Microbiological and clinical results of metronidazole plus amoxicillin therapy in Actinobacillus actinomycetemcomitans-associated periodontitis.

We report on the microbiological and clinical effects of mechanical debridement in combination with metronidazole plus amoxicillin therapy in 118 patients with Actinobacillus actinomycetemcomitans-associated periodontitis. Patients were categorized into 3 groups: 28 had localized periodontitis; 50 had generalized periodontitis, and 40 had refractory periodontitis. After initial treatment and metronidazole plus amoxicillin therapy 114 of 118 (96.6%) patients had no detectable A. actinomycetemcomitans. Significant reduction in pocket probing depth and gain of clinical attachment were achieved in almost all patients. Four patients were still positive for A. actinomycetemcomitans after therapy. Metronidazole resistance (MIC greater than 25 micrograms/ml) was observed in 2 of 4 strains from these patients. Patients still positive for A. actinomycetemcomitans or Porphyromonas gingivalis showed a significant higher bleeding tendency after therapy. It was concluded that mechanical periodontal treatment in combination with the metronidazole plus amoxicillin therapy is effective for subgingival suppression of A. actinomycetemcomitans in patients with severe periodontitis.     

Controlled-delivery chlorhexidine chip versus amoxicillin/metronidazole as adjunctive antimicrobial therapy for generalized aggressive periodontitis: a randomized controlled clinical trial

BACKGROUND: Subgingival application of chlorhexidine via a controlled-delivery device (CHX chip) improves the clinical outcome of scaling/root planing (SRP) in therapy for chronic periodontitis. Generalized aggressive periodontitis (GAP) is commonly treated with SRP and adjunctive antimicrobial medication. To date, the efficacy of CHX chips in GAP therapy has not been evaluated. AIM: To compare SRP plus adjunctive CHX chip placement with SRP plus adjunctive systemic amoxicillin/metronidazole with regard to clinical efficacy in first-line therapy for GAP. MATERIAL AND METHODS: Thirty-six GAP patients were treated with SRP and randomly with either placement of CHX chips or systemic amoxicillin/metronidazole. Clinical attachment level (CAL), probing depth (PD), bleeding on probing (BoP) and suppuration (Pus) were measured at baseline, 3 and 6 months after therapy. RESULTS: CAL, PD, BoP and Pus were significantly reduced in both groups after 3 months. In the CHX chip group, PD significantly increased again between 3 and 6 months. Finally, amoxicillin/metronidazole patients presented significantly more CAL "gain", PD reduction and less remaining deep sites after 6 months. Pus remained detectable in CHX chip patients only. CONCLUSIONS: In first-line non-surgical therapy for GAP, SRP plus adjunctive systemic amoxicillin/metronidazole was more efficacious in clinically relevant measures of outcome than SRP plus adjunctive placement of CHX chips.     

The combination of amoxicillin and metronidazole improves clinical and microbiologic results of one-stage, full-mouth, ultrasonic debridement in aggressive periodontitis treatment

Background: The aim of the present study is to assess clinical, microbiologic, and immunologic benefits of amoxicillin/metronidazole (AM) when performing full‐mouth ultrasonic debridement (FMUD) in generalized aggressive periodontitis (GAgP) treatment. Methods: Twenty‐four GAgP patients were divided into two groups: the FMUD group (n = 12), which received FMUD plus placebo, and the FMUD+AM group (n = 12), which received FMUD and 375 mg amoxicillin plus 250 mg metronidazole for 7 days. The following clinical outcomes were tested: plaque and bleeding on probing indices, pocket probing depth (PD), relative gingival margin position (GMP), and relative clinical attachment level (CAL). Total amount of Porphyromonas gingivalis (Pg), Aggregatibacter actinomycetemcomitans (Aa), Tannerella forsythia (Tf), and gingival crevicular fluid (GCF) concentration of interleukin (IL)‐10 and IL‐1β were also determined. All clinical, microbiologic, and immunologic parameters were assessed at baseline and at 3 and 6 months post‐therapy. The ANOVA/Tukey test was used for statistical analysis (α = 5%). Results: Amoxicillin/metronidazole used as an adjunct to the FMUD protocol added clinical and microbiologic benefits to GAgP treatment (P <0.05). FMUD+AM groups presented an additional PD reduction in initially deep PDs at the 3‐month follow‐up (3.99 ± 1.16 mm and 3.09 ± 0.78 mm for FMUD+AM and FMUD, respectively; P <0.05), a lower number of residual pockets at the 3‐ and 6‐month follow‐ups, and a statistical reduction in amounts of Aa (P <0.05). Analysis of Tf and Pg amounts, as well as IL‐10 and IL‐1β GCF concentrations failed to demonstrate a difference between the groups (P >0.05). Conclusion: It may be concluded that amoxicillin/metronidazole improves clinical and microbiologic results of FMUD in GAgP treatment.     

Systemic moxifloxacin vs amoxicillin/metronidazole adjunct to non-surgical treatment in generalized aggressive periodontitis

Background

The objective of this randomized clinical study was to evaluate the effect of systemic administration of moxifloxacin compared to amoxicillin and metronidazole, combined with non-surgical treatment in patients with generalized aggressive periodontitis (GAgP) in a 6-month follow-up.

Material and Methods

A total of 39 systemically healthy patients with GAgP were evaluated in this randomized clinical trial. Periodontal parameters were recorded at the baseline during the 1st, 3rd and 6th month. Patients received either 400 mg of moxifloxacin per os once daily or 500 mg of metronidazole and 500 mg amoxicillin per os three times daily for 7 days consecutively.

Results

No significant differences between groups were found in any parameters at the baseline. Both groups led to a statistically significant decrease in all clinical periodontal parameters compared to the baseline (PI, p<0.001 and GI, PD, BOP, CAL, p<0.01). There were no differences between the 1st and 3rd months or the 3rd and 6th months for clinical parameters in the groups. Also, no intergroup difference was observed in any parameters at any time, except the gingival index at 6th months.

Conclusions

Systemic administration of moxifloxacin as an adjunct to non-surgical treatment significantly improves clinical outcomes and provides comparable clinical improvement with less adverse events to that of combination of amoxicillin and metronidazole in the treatment of GAgP. Key words: Aggressive periodontitis, amoxicillin, metronidazole, moxifloxacin, nonsurgical periodontal debridement.     

Repeated metronidazole and amoxicillin treatment of periodontitis. A follow-up study

BACKGROUND: The prevailing concept is that little or no clear benefit is derived from antibiotic therapy in chronic periodontitis. Studies to determine the effect of metronidazole plus amoxicillin (M+A) on adult periodontitis are questionable because standard design for clinical trials was usually not used. In addition, there is no information about the effect of M+A as the sole therapy for periodontitis. METHODS: A randomized, triple-blind, controlled clinical trial was used to determine the effect of systemic administration of M+A, as the sole therapy, in progressive adult periodontitis. Forty-six subjects with moderate to advanced adult periodontitis who showed > or =2 mm attachment loss in at least 2 sites in the previous 2 months were entered in the study. Subjects were randomly distributed to a group who received 21 tablets of metronidazole 250 mg plus amoxicillin 500 mg, or to a group receiving a placebo (1 tablet every 8 hours for 1 week). Patients were examined every 2 months for 12 months. The M+A or placebo regimen was repeated at 4 and 8 months. No effort was made to change the oral habits of patients and they received no additional therapy. Differences between groups were assessed using the Mann-Whitney U test. The differences at every 2-month interval within each group were assessed using the ANOVA test. RESULTS: Seven subjects abandoned the study; at 12 months the M+A group had 20 subjects and the placebo group 19. There were no significant differences in the clinical parameters at baseline between the 2 groups. After 2 months and thereafter, the M+A group showed significant clinical improvement while the placebo group showed a progressive deterioration of periodontal status. At 12 months compared to baseline, subjects of the M+A group showed: 1) a significant overall mean attachment gain of 0.43 mm (P = 0.005); 2) a significant decrease of active sites (P< or =0.03); 3) a significant increase of sites gaining attachment level (P< or =0.01); 4) a significant reduction of pocket depth (P< or =0.00006); and 5) a significant decrease in percentage of bleeding on probing sites (BOP) (P< or =0.0005). Significant differences between both groups at all 2-month evaluations were found in overall mean attachment level (P < or =0.000004), in percent of active sites (P< or =0.03), and in percent of BOP sites (P< or =0.02). Sites exhibiting > or =2 mm of attachment loss in 2 successive or alternate evaluations, and periodontal abscess were noticed only in the placebo group. CONCLUSIONS: A 1-week course of systemic M+A every 4 months, as the only therapy, arrests the progression of adult periodontitis and significantly improves the clinical parameters of the disease.     

侵袭性牙周炎基础治疗中不同时机口服抗生素的短期疗效观察

目的 探讨侵袭性牙周炎(aggressive periodontitis,AgP)患者基础治疗过程中不同时机口服阿莫西林和甲硝唑的短期临床疗效,以期为AgP患者基础治疗中选择用药时机提供参考.方法 将45例AgP患者按照随机对照数字表法分为非用药组、洁治后用药组和刮治后用药组,每组15例.所有患者均接受牙周基础治疗,其中洁治后、刮治后用药组分别在洁治后及完成刮治后即刻口服阿莫西林胶囊和甲硝唑片,3个组均在基础治疗前和治疗后8周进行牙周检查.结果 洁治后、刮治后用药组患者探诊深度减少[M(Q25,Q75)][分别为2.5(1.8,3.3) mm、2.3(1.9,2.7) mm]和附着增加[M(Q25,Q75)][分别为0.9(0.5,1.4) mm、0.8(0.4,1.3) mm]均显著高于非用药组[探诊深度减少和附着增加分别为1.8(1.3,2.1) mm、0.4(0.2,1.0) mm],差异均有统计学意义(P＜0.05);其中在探诊深度≥7 mm的位点,洁治后用药组的探诊深度减少[4.0(3.0,5.0)mm]显著高于刮治后用药组[4.0(3.0,4.0) mm],P＜0.05.结论 AgP患者牙周基础治疗中辅助口服阿莫西林和甲硝唑较单纯牙周基础治疗可取得更好的疗效;有多个位点PD≥7 mm的患者可以在洁治后服药,但仍需要远期疗效观察及微生学研究.     

Clinical and microbiologic evaluation, by real-time polymerase chain reaction, of non-surgical treatment of aggressive periodontitis associated with amoxicillin and metronidazole

Background: The aim of the present study is to evaluate the clinical and microbiologic changes resulting from non‐surgical periodontal treatment associated with amoxicillin and metronidazole in individuals with aggressive periodontitis. Methods: Fifteen individuals with aggressive periodontitis received non‐surgical periodontal treatment and 45 days after completion of treatment were treated with antibiotics. Clinical data and samples of subgingival plaque were collected at baseline, 45 days after the non‐surgical periodontal treatment, and 1 month after the use of antimicrobial agents. After 3 and 6 months, only clinical data were collected. The presence and quantification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis (Pg), Tannerella forsythia (Tf), Treponema denticola (Td), and Dialister pneumosintes were determined by real‐time polymerase chain reaction. Results: All clinical parameters, with the exception of clinical attachment level (CAL), had significantly (P <0.05) improved at the end of the third month after non‐surgical therapy associated with antibiotics. There was significant (P <0.05) reduction in the quantities of Td and Tf. After 1 month, there were significant (P <0.05) reductions in the frequencies of Pg and Tf. Conclusion: Non‐surgical mechanical treatment associated with the use of amoxicillin and metronidazole led to an improvement in all clinical parameters studied, except for CAL, and significantly reduced the amount of subgingival Tf and Td.     

Adjunctive benefits of systemic amoxicillin and metronidazole in non-surgical treatment of generalized aggressive periodontitis: a randomized placebo-controlled clinical trial

BACKGROUND: The objective of this study was to assess the adjunctive clinical effect of the administration of systemic amoxicillin and metronidazole in the non-surgical treatment of generalized aggressive periodontitis (GAP). METHODS: Forty-one systemically healthy subjects with GAP were included in this 6-month double-blind, placebo-controlled, randomized clinical trial. Patients received a course of full-mouth non-surgical periodontal treatment delivered over a 24 h period using machine-driven and hand instruments. Test subjects received an adjunctive course of systemic antibiotic consisting of 500 mg amoxicillin and 500 mg metronidazole three times a day for 7 days. Clinical parameters were collected at baseline, and at 2 and 6 months post-treatment. RESULTS: In both the test and the placebo groups, all clinical parameters improved at 2 and 6 months. In deep pockets (> or =7 mm), the test treatment resulted in an additional 1.4 mm (95% confidence interval 0.8, 2.0 mm) in full-mouth probing pocket depth (PPD) reduction and 1 mm (0.7, 1.3 mm) of life cumulative attachment loss (LCAL) gain at 6 months. In moderate pockets (4-6 mm), the adjunctive benefit was smaller in magnitude: PPD reduction was 0.4 mm (0.1, 0.7 mm) and LCAL gain was 0.5 mm (0.2, 0.8 mm). In addition, the 6-month data showed LCAL gains > or =2 mm at 25% of sites in test patients compared with 16% in placebo (p=0.028). Similarly, PPD reductions of 2 mm or more were observed in 30% of sites in test and 21% of sites in placebo patients. Seventy-four percent of pockets with PPD > or =5 mm at baseline were 4 mm or shallower at 6 months in the test group. This compared with 54% in the placebo group (p=0.008). Disease progression at 6 months was observed at 1.5% of test and 3.3% of sites in test and placebo, respectively (p=0.072). CONCLUSIONS: These data indicate that a 7-day adjunctive course of systemic metronidazole and amoxicillin significantly improved the short-term clinical outcomes of full-mouth non-surgical periodontal debridement in subjects with GAP.     

Effectiveness of systemic amoxicillin/metronidazole as an adjunctive therapy to full-mouth scaling and root planing in the treatment of aggressive periodontitis: a systematic review and meta-analysis

Background: The systemic use of combined amoxicillin and metronidazole (AMX/MET) as an adjunctive treatment to full‐mouth scaling and root planing (FMSRP) has been proposed for the treatment of generalized aggressive periodontitis; however, its effectiveness and clinical safety remain to be defined. The purpose of the present meta‐analysis is to assess the effectiveness of FMSRP + AMX/MET compared to FMSRP alone. Methods: An electronic search of eight databases and a hand‐search of 10 international dental journals were conducted through September 11, 2011. Gain in clinical attachment level (CAL), reduction in probing depth (PD), secondary outcomes, and adverse events were analyzed. A random‐effect model was used to pool the extracted data. The weighted mean difference (MD) with 95% confidence interval (CI) was calculated for continuous outcomes, whereas risk difference (RD) with 95% CI was used for dichotomous data; heterogeneity was assessed with the χ²‐based Cochran Q test and I² statistic. The level of significance was set at P <0.05. Results: After the selection process, six randomized clinical trials were included. Results of the meta‐analysis showed significant CAL gain (MD, 0.42; 95% CI, 0.23 to 0.61; P <0.05) and PD reduction (MD, 0.58; 95% CI, 0.39 to 0.77; P <0.05) in favor of FMSRP + AMX/MET; moreover, no significant RD was found in the occurrence of adverse events (RD, 0.01; 95% CI, ?0.02 to 0.04; P >0.05). Conclusion: The findings of the meta‐analysis seem to support the effectiveness and the clinical safety of FMSRP + AMX/MET; however, future studies are needed to confirm these results.     

Cosmetic rehabilitation following successful treatment of aggressive periodontitis

With advances in periodontal therapy, many sufferers from aggressive periodontitis are retaining their teeth after successful treatment. This presents the practitioner with aesthetic and restorative challenges in these relatively young patients. Lifelong motivation is essential to the supportive therapy for these patients, and the maintenance of good aesthetics, combined with biologically acceptable corrective therapy, may help maintain a high level of motivation. Any treatment provided must naturally be conducive to maintaining long-term dental and periodontal health. This paper aims to demonstrate options for dealing with the aesthetic challenges posed by a number of patients who have undergone initial cause-related therapy for aggressive periodontitis. Clinical Relevance: Loss of gingival tissue, tooth positional changes and tooth loss present practitioners with challenges in relation to patient satisfaction with aesthetics following advanced periodontal breakdown. A range of techniques will be required, tailored to the consequences of periodontal attachment loss, in order to satisfy patient demands.     

Clinical results after nonsurgical therapy in aggressive and chronic periodontitis

Aim

This study aims to analyze factors influencing treatment results in aggressive (AgP) and chronic (ChP) periodontitis.

Methods

ChP [probing pocket depth (PPD)?≥?3.5 mm, attachment loss?≥?5 mm at >30 % of sites; age?>?35 years] and AgP (clinically healthy; PPD?≥?3.5 mm at >30 % of sites, radiographic bone loss?≥?50 % at 2 teeth; age?≤?35 years) were examined prior and 3 months after nonsurgical therapy according to the full-mouth disinfection concept. Adjunctive systemic antibiotics were used if Aggregatibacter actinomycetemcomitans had been detected at baseline.

Results

In 31 ChP (12 female, 10 smokers; 4,808 sites) and 28 AgP (16 female, 9 smokers; 4,769 sites), overall mean PPD reductions were less favorable in AgP (0.9?±?0.5 mm) than in ChP (1.3?±?0.4 mm; p?=?0.033). PPD reductions and relative vertical probing attachment level gain were more favorable at sites with initial PPD?≥?6 mm, bleeding on probing, and for adjunctive systemic antibiotics. Furthermore, PPD reductions were more favorable for increased baseline tooth mobility and maxillary teeth, whereas AgP, female sex, and multirooted teeth were associated with less favorable PPD reduction.

Conclusion

Regarding PPD reduction, AgP responded less favorably to nonsurgical treatment than ChP.     

Change in subgingival microbial profiles in adult periodontitis subjects receiving either systemically-administered amoxicillin or metronidazole

AIM: The current investigation evaluated changes in levels and proportions of 40 bacterial species in subgingival plaque samples during, immediately after and up to 1 year after metronidazole or amoxicillin therapy combined with SRP. METHOD: After baseline clinical and microbiological monitoring, 17 adult periodontitis subjects received full mouth SRP and 14 days systemic administration of either metronidazole (250 mg, TID, n=8) or amoxicillin (500 mg, TID, n=9). Clinical measurements including % of sites with plaque, gingival redness, bleeding on probing and suppuration, pocket depth (PD) and attachment level (AL) were made at baseline, 90, 180 and 360 days. Subgingival plaque samples were taken from the mesial surface of all teeth in each subject at baseline, 90, 180 and 360 days and from 2 randomly selected posterior teeth at 3, 7, and 14 days during and after antibiotic administration. Counts of 40 subgingival species were determined using checkerboard DNA-DNA hybridization. Significance of differences over time was determined using the Quade test and between groups using ANCOVA. RESULTS: Mean PD was reduced from 3.22+/-0.12 at baseline to 2.81+/-0.16 (p<0.01) at 360 days and from 3.38+/-0.23 mm to 2.80+/-0.14 mm (p<0.01) in the amoxicillin and metronidazole treated subjects respectively. Corresponding values for mean AL were 3.21+/-0.30 to 2.76+/-0.32 (p<0.05) and 3.23+/-0.28 mm to 2.94+/-0.23 mm (p<0.01). Levels and proportions of Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola were markedly reduced during antibiotic administration and were lower than baseline levels at 360 days. Counts (x10(5), +/-SEM) of B. forsythus fell from baseline levels of 0.66+/-0.16 to 0.04+/-0.02, 0.13+/-0.04, 0.10+/-0.03 and 0.42+/-0.19 in the amoxicillin group at 14, 90, 180 and 360 days respectively (p<0.001). Corresponding values for metronidazole treated subjects were: 1.69+/-0.28 to 0.02+/-0.01, 0.20+/-0.08, 0.22+/-0.06 and 0.22+/-0.08 (p<0.001). Counts of Campylobacter species, Eubacterium nodatum, Fusobacterium nucleatum subspecies, F. periodonticum and Prevotella nigrescens were also detected at lower mean levels during and immediately after therapy, but gradually increased after withdrawal of the antibiotics. Members of the genera Actinomyces, Streptococcus and Capnocytophaga were minimally affected by metronidazole. However, amoxicillin decreased the counts and proportions of Actinomyces species during and after therapy. CONCLUSIONS: The data suggest that metronidazole and amoxicillin are useful in rapidly lowering counts of putative periodontal pathogens, but must be accompanied by other procedures to bring about periodontal stability.     

Antimicrobial photodynamic therapy in the non-surgical treatment of aggressive periodontitis: a preliminary randomized controlled clinical study

BACKGROUND: The treatment of aggressive periodontitis has always presented a challenge for clinicians, but there are no established protocols and guidelines for the efficient control of the disease. METHODS: Ten patients with a clinical diagnosis of aggressive periodontitis were treated in a split-mouth design study to either photodynamic therapy (PDT) using a laser source with a wavelength of 690 nm associated with a phenothiazine photosensitizer or scaling and root planing (SRP) with hand instruments. Clinical assessment of plaque index (PI), gingival index (GI), bleeding on probing (BOP), probing depth (PD), gingival recession (GR), and relative clinical attachment level (RCAL) were made at baseline and 3 months after treatment with an automated periodontal probe. RESULTS: Initially, the PI was 1.0 +/- 0.5 in both groups. At the 3-month evaluation, the plaque scores were reduced and remained low throughout the study. A significant reduction of GI and BOP occurred in both groups after 3 months (P <0.05). The mean PD decreased in the PDT group from 4.92 +/- 1.61 mm at baseline to 3.49 +/- 0.98 mm after 3 months (P <0.05) and in SRP group from 4.92 +/- 1.14 mm at baseline to 3.98 +/- 1.76 mm after 3 months (P <0.05). The mean RCAL decreased in the PDT group from 9.93 +/- 2.10 mm at baseline to 8.74 +/- 2.12 mm after 3 months (P <0.05), and in the SRP group, from 10.53 +/- 2.30 mm at baseline to 9.01 +/- 3.05 mm after 3 months. CONCLUSION: PDT and SRP showed similar clinical results in the non-surgical treatment of aggressive periodontitis.     

Comparison of clinical outcomes following treatment of chronic adult periodontitis with subgingival scaling or subgingival scaling plus metronidazole gel

BACKGROUND, AIMS: Conventional treatment of chronic periodontitis involves mechanical debridement of periodontal pockets. Recently, subgingival antimicrobials have been used adjunctively following such debridement. This 2-centre study compared the clinical effects of subgingival scaling (SRP) with SRP plus subgingival application of 25% metronidazole gel, Elyzol (SRP+gel), in patients with chronic adult periodontitis. METHOD: Voluntary informed written consent was obtained from 45 subjects at the Eastman (mean age 46, range 34-63) and 43 subjects at RAF Halton (mean age 47, range 34-71) who participated in this blind, randomised split-mouth design study. All had at least 2 sites in each quadrant with probing pocket depth (PPD) > or = 5 mm. PPD, bleeding on probing (BOP), and clinical probing attachment levels (CAL) measured using a stent, were recorded at baseline and at 1, 3, 6 and 9 months post-therapy. After subgingival scaling of all quadrants, 2 quadrants were randomly selected to be treated with metronidazole gel. RESULTS: A paired t-test on baseline values showed no bias between groups. Both treatments effectively reduced the signs of periodontitis. At each follow-up visit, reduction in PPD, CAL and BOP after the combined treatment was greater than for SRP alone. Paired t-tests showed that the improvement in the SRP+gel group was statistically significantly better (p<0.001) than for SRP alone (mean 0.5 +/- 0.6 mm. 95% CI 0.4-0.6 mm.) Similarly, the % of sites which improved to a final pocket depth of < or = 3 mm and the % of sites which improved over the 9 months of the study by as much as > or = 2 mm were greater for SRP+gel than for SRP alone. CONCLUSIONS: At the end of the study, the mean reductions for PPD were 1.0 mm (SRP) compared to 1.5 mm (SRP+gel), and for CAL they were 0.4 mm (SRP) compared to 0.8 mm (SRP+gel), with mean difference for CAL between treatments of 0.4 +/- 0.6 mm (95% confidence intervals of 0.3-0.6 mm). The combination therapy of SRP+gel was superior to the conventional treatment of SRP alone, and these differences were maintained for 9 months.     

Microbiological and clinical effects of metronidazole and amoxicillin in Actinobacillus actinomycetemcomitans associated periodontitis

Abstract In this study, we evaluated the microbiological and clinical effects of mechanical debridement in combination with metronidazole and amoxicillin therapy in 48 patients with Actinobacillus actinomycetemcomitans-associated periodontitis, 3 months and at least 24 months after active treatment. The results of this study showed that 47 out of 48 patients were still negative for A. actinomycetemcomitans subgingivally, at the mucous membranes, the tonsillar area and in the saliva, 2 years after therapy. The clinical results showed that a reduction of probing pocket depth, probing attachment level, bleeding index and plaque index was not only seen in the time between baseline and 3 months after therapy, but further clinical improvement was observed between 3 and 24 months after active treatment. We conclude that combined mechanical debridement and metronidazole plus amoxicillin therapy is very effective in suppressing A. actinomycetemcomitans below cultivable levels over a long period of time, suggesting elimination of this organism, and that recolonization of A. actinomycetemcomitans seems to be a rare event. The elimination of A. actinomycetemcomitans is paralleled by a further improvement of the periodontal status of the patients, even up to 24 months after active treatment.