Supragingival and subgingival microbiota of adult patients with Down’s syndrome. Changes after periodontal treatment

In this longitudinal study, five adult Down’s syndrome patients with periodontitis were placed on a frequent recall visit schedule (every 6 weeks) after treatment, in order to investigate: 1) the microbiological status, both supragingivally and subgingivally, and the changes that occurred after treatment and 2) the effect of frequent professional supragingival plaque control on the subgingival microbiota and clinical variables in these patients. The clinical variables recorded were probing pocket depth, probing attachment level, bleeding on probing and presence of plaque (full mouth, six surfaces per tooth). Microbiological examination was performed separately for supragingival and subgingival samples from the same site for 14 species, using whole genomic DNA probes and the “checkerboard” DNA‐DNA hybridization technique. The findings indicate that, although a reduction of periodontal indices was noticed, plaque levels remained high (60%) even at the end of the experimental period. Periodontal pathogens including Porphyromonas gingivalis, Bacteroides forsythus and Actinobacillus actinomycetemcomitans were frequently detected both supragingivally and subgingivally (>30%). The presence of a species supragingivally and the presence at the same time points subgingivally were correlated. This finding suggested that supragingival plaque acts as a reservoir for reinfection of treated sites. A reduction of the percentages of detection of these species was noticed 1 month after an oral hygiene period as well as at 3 and 6 months after treatment. Inadequate oral hygiene as performed by these patients probably affected supragingival, and consequently subgingival, plaque composition.     

Clinical alterations in relation to the morphological composition of the subgingival microflora following scaling and root planning

The aim of the present study was to relate shifts in the composition of subgingival plaque in periodontal pockets to alterations of the clinical periodontal conditions following a single course of subgingival scaling and root planing during a period of professional supragingival plaque control. For this purpose, 36 pairs of contralateral periodontal pockets in 10 subjects with moderately advanced periodontitis were assessed for the degree of gingival inflammation, probing pocket depths, bleeding on probing, attachment levels and the amount of supragingival plaque. In addition, samples of subgingival plaque were analyzed morphologically by dark-field microscopy. All patients received detailed information about proper oral hygiene and every 1-2 weeks, professional removal of supragingivally located deposits. When the oral hygiene standard had been sufficiently improved, 1 course of subgingival scaling on 1 side of each jaw only (test side) was carried out. Clinical and microbiological examinations were repeated after the scaling as well as after 2 and 6 months, while patients were recalled for supragingival prophylaxis every 2nd to 4th week. Our data showed that a single course of subgingival scaling and root planing resulted in reduced probing depths, a gain in clinical attachment and a shift in the composition of the subgingival microflora to a composition found in relatively healthy periodontal conditions. In relatively shallow pockets, however, a possible influence of repeated sampling on the subgingival microflora could not be ruled out. Bleeding on gentle probing was a reliable parameter for predicting a subgingival microflora where motile bacteria hold an increased portion.(ABSTRACT TRUNCATED AT 250 WORDS)     

The effect of supragingival plaque control on the progression of advanced periodontal disease

Abstract. The aim of the present trial was to study the effect of meticulous supragingival plaque control on (i) the subgingival microbiota, and (ii) the rate of progression of attachment loss in subjects with advanced periodontal disease. An intra-individual group of sites exposed to non-surgical periodontal therapy served as controls. 12 patients with advanced periodontal disease were subjected to a baseline examination (BL) including assessments of oral hygiene status, gingival condition (BoP), probing depth, clinical attachment level and subgingival microbiota from pooled samples from each quadrant. The assessments were repeated after 12, 24 and 36 months. Following BL, a split mouth study was initiated. The patients received oral hygiene instruction, supragingival scaling and case presentation. 2 quadrants in each patient were identified as “test” and the remaining 2 as “control” quadrants. Subgingival therapy was performed in all bleeding sites in the control quadrants. Oral hygiene instructions and plaque control exercises were repeated once every 2 weeks during the initial 3 months of the study. Thereafter the plaque control program was repeated once every 3 months for the duration of the 3 years. Sites demonstrating loss of clinical attachment ≥2 mm in the test quadrants were treated subgingivally. The results showed that in both test and control quadrants repeated oral hygiene instructions and supragingival plaque removal procedures resulted in low plaque scores throughout the study. The gingival bleeding scores and the frequency of periodontal pockets ≥4 mm was, however, significantly higher in the test quadrants than in the control quadrants. At the end of the 3 year study, the control quadrants showed significantly more reduced (≥2 mm) pockets than the test quadrants, 265 versus 96. The number of sites in the test quadrants showing probing attachment loss ≥2 mm was more than 4× greater than in the control quadrants (59 versus 13). The microbiological findings indicate a more pronounced reduction only for P. gingivalis in the control quadrants. None of the other 4 marker bacteria consistently reflected or predicted the clinical parameters. The present study shows that only supragingival plaque control fails to prevent further periodontal tissue destruction in subjects with advanced periodontal disease.     

Amalgam restorations, plaque removal and periodontal health

Abstract. A total of 156 approximal subgingival amalgam overhanging margins were assessed in the buccal segments of 13 patients for plaque accumulation, gingival inflammation, pocket depth and gingival shrinkage. Recordings were made immediately before and 2, 4 and 8 weeks fallowing scaling, removal of overhangs, and oral hygiene instruction. Surfaces with overhangs were compared with control surfaces, which were either intact or contained supragingival amalgams. Initially it was found that gingival inflammation and pocket depth were more extensive adjacent to subgingival amalgam overhangs than to sound teeth or those with supragingivally located amalgams. This appeared to be due to preferential plaque accumulation in relation to subgingival overhangs. For all parameters compared, differences apparent at the baseline had disappeared by the end of the 8-week study period. Contouring of defective subgingival restorations, followed by effective scaling and oral hygiene instruction produced approximately 1 mm of gingival shrinkage, sufficient in most cases to produce clinical gingival health. Of the 156 subgingival fillings 83 (53 % ) became supragingival and 43 (28 %) reached the gingival crest by the end of the 8-week study period.     

Recolonization of a subgingival microbiota following scaling in deep pockets

The present investigation was carried out to study some aspects of the recolonization of a subgingival microbiota following subgingival instrumentation in sites with deep pockets. 16 patients were recruited for the 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 (greater than or equal to 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.     

Ultrastructure of nondecalcified supragingival and subgingival calculus

THE ULTRASTRUCTURE of nondecalcified supragingival and subgingival calculus was studied in mature deposits. To facilitate sectioning of the embedded material, a thin reinforcing film of plastic was painted on the block. A new film was applied for each section. Light microscopy showed that supragingival calculus was heterogeneous with islets of calcified material within the covering plaque and with noncalcified areas within the calculus. Under transmission electron microscopy supragingival calculus was heterogeneous, dominated by microorganisms, small needle-shaped crystals and large ribbon-like crystals. In the covering soft plaque small crystals were often scattered in the intermicrobial matrix. In the supragingival calculus itself noncalcified microorganisms were surrounded with densely packed small crystals. There were also rosettes and bundles of large crystals. Subgingival calculus was homogeneous in light microscopy. The covering plaque contained no calcified material and only calcified material was seen within the calculus itself. Transmission electron microscopy of subgingival calculus revealed crystals of small size only. Subgingivally very few noncalcified microorganisms were seen within the calculus. The bacterial cell wall seemed to be the structure that was last calcified, both supragingivally and subgingivally.     

Dark-pigmented Bacteroides species in subgingival plaque of adult patients on a rigorous recall program

This study was designed to examine human subgingival plaque for the presence of dark-pigmented Bacteroides (DPB) species in a large adult population that had been following a rigorous oral hygiene and recall program for 2 years. Subjects received scaling and root planing and oral hygiene instructions at the time of entry and then a prophylaxis and/or oral hygiene instructions at frequent intervals. Clinical measurements were determined and microbial flora identified in subgingival plaque. The DPB species were found in 63% of the subjects and 47% of the total sites. The N-acetyl-B-glucosaminidase-positive DPB species ( B. melaninogenicus, B. denticola or B. loescheii ), B. intermedius, B. gingivalis and strains of unclassified pigmenting Bacteroides were found in 25, 50, 3 and 40% of the subjects, respectively, and at 15, 35, 2 and 25% of the sites, respectively. Plaque and bleeding indices, probing depth and mean proportions of motile rods and spirochetes were higher at sites with DPB as compared to sites without DPB species. Sites with B. intermedius had higher plaque and gingival indices and greater loss of probing attachment than sites with DPB other than B. intermedius . The prevalence of B. intermedius and other DPB species was high even though subjects were on a rigorous oral hygiene and recall program.     

Microbiological and clinical effects of topical subgingival antimicrobial treatment on human periodontal disease

This study was undertaken to evaluate the microbiological and clinical effects of a subgingivally applied mixture of H2O2-NaCl and NaHCO3 followed by subgingival irrigation with 1% Betadine in the treatment of periodontal disease. 20 adults with moderate to severe periodontal disease were included in a split mouth design study. All patients were given oral hygiene instruction and were subjected to supragingival scaling in all 4 quadrants, and subgingival scaling and root planing of half the dentition. 10 patients were instructed to use the chemical antimicrobial mixture twice a day instead of dentifrice, and also received professional application of the mixture once every 14 days for 3 months in connection with reinstruction in oral hygiene procedures. The remaining 10 patients received oral hygiene instructions combined with professional tooth cleaning without use of chemicals once every 14 days during a 3-month period. The effect of treatment was evaluated by monitoring the subgingival microflora, clinical periodontal parameters, and by computer assisted subtraction analysis of serial standardized radiographs to determine changes in mass of the supporting alveolar bone. The present study revealed that subgingival debridement combined with mechanical plaque control resulted in decreased numbers of subgingival microorganisms including spirochetes and motile rods, and arrested the progressive breakdown of the periodontal tissues. Topical antimicrobial agents used in combination with subgingival scaling further reduced the subgingival microflora and substantially improved early periodontal healing including gain of probing attachment level and gain in radiographic alveolar bone mass during the 12 months of observation. No clinical improvement but a tendency to further periodontal breakdown was found in the unscaled quadrants, even in those which were subjected to a personal application of the topical antimicrobial mixture. This study indicates that professional and personal subgingival application of a mixture of H2O2-NaCl and NaHCo3 will significantly enhance the microbiological and clinical effects of periodontal scaling and root planing. These agents, and the topical mode of antimicrobial therapy seem promising in the management of human periodontal diseases.     

Comparison of the distribution of Actinomyces in dental plaque on inserted enamel and natural tooth surfaces in periodontal health and disease

The distribution of Actinomyces naeslundii, Actinomyces viscosus and Actinomyces odontolyticus in healthy and diseased adult populations was studied in 3 different ways. First, supragingival plaque formation at 2 through 72 h was examined in 12 periodontally healthy adults using a removable pre-measured surface of enamel bonded to molars and premolars. Second, a cross-sectional examination of the composition of both supragingival and subgingival plaque of unknown age was conducted in 205 adults exhibiting periodontal health to moderate disease. Third, the effects of oral hygiene instruction and root planing on the subgingival micro-flora of a subset of 19 subjects with moderate periodontitis were examined. The evaluation of 12 adults revealed that the predominant species in early plaque formation (2, 4 and 8 h) was A. odontolyticus, A. viscosus and A. naeslundii were present in developing plaques in almost all subjects in 2-h plaque, but absent in half the subjects when 4-, 8- or 24-h plaque was examined. These two species significantly increased in numbers per mm² enamel surface area in 48- and 72-h plaques. A. odontolyticus was not related to clinical signs of periodontal disease in 205 adults, and its subgingival proportions in plaque did not change following periodontal treatment of 19 individuals. A. naeslundii was found in significantly higher numbers in supragingival than subgingival plaques in the 205 adults examined. The mean proportion of A. naeslundii significantly decreased as the magnitude of probing depth and attachment loss increased. The proportions of A. naeslundii and A. viscosus were found to be significantly increased in subgingival plaques following periodontal treatment.     

Tetracycline fibers as an adjunct in the treatment of nifedipine-induced gingival enlargement

BACKGROUND: The hypothesis that nifedipine-induced gingival enlargement in periodontitis patients can be treated with the adjunctive use of tetracycline (TCN) fibers was tested in this study. METHODS: Ten patients (mean age 66 +/- 4 years) with chronic periodontitis combined with nifedipine-induced gingival enlargement participated. Full mouth recordings of clinical parameters (probing depth, clinical attachment level, bleeding on probing, presence or absence of plaque) were assessed at baseline and gingival enlargement was estimated from casts. Participants were instructed in proper oral hygiene and received supragingival scaling before being reassessed 1 month later. They subsequently received full-mouth scaling and root planing followed by the immediate placement of TCN fibers in all pockets >5 mm. Clinical parameters were reassessed at 3, 6, and 12 months after completion of treatment. RESULTS: TCN fiber placement was well tolerated by patients. All clinical parameters recorded displayed significant improvements after treatment, and they were preserved for the 12-month experimental period. A significant reduction of the percentage of pockets >5 mm was noticed after treatment. The reduction of enlargement was still observed at 12 months despite patients not achieving optimal oral hygiene. CONCLUSION: Placement of tetracycline fibers as an adjunct to mechanical treatment is an option for the non-invasive therapy of nifedipine-induced gingival enlargement in periodontitis patients whose general medical condition and concomitant ailments do not favor a surgical approach.     

The effect of subgingival debridement with hand and ultrasonic instruments on the subgingival microflora

The effect of hand or ultrasonic instrumentation on the subgingival microflora of periodontal pockets was investigated. Pockets with probing depths of 6-9 mm were selected in 12 patients and were randomly assigned per patient to the experimental and control groups. After oral hygiene instruction, instrumentation of the experimental pockets was carried out either by ultrasonic or by hand instruments in a split-mouth design. The treatment effect on the subgingival microbiota was evaluated by microscopic and culture studies of subgingival plaque samples, while in addition, supragingival plaque, bleeding after probing and probing pocket depth were scored. Examinations were carried out before and 7, 21 and 49 days after treatment. The hand and ultrasonic treatments were equally effective in reducing probing pocket depths and bleeding scores. At the end of the experimental period, the probing depths of 54% of the hand-treated pockets and 43% of the ultrasonic-treated pockets were reduced to 4 mm or less while the bleeding scores were reduced to 29% and 22%, respectively. The analysis of microscopical and cultural data did not show any differences between hand and ultrasonic debridement. Both treatments reduced the microscopical counts of rods, spirochetes and motiles and reduced the total colony-forming units and number of black-pigmented Bacteroides and Capnocytophaga, resulting in a subgingival microbiota consistent with periodontal health.     

Long-term effect of surgical/non-surgical treatment of periodontal disease

Abstract The present investigation describes the effect of periodontal therapy in a group of patients who, following active treatment, were monitored over a 5-year period. One aim of the study was to analyze the role played by the patients’ self-performed plaque control in preventing recurrent periodontitis. In addition, probing depth and attachment level alterations were studied separately for sites with initial probing depths of 4 mm which were treated initially by either surgical or non-surgical procedures. Following active treatment (surgical/non-surgical), the patients were maintained on a plaque control regimen for 6 months, which included professional tooth cleaning once every 2 weeks. During the subsequent 18 months, the interval between the recall appointments was extended to 12 weeks and included prophylaxis as well as oral hygiene instruction. Following the 24-month examination, the interval between the recall appointments was further extended, now to 4–6 months. In addition, the maintenance program was restricted to oral hygiene instruction and professional, supragingival tooth cleaning, but further subgingival instrumentation was avoided. Clinical examinations including assessments of the oral hygiene, the gingival conditions, the probing depths and the attachment levels were performed at Baseline and after 24 and 60 months after completion of active therapy. Assessments of plaque and gingivitis were repeated annually. The results of the examinations showed that the patients’ standard of self-maintained oral hygiene had a decisive influence on the long-term effect of treatment. Patients who during the 5 years of monitoring consistently had a high frequency of plaque-free tooth surfaces showed little evidence of recurrent periodontal disease, while patients who had a low frequency of plaque-free tooth surfaces had a high frequency of sites showing additional loss of attachment. The present findings demonstrated that sites with an initial pocket depth exceeding 3 mm responded equally well to non-surgical and surgical treatments. This statement is based on probing depth and attachment level data from sites which were free of plaque at the 6-, 12-, 24-, 36-, 48- and 60-month reexaminations. It is suggested that the critical determinant in periodontal therapy is not the technique (surgical or non-surgical) that is used for the elimination of the subgingival infection, but the quality of the debridement of the root surface.     

Comparison of the microbiota of supra- and subgingival plaque in health and periodontitis

BACKGROUND, AIMS: The purpose of the present investigation was to compare the microbial composition of supra and subgingival plaque in 22 periodontally healthy (mean age 32+/-16 years) and 23 adult periodontitis subjects (mean age 51+/-14 years). METHODS: A total of 2358 supra and separately subgingival plaque samples were collected from the mesial aspect of all teeth excluding 3rd molars in each subject. Samples were examined for the presence and levels of 40 bacterial taxa using whole genomic DNA probes and checkerboard DNA-DNA hybridization. Clinical assessments including dichotomous measures of gingival redness, bleeding on probing, plaque accumulation and suppuration, as well as duplicate measures of pocket depth and attachment level, were made at 6 sites per tooth. Mean counts (x10(5), % DNA probe count and % sites colonized for each species were determined separately for supra and subgingival samples in each subject and then averaged across subjects in the 2 clinical groups. Significance of differences between healthy and periodontitis subjects was determined using the Mann-Whitney test and adjusted for multiple comparisons. RESULTS: Mean total DNA probe counts (x10(5), +/-SEM) for healthy and periodontitis subjects in supragingival plaque were 72.1+/-11 and 132+/-17.5, respectively (p<0.01), and in subgingival plaque 22.1+/-6.6 and 100.3+/-18.4, (p<0.001). Porphyromonas gingivalis, Bacteroides forsythus and Treponema denticola could be detected in supragingival plaque samples of both healthy and periodontitis subjects. Actinomyces species were the dominant taxa in both supra- and subgingival plaque from healthy and periodontitis subjects. 4 Actinomyces species accounted for 63.2%, of supragingival and 47.2% of subgingival plaque in healthy subjects and 48.% and 37.8% in periodontitis subjects respectively. Increased proportions of P. gingivalis, B. forsythus, and species of Prevotella, Fusobacterium, Campylobacter and Treponema were detected subgingivally in the periodontitis subjects. P. gingivalis, B. forsythus and T. denticola were significantly more prevalent in both supra- and subgingival plaque samples from periodontitis subjects. CONCLUSIONS: The main differences between supra and subgingival plaque as well as between health and disease were in the proportions and to some extent levels of Actinomyces, "orange" and "red" complex species.     

Comparison of plaque microflora between Chinese and Caucasian population groups

This investigation was designed to compare the predominant plaque micro-organisms from a Chinese group of patients exhibiting periodontitis with an age-, sex- and periodontal disease-matched Caucasian group of patients. In addition to race, the 2 population groups differed with respect to diet and oral hygiene habits, or effectiveness at removing plaque. Clinical measurements were determined along with an evaluation for micro-organisms in supragingival and subgingival plaque. Although the Chinese and Caucasian population groups were similar with respect to composition of micro-organisms in subgingival plaque, notable differences were observed in supragingival plaque. The Chinese group had higher mean proportions of spirochetes, motile rods. Fusobacterium spp. and dark-pigmented Bacteroides species, while the Caucasian group had higher mean proportions of cocci, total Actinomyces spp., A. viscosus and total Streptococcus spp. in supragingival plaque. The microbial differences observed in supragingival plaque may be explained at least in part, if not totally, by the higher plaque index scores of the Chinese versus Caucasian population groups.     

Effects of oral hygiene measures on clinical and microbiological parameters of periodontal disease

The effects of a 12-week period of oral hygiene alone on gingival conditions and subgingival microflora in 15 patients with severe periodontitis were investigated. Clinical measurements and plaque samples from selected sites were taken at week 0 (baseline), week 6, and week 12. Plaque samples were also taken at week 13, that is, 1 week following debridement. At week 0, the patients were instructed in supragingival plaque control and at week 6, the hygiene regimen was supplemented with the subgingival use of a toothpick device. At week 12, the patients received a full mouth supra- and subgingival debridement under local anesthesia. In those patients who complied with oral hygiene instructions (subgroup A), the gingival condition improved moderately while no improvement was found in less compliant patients (subgroup B). No significant changes were noted in the subgingival microflora in either subgroups A or B throughout the 12-week period of oral hygiene alone. However, significant reductions for all microbial parameters were found 1 week after debridement. Therefore, while moderate clinical improvements followed oral hygiene alone, no measurable changes in the subgingival microflora were observed concomitantly.     

Periodic subgingival antimicrobial irrigation of periodontal pockets

The present investigation was undertaken to study the clinical effect of professionally performed periodic subgingival irrigation per se and as an adjunct to scaling and root planing. 10 patients suffering from moderate-severe periodontal disease participated in the study. Following an initial 3-month period of supervised supragingival plaque control, a total of 102 periodontal sites with probing pocket depth greater than or equal to 6 mm and "bleeding on probing" were selected and subjected to a Baseline examination comprising assessments of oral hygiene and gingival conditions, probing depths and probing attachment levels. The pockets in the various jaw quadrants were randomly assigned to one of the following treatment groups: (1) periodic subgingival irrigation with hydrogen peroxide, (2) periodic subgingival irrigation with chlorhexidine, (3) periodic subgingival irrigation with saline and (4) no subgingival treatment. During the first part of the study (baseline-32 weeks), no mechanical debridement of the subgingival area was performed. The irrigation treatment was carried out by the operator 3 times per week during weeks 1 + 2 and 5 + 6 of the trial. In the 2nd part of the trial (32-52 weeks), the sites were subjected to scaling and root planing combined with professional irrigation during weeks 32-38. The previously non-irrigated control sites were not subjected to adjunctive irrigation when mechanically debrided. During the entire study, the patients were recalled for professional tooth cleaning once every 4 weeks. Re-examinations were carried out at 4, 6, 32, 40 and 52 weeks. The results revealed that repeated professional irrigation of unscaled periodontal pockets with chlorhexidine or hydrogen peroxide resulted in a temporarily reduced frequency of bleeding sites, but not in any clinically significant changes in probing assessments. A similar improvement of bleeding scores was observed in the saline-irrigated control group. Scaling and root planing, in combination with an optimal supragingival plaque control, resulted in a marked resolution of the clinical symptoms of periodontal disease. Adjunctive irrigation with chlorhexidine or hydrogen peroxide did not improve the healing result above and beyond that obtained after mechanical debridement alone or in combination with saline irrigation. Hence, the study failed to demonstrate that professionally performed periodic subgingival irrigation with chlorhexidine or hydrogen peroxide, used alone or in combination with thorough mechanical debridement, has a significant therapeutic effect.     

The effect of plaque control after scaling and root planing on the subgingival microflora in human periodontitis

The aim of the present study was to evaluate the effect of a strict supragingival plaque control regimen on bacterial repopulation following scaling and root planing. 7 patients with moderate to severe inflammatory periodontal disease received a full-mouth scaling and subgingival curettage. Using a split-mouth design, 2 sites of opposite quadrants were submitted to professional supragingival plaque control 3 X a week while the contralateral sites served as controls. Clinical and bacterial examination were performed on days 7, 14, 28, 49, 56, 63 and 70 following therapy. All clinical parameters (P1I, GI, probing depth, attachment levels) showed significant improvement after scaling and root planing. Shifts in the subgingival bacterial population observed by dark field were also noticed following curettage: there was a decrease in the proportions of spirochetes and motile rods and an increase in that of coccoid cells. However, bacterial distribution tended to return to base line values towards the end of the observation period. No difference in the pattern of bacterial recolonization of the subgingival area could be detected between the sites under strict supragingival plaque control and the control sites.     

口腔卫生指导对慢性龈炎的临床疗效的影响

目的：探讨口腔卫生指导对慢性龈炎的临床疗效的影响。方法：采用随机分组法将100名慢性龈炎患者分为实验组和对照组。对照组行龈上洁治术和龈下刮治术,不作口腔卫生指导;实验组在龈上,下刮治后增加口腔卫生指导。分别于术后第1、2、4、12周通过探诊出血百分率来评价口腔卫生指导的效果。应用SPSS16.0软件对实验数据进行统计学分析。结果：在第1、2周,实验组与对照组相比探诊出血百分率无统计学差异（P〉0.05）,到第4、12周,实验组探诊出血百分率明显低于对照组,有统计学差异（P〈0.05）。结论：口腔卫生指导可以有效地控制探诊出血,从而影响慢性龈炎的远期临床疗效。     

Rationale of mechanical plaque control

Abstract Patients who have received extensive periodontal treatment also demonstrate a high susceptibility to periodontal disease. Maintenance of periodontal health following therapy includes a lifelong supportive care consisting of daily removal of the microbial plaque by the patient, supplemented by professional care in an individually designed programme. Mechanical supragingival plaque control by self care is of utmost importance. The goal is to create a positive attitude by information and motivation to give the patient knowledge and confidence. The patient should be advised to use appropriate aids and technique. A soft brush, an interspace brush, interdental tooth brushes or tooth picks are recommended m periodontal patients. Professional tooth cleaning involves removal of supragingival plaque from ail tooth surfaces using mechanically driven instruments and fluoride prophy paste and, when indicated, removal of calculus and subgingival plaque. Disclosing solution is used to visualize the plaque to the patient and to the clinician in order to reinforce instruction in oral hygiene. Oral hygiene measures alone seem to have limited effect on the subgingival microflora in cases of severe disease. In shallow and moderately deep pockets a good plaque control can change the subgingival flora towards a more “healthy” composition. Subgingival plaque removal is performed with hand- and/or ultrasonic instruments. Cracks within the cementum, grooves, fissures, resorption lacunae, furcations may create difficulties in cleaning the root surface. Ultrasonic instrumentation has a beneficial effect in creating a smooth surface without extensive removal of cementum. Besides, the cavitational activity contributes to plaque removal which makes the instrument further suitable during maintenance therapy. The result of the de-bridement is assessed on the healing response in the tissues. The frequency of maintenance visits must be given on an individual basis according to the needs of every special patient. The visit includes plaque evaluation (disclosion), oral hygiene instruction, probing depth measurements, registration of bleeding on probing, scaling (plaque removal) if indicated, tooth polishing, fluoride application and radiographs if indicated. The goal is to identify and treat signs of recurrence of periodontal disease in order to prevent further loss of attachment.