Assessment of relationships between site-specific variables

Risk factors of chronic periodontitis on healing response: a multilevel modelling analysis

Background

Chronic periodontitis is a multifactorial polygenetic disease with an increasing number of associated factors that have been identified over recent decades. Longitudinal epidemiologic studies have demonstrated that the risk factors were related to the progression of the disease. A traditional multivariate regression model was used to find risk factors associated with chronic periodontitis. However, the approach requirement of standard statistical procedures demands individual independence. Multilevel modelling (MLM) data analysis has widely been used in recent years, regarding thorough hierarchical structuring of the data, decomposing the error terms into different levels, and providing a new analytic method and framework for solving this problem. The purpose of our study is to investigate the relationship of clinical periodontal index and the risk factors in chronic periodontitis through MLM analysis and to identify high-risk individuals in the clinical setting.

Methods

Fifty-four patients with moderate to severe periodontitis were included. They were treated by means of non-surgical periodontal therapy, and then made follow-up visits regularly at 3, 6, and 12 months after therapy. Each patient answered a questionnaire survey and underwent measurement of clinical periodontal parameters.

Results

Compared with baseline, probing depth (PD) and clinical attachment loss (CAL) improved significantly after non-surgical periodontal therapy with regular follow-up visits at 3, 6, and 12 months after therapy. The null model and variance component models with no independent variables included were initially obtained to investigate the variance of the PD and CAL reductions across all three levels, and they showed a statistically significant difference (P < 0.001), thus establishing that MLM data analysis was necessary. Site-level had effects on PD and CAL reduction; those variables could explain 77–78% of PD reduction and 70–80% of CAL reduction at 3, 6, and 12 months. Other levels only explain 20–30% of PD and CAL reductions. Site-level had the greatest effect on PD and CAL reduction.

Conclusions

Non-surgical periodontal therapy with regular follow-up visits had a remarkable curative effect. All three levels had a substantial influence on the reduction of PD and CAL. Site-level had the largest effect on PD and CAL reductions.

Electronic supplementary material

The online version of this article (10.1186/s12911-017-0533-2) contains supplementary material, which is available to authorized users.

[The relationship between inflammatory periodontal diseases and cardiovascular diseases]

Estimated the relationship between inflammatory periodontal diseases and the risk of developing cardiovascular disease. Installed combined effect of periodontitis and cardiovascular disease.

Relative Contribution of Patient-, Tooth-, and Site-Associated Variability on the Clinical Outcomes of Subgingival Debridement. I. Probing Depths

BACKGROUND

The objective of this clinical trial was to assess the relative contribution of patient-, tooth-, and site-associated variables on changes in probing depths (PD) following delivery of a standard non-surgical phase of periodontal therapy.

METHODS

Ninety-four (94) systemically healthy subjects with severe generalized periodontitis were included in this 6-month prospective longitudinal study. Medical, periodontal, and microbiological parameters were collected at baseline and 2 and 6 months after completion of oral hygiene instructions, motivation, and subgingival debridement using a piezoelectric instrument. The relative contribution of patient-, tooth-, and site-associated variables was evaluated with a hierarchical multilevel analysis.

RESULTS

Eighty percent (80%) of variability in PD reductions was attributed to site level parameters, while 12% was at the tooth level and 8% at the patient level. The multilevel analysis associated PD reductions with patient factors (cigarette smoking status and carriage of the rare allele of a specific polymorphism for the interleukin-6 [IL-6] gene), tooth factors (tooth mobility and tooth type), and site factors (mesial and distal location). Cigarette smoking and carriage of the rare allele of the IL- 6-174 G/C polymorphism were associated with less PD reduction. Incisors and canines responded better than premolars and molars. A dose-dependent effect of mobility was observed: teeth with higher baseline mobility resulted in significantly greater decreases in PD. At the site level, greater reductions were observed at interdental sites (compared to facial or oral), and at deeper sites (1.2 mm for 4 to 5 mm pockets and 2.4 mm for pockets > or =6 mm).

CONCLUSION

These data provided an estimation of the relative contribution of site-, tooth-, and patient-associated variables in terms of PD reductions following a standard course of machine-driven subgingival debridement.

Effect of non-surgical periodontal therapy on C-telopeptide pyridinoline cross-links (ICTP) and interleukin-1 levels

BACKGROUND

Biochemical markers harvested from gingival crevicular fluid (GCF) may be useful to identify and predict periodontal disease progression and to monitor the response to treatment. C-telopeptide pyridinoline cross-links (ICTP), a host-derived breakdown product specific for bone, and interleukin-1beta (IL-1), a potent bone-resorptive cytokine, have been associated with periodontal tissue destruction. The aim of this study was to examine the effect of non-surgical periodontal therapy on GCF levels of ICTP and IL-1.

METHODS

Twenty-five chronic periodontitis subjects were monitored at 8 sites per subject at baseline prior to scaling and root planing and 1, 3, and 6 months after therapy. Four shallow (probing depths < 4 mm) and 4 deep (probing depths > or = 5 mm) sites were monitored for both marker levels and clinical parameters. GCF was collected for 30 seconds on paper strips, and levels of ICTP and IL-1 were determined using radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques, respectively. Clinical measurements included probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP).

RESULTS

Deep sites exhibited significantly (P<0.001) higher ICTP and IL-1 levels compared to shallow sites at all time intervals. ICTP demonstrated a stronger association to clinical parameters than IL-1 including a modest correlation (r = 0.40, P<0.001) between ICTP and attachment loss. Significant improvements in PD, CAL, and BOP were observed at 1, 3, and 6 months in all sites (P<0.01). However, non-surgical mechanical therapy did not significantly reduce ICTP and IL-1 levels over the 6-month period. Further examination of subjects based on smoking status revealed that ICTP levels were significantly reduced at 3 and 6 months and IL-1 levels reduced at 3 months among non-smokers only.

CONCLUSIONS

A single episode of non-surgical mechanical therapy did not significantly reduce biochemical markers associated with bone resorption in patients exhibiting chronic periodontitis. Future longitudinal studies are warranted to specifically evaluate the relationship between C-telopeptide pyridinoline cross-links and periodontal disease progression.

A re-analysis of a caries clinical trial by survival analysis

The decline in caries prevalence, the increases in the level of fluoride exposure, and the lack of placebo control subjects have complicated caries clinical trials in recent times. There has been a substantial increase in the numbers of subjects required for the detection of statistically significant differences between dental products, and hence, the cost of these trials has grown enormously. This study uses a new statistical approach to the analysis of the data from these trials with the ultimate aim of providing a more sensitive method of analysis. The new approach uses survival analysis, where the outcome measure is the survival time of an individual tooth surface. It exploits recent developments in the analysis of clustered survival data where survival times within the same cluster or subject are correlated. To illustrate, the new method of analysis was used for the North Wales, UK, caries clinical trial. It is concluded that survival analysis uses most of the data available in a caries clinical trial, an outcome measure that is easily understood and may lead to a more sensitive method of analysis.

Relationship between crevicular aspartate aminotransferase levels and periodontal disease progression

BACKGROUND

Aspartate aminotransferase (AST), an enzyme released from necrotic cells, has been identified in gingival crevicular fluid (GCF), and elevated levels are associated with periodontal tissue destruction. The aim of this study was to examine the relationship between elevated GCF levels of AST and periodontal disease progression.

METHODS

Over a 12-month period, 8 to 10 interproximal sites in 41 periodontitis subjects (PS) and 15 healthy subjects (HS) were monitored. Clinical measurements included relative attachment level (RAL), probing depth, and bleeding on probing (BOP). Semiquantitative levels of GCF AST (< 800 microIU, > or = 800 microIU, and > or = 1,200 microIU) were determined using a chairside assay. At the 6- and 12-month visits, scaling and root planing and prophylaxis were performed in the PS and HS, respectively. Sensitivity, specificity, positive predictive values (PPV), and negative predictive values (NPV) were calculated for 2 diagnostic criteria (AST > or = 800 microIU, AST > or = 1,200 microIU) utilizing 4 thresholds of disease progression as determined by 2 methods (absolute change in relative attachment level and cumulative sum [CUSUM]).

RESULTS

The percentage of sites exhibiting AST > or = 800 microIU, AST > or = 1,200 microIU, and BOP in the PS was significantly (P<0.02) lower at 6 and 12 months compared to baseline. The use of crevicular AST activity to monitor periodontal disease progression was associated with many false-positive results. Overall, low specificities, PPV, and odds ratios were demonstrated by the assay when using 2 diagnostic criteria and 4 thresholds of disease progression. The high NPV suggest that a negative AST test result was indicative of a periodontally stable site.

CONCLUSIONS

These results demonstrate that elevated levels of AST were present at sites that did not subsequently exhibit disease progression. The high prevalence of AST-positive sites due to gingival inflammation diminished the test's ability to discriminate between progressive and stable, but inflamed, sites.

Long-term stability of clinical attachment following guided tissue regeneration and conventional therapy

44 patients (34% smokers) presenting with severe periodontitis were treated with full mouth root planing (RPL). In each patient, 1 intrabony defect was treated with guided tissue regeneration (GTR). After 1 year of monthly prophylaxis, full mouth plaque (FMPS) and bleeding (FMBS) scores were 8.3 +/- 4.1% and 5.6 +/- 3.8%. At 1 year, the GTR treated sites were matched, in each patient, with 1 RPL site, in terms of probing attachment level (PAL 6.8 +/- 2.4 mm GTR, and 6.5 +/- 2.3 mm RPL). At this point, 24 patients took part in a supportive periodontal care program. 20 patients did not participate, and received only sporadic care by general dentists. At 5 years, all patients were reexamined. FMPS was 10.5 +/- 6.8% and FMBS 7.7 +/- 6.4%. A significant PAL loss was observed in both sites (1.2 +/- 1.4 mm GTR, 1.3 +/- 1.3 mm RPL, p < 0.0001) between 1 and 5 years. Differences in PAL loss between GTR and RPL sites were not statistically significant. Only a minority of sites (34%), however, lost PAL, while 66% remained stable. 75% of the matched sites (GTR and RPL) within the same patients were concordant in terms of PAL stability. The 23 patients in which both sites remained stable, had good oral hygiene, complied with the recall system, and did not smoke. The 10 patients in which both sites lost PAL showed deteriorating oral hygiene, did not comply with the recall system, and smoked. PAL loss in the GTR and/or RPL sites was consistently observed in patients (losers) showing PAL loss in other teeth. Losers had, in general, negative subjects characteristics, and showed a higher prevalence of tooth loss.

IN CONCLUSION

(i) GTR and RPL sites showed comparable susceptibility to periodontal breakdown; (ii) stability of outcomes was consistently associated with good oral hygiene, compliance with a supportive periodontal care program, and no cigarette smoking.

Evaluation of periodontal treatments using controlled-release tetracycline fibers: microbiological response

In a 12-month multi-center study of 116 adult periodontitis subjects, six putative periodontal pathogens were monitored by DNA probe methods in a subset of 31 subjects. Monitored species included Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), Eikenella corrodens (Ec), Campylobacter rectus (Cr), and Actinobacillus actinomycetemcomitans (Aa) with an average detection limit of 1.8 x 10(4) bacterial colony forming units/sample. The microbiological response to four periodontal treatments was studied, one treatment in each quadrant; scaling and root planing (S), scaling and root planing with tetracycline (TC) fiber (SF), a single application of TC fiber (F) and two serial applications of TC fiber (FF). Generally two sites were sampled in each quadrant, however, in some quadrants only one site was selected. These treatments were evaluated at baseline; immediately following therapy; and post-treatment at 1, 3, 6, and 12 months. The study was conducted with a split-mouth design with no maintenance therapy over a 12-month period. At baseline, 70.8% of sites had detectable Fn; 42.9% Pg; 63.5% Pi; 29.7% Ec; 28.3% Cr; and 5.5% Aa. No significant differences were seen in baseline proportions of these species between centers. Numbers and proportions of detectable pathogens (with the exception of Pg) exhibited a triphasic temporal response: a precipitous initial decrease immediately following therapy; a rise in proportions in the 1- to 3-month post-therapy period; and a spontaneous decline in the absence of therapy over the 3- to 12-month period.(ABSTRACT TRUNCATED AT 250 WORDS)

A 6-month multi-center evaluation of adjunctive tetracycline fiber therapy used in conjunction with scaling and root planing in maintenance patients: clinical results

The purpose of this study was to compare the efficacy of scaling and root planing (S and RP) alone versus tetracycline fiber therapy used adjunctively with S and RP in the treatment of localized recurrent periodontitis sites in maintenance patients. A total of 113 patients receiving regular supportive periodontal therapy (SPT) were treated with whole mouth S and RP. Two non-adjacent sites in separate quadrants were selected in each patient for monitoring based on criteria that the sites were 5 to 8 mm deep and had a history of bleeding on probing. The chosen sites were randomly assigned to one of the two treatment groups. Probing depth (PD), bleeding on probing (BOP), and clinical attachment level (CAL) were measured at baseline and 1, 3, and 6 months. At 1, 3 and 6 months, adjunctive fiber therapy was significantly better in reducing PD (P < 0.05) and reducing BOP (P < 0.05) than S and RP alone. At 6 months, fiber therapy was significantly better in promoting clinical attachment gain (P < 0.05) than S and RP alone. Overall, these results indicate that fiber therapy significantly enhanced the effectiveness of S and RP in the management of localized recurrent periodontitis sites, in patients receiving regular supportive periodontal treatment.

Association of clinical risk factors with treatment outcomes

A patient's decision to accept treatment recommended by his dental health care provider will be strongly influenced by the quality of the information he is given. Estimates of prognosis and treatment predictability must be based on the evidence available from the literature and the practitioners' own experience. Thorough, accurate, and relevant clinical and adjunctive diagnostic data will be a major influence in the development of the patient's individualized treatment strategy. Some clinical findings such as severity of disease for age, deepening pockets accompanied by loss of clinical attachment, frequent bleeding on probing, and bone loss can be considered as risk and prognosis factors. "Hard" data implicating specific clinical or diagnostic findings as risk factors or markers are difficult to find because there are few randomized longitudinal trials available. A new approach which attempts to focus on reducing the risk of undesirable outcomes while improving the probability of successful outcomes following treatment has been referred to as the Treatment Predictability Model. A key feature of this approach is the focus on individual patient circumstances and preferences through the use of decision analysis techniques. A large scale, long-term project utilizing a practice-based research network (PBRN) provided some descriptive information about factors that could distinguish between responders and nonresponder patients undergoing treatment for advanced periodontitis. Bacterial colonization, level of post-treatment plaque control, and smoking were major predictive variables in this group of periodontitis patients. The predictive treatment approach may be one way to develop evidence that will improve the predictability of outcomes for individual patients.

Effect of antibody in gingival crevicular fluid on early colonization of exposed root surfaces by mutans streptococci

The effect of antibody to Streptococcus mutans in gingival crevicular fluid (GCF) on the recolonization of cleaned buccal root surface sites by indigenous mutans streptococci was studied. Seven subjects (mean age = 64 years) were selected from a population of 28 on the basis of the presence of appropriate sites with and without detectable immunoglobulin G (IgG) antibody in GCF to formalin-killed S. mutans and adequate levels of mutans streptococci in saliva available for root surface recolonization. Root surfaces exposed to GCF that did or did not contain antibody were then cleaned and sampled for residual plaque organisms (total cultivable flora and mutans streptococci) directly after cleaning (time 0) as well as 24 h later. One subject failed to recolonize at 24 h at any (antibody-positive or antibody-negative) experimental site. For each of the remaining 6 subjects, the mean levels of mutans streptococci (mean percentage of total flora) were lower at sites with IgG antibody to S. mutans in GCF than at antibody-negative sites in the same subject. In each of the 6 subjects, the site with the highest recolonization level was antibody-negative. Comparison based on intrasubject randomization of sites suggested diminished recolonization of mutans streptococci at sites with antibody 24 h after cleaning. The results support the idea that antibody in GCF can modify the early colonization of gingival root surface areas by potentially cariogenic plaque bacteria such as mutans streptococci.

Subgingival minocycline hydrochloride ointment in moderate to severe chronic adult periodontitis: a randomized, double-blind, vehicle-controlled, multicenter study

The safety and efficacy of subgingivally-applied 2% minocycline ointment was evaluated in a randomized, double-blind study of 103 adults with moderate to severe periodontitis. Two groups were compared; one received the test minocycline ointment and the other a vehicle control. Both groups had scaling and root planing at baseline, after which the test or control ointments were applied with an applicator into the periodontal pockets at baseline, and at 2, 4, and 6 weeks. Assessment of clinical response was made by measuring probing depth and probing attachment level and gingival bleeding. These measurements were made at baseline prior to scaling and root planing, and at weeks 4 and 12. Microbiological assessment of the subgingival flora was carried out with DNA probes at baseline, and at weeks 2, 4, 6, and 12 to identify and quantify Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans. Subgingival minocycline ointment resulted in statistically significantly greater reduction of P. gingivalis at weeks 2, 4, 6, and 12; P. intermedia at weeks 2, 4, 6, and 12; and A. actinomycetemcomitans at weeks 6 and 12. Probing depth reductions were seen for both groups at weeks 4 and 12; however, this reduction was statistically significantly greater in subjects treated with minocycline ointment. Reduction in gingival index and probing attachment gain were seen in both groups, however, the differences between the groups were not statistically significant.(ABSTRACT TRUNCATED AT 250 WORDS)

A 2-year study of adjunctive minocycline-HCl in Actinobacillus actinomycetemcomitans-associated periodontitis

To study the effects of a step-wise treatment regimen on Actinobacillus actinomycetemcomitans-(Aa) associated periodontitis, 4 clusters among 33 patients harboring the organism were followed during successive periods of systemic minocycline plus mechanical debridement and minocycline plus modified Widman flap treatment. Localized periodontitis was found in 2 clusters, one with 7 localized juvenile periodontitis patients and a 24-year old male with localized destruction and extremely low plaque levels (LJP), and the other consisting of 10 patients with plaque and gingivitis and a wider age range (16 to 54 years, LP). Generalized severe and moderate periodontitis was found in 2 clusters which were further discriminated by severe gingivitis and high levels of supragingival plaque (9 patients, GSP), and mild inflammation and low plaque levels (6 patients, GMP). Mean percentages of Aa, as determined by selective cultivation of microbiota from at least 2 periodontal pockets of 6 mm or more were 63, 16, 33, and 7.8% in the clusters (P < 0.01). Six months after active treatment, Aa was present in 6/9 patients and 50% of sites in GSP, and 3/6 patients and 46% of sites in GMP patients. In contrast, the organism was virtually eliminated by scaling and flap procedures in the localized periodontitis clusters, and did not reappear after 6 months (P < 0.05). Combined antibiotic, mechanical, and surgical therapy resulted in a persistence of 20% of sites with residual probing depth of > or = 4 mm in GMP patients after active therapy. At this point, 3 of the GMP patients and 1 GSP patient left the study. Multiple regression analysis showed a significant influence of log-transformed numbers in Aa in cheek and saliva samples at the end of the study, and cluster on the percent residual number of sites with periodontal probing depth of > or = 7 mm (P < 0.001). The present results suggest that the applied therapy would be appropriate in localized forms of Aa periodontitis, but inappropriate in more severe and generalized forms to predictably eliminate Aa. Controlled long-term studies with larger groups of patients will be needed to establish the difference in treatment response suggested by these studies.

Autogenous and allogeneic bone grafts in periodontal therapy

This article is limited to a review of bone autografts and allografts, as used in periodontal therapy. The various graft materials are discussed with respect to case reports, controlled clinical trials, and human histology. Other reviewed areas are wound healing with periodontal bone grafts, tissue banking and freeze-dried bone allografts, and the use of bone grafts in guided tissue regeneration.

Subgingival temperature (I). Relation to baseline clinical parameters

44 subjects ranging in age from 14-71 years were measured at 6 sites per tooth for gingival redness, plaque accumulation, suppuration, bleeding on probing, pocket depth and attachment level. Subgingival temperatures were measured at the same 6 sites per tooth using a periodontal temperature probe (Periotemp, Abiodent, Danvers, MA). This instrument was also used to measure each subject's sublingual temperature in order to compute the differences between sublingual and subgingival temperature. Relationships were sought between the baseline clinical parameters and the temperature variables in subjects and at sites. The mean and standard deviation of the sublingual temperatures for the 44 subjects was 36.6 +/- 0.4 degrees C (range 35.8-37.6 degrees C). The mean of each subject's mean whole mouth subgingival temperature was 1.9 degrees C lower, 34.8 +/- 0.6 degrees C (range 33.4-36.1 degrees C). The differences of the mean subgingival temperature from sublingual ranged from -0.8 to -3.2 degrees C (average -1.9 +/- 0.5 degrees C). Mean temperature difference for a subject correlated with % of sites with plaque (rs = 0.45), redness (rs = 0.33), bleeding on probing (rs = 0.44), % of sites with attachment level greater than 3 mm (rs = 0.44), mean pocket depth (rs = 0.44) and mean attachment level (rs = 0.39). There were higher mean temperatures at sites exhibiting or not exhibiting plaque (35.0, 34.5 degrees C), redness (34.9, 34.6), bleeding on probing (35.1, 34.7) and suppuration (35.4, 34.8). Sites with pockets less than 4, 4-6 and greater than 6 mm had mean temperatures of 34.6, 35.2, 35.8 degrees C, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparison of the benzoyl-DL-arginine-naphthylamide (BANA) test, DNA probes, and immunological reagents for ability to detect anaerobic periodontal infections due to Porphyromonas gingivalis, Treponema denticola, and Bacteroides forsythus

Most forms of periodontal disease are associated with the presence or overgrowth of anaerobic species that could include Treponema denticola, Porphyromonas gingivalis, and Bacteroides forsythus among others. These three organisms are among the few cultivable plaque species that can hydrolyze the synthetic trypsin substrate benzoyl-DL-arginine-naphthylamide (BANA). In turn, BANA hydrolysis by the plaque can be associated with periodontal morbidity and with the presence of these three BANA-positive organisms in the plaque. In this investigation, the results of the BANA test, which simultaneously detects one or more of these organisms, were compared with the detection of these organisms by (i) highly specific antibodies to P. gingivalis, T. denticola, and B. forsythus; (ii) whole genomic DNA probes to P. gingivalis and T. denticola; and (iii) culturing or microscopic procedures. The BANA test, the DNA probes, and an enzyme-linked immunosorbent assay or an indirect immunofluorescence assay procedure exhibited high sensitivities, i.e., 90 ot 96%, and high accuracies, i.e., 83 to 92%, in their ability to detect combinations of these organisms in over 200 subgingival plaque samples taken from the most periodontally diseased sites in 67 patients. This indicated that if P. gingivalis, T. denticola, and B. forsythus are appropriate marker organisms for an anaerobic periodontal infection, then the three detection methods are equally accurate in their ability to diagnose this infection. The same statement could not be made for the culturing approach, where accuracies of 50 to 62% were observed.

Comparison of various detection methods for periodontopathic bacteria: can culture be considered the primary reference standard?

The development of diagnostic tests for a periodontal infection raises the issue as to what the appropriate reference standard, or "gold standard," should be for the evaluation of a new test. The present research was initiated to compare the ability of several detection methods, i.e., a serial dilution anaerobic culture and/or microscopic procedure, a DNA probe procedure, and immunological reagents using both an enzyme-linked immunosorbent assay and an indirect immunofluorescence assay to detect Treponema denticola, Porphyromonas gingivalis, Bacteroides forsythus, and Actinobacillus actinomycetemcomitans in subgingival plaque samples taken from 204 periodontally diseased tooth sites. The prevalence of the four monitored species varied as a function of both the species and the detection method. Spirochetes were present in 99% of the plaques, whereas A. actinomycetemcomitans was detected at the lowest frequency. The culture method yielded the lowest prevalence values for the three cultivable species. This raised the question as to which results, those obtained by culture or those obtained by the DNA probes and the immunological reagents, were the most reliable. This issue was addressed by looking at the prevalence profile of the monitored organisms, as determined by all the detection methods. If the species was detected by three or four of the detection methods, then it was considered present, whereas if it was absent by three or four of the detection methods, then it was considered absent. This approach showed the DNA probes and immunological reagents to be significantly superior (P less than 0.05) to the culture approach for the detection of P. gingivalis, A. actinomycetemcomitans, and B. forsythus and to be comparable to the microscopic approach in the detection of T. denticola.

Relation of counts of microbial species to clinical status at the sampled site

The purpose of the present investigation was to relate clinical characteristics at a site to the frequency of detection, absolute counts and proportions of 14 subgingival species. Subgingival plaque samples were removed by curette from the mesial surface of 2299 teeth in 3 healthy and 87 subjects with periodontal attachment loss. Samples were dispersed, diluted and plated on Trypticase soy agar supplemented with 5% sheep blood. After 7 days of anaerobic incubation, colonies were lifted onto nylon filters, lysed and the DNA fixed to the filters. Digoxygenin-labeled DNA probes were used to identify colonies of each test species. Measurements of pocket depth, attachment level, recession, redness, bleeding on probing and suppuration were made at each sampled site. Total viable counts at sites ranged from 10(3) to greater than 10(8) and were strongly related to pocket depth. Mean total counts at sites less than 3 mm averaged 4.6 x 10(6), while mean counts at sites greater than 7 mm averaged 2.0 x 10(7). Species enumerated and % of sites colonized were as follows; V. parvula 44; S. sanguis II 36; B. intermedius I 33; C. ochracea 31; B. intermedius II 30; S. sanguis I 29; B. gingivalis 27; S. intermedius 25; P. micros 24; W. recta 23; F. nucleatum ss vincentii 18; B. forsythus 15; A. actinomycetemcomitans serotype a 10; A. actinomycetemcomitans serotype b 8. Counts of B. intermedius II were higher at sites which exhibited gingival redness while B. intermedius I was higher at sites which bled on probing. A. actinomycetemcomitans serotype b was more frequent and at higher mean % at sites without recession. The opposite was true for S. sanguis II. B. gingivalis was somewhat more prevalent and at higher levels at suppurating sites. B. gingivalis, B. intermedius I and II and B. forsythus were found more frequently and at higher levels at sites with deeper pockets, while V. parvula was less prevalent at sites with pocket depths less than 4 mm. B. gingivalis, B. intermedius I and A. actinomycetemcomitans serotype b increased with increasing pocket depth in both localized and widespread disease subjects, but mean counts were higher in the localized disease subjects at any pocket depth. Only W. recta was found at higher levels at deep sites in widespread disease subjects when compared with similar sites in localized disease subjects. No suspected pathogens were detected in 38% of shallow sites, 31% of intermediate sites and 22% of deep sites, 2/3 of deep pockets, but less than 1/2 of shallow pockets harbored at least 2 of the suspected pathogens.