The survival rate of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus following 4 randomized treatment modalities

Influence of periodontal surgery on the subgingival microbiome-A systematic review and meta-analysis

OBJECTIVE

The objective of this systematic review and meta-analysis was to evaluate the effect of periodontal surgery on the subgingival microbiome.

BACKGROUND

Periodontitis is a chronic inflammation of the tooth supporting tissues caused by the dysbiosis of the subgingival biofilm. It is managed through different non-surgical and surgical treatment modalities. Recent EFP S3 guidelines recommended performing periodontal surgery as part of Step 3 periodontitis treatment after Step 1 and Step 2 periodontal therapy, with the aim to achieve pocket closure of persisting sites. Changes in the sub-gingival microbiome may explain the treatment outcomes observed at different time points. Various microbiological detection techniques for disease-associated pathogens have been evolved over time and have been described in the literature. However, the impact of different types of periodontal surgery on the subgingival microbiome remains unclear.

METHODS

A systematic literature search was conducted in Medline, Embase, LILACS and Cochrane Library supplemented by manual search (23DEC2019, updated 21APR2022).

RESULTS

From an initial search of 3046 studies, 28 were included according to our specific inclusion criteria. Seven microbiological detection techniques were used to analyse disease-associated species in subgingival plaque samples: optical microscope, culture, polymerase chain reaction (PCR), checkerboard, enzymatic reactions, immunofluorescence and 16S gene sequencing. The included studies exhibited differences in various aspects of their methodologies such as subgingival plaque sample collection or treatment modalities. Clinical data showed a significant decrease in probing pocket depths (PPD) and clinical attachment loss (CAL) after periodontal surgery. Microbiological findings were overall heterogeneous. Meta-analysis was performed on a sub-cohort of studies all using checkerboard as a microbiological detection technique. Random effect models for Treponema denticola (T. denticola), Porphyromonas gingivalis (P. gingivalis) and Tannerella forsythia (T. forsythia) did not show a significant effect on mean counts 3 months after periodontal surgery. Notably, Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) showed a significant increase 3 months after periodontal surgery. 16S gene sequencing was used in one included study and reported a decrease in disease-associated species with an increase in health-associated species after periodontal surgery at 3 and 6 months.

CONCLUSION

This systematic review has shown that the effect of periodontal surgery on the changes in subgingival microbiome is heterogeneous and may not always be associated with a decrease in disease-associated species. The variability could be attributed to the microbiological techniques employed for the analysis. Therefore, there is a need for well-designed and adequately powered studies to understand how periodontal surgery influences the subgingival microbiome and how the individual's microbiome affects treatment outcomes after periodontal surgery.

Systemic antibiotics in the treatment of periodontitis

Despite the fact that several clinical studies have shown additional benefits when certain systemic antibiotics are used as adjuncts to periodontal treatment, clear guidelines for the use of these agents in the clinical practice are not yet available. Basic questions concerning the use of systemic antibiotics to treat periodontitis remain unanswered, such as: which drug(s) should be used; which patients would most benefit from treatment; which are the most effective protocols (i.e. doses and durations); and in which phase of the mechanical therapy should the drug(s) be administered? Although not all of those questions have been directly addressed by controlled randomized clinical trials, recent concepts related to the ecology of periodontal diseases, as well as the major advances in laboratory and clinical research methods that have occurred in the past decade, have significantly broadened our knowledge in this field. This article endeavored to provide a 'state of the art' overview on the use of systemic antibiotics in the treatment of periodontitis, based on the most recent literature on the topic as well as on a compilation of data from studies conducted at the Center of Clinical Trials at Guarulhos University (São Paulo, Brazil) from 2002 to 2012.

Adhesion of periodontal pathogens to self-ligating orthodontic brackets: An in-vivo prospective study

INTRODUCTION

Our aims were to analyze adhesion of periodontopathogens to self-ligating brackets (Clarity-SL [CSL], Clippy-C [CC] and Damon Q [DQ]) and to identify the relationships between bacterial adhesion and oral hygiene indexes.

METHODS

Central incisor brackets from the maxilla and mandible were collected from 60 patients at debonding after the plaque and gingival indexes were measured. Adhesions of Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Prevotella intermedia (Pi), Fusobacterium nucleatum (Fn), and Tannerella forsythia (Tf) were quantitatively determined using real-time polymerase chain reactions. Factorial analysis of variance was used to analyze bacterial adhesion in relation to bracket type and jaw position. Correlation coefficients were calculated to determine the relationships between bacterial adhesion and the oral hygiene indexes.

RESULTS

Total bacteria showed greater adhesion to CSL than to DQ brackets, whereas Aa, Pg, and Pi adhered more to DQ than to CSL brackets. CC brackets showed an intermediate adhesion pattern between CSL and DQ brackets, but it did not differ significantly from either bracket type. Adhesion of Fn and Tf did not differ significantly among the 3 brackets. Most bacteria were detected in greater quantities in the mandibular than in the maxillary brackets. The plaque and gingival indexes were not strongly correlated with bacterial adhesion to the brackets.

CONCLUSIONS

Because Aa, Pg, and Pi adhered more to the DQ brackets in the mandibular area, orthodontic patients with periodontal problems should be carefully monitored in the mandibular incisors where the distance between the bracket and the gingiva is small, especially when DQ brackets are used.

Microbiological basis for periodontal therapy

The search for the etiologic agents of periodontal diseases started in the Golden Era of medical bacteriology, when the etiologic agents of many bacterial infections were isolated and characterized. After the initial enthusiasm in establishing the infectious nature and the true agents of periodontal diseases, this concept was virtually ignored for the next four decades. Until the early 1970s treatment regimens based on the non-specific plaque hypothesis were directed towards a non-specific reduction in plaque amount. Later, the specific plaque hypothesis established the role of some microorganisms such as A. actinomycetemcomitans, P. gingivalis, T. forsythensis, T. denticola, P. intermedia and F. nucleatum in different forms of periodontal diseases. It was recently suggested that these suspected periodontal pathogens seem to not act alone and interactions between species, especially the balance between pathogenic and beneficial species affect both progression of disease and response of tissues to periodontal therapy. Nowadays it is well established that one of the goals of therapy is to control such periodontal pathogens. Among the most commonly used therapies to treat periodontal infections are scaling and root planing (SRP), supragingival plaque control and periodontal surgeries. Many studies confirmed the reduction of "red complex" species by SRP, and apically repositioned flap can lead to an additional beneficial effect in the subgingival microbiota by decreasing levels of "red" and "orange complexes" species. Furthermore, the level of plaque control maintained by the patients has been considered a crucial step in preventing recurrence of destructive periodontitis.

Clinical and microbiological parameters in patients with self-ligating and conventional brackets during early phase of orthodontic treatment

OBJECTIVE

To determine the effect of different bracket designs (conventional brackets and self-ligating brackets) on periodontal clinical parameters and periodontal pathogens in subgingival plaque.

MATERIAL AND METHODS

The following inclusion criteria were used: requirement of orthodontic treatment plan starting with alignment and leveling, good general health, healthy periodontium, no antibiotic therapy in the previous 6 months before the beginning of the study, and no smoking. The study sample totaled 38 patients (13 male, 25 female; mean age, 14.6 ± 2.0 years). Patients were divided into two groups with random distribution of brackets. Recording of clinical parameters was done before the placement of the orthodontic appliance (T0) and at 6 weeks (T1), 12 weeks (T2), and 18 weeks (T3) after full bonding of orthodontic appliances. Periodontal pathogens of subgingival microflora were detected at T3 using a commercially available polymerase chain reaction test (micro-Dent test) that contains probes for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Tannerella forsythia, and Treponema denticola.

RESULTS

There was a statistically significant higher prevalence of A actinomycetemcomitans in patients with conventional brackets than in patients with self-ligating brackets, but there was no statistically significant difference for other putative periodontal pathogens. The two different types of brackets did not show statistically significant differences in periodontal clinical parameters.

CONCLUSION

Bracket design does not seem to have a strong influence on periodontal clinical parameters and periodontal pathogens in subgingival plaque. The correlation between some periodontal pathogens and clinical periodontal parameters was weak.

Periodontal healing after non-surgical therapy with a new ultrasonic device: a randomized controlled clinical trial

AIM

The aim of this study was to compare the clinical and microbiological healing outcomes following non-surgical periodontal therapy using the new Vector ultrasonic system versus scaling and root planing (S/RP) with Gracey curettes.

MATERIAL AND METHODS

The study comprised 20 chronic periodontitis patients. Using a split-mouth design, both treatment modalities were randomly applied to one quadrant of the upper and the lower jaws each. Clinical and microbiological parameters were assessed at baseline, 4 weeks, and 6 months after treatment. Furthermore, post-operative hypersensitivity was assessed. The Wilcoxon signed rank test (alpha=0.05) was used for statistical analysis.

RESULTS

Both therapies provided statistically significant clinical and microbiological improvements of periodontal conditions after 4 weeks and 6 months. Hypersensitive teeth were found only 4 weeks after S/RP. Besides a significantly better bleeding on probing reduction in deep S/RP sites, no other clinical and microbiological parameters revealed significant differences between the sites treated with the Vector system or S/RP.

CONCLUSION

Both the Vector system and S/RP provided favourable periodontal healing results, although in deep pockets S/RP appeared to achieve a better resolution of inflammation.

Periodontal healing after non-surgical therapy with a modified sonic scaler: a controlled clinical trial

AIM

The aim of this study was to compare the clinical and microbiological healing outcomes following non-surgical periodontal therapy using a modified sonic scaler system versus scaling and root planing (S/RP) with hand instruments.

MATERIAL AND METHODS

The study comprised 20 chronic periodontitis patients. Using a split-mouth design, both treatment modalities were randomly applied to one quadrant of the upper and lower jaws. Clinical and microbiological parameters were assessed at baseline, 4 weeks, and 6 months after treatment. Furthermore, post-operative hypersensitivity was investigated. The Wilcoxon signed-rank test (alpha = 0.05) was used for statistical analysis.

RESULTS

With both therapy methods, periodontal conditions showed statistically significant clinical and microbiological improvements after 4 weeks and 6 months. Hypersensitive teeth were found only 4 weeks after S/RP. Besides a significantly better bleeding on probing reduction in deep S/RP sites and less time required for root instrumentation by the sonic scaler, no other clinical and microbiological parameters revealed significant differences between sites treated with the sonic scaler or S/RP.

CONCLUSION

The sonic scaler system and S/RP seem to provide similarly favourable periodontal healing results, although in deep pockets S/RP appeared to achieve a better resolution of inflammation.

Clinical effects of scaling and root planing on untreated teeth

OBJECTIVE

The aim of this report is to examine whether scaling and root planing (SRP) in one area of the mouth may affect periodontal improvement in untreated areas in the same patient, possibly through systemic effects of treatment.

MATERIAL AND METHODS

Twenty patients diagnosed with generalized aggressive periodontitis were randomized into treatment (n=11) and no treatment (n=9) groups. Within the treatment group, three quadrants were treated by SRP at week 0, 3, 12, and 24, while a single experimental quadrant remained untreated throughout the study. The outcome for all teeth was assessed using clinical parameters, subtraction radiography, and pathogenic bacteria levels in the subgingival flora over the 24-week study period.

RESULTS

Compared with sites in no treatment patients, the treated sites in the treated patients showed a 1 mm decrease in probing depth (PD) (p<0.01) and a 0.5 mm increase in bone height (p<0.01) by 24 weeks. In untreated sites within treated subjects, however, PDs tended to improve (p=0.09) but at a reduced rate compared with treated sites. The levels of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythensis (Bacteroides forsythus) remained unchanged in untreated sites while levels of Prevetolla intermedia and Treponema denticola tended to decrease as compared with controls but did not reach significance.

CONCLUSIONS

This study indicates that untreated sites in treated periodontitis patients show a trend towards clinical improvement and exhibit reductions in some but not all periodontopathic bacterial species tested.

Clinical and microbiologic changes after removal of orthodontic appliances

The goal of this study was to evaluate the clinical and microbiological factors associated with orthodontic appliances during an episode of gingival inflammation and the impact of appliance removal on periodontal health. This prospective study included 10 patients, aged 12 to 20 years, with clinical signs of gingival inflammation at the final phase of orthodontic treatment (appliance removal). Plaque index, gingival index, and probing depth were evaluated, and microbiological samples were collected from teeth 16, 11, and 26 at 2 times: during the gingival inflammation (baseline) and 30 days after the removal of the appliance and professional prophylaxis. Polymerase chain reaction analysis was used to detect Porphyromonas gingivalis, Bacteroides forsythus, Actinobacillus actinomycetemcomitans, Prevotella intermedia, and Prevotella nigrescens. A statistically significant improvement of the plaque and gingival indexes was seen, as well as a reduction in probing depth (P <.05). Periodontal pathogens were associated with gingival inflammation during orthodontic treatment. The improvement in periodontal health at 30 days was concomitant with a reduction of sites positive for A. actinomycetemcomitans and B. forsythus (P <.05). Periodontal pathogens associated with gingival inflammation during orthodontic treatment can be significantly reduced by orthodontic appliance removal and professional prophylaxis.

Clinical Responses to Mechanical Periodontal Treatment in Chinese Chronic Periodontitis Patients with and withoutActinobacillus actinomycetemcomitans

BACKGROUND

The purpose of this study was to compare 12-month clinical responses to mechanical periodontal treatment in Chinese chronic periodontitis patients at sites with and without Actinobacillus actinomycetemcomitans at baseline, and to investigate the ability of mechanical periodontal treatment to eliminate A. actinomycetemcomitans.

METHODS

Nineteen patients and a total of 76 selected sites with a mean probing depth (PD) of > or = 7 mm were studied. Whole mouth presence or absence of supragingival plaque (PI%), bleeding on probing (BOP%), probing depth (PD), and probing attachment level (PAL) were recorded at six sites per tooth at baseline and after 3, 9, and 12 months. Baseline subgingival plaque samples were taken from the deepest PD site in each quadrant using sterile paper points and were cultured on TSBV plates for 5 days in a 5% CO2-air incubator. All sites received mechanical periodontal treatment, which included oral hygiene instructions and supragingival and subgingival instrumentation with or without surgical access, with maintenance care being provided once every 3 months thereafter.

RESULTS

At baseline, A. actinomycetemcomitans was isolated in 13 of the 19 subjects (68%) and in 29 out of the 76 sampled sites (38%). At the end of 12 months, in three of the initially A. actinomycetemcomitans-positive subjects, A. actinomycetemcomitans was not detected in the sampled sites, while one subject, in whom A. actinomycetemcomitans was not initially found at the sampled sites was A. actinomycetemcomitans-positive at 12 months. Multi-level variance component models showed there was no statistically significant difference in all clinical parameters between A. actinomycetemcomitans-positive and -negative subjects (P > 0.05). In the sampled sites of the initially A. actinomycetemcomitans-positive subjects, the mean PD was reduced from 7.6 +/- 1.6 mm to 3.2 +/- 1.8 mm, the mean PAL gain was 1.4 +/- 2.0 mm, and the mean recession was 3.0 +/- 2.3 mm. The corresponding figures in the sampled sites of the initially A. actinomycetemcomitans-negative subjects were 7.5 +/- 1.6 mm to 2.7 +/- 1.0 mm, 2.3 +/- 2.6 mm and 2.4 +/- 2.2 mm for mean PD changes, PAL gain, and mean recession, respectively.

CONCLUSIONS

Favorable clinical responses to mechanical periodontal therapy may occur in Chinese chronic periodontitis patients at sites infected with A. actinomycetemcomitans. The mere detection of subgignival A. actinomycetemcomitans does not necessarily imply poorer treatment outcomes in the control of chronic periodontitis.

Detection of highly and minimally leukotoxic Actinobacillus actinomycetemcomitans strains in patients with periodontal disease

This study examined the prevalence of highly and minimally leukotoxic Actinobacillus actinomycetemcomitans in patients with periodontal disease. Pooled subgingival plaque samples from 136 patients with some form of periodontal disease were examined. Subjects were between 14 and 76 years of age. Clinical examinations included periodontal pocket depth (PD), plaque index (PI) and bleeding index (BI). The obtained plaque samples were examined for the presence of highly or minimally leukotoxic A. actinomycetemcomitans strains by the polymerase chain reaction (PCR). Chi-square and logistic regression were performed to evaluate the results. Forty-seven subjects were diagnosed with gingivitis, 70 with chronic periodontitis and 19 with aggressive periodontitis. According to chi-square there was no significant correlation detected between PD (chi2 = 0.73), PI (chi2 = 0.35), BI (chi2 = 0.09) and the presence of the highly leukotoxic A. actinomycetemcomitans. The highly leukotoxic A. actinomycetemcomitans strains were correlated with subjects that were 28 years of age and younger (chi2 = 7.41). There was a significant correlation between highly leukotoxic A. actinomycetemcomitans and aggressive periodontitis (chi2 = 22.06). This study of a Brazilian cohort confirms the strong association between highly leukotoxic A. actinomycetemcomitans strains and the presence of aggressive periodontitis.

Bactericidal activity of citrate against Gram-positive cocci

AIMS

Coagulase-negative staphylococci (CNS) are now important nosocomial pathogens and are usually resistant to multiple antibiotics. Citrate is an alternative antimicrobial product which has been used as a preservative.

METHODS AND RESULTS

In this pilot study the bactericidal activity of Na citrate against 10 isolates of CNS and 6 other gram-positive pathogens was examined and compared with that of Na lactate.

CONCLUSIONS

All staphylococci tested were susceptible (> or = 2 log(10) killing) to citrate at 6.25-25 mg ml(-1). Na lactate showed only modest killing at 50 or 100 mg ml(-1).

SIGNIFICANCE AND IMPACT OF THE STUDY

Citrate may warrant broader evaluation as an antimicrobial additive such as in topical agents.

A multidisciplinary approach to the diagnosis and treatment of early-onset periodontitis: a case report

BACKGROUND

The diagnosis and treatment of early-onset forms of periodontitis (EOP) represent a major challenge to periodontists. In this case report, we describe a multidisciplinary approach for the treatment of a patient with severe generalized juvenile periodontitis (GJP). Our approach incorporates clinical laboratory evaluation with conventional concepts of periodontal pathogenesis and therapeutics to diagnose and effectively treat EOP.

METHODS

The 17-year-old female patient presented with clinical and radiographic evidence of severe attachment loss. Microbiological testing showed the presence of known periodontal pathogens including Actinobacillus actinomycetemcomitans, Prevotella intermedia, and Porphyromonas gingivalis. Routine immunological tests did not reveal any of the functional defects thought to play a role in the pathogenesis of EOP After initiation of therapy, which consisted of scaling and root planing, supplemented with administration of systemic antibiotics, a reduction in probing depth and gain in clinical attachment could be demonstrated. Microbiological testing was used to monitor the composition of the periodontal microbiota and to adjust antimicrobial therapy accordingly.

RESULTS

Using a non-surgical approach to treatment, except for 2 root amputations performed without flap reflection, we have been able to stabilize this patient's periodontal condition over the course of a 2-year follow-up period.

CONCLUSIONS

This treatment strategy provides an efficacious alternative to more aggressive forms of therapy and should therefore be considered for the treatment of patients with severe EOP.

Acquisition and colonization stability of Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis in children

The presence of Porphyromonas gingivalis has been shown to be a risk factor for periodontitis in adults, and Actinobacillus actinomycetemcomitans has been implicated as a pathogen in early-onset periodontitis. Both species have been shown to establish stable colonization in adults. In cross-sectional studies, both A. actinomycetemcomitans and P. gingivalis have been detected in over one-third of apparently healthy children. Information on the stability of colonization with these organisms in children could help to elucidate the natural history of the development of periodontitis. For this purpose, samples previously collected from a cohort of 222 children between the ages of 0 and 18 years and previously examined for the presence of P. gingivalis with a PCR-based assay were examined for the presence of A. actinomycetemcomitans. It was detected in 48% of subjects and, like P. gingivalis, was found at similar frequencies among children of all ages (P = 0.53), suggesting very early initial acquisition. One hundred one of the original subjects were recalled after 1 to 3 years to determine the continuing presence of both A. actinomycetemcomitans and P. gingivalis. The prevalence of both species remained unchanged at resampling. However, in most children both species appeared to colonize only transiently, with random concordance between the results of the first and second sampling. Stability of colonization was unrelated to age for A. actinomycetemcomitans, but P. gingivalis was more stable in the late teenage years.

Effect of initial periodontal therapy on the frequency of detecting Bacteroides forsythus, Porphyromonas gingivalis, and Actinobacillus actinomycetemcomitans

BACKGROUND

Porphyromonas gingivalis, Bacteroides forsythus, and Actinobacillus actinomycetemcomitans have been described as periodontopathic bacteria, and their presence in subgingival pockets can lead to development of periodontal disease. Until now, clinical parameters have been used to evaluate the effect of conventional periodontal treatment without microbiological parameters. The present study examined the microbiological effects of initial periodontal therapy using DNA probes and the polymerase chain reaction (PCR).

METHODS

Twenty-six patients with periodontitis, 10 males and 16 females, were given instructions regarding oral hygiene, then thoroughly treated by conventional scaling and root planing. Bacterial samples were collected on paper points from 4 sites per patient at baseline and after initial therapy (total: 104 sites). Clinical parameters including probing depth, attachment level, and bleeding on probing were also recorded for each site at baseline and after therapy. A DNA probe kit was used to monitor the frequency of B. forsythus, P. gingivalis, and A. actinomycetemcomitans, the last of which was identified by PCR.

RESULTS

At baseline, B. forsythus was the bacterium most frequently detected. DNA probe analysis also showed that more than half of the sites were colonized by both B. forsythus and P. gingivalis. Initial therapy resulted in significant clinical improvement such as significant reduction in the frequency of B. forsythus and P. gingivalis detected using the DNA probe. A. actinomycetemcomitans was difficult to detect using the DNA probe, but PCR indicated that levels of A. actinomycetemcomitans did not significantly decrease.

CONCLUSIONS

These results indicate that initial conventional therapy can eliminate B. forsythus and P. gingivalis, but not A. actinomycetemcomitans. When levels of these bacteria decreased to below-detectable levels, clinical improvement was significant. These results indicate that monitoring levels of these three periodontopathic bacteria may render periodontal therapy more effective and accurate.

The prevalence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Bacteroides forsythus in humans 1 year after 4 randomized treatment modalities

The relationship between probing attachment changes in treated periodontal pockets and the prevalence of selected periodontal pathogens was assessed in 10 patients with adult periodontitis 1 year following randomized therapy. All patients had at least 1 tooth in each quadrant with an inflamed pocket of probing depth > or =5 mm and clinical attachment loss and harbored at least one of the following 3 major periodontal pathogens: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, or Bacteroides forsythus. The number of target organisms per site was determined preoperatively; at 1 week; and at 1, 3, 6, and 12 months postoperatively utilizing DNA probes. The following clinical parameters were measured and recorded preoperatively and at 1, 3, 6, and 12 months post-treatment: gingival fluid flow, gingival index, plaque index, probing depth, probing attachment level, gingival recession, and bleeding on probing. One quadrant in each patient was randomly assigned to 1 of the following 4 treatments: 1) scaling and root planing; 2) pocket reduction through osseous surgery and apically-positioned flap; 3) modified Widman flap; and 4) modified Widman flap and topical application of saturated citric acid at pH 1 for 3 minutes. All 4 treatments were rendered in one appointment using local anesthesia. No postoperative antibiotics were used, but patients rinsed with 0.12% chlorhexidine for the first 3 months postoperatively and received a prophylaxis every 3 months. This investigation revealed: 1) 30.0% of the sites were infected by at least 1 species at 3, 6, and 12 months postoperatively. 2) Failing sites were infected by a high number of both Pg and Bf These sites had a mean of 24.2+/-9.0 x 10(3) Pg and 93.1+/-42.0 X 10(3) Bf while stable sites had a mean of 6.8+/-0.5 x 10(3) Pg and 7.2+/-1.2 x 10(3) Bf (P = 0.06 and P = 0.05, respectively). 3) The infected sites lost significantly more mean clinical attachment at 12 months (1.5+/-0.5 mm compared to a loss of 0.2+/-0.3 mm for uninfected sites, P = 0.017). 4) The infected sites had a significantly greater BOP (67+/-14% versus 25+/-8% for uninfected sites at 12 months, P = 0.012). 5) The choice of treatment modality did not affect the prevalence of the target species at 1 year post-treatment. These results suggest that prevalence of microbial pathogens negatively affects the 1 year outcome of periodontal surgical and nonsurgical therapy.