rats fed Diet 2000 on the activities of glycogen induced peritoneal Mφ.
As a result we observed mild alveolar bone resorption with slight inflammation when the rats were fed Diet 2000 for six months. In the periodontal tissue, we found inflammatory cell infiltration, destruction of the periodontal ligament, and lacunae in the alveolar bone due to resorption. The phagocytic activity of Mφ treated with Bone-sups was suppressed before the periodontal tissue, which is inflammatory condition such as alveolar bone resorption. Furthermore the phagocytic activity of resident Mφ taken from rats on the Diet 2000 was suppressed. After one month of the Diet 2000, the activity of acid phosphatase (AcP), a lysosomal enzyme of Mφ, was suppressed, but by six months it was enhanced. The activity of β-N-acetyl-D-glucosaminidase (NAG), another lysosomal enzyme of Mφ, was suppressed over the total period of Diet 2000 before the periodontal tissue was destroyed.
These findings suggest that the capacity for defense against infection by Mφ is suppressed when periodontitis is initiated by Diet 2000 feeding and that Mφ activities are influenced by some factors elaborated by cells in the alveolar bone.

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We investigated the immunohistochemical localization of the chondroitin sulfates (chondroitin-4 sulfate, -6 sulfate and dermatan sulfate) in demineralized rat periodontal tissue using monoclonal antibodies (2-B-6, 3-B-3). Also, fixative and demineralized methods were established using these monoclonal antibodies. The result showed that the most effective combination of fixative and demineralized methods was 2% glutaraldyhyde 1% paraformaldyhyde and 5% EDTA.
Chondroitin-4 sulfate and dermatan sulfate were widespread in gingival conective tissue and periodontal membrane, with an especially strong response of dermatan sulfate shown along collagen fiber bundles. Chondroitin-6 sulfate was located in peripheral blood vessels. In alveolar bone, chondroitin-4 sulfate and dermatan sulfate were found inside Hareversion canals, Volkman's canals and lacunae. Chondroitin-6 sulfate was localized at peripheral blood in alveolar bone. In cementum, chondorointin-4 sulfate and dermatan sulfate were found at lacunae of cellular cementum and a part of embedding Sharpey's fiber.

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Production of 9 enzymatic activities of 527 strains freshly isolated from periodontal pockets in advancing periodontitis were investigated. Of these isolates, two strains showed lecithinase activity on egg yolk agar plate. Collagenase, plasmin and lipase were produced by 28 strains, 26 strains and 22 strains, respectively.
Two lecithinase-producing strains were identified as Bacteroides intermedius. Nineteen strains of B. intermedius and 1 strain of Fusobacterium species produced lipase on egg yolk agar plate. All of the 28 collagenase-producing strains were B. gingivalis. B. gingivalis (20 strains) and non black-pigmented Bacteroides (6 strains) showed plasmin activity. These results indicate that Bacteroides species, mainly B. gingivalis and B. intermedius may exert an important influence on the exacerbation of the disease.

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We have established a method to observe circulation in a small area of the human gingiva. Reflected light photoplethysmographs (RLP) and transilluminated light photopletysmographs (TLP) were recorded from healthy gingiva in 2 young adults of twenties. A tungsten-lamp, connected to a stabilized power source, was used to illuminate the gingiva. The reflected or transilluminated light was collected using a fibre-optic bundle. A CdSe photoconductive cell was used as the photodetector. The ECG was recorded simultaneously.
The results were as follows:
1) RLP and TLP were both synchronous with the heart beat and showed a dicrotic-notched wave form.
2) When the light-collecting fibre was 0.5 mm from the surface of the gingiva, the dicrotic notch with TLP was clearer than that with RLP.
3) When the light-collecting fibre was placed less than 0.5 mm from the gingival surface, clear dicrotic notches were seen in RLP.
4) When the surface of the gingiva was covered with white opaque paint to prevent transilluminated light, definite dicrotic notches were observed with RLP.
5) RLP was produced mainly by the pulsation of the gingival surface, and the pulsatile movement of the tooth had a little effect on RLP.
6) RLP was consisted from the light reflected from the surface of the gingiva and also from the light reflected after penetrating some distance in the gingival tissue.

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It is important to defermine the changes in alveolar bone during periodontal treatments . At present, radiography is widely used to determine the changes . But small changes in alveolar bone cannot be detected on X-ray films. To detect these small changes, a direct observation system using γ-ray from ¹³³Ba was considered. Using a maltichannel analyzer, γ-ray absorption through the bone was detected in this method.
This method was compared with densitometric measurement on the films using sliced animal bone. The newly developed method detected the bone changes more accurately.
To evaluate the influence of soft tissue, Mix-D was used in both measurements. ¹³³Ba absorptiometry showed that soft tissue did not influence the measurement more than the densitometric method.

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We present studies for development of an enzymatic diagnostic method for periodontitis. A rapid and sensitive diagnostic method named SK-013 was provided by Sunstar Inc. to evaluate the peptidase activities specifically derived from periodontopathic bacteria such as Bacteroides gingivalis, Bacteroides forsythus and Treponema denticola and some strains of Capnocytophaga species. The results obtained indicated the specificity of the enzymatic reaction in this system.

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SK-013 was developed for rapid detection of the peptidase activity in subgingival plaque samples. The purpose of this study was to determine whether SK-013 could be a marker for the presence of periodontopathic bacteria including Treponema denticola, Bacteroides gingivalis and Bacteroides forsythus which produce trypsin-like enzyme.
Subgingival plaque samples were taken with 3 paper points from 10 clinically healthy sites and 30 periodontal diseased sites. The SK-013 activity of plaque sample was assayed and the cells of T. denticola, B. gingivalis and B. forsythus in the sample were counted by immunofluorescence technique. In diseased sites, both the SK-013 activity and the cell counts of these organi^sms were significantly higher than those in healthy sites. The proportions and cell counts of these organisms and the SK-013 activity were closely correlated with clinical parameters including Gingival Index, Plaque Index, and Probing depth. The correlation between the presence of these organisms and the SK-013 activity was significant. Correlation coefficients between the presence of T. denticola and the SK-013 activity were higher than those of others.
These findings indicate that the SK-013 activity is a useful indication of T. denticola, B. gingivalis and B. forsythus in subgingival plaque, and it could be used to diagnose periodontitis.

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There have been various laboratory methods for the microbiological diagnosis of periodontal disease. However, there have been some disadvantages in these methods.
In this study of the application of a chair-side test for microbiological diagnosis, the activity of peptidases in periodontal pockets of patients was examined by using the assay system SK-013. SK-013 consists of synthetic substrates and is capable of rapidly (in 15 min) evaluating the activity of specific peptidase from Treponema denticola and Bacteroides species. Using SK-013, we evaluate the correlation betweenthe enzymatic activity, clinical periodontal parameters and subgingival level of microorganisms, including phase contrast microscopy. We calculated the sensitivity and efficacy of SK-013 as a diagnostic indicator in the presence of Spirochetes and in periodontitis. A positive correlation were demonstrated between enzymatic activity, clinical periodontal parameters, the numbers of total cell count, Spirochetes, and M & S ratio. SK-013 was highly sensitive and efficacous (sensitivity: 92%, efficacy: 96%).
We concluded that the assay system SK-013 is a useful chair-side method for diagnosing periodontal disease.

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The purpose of the present study was to examine the diagnostic value of the SK-013 (Sunstar, Osaka) in evaluating the effect of initial preparation. The SK-013 is a highly sensitive reagent to measure peptidase activity specifically produced by Bacteroides gingivalis, Bacteroides forsythus, and Treponema denticola. Thirty-six sites in 16 periodontitis patients were monitored in this study. The clinical status of each site was assessed using the clinical indices such as gingival index (GI), plaque index (PlI), probing depth (PD), and bleeding on probing (BOP). The composition of subgingival microflora in samples was determined using phase contrast microscopy. Clinical, microbiological, and enzymatic examinations were made at five separate appointments, as follows: (1) at baseline prior to plaque control instruction; (2) 4 weeks following plaque control instruction; and (3) 2, 4, 8 weeks following scaling and root planing of periodontal sites. The results of these examinations were compared statistically. The correlation was positive between the total counts of bacteria including spirochetes and motile rods and the enzymatic activity identified using the SK-013. Also the enzymatic profile was highly correlated with microbiological findings other than clinical indices. These results show that the SK-013 is a clinically useful diagnostic method for assessing the effect of initial periodontal therapy.

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Samples of subgingival bacteria were collected from two sites of anteriors with. 6mm 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 postperiodontal treatment stages, in order to monitor the clinical effects of periodontal treatment and possibly to determine the presence or absence ofactive disease. “Non effectivesite” 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 exsting organisms but also an abnormality in host resistance.

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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 mechanism

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The purpose of this study was to investigate the variations in oral hygiene conditions after oral hygiene instruction.
We divided the patients with periodontitis into three groups according to the number of times oral hygiene instruction had to be given to achieve the O'Leary plaque control record (PCR) of 20%.
The first group was those who achieved PCR 20% quickly (early achievement group), The second group was those who achieved PCR 20% gradually but slowly (slow achievement group). And the third group was those who showed no progress at all (non achievement group).
Results showed that there were statistical differences among the average changes in PCR and residual plaque score (PS) of the teeth surfaces in each group.
Especially the early achievement group were significantly superior to the other groups in improvement of PS of mandibular lingual surface with one oral hygiene instruction.
We also have investigated differences in the probing depth, age and sex at initial treatment among these three groups. The average probing depth at initial treatment was significantly deeper in the non achievement group than in the early achievement groups, and there were more males than females in the early achievement and non achievement groups.

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The purpose of this study was to investigate the effects of different methods of brushing on plaque removal, using O'Leary's plaque Control Record during initial preparation.
The results were as follows:
. There were many1 40-50 year-old patients and they showed a 63.0 percent first visit Plaque Control Record average.
2. Many of the patients entering the clinic had periodontal disease in mild stages.
3. In most cases the toothbrushing methods were the Rolling method and the Modified Stillman's method. Of the patients, 73.5% achieved Plaque Control scores at the 20 percent level.
4. Of the patients who had achieved a Plaque Control Record at the 20 percent level, half of the patients instructed to brush using the Rolling method had developed moderate forms of periodontal diseases, and half of the patients instructed to use the Modified Stillman's method had developed mild forms of periodontal disease.
There is a close relationship between toothbrushing methods and the progression of diseases, and this trolled . shows that Plaque removal methods should be con-

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The effects of ultrasonic scaling in combination with povidone-iodine solution were examined clinically.
The results obtained were as follows:
1. Three days after instrumentation, significant improvement was found in all experimental groups. Thereafter the improvement was at the same level and backing in each group.
2. Clinical findings, with exception of plaque index, showed improvement with ultrasonic scaling in combination with povidone-iodine solution in comparison with ultrasonic scaling alone and root planing.

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