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Examines the effects of periodontal therapy on gingival and systemic immunological parameters. Preparation of gingival tissue specimen for immunohistochemical analysis; Effectiveness of non-surgical periodontal therapy in reducing gingivitis; Reduction in the size of inflammatory lesions.

The aim of the present investigation was to study the expression of specific α/β T cell receptor (TCR) gene products in relation to some microbiological and immunological features of advanced destructive periodontitis. 21 individuals with advanced periodontal disease (diseased group) and 16 age- and sex-matched healthy subjects (healthy group) were recruited. Following a clinical examination of the diseased group, the 3 deepest interproximal sites in the upper and lower premolar- or molar segments (i.e., 12 sites in each individual) were selected for further analysis. Samples from the subgingival microbiota were obtained from the pocket of the selected sites and were prepared for a microbiological examination. The gingival tissue at one of the selected sites was also biopsied. Each excised soft tissue specimen was divided into 2 equal portions. One portion of the biopsy was prepared for histometric and morphometric analyses. The 2nd portion was snap frozen and prepared for immunohistochemical analysis. A sample of peripheral blood was obtained from each individual of the diseased and the healthy group and prepared for immunohistochemical analysis. The selected sites of the diseased group harbored varying numbers of microorganisms which have been associated with periodontal disease. The excised gingival tissue contained inflammatory lesions with substantial numbers of lymphocytes and plasma cells including T- and B-cells and a TCR V α/β gene repertoire dominated by Vβ 17. The TCR profile of the lesion, however, differed markedly from that of the circulating blood of the diseased subjects. While only minor differences were observed between the blood samples of the diseased and the healthy subjects regarding the TCR genes, CD5, HLA-DR and CD5+CD19 positive cells occurred in higher proportions in the blood samples of the subjects susceptible to periodontal disease than in healthy controls. It may be suggested that (i) TCR Vα/Vβ expression in peripheral blood samples of subjects with periodontal disease does not differ from that of healthy individuals, and (ii) the periodontitis lesion expresses a unique TCR repertoire in which the Vβ 17 gene dominates. [ABSTRACT FROM AUTHOR]

The purpose of the present investigation was to study characteristics of the plaque associated lesions in the gingiva and the adjacent periimplant mucosa sampled from the same subjects. 20 partially edentulous patients (12 female and 8 male, 30-60 years of age) volunteered to participate in the study. They had all been treated for moderate to advanced periodontal disease. Edentulous regions had been restored with implants. The restorative therapy had been completed 6-24 months prior to soft tissue biopsy. Samples of gingival tissue (GM) and periimplant mucosa (PIM) from an "interproximal surface" of one tooth site and one implant site of the same jaw were harvested. One portion of the biopsy was embedded in EPON®, stained in PAS and toluidine blue and used for histometric and morphometric analyses. The 2nd portion of the biopsy was snap frozen in liquid nitrogen. 15 sections, about 5 µm thick, were prepared in a cryostat and used for immune histochemical staining. The analysis of the sections included determination of the size of the lesions as well as assessments of various cells and cell markers. In all samples of both PIM and GM discrete infiltrates of inflammatory cells (ICT) were found in the connective tissue lateral to the junctional epithelium. The ICT of PIM occupied on the average 0.17 ± 0.14 mm² of the soft tissue, while the corresponding lesion in GM occupied an area that was 0.25 mm² ± 0.21 mm² large. The density of CD19 positive cells was 7 times higher in GM than in PIM (3.7 versus 0.5) while the densities of CD3 positive cells were 7.5 (GM) and 4.7 (PM) respectively. The density of PMN elastase positive cells was about 3 times higher in GM than in PIM (3.7 versus 1.2). Care must be exercised when these differences are interpreted. It is possible that a prolonged exposure of the implant site to the oral environment may induce both qualitative and quantitative changes of the infiltrate in PIM. [ABSTRACT FROM AUTHOR]

The aim of the present investigation was to study some tissue characteristics of the ridge mucosa before and after implant installation. 9 partially edentulous patients were included in the study. At the time of fixture installation, 1 recipient site in each patient was selected for soft tissue biopsy. Abutment connection and restorative therapy were performed after 3-6 months. When the implants had been in function for about 6 months, a soft tissue sample was obtained from the keratinized peri-implant mucosa at the 1 implant site from which the first biopsy was obtained. Each biopsy was divided into 1 mesial and 1 distal portion. The mesial tissue portion was fixed in a buffered fixative and embedded in EPON®. Sections were produced, stained in PAS and toluidine blue and used for histometric and morphometric analyses. The distal portion of the biopsies were embedded, snap frozen in liquid nitrogen and stored in a freezer at -70 ° C. From each tissue portion, 15 sections were prepared in a cryostat and exposed to immunohistochemical staining. A panel of monoclonal antibodies was used and the avidin-biotin method for staining was applied. The sections were examined morphometrically. Both tissues harbored a well keratinized oral epithelium and a connective tissue, the composition of which was close to identical in terms of collagen, cells and vascular structures. The peri-implant mucosa, however, also included a junctional epithelium which evidently allowed the penetration of products from the oral cavity. As a consequence, the periimplant mucosa in comparison to the masticatory mucosa was found to contain significantly enhanced numbers of different inflammatory cells. [ABSTRACT FROM AUTHOR]

The aim of the present investigation was to study the local nature of human periodontal disease by assessing the microbiota and the composition of the tissue lesions at sites with progressive attachment loss in periodontitis susceptible subjects. 300 subjects with periodontal disease were monitored for 2 years without treatment. 8 subjects lost >2 mm of attachment at ≥3 sites during both the first and the second 12 month interval. These 8 subjects (progressive disease group; PD)were recalled for a microbiological and histopathological examination. A group of age- and sex-matched subjects were identified who during the 2 years of monitoring exhibited gingivitis and deep pockets, but no further attachment loss. This group of 11 subjects (non-progressive disease group; NPD) served as controls. From the 8 active disease subjects, ≥ 1 interproximal site which had displayed disease activity (progressive disease active; PDA) and ≥ 1 contralateral site without disease progression (progressive disease inactive; PDI) were sampled. From the 11 control subjects, 1 site/subject was sampled (NPD). The total number of viable micro-organisms (TVC) in the subgingival microbiota was estimated and a series of bacterial species were identified and enumerated. The gingival tissue of the sampling site was excised and the soft tissue prepared for morphometrical and immunohistochemical analyses. No differences were observed in the subgingival microbiota of the sample sites in the subjects who exhibited disease progression (PD) when compared with the subjects with periodontally diseased but stable conditions (NPD). Furthermore, no marked difference could be noted between progressive (PDA) and non-progressive (PDI) sites in the PD group of subjects. The results from the morphometric determinations revealed that the lesions from the PD and NPD subjects on the average were of similar size, but the PD lesions were comprised of a larger relative volume of plasma cells, a higher % number of plasma cells and monocytes/macrophages and a lower numerical density of lymphocytes than the corresponding sites in the NPD group. Both T cell markers (CD3 and CD4) and B cell markers (CD22) examined were significantly elevated in the PDA compared to the PDI lesions. The CD4/CD8 ratios calculated from assessments made in the PD and NPD tissue samples were 2.4 and 2, while the corresponding ratios for PDA and PDI lesions were 3 and 2.1 (p<0.05) respectively. The present data indicate that differences exist between disease active and inactive subjects and sites and it is suggested that the human model described may be used to study disease progression using shorter time intervals between examinations and additional parameters. [ABSTRACT FROM AUTHOR]

The present investigation was performed in order to study the reaction of the gingiva in the deciduous and permanent dentition of dogs to 3 weeks of plaque accumulation. The study was carried out in 10 beagles, divided into 2 groups of 5 dogs each; group I and group II. When the dogs of group I were 10 weeks old, a meticulous plaque control regimen was initiated in order to establish clinically healthy gingiva. After 6 weeks of plaque control, the gingivae of the lower deciduous molars was exposed to a clinical examination, and biopsies as well as bacterial plaque samples were harvested from tooth 03P and 02P. A second plaque control regimen was initiated when the same dogs were 15 months old. After 6 weeks of plaque control, the gingiva of the permanent dentition was examined and biopsies sampled from tooth P3 and P4. In the dogs of group II, plaque control regimens of 3 weeks duration were initiated when the animals were 10 weeks and 15 months old. Clinical examinations were performed at the end of each 3-week period. Immediately after the clinical examinations. 3-week periods of plaque accumulation were initiated. Examinations and plaque sampling were performed after each of these 3-week periods and biopsies were sampled from the deciduous and permanent dentition as described for group I. The biopsies were processed for histometric and morphometric measurements. The findings from the experiment showed that careful plaque control resulted in the establishment of clinically healthy gingiva. In both the deciduous and permanent dentition, however, a clinically healthy gingiva was found to contain a small inflammatory cell infiltrate (ICT). 3 weeks of plaque accumulation resulted in both dentitions in the development of clinical signs of gingivitis and in the formation of comparatively large ICT. The large ICT of the permanent gingiva resided in the coronal portion of the free gingival unit, while in the deciduous dentition, the inflammatory lesion occupied a narrow tissue portion along the entire border of the dento-gingival epithelium. The ICT of the permanent gingiva harbored a larger portion of plasma cells than the inflammatory lesion studied in the deciduous dentition. [ABSTRACT FROM AUTHOR]

The aim of the present investigation was to study the validity of 2 different methods of sampling the subgingival microbiota. The composition of the flora was estimated using the dark-field microscope. Subgingival samples were obtained using either a curette or a Hamilton microsyringe for a subgingival washing. The method of determination of the composition of the subgingival microorganisms was found to be very reproducible when the same investigator performed the counting. Samples obtained by the washing technique had a slight but significantly higher proportion of coccoid cells when compared to samples obtained by curette. The calculation of the reproducibility of the washing technique as assessed in 6 immediately repeated samples from the same sites yielded a coefficient of variation of 40% for spirochetes and motile rods. When 9 repeated samples from each of 28 sites (14 with a curette, 14 with washing) were studied over a period of 32 days, no systemic alterations were observed in the % of spirochetes and motile rods. The variation within each individual site was high. For curette samples and washing samples, the coefficients of variation for spirochetes and motile rods were 85% and 63%, respectively. The present investigation clearly demonstrated that care should be taken in the interpretation of single samples of subgingival microbiota. A more relevant picture of the actual situation is achieved when trends of repeated samples over time are studied. [ABSTRACT FROM AUTHOR]

The present investigation was performed to study the effect of long-term, low dosage tetracycline Therapy on advanced periodontal disease in humans. 14 volunteers participated in the trial. Each of the participants had at least 4 pairs of diseased sites around contralateral premolars and incisors with deep pockets and advanced bone loss. The trial extended over a 50-week period and was designed as a double-blind split-mouth study. A Baseline examination included assessments of oral hygiene, gingival conditions, probing depth, attachment level and analysis of the composition of the subgingival microbiota in samples obtained from 8 selected diseased sites. All participants received oral hygiene instruction. In each patient 2 quadrants of the mouth, chosen at random, were treated by scaling and root planing. The 2 remaining quadrants were left unsealed. Following the Baseline examination the patients were randomly distributed into 2 groups of 7 members each. in one of the groups the patients received tetracycline on a daily basis during a 50-week period. The participants of the control group received placebo. Reexaminations were performed 2, 10, 20, 30 and 50 weeks after the Baseline examination. The findings demonstrated that in patients with advanced periodontal disease long-term tetracycline therapy in the absence of scaling resulted in the establishment of a subgingival microbiota almost devoid of motile bacteria and in markedly reduced signs of gingivitis, probing depth and attachment loss. ln fact, the alterations observed as a result of tetracycline administration to patients with excellent self-performed plaque control were similar to those obtained by conventional scaling and root planing in the control group. [ABSTRACT FROM AUTHOR]

The microflora of periodontal pockets and some histopathological characteristics of adjacent tissues from individuals with clinical signs of juvenile periodontitis were studied. Adult individuals with ordinary, rapidly advancing periodontitis served as controls. All of the patients had been referred for specialist treatment. Using criteria defined by Baer (1971), the patients were assigned to one juvenile periodontitis (eight patients), one post-juvenile periodontitis (seven patients) and one adult periodontitis group (seven patients). Only lesions around the first molars and central incisors were studied. Bacterial samples were obtained from each site and were examined by darkfield microscopy and different morphological forms identified. The soft tissue of the diseased sites was excised. The biopsies were placed in a fixative, cut in 1-mm-thick blocks and embedded in Epon. In semithin sections the infiltrated connective tissue (ICT) was identified and the ICT portion further processed for electron microscopy. The numeric and volumetric densities of different cells and structures of the ICT were determined using a morphometric point-counting procedure. The results showed that juvenile periodontitis lesions are associated with a subgingival microflora, the composition of which is different from that of adult periodontitis. Thus, in patients belonging to the adult periodontitis and post-juvenile periodontitis groups, motile microorganisms dominated the subgingival plaque samples, whereas deep pockets in juvenile periodontitis lesions contained a flora dominated by coccoid cells and straight non-motile rods. The most pronounced difference in the composition of ICT between the juvenile on one hand and the post-juvenile and adult periodontitis lesions on the other, was related to the amount of extracellular structures. Thus, in post-juvenile and adult periodontitis lesions, collagen and residual tissue made up around 50 % of the infiltrate. In the juvenile periodontitis lesions, however, extracellular structures occupied only around 20 % of the volume. In the ICT of the juvenile periodontitis sites, around 70 % of the volume was occupied by plasma cells and blast cells. The corresponding figures for the post-juvenile and adult periodontits sites were 50 and 30 %. [ABSTRACT FROM AUTHOR]

Abstract Objectives: The aim of the present investigation was to study local (gingival) and systemic host defense characteristics in a sample of children exhibiting local prepubertal periodontitis (LPP). Material and methods: 2 groups of subjects were included in the present study. One group consisted of 11 children (9.5±2.0 years) with signs of periodontal disease (LPP group). A 2nd group comprised 21 adults (48.1±5.8 years) with advanced periodontal disease: adult periodontitis (AP) group. Gingival biopsies and a sample of peripheral blood were obtained in each individual of the AP group and in 7 out of the 11 subjects in the LPP group. The biopsies were prepared for morphometrical and immunohistochemical analysis and the blood samples prepared for immunohistochemical analysis. Results: The cellular infiltrates in the biopsies of the LPP group contained a larger proportion of lymphocytes and, in particular B cells, than was the case in the AP group. The TCR Vα/Vβ gene expression in the lesions in the AP group was dominated by Vβ 17 and in the LPP group by Vα 2. The content in peripheral blood of various lymphocyte sub-populations and TCR Vα/Vβ gene expression in the 2 groups was almost similar. Conclusion: It is suggested that (i) the systemic host response in children with prepubertal periodontitis has many features in common with that seen in adult patients but that (ii) local defense mechanisms in the periodontitis lesion of LPP differ from those in adult periodontitis. [ABSTRACT FROM AUTHOR]

The present clinical trial was performed to study the effect of systemic administration of metronidazole and amoxicillin as an adjunct to mechanical therapy in patients with advanced periodontal disease. 16 individuals, 10 female and 6 male. aged 35-58 years. with advanced periodontal disease were recruited. A baseline examination included assessment of clinical, radiographical, microbiological and histopathological characteristics of periodontal disease. The 16 patients were randomly distributed into 2 different samples of 8 subjects each. One sample of subjects received during the first 2 weeks of active periodontal therapy. antibiotics administered via the systemic route (metronidazole and amoxicillin). During the corresponding period, the 2nd sample of subjects received a placebo drug (placebo sample). In each of the 16 patients, 2 quadrants (1 in the maxilla and 1 in the mandible) were exposed to non-surgical subgingival sealing and root planing. The contralateral quadrants were left without subgingival instrumentation, Thus, 4 different treatment groups were Formed: group 1: antibiotic therapy but no scaling, group 2: antibiotic therapy plus scaling, group 3: placebo therapy but no scaling, group 4: placebo therapy plus scaling. Re-examinations regarding the clinical parameters were performed. samples of the subgingival microbiota harvested and 1 soft tissue biopsy from 1 scaled and 1 non-settled quadrant obtained 2 months and 12 months after the completion of active therapy. The teeth included in groups 1 and 3 were following the 12-month examination exposed to non-surgical periodontal therapy and subsequently exited from the study. Groups 2 and 4 were also re-examined 24 months after baseline. The findings demonstrated that in patients with advanced periodontal disease, systemic administration of metronidazole plus amoxicillin resulted in (i) an improvement of the periodontal conditions, (ii) elimination/suppression of putative periodontal pathogens such as A. actinomycetemcomitans, P. gingivalis. P. intermedia and (iii) reduction of the size of the inflammatory lesion. The antibiotic regimen alone, however, was less effective than mechanical therapy with respect to reduction of BoP positive sites. probing pocket depth reduction, probing attachment gain. The combined mechanical and systemic antibiotic therapy (group 2) was more effective than mechanical therapy alone in terms of improvement of clinical and microbiological features of periodontal disease. [ABSTRACT FROM AUTHOR]

Background Loss of teeth results in marked qualitative and quantitative alterations of the alveolar process at the edentulous site. It was observed that a graft comprised of bovine bone mineral placed in the fresh extraction socket delayed tissue modeling, but preserved the dimension of the ridge at edentulous sites. Objective To analyze the influence of a biphasic synthetic graft on tissue modeling and remodeling during healing of extraction wounds. Material and methods Five beagle dogs were used. Two premolars in the maxilla and two in the mandible were included. Full thickness flaps were elevated and the distal roots were removed. An alloplastic graft ( BPCAP; α- TCP core coated with nanocrystalline biomimetic hydroxyapatite) embedded in porcine collagen was placed to fill the fresh extraction socket of the premolar sites. Flaps were replaced to cover the entrance of the extraction sockets during early healing. The extraction and grafting procedures were scheduled to allow for the study of 1, 2, and 3 months socket healing. The biopsies from the maxillary sites were decalcified, embedded in paraffin, and stained to allow the study of various aspects of hard tissue formation. The biopsies from the mandibular sites were processed for ground sectioning and used to evaluate alterations of ridge dimensions after 3 months of socket healing. Results and conclusion It was documented that the biphasic alloplastic graft did not undergo marked resorption during tissue modeling and remodeling, but allowed large amounts of bone to form within the post-extraction site. Grafting the experimental sites with this biomaterial furthermore counteracted ridge resorption that otherwise occurs following tooth extraction. [ABSTRACT FROM AUTHOR]

INTRODUCTION: The available studies on extraction wound repair in humans are affected by significant limitations and have failed to evaluate tissue alterations occurring in all compartments of the hard tissue defect. AIM: To monitor during a 6-month period the healing of human extraction sockets and include a semi-quantitative analysis of tissues and cell populations involved in various stages of the processes of modeling/remodeling. MATERIAL AND METHODS: Twenty-seven biopsies, representative of the early (2-4 weeks, n=10), intermediate (6-8 weeks, n=6), and late phase (12-24 weeks, n=11) of healing, were collected and analysed. RESULTS: Granulation tissue that was present in comparatively large amounts in the early healing phase of socket healing, was in the interval between the early and intermediate observation phase replaced with provisional matrix and woven bone. The density of vascular structures and macrophages slowly decreased from 2 to 4 weeks over time. The presence of osteoblasts peaked at 6-8 weeks and remained almost stable thereafter; a small number of osteoclasts were present in a few specimens at each observation interval. CONCLUSIONS: The present findings demonstrated that great variability exists in man with respect to hard tissue formation within extraction sockets. Thus, whereas a provisional connective tissue consistently forms within the first weeks of healing, the interval during which mineralized bone is laid down is much less predictable. [ABSTRACT FROM AUTHOR]

Objective: To analyse the soft tissue healing at titanium implants coated with type 1 collagen. Material and methods: Six dogs were used. The mandibular pre-molars and the three anterior maxillary pre-molars were extracted. Three months later mucoperiosteal flaps were raised and two test and two control implants were installed (3i® TG Osseotite®3.75 × 10 and 2.8 mm transmucosal collar). The test implants were coated with a purified porcine type I collagen. Cover screws were placed and flaps were sutured. The sutures were removed 2 weeks later and a plaque-control programme was initiated. Another 2 weeks later, the procedure was repeated in the contra-lateral mandibular region. Four weeks after the second implant surgery, biopsies were obtained and prepared for histological examination. Results/Conclusion: The vertical dimensions of the epithelial and connective tissue components as well as the composition of the connective tissue portion facing the implant were similar at collagen-coated and uncoated implants after 4 and 8 weeks of healing. It is suggested that soft tissue healing to implants coated with type I collagen was similar to that at non-coated titanium implants and that no adverse reactions to the collagen-coated implants occurred. [ABSTRACT FROM AUTHOR]

The aim of the experiment was to analyze the reaction of the marginal gingival tissues to 21 days of plaque formation on buccal tooth surfaces in the deciduous and permanent dentition of beagle dogs. In order to enhance the formation of plaque, the buccal surfaces of the experimental teeth were coated with a composite filling material 5 beagle dogs were used. The animals were monitored during 2 periods, called period A (42 days during the deciduous dentition) and period B (42 days during the permanent dentition). The dogs were 10 weeks old at the initiation of period A. Following 3 weeks of plaque control, a groove was prepared into the enamel of the buccal surfaces of the mandibular right 3rd (03P) and 2nd (02P) premolars. A cotton ligature was subsequently attached to the groove using an enamel/etch-technique and a composite filling material. The groove and the ligature did not interfere with the gingival margin but the composite material extended into the subgingival niche. The plaque control measures were abandoned. The animals formed plaque during the following 21 days. A clinical examination was performed and subgingival bacteria sampled on day 21. Moreover, biopsies were harvested front the 03P and 02P tooth regions. The biopsies were prepared for histometric and morphometric analyses. A 2nd plaque control regimen was initiated. Period B started when the dogs were 1.5 months old. Following 3 weeks of enhanced plaque control, a cotton ligature was attached as described above at the buccal surfaces of the mandibular left 3rd (p3) and 4th (P4) premolars. The oral hygiene regimen was terminated and plaque allowed to accumulate. The clinical examination, bacterial sampling and biopsy were repeated after 21 days of plaque formation. It was observed that the height of the free marginal gingiva (hFG) was smaller in the deciduous than in the permanent dentition. The volume of the free gingival unit which was occupied by an infiltrated connective tissue (JCTJ and the total portion of inflammatory cells residing in the dentogingival epithelium were similar in the 2 dentitions. In the apical 3rd of the dentogingival epithelium, the volume of leukocytes was significantly larger in the deciduous than in the permanent dentition. The proportion of plasma cells within the ICT was about 4-5 × larger in the permanent than in the deciduous dentition. Black-pigmented Bacteroides occurred in 3 out of 5 dogs in the subgingival microbiota, representing 21 days of plaque formation in the deciduous dentition, whereas in the permanent dentition, black-pigmented Bacteroides occurred in all and Porphyromonas (Bacteroides) gingivalis in 3 of the 5 dogs. [ABSTRACT FROM AUTHOR]

Orthodontic tooth extrusion is used at crown lengthening procedures or in conjunction with periodontal therapy aimed at eliminating or reducing angular bone defects. A technique for orthodontic extrusion combined with resection of the supracrestal attachment fibers (fiberotomy) was recently proposed as an adjunct to certain restorative procedures. The aim of the present investigation was to analyze reactions of the periodontal tissues to orthodontic extrusion when combined with fiberotomy. In 5 beagle dogs, the mesial roots of the 2nd, 3rd and 4th hemisected mandibular premolar were used as target roots while the distal roots served as reference units. After a baseline examination, an orthodontic extrusion device (stent) was installed and reactivated at 2-week intervals during an 8-week period of active tooth movement. Immediately following the installation of the stent and once every 2nd week, the target roots were exposed to fiberotomy. After the active period, the teeth were retained in their new position for a period of 8 weeks. Clinical, radiographical and histological measurements were performed. The results from the investigation demonstrated that orthodontic extrusion combined with supracrestal fiberotomy resulted in a coronal displacement of the tooth and was associated with pronounced recession of the gingival margin and extensive loss of connective tissue attachment. The degree of gingival recession and the amount of loss of connective tissue attachment were, however, less extensive than the amount of tooth extrusion. Thus, repeated fiberotomy obviously failed to entirely prevent coronal migration of the attachment apparatus. It was also observed that undesired attachment loss had occurred at the reference roots. [ABSTRACT FROM AUTHOR]

The present investigation was carried out to study some aspects of tile recolonization of a subgingival microbiota following subgingival instrumentation in sites with deep pockets. 16 patients were recruited for tile study. From each patient 4 inflamed gingival sites with deep pockets were selected. These sites were examined for plaque, overt gingivitis, bleeding on probing and probing depth. Samples of the subgingival microbiota were obtained and examined in the darkfield microscope and in a Neubauer chamber. Following the Baseline examination the teeth of all 4 jaw quadrants were carefully scaled and planed. Subgingival instrumentation was carried out under local anesthesia and required between 2-4 appointments. The patients were subsequently divided into 2 groups (Groups A and B) consisting of 9 and 7 subjects, respectively. During the first 16 weeks of maintenance the patients of Group A were not supervised regarding their self-performed plaque control measures and they accumulated supragingival plaque. The patients of Group B, however, were during these 16 weeks recalled once every 2 weeks for professional tooth cleaning. In addition they rinsed twice daily with a 0.2% solution of chlorhexidine digluconate. Reexaminations including assessments of the same parameters as those studied at Baseline were performed after 2, 4, 8, 12 and 16 weeks. After the 16-week examination the patients of Group A received a new sequence of subgingival scaling and root planing. During the subsequent 16 weeks the patients of Group A were also recalled for professional tooth cleaning. They were reexamined 18, 20, 24, 28 and 32 weeks after the Baseline examination. Subgingival scaling followed by carefully supervised oral hygiene measures resulted in a marked improvement of periodontal conditions. This improvement was accompanied by a pronounced and sustained reduction in the motile segments of the subgingival microbiota. In the presence of supragingival plaque (Group A), however, a subgingival microbiota containing large numbers of spirochetes and motile rods was soon (4-8 weeks) reestablished. A small number of sites with deep pockets (&ges;8 mm) was not substantially reduced in depth following subgingival instrumentation. In these sites which were kept free from supragingival deposits a subgingival microbiota with a large proportion of motile bacteria soon recurred. [ABSTRACT FROM AUTHOR]