The purpose of this study is to evaluate the effects of oral microorganisms and the conditions of the roots upon the reattachment of the gingiva to the denuded surface of the root. Experiments were performed using germfree (GF) and conventional (CV) rats. A small elastic ring was applied around the cervix of the mandibular first molar of the rat. The ring produced continuous pressure against the periodontium to make a pocket. The evaluation of the condition of the teeth and the periodontium was made on 0, 2, 4, 7, 14, 28 and 56 days following the removal of the rings from the teeth.
The histopathological pattern of the periodontium, the level of the epithelial attachment and the height of the alveolar bone were the items observed.
The results were as follows:
1. Periodontal pockets were produced by the elastic ring, applied for 14 days, both in GF and in CV.
2. The periodontal pocket in CV, measured at the removal of the ring, was about 1.5 times the depth of the one in GF.
3. Histopathological changes observed near the pocket in GF were the decrease of epithelial thickness and the hyaline degeneration together with irregular arrangement of the transseptal fibers. The changes in CV were the ulceration or the proliferation of the epithelium lining the lateral wall and the diffuse infiltration of round cells from the base of the pocket to the margin and to the alveolar bone. Numerous, newly formed engouged capillaries, and partial disappearance of the collagen fibers were also seen.
4. The resorption of the alveolar bone observed at the removal of the ring existed both in GF and in CV. The extent of the resorption in CV was greater than the one in GF.
5. The level of the base of the epithelial attachment in GF moved coronally, following the removal of the ring. This indicated that the reattachment process was in progress. The reattachment was significantly observed at the medial side. In CV, the apical migration of the epithelial attachment together with the proliferation of the epithelium was observed. Little change was seen at the distal side in CV.
6. The height of the alveolar bone in GF was not changed following the removal of the elastic ring. The reduction in the height of the alveolar bone was observed at the medial side in CV following the removal of the ring. Significant changes were not found at the distal side.
7. The histological pattern of the reattachment in GF at the medial side differed from the one at the distal side. The absorption of the cementum was often encountered and the collagen fibers arranged parallel to the root at the medial side. The pattern of the reattachment observed at the distal side was characterized by the collagen arrangement which was vertical to the surface of the root.
8. It was suggested that the gingival reattachment to the denuded surface of the root was strongly affected by the microorganisms and their metabolic products..

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The effect of toothbrushing may be consist of plaque removal and gingival massage. However, analytical study of these two factors has not been demonstrated yet. The purpose of the present study was to analyze the effect of toothbrushing on experimental gingivitis, and to make clear the influence of plaque removal and/or gingival massage.
Four monkeys (Macacca irus) were used, and to establish gingivitis they were fed soft diet during 8 months of preparatory period. An experimental period of 28 days, each monkey's mouth was separated in following four quadrants; 1) Toothbrushing (plaque removal plus gingival massage) 2) Plaque removal 3) Gingival massage 4) Control (no treatment). During 28 days, clinical examinations were repeated and biopsies were sampled on day 4, 7, 14 and 28. The biopsy material was subjected to histometric analysis.
The results showed that:
1) During experimental period, Gingival Index and pocket depth decreased gradually in all treated quadrants, except for control. However, the improvement of gingivitis was most remarkable in toothbrushing quadrant.
2) Gingival shrinkage occurred in toothbrushing and gingival massage quadrant.
3) The percentage-area of infiltrated connective tissue, and the number of inflammatoly cells within the connective tissue decreased gradually in all treated quadrants.
However, these two parameters showed most marked decrease in toothbrushing quadrant.
4) The number of leucocytes within the sulcular epithelium decreased rapidly in all treated quadrants.
5) Collagen density increased gradually in all treated quadrants with decrease of inflammatory cells.
The present experiment demonstrated that a gingival inflammation may be improved by gingival massage alone (without plaque removal). It seemed that the effect of toothbrushing on gingivitis results from both plaque removal and gingival stimulation (massage) with toothbrush.

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The present experiment was undertaken to study about early stages in the regeneration of the junctional epithelium following gingivectomy in rats. Gingivectomy was carried out on the lingual side of the maxillary molar teeth. At intervals of 0 hour to 28 days post-operatively, the maxillary molar teeth were extracted with the surrounding gingiva and coronal portion of the alveolar crest in situ. The sections were examined in light and electron microscope. The results were followed.
1) After 2 days, the epithelial cells were put in contact with the enamel. New junctional epithelium was consisted of the oral epithelium. The junctional epithelium was attached to the enamel surface by means of the basal-lamina-like structure and halfdesmosomes.
2) After 3 to 5 days, the junctional epithelium was consisted of the same epithelial cells both the apical and the coronal parts. These newly formed epithelial cells of the apical part provided with welldeveloped Golgi complexes, elements of rough endoplasmic reticulum, but the epithelial cells of the coronal part possessed few organelles. From these results, it was postulated that the epithelial cells had migrated from the apical toward the coronal part. In the junctional epithelium, the epithelial cells seemed to be always supplied and renewed from the oral epithelium. The sulcular epithelium was consisted of keratinized epithelium.
3) Formation of the new junctional epithelium following gingivectomy was completed in 28 days. The cells of new junctional epithelium were provided with the Golgi complexes, elements of endoplasmic reticulum. The junctional epithelial cells showed appearances of numerous intracytoplasmic vacuoles. The cells constituting the coronal part of the oral sulcular epithelium showed keratinization.
It seems, therefore, that the gingival sulcus following gingivectomy in rats had been reformed by the newly formed junctional epithelium and the keratinized oral sulcular epithelium.

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This investigation was experimentally made on the process of the bacterial plaque and the distribution of collagen fibers on the denuded root surface in rats. By scanning electron microscopy, the bacterial plaque was found on the denuded root surface and the plaque consisted of predominantly cocci and rods in 1-3 days.
After 5-7 days, the bacterial plaque was dominated by coccal forms and filaments. After 2-4 weeks, the bacterial plaque was composed of cocci, rods, filaments or mixtures of a variety of morphological types. A number of globules ranging could be observed on the denuded root surface. Through continued exposure in the mouth, the number and size of the globules increased. The undulating surface of continuous plaque was formed by growth and coalescence of the globules. The plaque deposited in the collagen fibers on the denuded root surface extended to the flattened portion.
I also found out the break-down of collagen fibers which had remained on the denuded root surface. The surface of the fibers on the denuded root surface under the bacterial plaque suggested calcification. These collagen fibers occurred as degeneration and combination. Such degenerated collagen fibers on the denuded root surface combined with collagen fibers of the matrix and became indistinct.

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It has been reported by a number of studies that bacterial plaque is a major etiologic factor in periodontal disease.
The purpose of the present study was to clear the relationship between a rapid plaque formation after toothbrushing withdrawal and subclinical gingival inflammation and to observe microbial population shifts in developing supragingival plaque.
The facial and lingual areas of six selected teeth (6/41|14/6) were assessed in a total of 40 dental students with normal dentition and a clinically healthy gingiva. The subjects were at randam divided into four groups. After a thoroughly plaque removal, the selected teeth were photographed under a standardized condition and gingival exudate measurements were undertaken on the upper three teeth (6|14). Subsequent to the first examination the subjects were given instructions not to brush their teeth for 12, 24, 48 and 72 hours respectively. They were rechecked each time and after the plaque samples were collected from the other areas except the selected teeth, bacterial smears were prepared. The selected teeth were photographed in the same criteria as the first examination following application of a disclosing solution (MT-1000) and the stained area on photograph was examined planimetrically.
The results were as follows:
1) When compared upper teeth with lowers, plaque accumulated slowly on lower teeth, while in the buccal side of upper teeth the plaque accumulation was remarkably high in order of 6, 4, 6, 1, 4 and 1 since 48 hours toothbrushig withdrawal and in the lingual side a significant increase in plaque accumulation was observed in order of 6, 4, 1, 6, 4 and 1 at 72 hours toothbrushing withdrawal.
2) The more increase in gingival exudate amounts was found in the buccal side than the lingual side of all the teeth. There was a significant increase in gingival exudate amounts of all the teeth except 4 since 48 hours toothbrushing withdrawal. A close correlation between plaque accumulation and gingival exudate amounts was demonstrated.
3) Predominant microorganisms were Gram positive cocci being decreased throughout the experimental periods. The frequency in Gram negative cocci and Gram positive rods did not change, whereas Gram negative rods and filaments had a tendency to increase with plaque age.

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This study was undertaken to clarify the effect of chloramphenicol (CP), rifampicin (RFP) and chlorhexidine (CH) on the adherence of Str. mutans to smooth surfaces and ultrastructural changes of insoluble glucans (IG).
The results obtained were as follows:
1) The structures of IG in TSB with 5% sucrose (control) could be observed.
(a) Amorphous structures on the smooth surfaces, which was accompanied with protrusions.
(b) Band-like structures consisted of 40-120nm in width, which connected cells to cells, and cells to massive structures.
(c) Massive structures which connected band-like structures.
2) Microcolonies, which were composed of structures mentioned above and cells, appeared as the cumulonimbus-like structures of strata. Among microcolonies, band-like structures developed into net-like structures.
3) Treated with MIC and 2 MIC, which indicated remarkable values of inhibition, there were considerable amounts of deposits under SEM observation. In comparison with control, they gave rise to decreased band-like structures and decreased massive structures accompanied with remarkable constrictions.
4) In the treatment with 1/2 MIC (MAC), the amounts of synthesized IG differed between drugs. In case of CP in 1/2 MIC, bacterial cells indicated a normal growth. Inhibitory effects of synthesizing IG could not be recognized at all, however there could be observed less developed band-like structures and their bulb formations at the ends. It is reasonable to presume that such phenomena indicated qualitative differences.
5) In system synthesizing IG from crude GTase, there was no inhibition of synthesizing IG in CP and RFP, but a 40.6% inhibition in CH including 1, 000 MIC. These results suggest that in case of CP or RFP, the inhibition of IG synthesis in cell growing system was due to the inhibition of synthesizing GTase closely associated with the inhibition of cell growth, but in CH it was due to not only the thing mentioned above but also the inhibition of GTase activities.
6) It appeared obvious that the band-like structures protruded from cells were responsible for adherence of Str. mutans to smooth surfaces.

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They say that the increase of pocket fluid combine with aggravation of periodontal disease. This mechanism and component are generally considered, however, the lipid substance in exudate still remains unknown, except for the report of WATANABE. His report contained that the amount of triglyceride in human serum and pocket fluid tend to increase, on the other hand in human gingiva was tend to decrease in propotion to the aggravation of the disease.
From his report, the authers investigate about the amount of diglyceride (DG) and monoglyceride (MG).
By way of study material, a total of 29 patients (13 males and 16 females) who visited the Department of Periodontology, Nihon University Dental Hospital, were selectively used. The subjects, who ranged from 20 to 72 years in age, were free from any systemic disease except for some kind of periodontal complaint.
The areas of pocket fluid collection (facial of 3-3 or 3-3) studied according to PMA index. In collecting the exudate from the periodontal pockets, filter paper strips (Whatman Co., No. 2, 1×12mm) was used. Total lipids were extracted with chloroform/methanol (2: 1v/v). The separation of the extract was achieved by thin-layer chromatography. The amount of diglyceride and monoglyceride in them was determined by the enzyme method-the endpoint method (reagents: Boehringer Mannheim) using the ultraviolet absorption spectrophotometry.
As a result of the study, the authors arrived at the following conclusions:
1. In this study identified that DG and MG were concluded in pocket fluid by use of thin-layer chromatography.
2. The amount of DG and MG were inclined to increase in proportion to the aggravation of the disease.

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Disturbance due to the long term administration of Dihydrotachysterol (DHT) are known on the experimental to cause a progeria-like syndrome.
In the present study, DHT was administered once daily for 28th days with 50μg per 100g weight of Sprague-Dawley female rats weighing 180-220g by the tuberculin syringe and attached stomach tube, and traumatic occlusion was experimentally induced by loading abnormal forces to rats.
The rats were divided into 4 groups; 1) control group, 2) DHT administered group, 3) DHT administration plus traumatic occlusion group, 4) Traumatic occlusion group.
The traumatic occlusion was induced by the method of Hieda and Ikeda.
In Group 2 and 3, the animal weight showed a trend of decrease until the 5th day of experiment but after the both groups were maintained with same weight and Group 1 and 4 showed almost linear increase until the 28th day of experiment.
The rats administered with DHT showed a tendency of almost atrophy of skin, kyphosis and atrophy of skelton.
According to the DHT administration, serum calcium level was markedly increased and serum phospholic acid or mandibular bone calcium were reduced.
On histological changes in Group 2 or Group 3, the eosinophilic substance like a layer or hematorylino-philic substance on the surface of alveolar bone or comentum.
This substance was recognized like inmineralized tissue (Cementoid, Osteoid) and was markedly seen at the root apex area or root central area and and especially, a periodontal space showed a tendency of narrowing at the above area and arrangement of the periodontal fiber was irregular.
In Group 3, changes of the periodontal structure showed marked histological changes in the central area of buccal root surface, a periodontal space was narrowed on the compressed side and widend on the traction side and alveolar bone of the compressed side showed osteoclastic resorption and almost were not observed eosinophilic substance, but in periodontal space of the traction side was observed a little osteoid formation and in generally eosinophilic substance formation at root apex area or bifurcation area were reduced compaired with Group 2.

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The present study was made in vivo and weekly observed to the wear of toothbrush bristles under Bass technique reference to the toothbrushing force, and also to the pollution of the toothbrush bristles.
The results obtained were as follows:
1. Toothbrushing force in Bass technique was 218g on average.
2. Discrepancy in the individual tooth brushing patterns which were evident from the brushing force curve was due to the individual variation in relation to grasp of the toothbrush.
3. At one week after brushing, the wear of the toothbrush bristles were a little regardless of the toothbrushing forces. At four weeks after brushing, the tip of bristles was observed to overspread above average of the brushing force.
4. At one week after brushing, coccoid microorganisms were observed at the round cut off tip of the bristles. Thereafter, coccoid and rod-like microorganisms were observed around the tip of the bristles.

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Our study was designed to establish a rational system for the dental care management and treatment of periodontal disease in mental deficient adults. As the first part of the study, the status of oral hygiene and periodontal disease was evaluated in this report.
Subjects were 45 persons institutionalized for mental deficiency in Hokkaido, aged 17 to 52, IQ from 72 to under 14, The Plaque Accumlation Rate (Pl. R.), Gingival Index (G. I.) and Pathological Pocket Rate (Po. R.) were evaluated on every permanent tooth except third molars, C₄ and teeth with artifical crowns.
Pl. R. was evaluated by the following modified Kawasaki's method. The tooth surface was divided into 10 sections, and plaque accumulatd sections were assessed.
Pl. R.=Number of plaque accumulated section/Number of the examined section×100 (%)
G. I. was evaluated by the modified system of Löe & Silness's method. Pocket depth was measured at six points of the tooth, and the pathological Pocket Rate (Po. R.) was assessed by following system.
Po. R.=Number of teeth with deeper than 4mm pocket/Nuber of the examinded teeth×100 (%)
The results were as follows:
1. Pl. R. was 51.9%, in which there was statistical significance between the high IQ group (IQ>36) and the low IQ group (IQ<35), but not between age groups.
2. G. I. was 1.37 and Po. R. was 28.1%. Both increased with age and the degree of mental deficiency, and statistical significance was found between IQ groups. G. I. and Po. R. were higher in the subjects who took Phenytoin than in the others.
3. Significant correlation was found between Pl. R. and G. I., but not between other indices and rates.

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