Effect of initial periodontal therapy on gingival crevicular fluid cytokine profile in subjects with chronic periodontitis.

Cytokines are thought to play an important role in the pathogenesis of periodontal disease. Because periodontal disease is known for its inhomogeneous distribution within the dentition, it is unclear to what extent the detection of various cytokines at different sites correlates with presence of disease. We evaluated whether levels of 12 cytokines in gingival crevicular fluid (GCF) discriminated periodontally diseased sites from healthy ones, or periodontally diseased persons from healthy ones, and assessed the impact of nonsurgical periodontal therapy on these readings. This study included 20 periodontally healthy persons (H) and 24 patients with chronic periodontitis (P). In every participant, we measured the plaque index, gingival index, probing pocket depth (PD), bleeding on probing, and recession at six sites of every tooth. GCF was collected with Durapore® filter strips from two healthy sites (PD<4 mm; HH) in group H, and from two periodontally diseased sites (PD≥5 mm; PP) and two periodontally healthy sites (PD≤3 mm; PH) in group P. The periodontally diseased participants underwent comprehensive nonsurgical periodontal therapy including deep scaling and root planing under local anesthesia. In these participants, GCF samples were again collected at the same sites 1 and 3 months after therapy. Twelve cytokines (il-1ß, il-1ra, il-6, il-8, il-17, b-fgf, g-csf, gm-csf, ifn-γ, mip-1ß, vegf, and tnf-α) were assessed using the Bio-Plex suspension array system. Mean plaque index, gingival index, bleeding on probing, PD, and recession were significantly different between groups H and P. Differences between PP and PH sites were not significant for any of the cytokines. Il-1ra, il-6, il-17, b-fgf, gm-csf, mip-1ß, and tnf-α differed significantly between HH sites and both PH and PP sites, whereas il-8 was significantly higher only at PP sites. Periodontal treatment increased gm-csf and decreased il-1ra levels in PP sites. Il-1ra, il-6, il-8, il-17, b-fgf, gm-csf, mip-1ß, and tnf-α identified patients with chronic periodontitis, rather than diseased sites, suggesting a generalized inflammatory state that is not limited to clinically diseased sites only.

Systemic Biomarkers in 2-Phase Antibiotic Periodontal Treatment: A Randomized Clinical Trial.

Accumulating evidence suggests that periodontal infections may have an impact on systemic health. In patients with untreated periodontitis, very high values for several inflammatory markers in serum are expressed simultaneously. We investigated to what extent these peak values change after nonsurgical and surgical periodontal treatment, with adjunctive antibiotics administered during the first or the second treatment phase. In a single-center, randomized, placebo-controlled, and double-masked clinical trial, 80 patients with chronic or aggressive periodontitis were randomized into 2 treatment groups: group A, receiving systemic amoxicillin and metronidazole during the first, nonsurgical phase of periodontal therapy (phase 1), and group B, receiving the antibiotics during the second, surgical phase (phase 2). Serum samples were obtained at baseline (BL), 3 mo after phase 1 (M3), and 6 and 12 mo after phase 2 (M6, M12). Samples were evaluated for 15 cytokines and 9 acute-phase proteins using the Bio-Plex bead array multianalyte detection system. For each analyte, peak values were defined as greater than mean +2 SD of measurements found in 40 periodontally healthy persons. Sixty-six patients showed a peak value of at least 1 analyte at BL. At M12, the number of these patients was only 36 (P = 0.0002). This decrease was stronger in group A (BL: 35, M12: 19, P = 0.0009) than in group B (BL: 31, M12: 17, P = 0.14). Twenty patients displayed peak values of at least 4 biomarkers at BL. The nonsurgical therapy delivered in the first phase reduced most of these peaks (group A, BL: 9, M3: 4, P = 0.17; group B, BL: 11, M3: 2, P = 0.01), irrespective of adjunctive antibiotics. The reductions obtained at M3 were maintained until M12 in both groups. Initial, nonsurgical periodontal therapy reduced the incidence of peak levels of inflammatory markers. Antibiotics and further surgical therapy did not enhance the effect (Clinicaltrials.gov NCT02197260).

Anti-apolipoprotein A-1 autoantibodies as biomarker for atherosclerosis burden in patients with periodontitis.

BACKGROUND AND OBJECTIVE: Anti-apolipoprotein A-1 (anti-apoA-1) IgG is a potential marker of atherosclerotic plaque vulnerability and cardiovascular complications. In patients with periodontitis the presence of anti-apoA-1 IgGs in serum and their association with atherosclerosis is unknown. MATERIAL AND METHODS: One-hundred and thirty subjects with periodontal disease and 46 healthy subjects, matched for age and gender, participated in this study. Anti-apoA-1 IgG, high-sensitivity C-reactive protein (hsCRP) and matrix metalloproteinase (MMP) -2, -3, -8 and -9 were measured in serum samples. An ankle-brachial index (ABI) value below 1.11 served as a surrogate marker of atherosclerosis. Predictive accuracies of biomarkers for abnormal ABI were determined using receiver-operating characteristics curves and logistic regression analyses. RESULTS: Compared with healthy controls, periodontitis patients showed lower median ABI values (1.10 vs. 1.15; p < 0.0001), a higher prevalence of anti-apoA-1 IgG positivity (23.8% vs. 6.5%; p = 0.009) and higher concentrations of hsCRP (1.62 mg/L vs. 0.85 mg/L; p = 0.02) and MMP-9 (435 µg/mL vs. 283 µg/mL; p < 0.0001). In patients younger than 50 years of age (n = 66), anti-apoA-1 IgG was found to be the best predictor for an abnormal ABI (area under the curve = 0.63; p = 0.03). Anti-apoA-1 IgG positivity increased the risk of having an abnormal ABI (odds ratio = 4.20; p = 0.04), independently of diabetes, smoking and body mass index. CONCLUSIONS: Anti-apoA-1 IgG positivity and atherosclerosis, as reflected by abnormal ABI, were more prevalent in periodontitis patients than in age- and gender-matched controls. In younger periodontitis patients, anti-apoA-1 IgG was found to be the best predictor of atherosclerosis burden.

Anti-infective surgical therapy of peri-implantitis. A 12-month prospective clinical study.

AIM: The aim of this prospective cohort study was to evaluate an anti-infective surgical protocol for the treatment of peri-implantitis. MATERIALS AND METHODS: Thirty-six implants in 24 partially dentate patients with moderate to advanced peri-implantitis were treated using an anti-infective surgical protocol incorporating open flap debridement and implant surface decontamination, with adjunctive systemic amoxicillin and metronidazole. Treatment outcomes were assessed at 3, 6 and 12 months. Patient-based statistical analyses using multiple regression analyses were performed. RESULTS: There was 100% survival of treated implants at 12 months. At 3 months, there were statistically significant (P < 0.01) reductions in mean probing depths (PD), Bleeding on Probing (BoP) and suppuration. The greater the mean PD at baseline, the greater the PD reduction at 3 months. At 3 months, there was also a significant mean facial mucosal recession of 1 mm (P < 0.001). All these changes were maintained at 6 and 12 months. At 12 months, all treated implants had a mean PD < 5 mm, while 47% of the implants had complete resolution of inflammation (BoP negative). At 12 months, 92% of implants had stable crestal bone levels or bone gain. There were no significant effects of smoking on any of the treatment outcomes. CONCLUSIONS: For the treatment of peri-implantitis, an anti-infective protocol incorporating surgical access, implant surface decontamination and systemic antimicrobials followed by a strict postoperative protocol was effective at 3 months with the results maintained for up to 12 months after treatment.

Myeloid-related protein (MRP8/14) expression in gingival crevice fluid in periodontal health and disease and after treatment.

BACKGROUND AND OBJECTIVE: Myeloid-related protein (MRP8/14) and its subunits are biomarkers of inflammation. The present study evaluated whether gingival crevice fluid levels of these markers discriminate periodontitis from healthy sites in patients with chronic periodontitis or diseased from healthy subjects, and whether these biomarkers detect longitudinal changes after therapy. MATERIAL AND METHODS: Levels of MRP8/14, MRP14 and total protein were quantified in 19 periodontitis patients before non-surgical periodontal therapy, after 3 and 6 mo of treatment, and were measured once in 11 periodontally healthy subjects. In total, diseased subjects contributed 59 sites with probing depths >4 mm (PP) and 21 sites <4 mm (PH); healthy subjects contributed 91 sites (HH). RESULTS: Overall, in diseased subjects, MRP8/14, MRP14 and total protein were not significantly different between PP and PH sites. However, at baseline, MRP8/14 and total protein had significantly higher values at sites in periodontally diseased than in healthy subjects. Clinical improvement was associated with a significant decrease of MRP8/14 and MRP14 from baseline to month 6 in PP sites. Interestingly, a similar decrease was observed in PH sites for all three markers. At 6 mo, however, levels of MRP8/14 and protein in PP and PH sites of patients were still significantly higher than in healthy subjects. CONCLUSION: Gingival crevice fluid levels of MRP8/14 did not differentiate between clinically diseased and healthy sites in patients with chronic periodontitis. However, this marker was elevated in periodontally diseased compared with healthy subjects, and its values decreased following therapy. MRP8/14 may be used to monitor the response to treatment.

Cytokines in gingival crevicular fluid of adolescents and young adults.

BACKGROUND/AIM: The purpose of this study was to compare the levels of the cytokines interleukin-1beta (IL-1beta), IL-4, and IL-8 in the gingival crevicular fluid (GCF) of adolescents and young adults. METHODS: Twenty-five adolescents aged between 14 and 16 years (Group A) and 20 periodontally healthy young adults aged between 25 and 35 years (Group B) were selected from two private dental clinics limited to pedodontics and periodontics respectively in Piraeus Greece. All subjects were systemically healthy. Clinical examination included probing pocket depth (PPD), presence or absence of plaque, and bleeding on probing (BOP). GCF was collected from four sites per subject. IL-1beta, IL-4, and IL-8, measured as total amounts (pg/30 s), were evaluated in 180 samples using a commercially available sandwich enzyme-linked immunosorbent assay. RESULTS: IL-1beta mean levels of Groups A and B were adjusted for BOP and PPD. Differences of IL-1beta mean levels between the two age groups were statistically significant (F = 50.245, P < 0.001) in favour of Group A. Adolescents showed statistically significantly lower mean levels of IL-4 than young adults in the presence of BOP (F = 10.690, P = 0.001). There was no statistically significant difference between adolescents and adults for the means of IL-8 adjusted for BOP and plaque presence (F = 2.032, P = 0.161). CONCLUSIONS: Within the limits of this study the differences reported in mean levels of IL-1beta and IL-4 may be attributed to the different age status.

Enamel matrix derivative and systemic antibiotics as adjuncts to non-surgical periodontal treatment: biologic response.

BACKGROUND: Short-term clinical observations suggest an anti-inflammatory effect of enamel matrix derivative (EMD). The purpose of this study was to evaluate the anti-inflammatory capacity of EMD, used as an adjunct to non-surgical periodontal treatment of deep lesions in chronic periodontitis patients, by monitoring inflammatory markers in gingival crevicular fluid (GCF). METHODS: Sixteen subjects were randomly assigned to treatment with EMD or placebo in contralateral dentition areas. Half of the subjects received 250 mg metronidazole and 375 mg amoxicillin three times a day for 7 days; the other half received a placebo. GCF samples were collected from one interproximal lesion in each of the contralateral quadrants before treatment and after 10 days and 2, 6, and 12 months. Total protein content was determined according to the Bradford method. Myeloid-related protein (MRP) 8/14 and interleukin (IL)-1beta were analyzed quantitatively by enzyme-linked immunosorbent assay (ELISA), and elastase activity was determined using a low molecular weight fluorogenic substrate. RESULTS: No significant differences were observed between sites treated with or without EMD for any biochemical parameter. Two months after treatment, subjects treated with antibiotics exhibited less clinical signs of inflammation. Furthermore, these subjects had lower MRP 8/14 levels only at day 10 compared to those receiving the placebo. For total protein, IL-1beta, and elastase, no statistically significant differences were noted for subjects with or without antibiotic therapy at any time point. CONCLUSIONS: Improved healing of the soft tissues has been noted clinically in non-surgically treated sites in subjects treated with antibiotics. The expression of inflammatory mediators in GCF corroborated this finding only in part. EMD did not seem to further affect the expression of inflammatory mediators.

Viruses in periodontal disease - a review.

The purpose of this review was to evaluate the evidence supporting the hypothesis that viral infection plays a role in the development of periodontitis. An involvement in periodontal diseases has been suspected specifically for human immunodeficiency virus (HIV) and herpes viruses. An association has been demonstrated between HIV infection and some distinct forms of periodontal infection, i.e. necrotizing lesions. Furthermore, reports of increased prevalence and severity of chronic periodontitis in HIV-positive subjects suggests that HIV infection predispose to chronic periodontitis. Several studies, most of them from the same research group, have demonstrated an association of herpesviruses with periodontal disease. Viral DNA have been detected in gingival tissue, gingival cervicular fluid (GCF) and subgingival plaque from periodontaly diseased sites. In addition markers of herpesviral activation have been demonstrated in the GCF from periodontal lesions. Active human cytomegalovirus (HCMV) replication in periodontal sites may suggest that HCMV re-activation triggers periodontal disease activity. Concerns regarding sampling, methods and interpretation cast doubts on the role of viruses as causes of periodontal disease.

Predictive value of clinical and microbiological parameters for the treatment outcome of scaling and root planing.

OBJECTIVES: To compare the clinical and microbiological outcome of non-surgical periodontal therapy after 6 months with data obtained after hygienic phase or 6 weeks after completion of non-surgical therapy, in order to evaluate the value of clinical and microbiological parameters to predict treatment success. MATERIAL AND METHODS: Clinical and microbiological data were available from 271 sites in 10 systemically healthy non-smokers with moderate-to-advanced chronic periodontal disease (24-32 sites per individual). Subgingival plaque samples were tested for the presence of Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Tannerella forsythensis and Treponema denticola using RNA probes. RESULTS: Stepwise multiple linear regression analysis revealed a significant impact of the number of sites with visible plaque index >1 after hygienic phase on the bleeding tendency of a subject at month 6 (p<0.01). Furthermore, an association could be demonstrated between the number of residual pockets (PD>3 mm) 6 months after therapy and the number of bleeding sites and suppurating sites after hygienic phase (p=0.016). Six weeks after therapy, the mean total bacterial loads had a significant impact on the bleeding tendency of a subject at month 6 (p<0.01). Although the average numbers of sites with persisting P. gingivalis, A. actinomycetemcomitans, T. forsythensis and T. denticola seemed to be very similar 6 weeks and 6 months after therapy, large variations were noted between subjects, and therefore the microbiological status of a subject at week 6 could not predict the status at month 6. CONCLUSIONS: The present study showed a limited potential of microbiological tests, performed after hygienic phase or shortly after non-surgical periodontal therapy, to predict the clinical outcome 6 months later, but confirmed the importance of an establishment of perfect oral hygiene before non-surgical therapy.

Interest in periodontology and preferences for treatment of localized gingival recessions.

OBJECTIVES: The purpose of this study was to evaluate the views, knowledge and preferences of a large sample of practising dentists in periodontics, focusing specifically on the treatment of gingival recessions, and to compare the findings with the current evidence available in the dental literature. METHODS: We conducted a cross-sectional postal survey of 3780 dentists, representing the majority of all dentists working in Switzerland. The questionnaire consisted of 17 questions, most of them giving the possibility of multiple choices of answers. The demographic profile, interests and satisfaction in periodontics were associated with the choice of treatment options offered for the management of six clinical situations. RESULTS: One thousand two hundred and one dentists sent back the questionnaire within three months and were thus included in the analysis. In general, the interest and the satisfaction in periodontics were moderate to high (6-7 on an analogue scale from 1 to 10). Specialists in periodontics indicated a significantly higher interest and satisfaction in periodontics than the general dentists (p<0.001), and practitioners working in urban areas indicated a slightly higher interest (p=0.027) and satisfaction (0.047) than their colleagues established in a rural setting. The predominant indication of root coverage procedures was aesthetics (90.7%). The region in which dentists worked was the only significant predictor for choosing "no treatment" of buccal recessions: dentists from the German-speaking part were significantly less inclined to surgically treat gingival recessions than their colleagues from the French or Italian part. For those who opted for therapy, a free tissue graft was generally the favourite option, followed by a connective tissue graft and a coronally advanced flap. Throughout, only a small fraction of the dentists considered using a guided tissue regeneration procedure. The relative odds for not extracting teeth with severe periodontal disease were higher if the dentist was a specialist than a generalist. Satisfaction in practicing periodontics also positively strengthened the inclination towards keeping severely compromised teeth. CONCLUSIONS: Aesthetic concerns were the predominant indication for root coverage procedures. Further research should therefore include aesthetic aspects as primary clinical outcome variables. Specific training of dentists and their satisfaction in periodontics influenced treatment decisions. Specialists involved in continuing education should inform practicing dentists more efficiently on the potential and usefulness of periodontal therapy for saving and maintaining periodontally compromised teeth.

Enamel matrix proteins and systemic antibiotics as adjuncts to non-surgical periodontal treatment: clinical effects.

OBJECTIVES: The purpose of the present study was to evaluate the clinical effects of non-surgical periodontal treatment, supplemented with enamel matrix derivative (EMD) and/or systemic antibiotics, in deep periodontal pockets of patients with chronic periodontitis. METHODS: This was a randomized, placebo-controlled longitudinal clinical trial of 12 months duration. Using a split-mouth design, 16 subjects were randomly assigned to scaling and root planing (SRP) with EMD or placebo in contra-lateral dentition areas. One half of the subjects received 250 mg metronidazole and 375 mg amoxicillin three times a day for 7 days and the other half received a placebo. One inter-proximal periodontal lesion was chosen as study site in each of the contra-lateral quadrants. RESULTS: Subjects treated with systemic antibiotics yielded significantly better clinical results than those treated with placebo. In these cases, probing pocket depth was reduced significantly more after 6 months (3.0+/-2.1 mm versus 1.6+/-1.4 mm, p=0.05), and the mean clinical attachment gain was significantly greater after 6 months (2.3+/-1.9 mm versus 0.7+/-1.6 mm, p=0.02) and 12 months (2.3+/-3.5 mm versus 0.4+/-3.8 mm, p=0.02). Sites treated with the antibiotics plus EMD gained the largest amount of clinical attachment. There was no significant benefit of EMD adjunctive to SRP in subjects not treated with antibiotics. CONCLUSIONS: The present study supports the notion that optimal repair and regeneration of the periodontium requires suppression of the microbiota causing periodontal disease.

Geometric alignment and chromatic calibration of serial radiographic images.

OBJECTIVE: To develop software for automated registration and intensity calibration of serial dental radiographs for the analysis of longitudinal changes in bone density. METHODS: Serial dental radiographs were acquired using a positioning device designed to minimize projection divergence. Each radiograph included an image of a standardized aluminium wedge. The radiographs were scanned on a flatbed scanner (AGFA Duo Scan) with a spatial resolution of 300 dpi, and pixel intensity coded in 16-bit grey scale. The intensity was calibrated using serial images of selected areas with defined thickness of the aluminium wedge. A robust B-splines multiresolution registration algorithm was implemented to overcome the acquisition misalignment. Radiographs, taken before and after periodontal therapy, were subtracted to assess bone density evolution. RESULTS: The intensity calibration decreased the maximum intensity variations between serial radiographs from 30+/-17% to 1+/-1% (mean+/-standard deviation), and improved the visual comparison between the radiographs. The registration stage allowed correcting the misalignment of the radiographs on the scanner screen and superimposing the radiography contents. The observed residual motion was about 0.02+/-0.01 mm. CONCLUSION: Very user-friendly software was developed. The manipulator needs to scan the radiographs only one time. The software performs all subsequent processing steps.

Periodontitis as an infectious disease: specific features and their implications.

Periodontitis may be viewed as an infectious disease with a number of specific characteristics. Pathogens of the subgingival microbiota can interact with host tissues even without direct tissue penetration. Hence, antimicrobial agents must be available at a sufficiently high concentration not only within the periodontal tissues, but also outside, in the environment of the periodontal pocket. The subgingival microbiota accumulate on the root surface to form an adherent layer of plaque with the characteristics of a biofilm. Several mechanisms, such as diffusion barriers, and selective inactivation of agents lead to an increased resistance of bacteria in biofilms. Mechanical supragingival plaque control is indispensable to prevent the re-emergence of periodontal pathogens and the re-establishment of a biofilm in treated sites. Since specific features have important implications for the use of antimicrobial agents in periodontal therapy, extrapolations from experiences made in the therapy of other infections are only partially valid. The ultimate evidence for the efficacy of systemic or local chemotherapy must be obtained from treatment studies in humans with adequate follow-up.

Development and applications of injectable poly(ortho esters) for pain control and periodontal treatment.

Poly(ortho esters) with a low glass transition temperature are semi-solid materials so that therapeutic agents can be incorporated at room temperature, without the use of solvents, by a simple mixing procedure. When molecular weights are limited to < 5 kDa, such materials are directly injectable using a needle size no larger than 22 gauge. Somewhat hydrophilic polymers can be produced by using the diketene acetal 3,9-diethylidene-2,4,8,10-tetraoxaspiro[5.5]undecane and triethylene glycol (TEG), while hydrophobic materials can be produced by using the diketene acetal and 1,10-decanediol. Molecular weight can be reproducibly controlled by using an excess of the diol, or by use of an alcohol that acts as a chain-stopper. Erosion rates can be controlled by varying the amount of latent acid incorporated into the polymer backbone. Toxicology studies using the TEG polymer have been completed and have shown that the polymer is non-toxic. Toxicology studies using the decanediol polymer are underway. Development studies using the TEG polymer aimed at providing a sustained delivery of an analgesic agent to control post-surgical pain are under development and human clinical trials using the decanediol polymer for the treatment of periodontitis are also underway.

Bioerodible injectable poly(ortho ester) for tetracycline controlled delivery to periodontal pockets: preliminary trial in humans.

The semisolid consistency of poly(ortho esters) (POEs) containing tetracycline free base allows direct injection in the periodontal pocket and shows sustained and almost constant in vitro release in phosphate buffer, pH 7.4 at 37 degrees C, for up to 14 days. Total polymer degradation concomitant with drug release was obtained. Formulations containing 10% or 20% (wt/wt) tetracycline were evaluated in a panel of 12 patients suffering from severe and recurrent periodontitis. In the first trial including 6 patients, single-rooted teeth and molar teeth with furcations were treated immediately after scaling and root planing. Patients tolerated both formulations well, experienced no pain during application, and showed no signs of irritation or discomfort during the observation period. However, retention of the formulation was minimal in this first study. An improved clinical protocol followed in the second study (stopping bleeding after scaling and root planning) prolonged the retention of the formulations in the inflamed periodontal pockets. For up to 11 days, tetracycline concentrations in the gingival crevicular fluid were higher than the minimum inhibitory concentration of tetracycline against most periodontal pathogens.

[Quality of water of dental units. A survey in the region of Berne, Switzerland]. / Wasserqualität in zahnärztlichen Behandlungseinheiten: Eine Standortbestimmung in der Region Bern.

The aim of this study was to assess the microbial contamination of the water from 175 dental units, which had not been in use for at least 12 hours, and to determine the usefulness of rinsing the water lines for 3 minutes. Only 10% of all units fulfilled all criteria for drinking water. Frequently the total bacterial counts markedly exceeded 100 CFU/ml. In all cases the rinsing decreased bacterial loads significantly. Bacterial contamination of water lines increased with the time the dental units remained unused. It is recommended to rinse dental unit water lines daily for at least 3 minutes before working on patients.

Treatment of peri-implantitis by local delivery of tetracycline. Clinical, microbiological and radiological results.

The purpose of this study was to investigate the clinical, microbiological and radiological effects of peri-implantitis therapy by local delivery of tetracycline. In 25 partially edentulous patients, 30 implants with radiographic evidence of circumferential bone loss, and peri-implant probing depths > or =5 mm were treated with polymeric tetracycline HCl-containing fibers. Clinical and microbial parameters were recorded at baseline, and 1, 3, 6, and 12 months (M) after treatment. Standardized radiographs were obtained at baseline, M3, and one year after treatment. Two patients were discontinued from the study after 180 days because of persisting active peri-implantitis with pus formation. The remaining subjects showed a significant decrease of mean peri-implant probing depth from 6.0 to 4.1 mm (M1, P<0.001), which was maintained over 12 months. In comparison to baseline, the bleeding tendency was significantly reduced after one month, and thereafter (P<0.001). No significant recession of the mucosal margin was noted. The radiologically determined distance from the shoulder of the implant to the bottom of the bony defect decreased slightly, but not significantly, from 5.2 to 4.9 mm. At M1, M3 and M6, mean total anaerobic cultivable bacterial counts were significantly lower than at baseline (P<0.001). A significant decrease in frequency of detection was noted for Prevotella intermedia/nigrescens, Fusobacterium sp., Bacteroides forsythus, and Campylobacter rectus (P<0.01). Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Eikenella corrodens had very low baseline frequencies that could not be significantly suppressed further. In conclusion, therapy of peri-implantitis by local delivery of tetracycline had a positive effect on clinical and microbiological parameters.