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

Design and implementation of clinical trials of antimicrobial drugs and devices used in periodontal disease treatment

The design and implementation of clinical trials (CTs) carried out to evaluate antimicrobial and anti-infective drugs and devices are one of the most difficult challenges in contemporary periodontal research and product development. The overwhelming amount of evidence which has established a microbial etiology for periodontitis is the basis for developing and testing antimicrobial treatments. Well-designed antimicrobial CTs start with a carefully crafted hypothesis and a protocol which explicitly integrates the requirements of the patient, the clinician, the sponsor, and regulatory authorities. Surrogate variables for effectiveness must be clinically relevant, scientifically sound, and statistically valid. Currently, clinical attachment level measurements and alveolar bone assessments are accepted as proof of effectiveness. Indication and claim support of the antimicrobial product guide the design and implementation of the CT. Adverse microbiologic consequences, such as lack of antimicrobial susceptibility, wrong spectrum, incorrect dosage, non-compliance, and drug interference, must be monitored. Successful CTs balance a large group of variables used to screen, randomize, and assign subjects to experimental and control groups to ensure that prognostic and risk factors are properly accounted for.

Multi-center comparative evaluation of subgingivally delivered sanguinarine and doxycycline in the treatment of periodontitis. I. Study design, procedures, and management

The design and conduct of a 9-month multi-center clinical trial to evaluate the safety and efficacy of subgingivally delivered 5% sanguinarium chloride (SC) and 10% doxycycline hyclate (DH) from a biodegradable drug delivery system in the treatment of adult periodontitis is described. The 3-group randomized study of 180 adults with moderate to severe periodontitis was a modified double-blind parallel design. One group received DH, one group received SC, and the other group received the vehicle control (VC). Patients selected had two quadrants with a minimum of four periodontal pockets > or = 5 mm in depth with two sites > or = 7 mm. All qualifying sites exhibited bleeding on gentle probing. Qualifying sites were treated at baseline and again at 4 months. Clinical response was assessed by measuring attachment level, probing depth, and bleeding on probing at monthly examinations at qualifying sites and the entire dentition. The plaque index was measured monthly to verify oral hygiene status. The parallel design afforded the opportunity to distinguish between treatment effectiveness of SC, DH, and VC independent of possible crossover effects. Also the effectiveness of oral hygiene in untreated sites of the mouth could be evaluated. Finally, treatment effects in moderate (5 to 6 mm) and deep (> or = 7 mm) pockets in both treated and untreated sites could be compared. The design was capable of simulating a periodontal practice maintenance program and assessing the response according to maintenance and treatment history. Study management procedures that emphasized center examiner and therapist training and adherence to protocol and procedures to reduce variability are described.

Multi-center comparative evaluation of subgingivally delivered sanguinarine and doxycycline in the treatment of periodontitis. II. Clinical results

The clinical safety and effectiveness of a subgingivally delivered biodegradable drug delivery system containing either 10% doxycycline hyclate (DH), 5% sanguinarium chloride (SC) or no agent (VC) was evaluated in a 9-month multi-center trial. The study was a randomized parallel design with 180 patients who demonstrated moderate to severe periodontitis. All patients had at least two quadrants with a minimum of four qualifying pockets > or = 5 mm that bled on probing. Two of the qualifying pockets were required to be > or = 7 mm. At baseline and at 4 months all qualified sites were treated with the test article administered via syringe. Probing depth reduction (PDR), attachment level gain (ALG), bleeding on probing reduction (BOP), and plaque index were determined monthly. Analysis of efficacy data from the 173 efficacy-evaluable patients indicated that all treatments gave significant positive clinical changes from baseline at all subsequent timepoints. DH was superior to SC and VC in PDR at all timepoints (P < or = 0.01 to 0.001) with a maximum reduction of 2.0 mm at 5 months. For ALG, DH was superior to VC at months 2, 3, 4, 5, 6, 8, and 9 (P < or = 0.04 to 0.002) and superior to SC at months 5, 6, 7, 8, and 9 (P < or = 0.01 to 0.001) with a maximum ALG of 1.2 mm at 6 months. For BOP reduction, DH was superior to VC at all time points (P < or = 0.05) and to SC at months 3, 5, 6, 8, and 9 (P < or = 0.03). For DH, the maximum ALG in deep (> or = 7 mm) pockets was 1.7 mm and PDR 2.9 mm compared to 0.8 mm and 1.6 mm, respectively for moderate (5 to 6 mm) pockets. Test articles were applied without anesthesia and no serious adverse events occurred in the trial. The results of this study indicate that 10% doxycycline hyclate delivered in a biodegradable delivery system is an effective means of reducing the clinical signs of adult periodontitis and exhibits a benign safety profile.

Experimental apexigenesis in baboons

Apexification with calcium hydroxide is a routine procedure. However, some clinical reports suggest that root completion can occur by controlling the infection without use of a catalyst. The present study investigated the use of tetracycline treatment (in root canals) on root growth in immature teeth, rendered non-vital experimentally. Incisors in 3 young baboons were exposed and canals were left open. After 2 months all canals were cleaned and treated with either tetracycline or formocresol. Some canals in each group were filed. Animals were sacrificed after 6 months. Bacterial evaluations were done before placing medications, one week later and six months after that. The number of bacteria were reduced in all treatment groups. Root growth almost near completion was observed in more teeth treated with tetracycline than in the formocresol group.

Analysis of the leaching and toxicity of new amine activators for the curing of acrylic bone cements and composites

The comparative reactivity of new tertiary amine activators with the basic chemical structure of N,N-dimethyl-4-toluidine, but reduced toxicity, is analysed. The leaching of the amine compounds from cured cements was studied by analysis of the concentration of the corresponding amine in a physiological saline solution after 3 months of immersion, giving lower values for the new amine compounds as compared to N,N-dimethyl-4-toluidine. The acute toxicity was determined by intravenous injection of saline solutions of the corresponding chlorhydrates in mice and the cytotoxicity by the evolution of specific culture media. The results obtained demonstrate a lower acute toxicity and cytotoxicity of the new activators, even with a noticeable antiseptic action, which makes these materials very interesting from a practical point of view as activators of the curing process of acrylic bone cements for orthopaedic surgery and dentistry.

Sustained local delivery of chlorhexidine in the treatment of periodontitis: a multi-center study

The safety and efficacy of a degradable, subgingivally placed drug delivery system containing 2.5 mg chlorhexidine (CHX) were evaluated in a randomized, blinded, multi-center study of 118 patients with moderate periodontitis. A split-mouth design was used to compare the treatment outcomes of scaling and root planing (SRP) alone with the combined use of SRP and the CHX in pockets with probing depths of 5 to 8 mm. The two maxillary quadrants were used for the two treatment arms of the study. Scaling and root planing was performed at baseline only, while the CHX was inserted both at baseline and at 3 months. Clinical and safety measurements including probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) as well as gingivitis, plaque, and staining indices were recorded at baseline, and at 1, 3, and 6 months. The average PD reduction in the CHX-treated sites was significantly greater than in the sites receiving SRP alone at both 3 and 6 months with a mean difference of 0.42 mm (P < or = 0.01) at 6 months. The reduction in CAL at the treated sites was greater than at the SRP sites, although the difference was statistically significant at the 6-month visit only. An analysis of patients with initial probing depths of 7 to 8 mm (n = 56) revealed a significantly greater reduction in PD and CAL in those pockets treated with CHX compared to SRP at both 3 and 6 months. The mean differences between test and control sites at 6 months were 0.71 mm and 0.56 mm PD and CAL respectively.

Subgingival delivery of therapeutic agents in the treatment of periodontal diseases

This article reviews the current status of controlled local delivery of antibacterial agents in the treatment of periodontitis. The principle of local intrapocket delivery of antibacterial agents and their delivery are discussed. The dosage forms include fibers, film/slabs, and injectable systems, some of which are degradable, while others are not and need to be removed at the termination of the treatment. The antibacterial agents used cover a range of antibiotics as well as antiseptics, and the composition of the delivery systems, their reported use, and the clinical results are summarized. The use of these systems in clinical practice is relatively recent, and therefore their application and integration into the dental office are not yet clearly defined. Clinical applications that have been tested are critically reviewed, and clinical situations in which controlled delivery of antibacterial agents may prove to be clinically useful are suggested for scientific evaluation.

Full- versus partial-mouth disinfection in the treatment of periodontal infections. Long-term clinical observations of a pilot study

A classical treatment for chronic adult periodontitis consists of four to six consecutive sessions of scaling and root planing at a 1- to 2-week interval. Such a so-called "quadrant or sextant therapy" might result in a reinfection of a previously disinfected area by bacteria from an untreated region. The purpose of this study was to investigate, over an 8-month period, the clinical benefits of full-mouth disinfection within a 24-hour period in the control of chronic periodontitis. Ten adult patients with advanced chronic periodontitis were randomly assigned to a test and a control group. The control group received the standard scheme of initial periodontal therapy, consisting of scaling and root planing of the four quadrants was performed within 24 hours and immediately followed by a thorough supra- and subgingival chlorhexidine application to limit any transfer of bacteria. The latter involved tongue brushing with a 1% chlorhexidine gel for 60 seconds, mouthrinsing with a 0.2% chlorhexidine solution twice for 60 seconds, repeated subgingival irrigation of all pockets with a 1% chlorhexidine gel (3 times within 10 minutes), and mouthrinsing twice daily with a 0.2% chlorhexidine solution during 2 weeks. In addition, both groups received thorough oral hygiene instructions. The plaque index, gingival index, probing depth, gingival recession, and bleeding on probing were recorded prior to professional cleaning and at 1, 2, 4, and 8 months afterwards. Although the test group scored higher plaque indices than the control group, especially at months 2 and 4, the gingival index and bleeding tendency showed similar improvements with time. However, when the gingival/plaque ratio was considered, the latter was lower in the test group at all follow-up visits. For pockets > or = 7 mm, full-mouth disinfection showed a significantly (P = 0.01) higher reduction in probing depth at each follow-up visit with, at month 8, a reduction of 4 mm (from 8 mm to 4 mm), in comparison to 3 mm (from 8 mm to 5 mm) for the classical therapy. The increase in gingival recession in the full-mouth disinfection group remained below 0.7 mm, while in the control group it reached 1.9 mm after 8 months. This resulted in a gain of clinical attachment level of 3.7 mm for the test group versus 1.9 mm for the control group. A radiographical examination also indicated a superior improvement for the test group when compared to the control group. This pilot study suggests that a full-mouth disinfection in one day results in an improved clinical outcome in chronic periodontitis as compared to scalings per quadrant at 2-week intervals over several weeks.

Antimicrobial treatment of periodontal diseases disturbs the human ecology: a review

Periodontal diseases are associated with specific pathogenic microorganisms and therefore antimicrobial agents are often used in the treatment of patients with periodontitis refractory to conventional mechanical therapy. Perorally administered antimicrobial agents often lead to ecological disturbances in the normal oral and intestinal microflora with overgrowth of potentially pathogenic microorganisms, which may spread within the host or from patient to patient, causing infections. The use of antimicrobial agents also promotes the emergence of bacterial drug resistance, both in the periodontal pocket and in the normal oral and intestinal microflora. Topical administration of antimicrobial agents in the periodontal pockets causes restricted disturbances in the intestinal microflora, although there is a substantial risk of development of resistance at the site of application. A number of clinical studies imply that correct use of antimicrobial agents might be beneficial for a subset of patients with adult or juvenile periodontitis. The choice of antimicrobial agent should always be based on accurate microbial analyses of the subgingival microflora and in vitro antimicrobial susceptibility tests of the most important periodontal pathogens. Preferably, agents with low potential of causing ecological disturbances should be used.

Supportive care after active periodontal treatment: a review

This review concerns the most significant questions regarding supportive (maintenance) care after active periodontal treatment: the effectiveness and ideal frequency of maintenance appointments, the adequacy of the supportive therapy according to patient needs, the possible alternatives to currently accepted protocols, and the relative value of personal oral hygiene in the overall context of supportive care. Periodontal diseases are infections with a high potential for recurrence, progressive loss of attachment and eventually, tooth loss. Current therapies for periodontal diseases are highly predictable in arresting disease activity. Supportive periodontal care has been shown to be very effective in maintaining support when adapted to each particular case. Nevertheless, current maintenance therapies may be unsuccessful in preventing further loss of attachment in a small number of sites for some patients. Tests aiming at bacterial identification and the subgingival application of antimicrobials may be helpful in the management of such cases, however the practical value in a specific setting is not known. There is growing evidence of the fundamental role of personal oral hygiene in supportive periodontal care. In cases with rapid and severe periodontal destruction and where local and/or systemic risk factors are present, personal oral hygiene becomes a key factor in the long-term preservation of periodontal support.

Adjunctive controlled topical application of tetracycline HCl in the treatment of localized persistent or recurrent periodontitis. Effects on clinical parameters and elastase-alpha1-proteinase inhibitor in gingival crevicular fluid

35 patients receiving regular supportive periodontal therapy (SPT) and showing signs of localized persistent or recurrent periodontitis were enrolled in the study. Within 1 week after SPT, each patient had a tetracycline HCl loaded ethylene vinyl acetate co-polymer fiber placed into the periodontal pocket of 1 randomly selected tooth with persistent or recurrent periodontitis (test); the fiber was removed after 9.5+/-2.0 days. A non-adjacent tooth with persistent or recurrent periodontitis in a separate quadrant, which received no further treatment, served as a control. A total of 28 patients completed the 6-month study. Compared to control teeth, in test teeth at 6 months significantly (p<0.01) lower scores were found for gingival index, pocket probing depths, and PMN elastase-alpha1-proteinase inhibitor concentrations in gingival crevicular fluid. With the exception of plaque index scores, test teeth demonstrated significant reductions from baseline to 6 months in all parameters (p<0.05). Conversely, all parameter measurements in control teeth, except bleeding on probing, showed no significant difference between baseline and 6-month values. The results suggest that the use of controlled topical application of tetracycline HCl may improve periodontal health and reduce the risk of disease progression in localized persistent or recurrent periodontitis. Moreover, the effects of this application appear to be sustained for at least 6 months.

Comparison of 3 periodontal local antibiotic therapies in persistent periodontal pockets

The aim of this study was to evaluate the efficacy of 3 commercially available periodontal systems for local delivery of antibiotics as adjuncts to scaling and root planing in treatment of sites with persistent periodontal lesions following a course of scaling and root planing. Fifty-four patients with 4 pockets > or = 5 mm and bleeding on probing and/or suppuration were randomized in 4 treatment groups including: scaling and root planing plus application of 25% tetracycline fiber (S + Tet) (13 patients), scaling and root planing plus application of 2% minocycline gel (S + Min) (14 patients), scaling and root planing plus application of 25% metronidazole gel (S + Met) (14 patients), and scaling and root planing alone (S) (13 patients). Clinical measurements were taken at baseline and 6 weeks after the end of treatment periods. All treatments were applied using the distributors' recommended protocols and resulted in significant improvement in probing depth, attachment level, bleeding on probing and the modified gingival index (MGI) scores. The improvements in clinical parameters were greater in all three adjunctive treatment groups than scaling and root planing alone. The mean probing depth reductions were: S + Tet = 1.35 mm, S + Met = 0.95 mm, S + Min = 0.87 mm and S = 0.60 mm. The probing depth reduction was significantly greater in the scaling plus tetracycline fiber group than the scaling and root planing alone group (P = 0.002). The difference between groups in improvement of attachment level or bleeding on probing was not significant Scaling plus tetracycline fiber treatment resulted in the greatest reduction in the MGI scores which was significantly greater than all other groups. While the frequency of sites with suppuration was markedly reduced following all treatments, it reached zero in the scaling plus tetracycline fiber group. No serious adverse effects were observed or reported for any treatment. While all three locally applied antimicrobial systems seem to offer some benefit over scaling and root planing alone, a treatment regimen of scaling and root planing plus tetracycline fiber replacement gave the greatest advantage in the treatment of persistent periodontal lesions at least during the 6-week period following treatment.

The effect of tetracycline fiber therapy on beta-glucuronidase and interleukin-1 beta in crevicular fluid

Treatment with the tetracycline HCL-containing (Actisite infinity) fiber has been shown to improve clinical measures of periodontitis, as well as reduce the number of sites infected with putative periodontal pathogens. In this study, we examined the effect of the tetracycline fiber on biochemical mediators of the host's inflammatory response in gingival crevicular fluid (GCF). The total amount of the lysosomal enzyme beta-glucuronidase (beta G), considered a marker of primary granule release from polymorphonuclear leukocytes and interleukin-1 beta, a cytokine with important proinflammatory effects, were examined in GCF. Patients with localized recurrent periodontitis were followed over a 16 week period. Treated teeth (Tx), teeth adjacent to treated teeth (ADJ) and control teeth (Cx) were studied. Following fiber therapy, the Tx teeth displayed statistically significant reductions in mean probing depth, depth of the deepest site and bleeding on probing over the 16 weeks of the trial. Significant reduction in the depth of the deepest site was also seen for the ADJ teeth over 16 weeks. Total beta G in GCF was reduced for the Tx teeth comparing baseline to 16 weeks, but no significant changes were observed for the ADJ or Cx teeth. Prior to treatment, total beta G for the Tx teeth was 211 +/- 49 U (mean +/- standard error), versus 146 +/- 174 U for the ADJ teeth and 121 +/- 33 U for the Cx teeth. 16 weeks treatment, the mean values for these 3 categories of teeth were comparable (Tx = 95 +/- 20 U, ADJ = 93 +/- 42 U and Cx = 103 +/- 29 U). For the Tx teeth, the maximum reduction in total beta G following therapy occurred at 6 weeks (65%). Total IL-1 beta was significantly reduced for the Tx teeth at 3 and 6 weeks, but rebounded at 16 weeks. In contrast to what was seen for beta G, the maximum reduction in total IL-1 beta for the Tx teeth was observed at 3 weeks (68%). These data suggest that host mediators associated with increased risk for active disease are reduced following tetracycline fiber therapy. Future studies will determine the relative importance of a reduced microbial challenge versus a tetracycline-mediated direct modification of the host response to account for the reduction in the host inflammatory response in GCF following tetracycline fiber therapy.

Local and systemic chemotherapy in the management of periodontal disease: an opinion and review of the concept

Periodontal disease appears to arise from the interaction of pathogenic bacteria with a susceptible host. The main aims of disease management have been to establish a high standard of oral hygiene and to professionally and thoroughly debride the root surface Chemical agents could be considered for both aspects of management. Chemoprevention using supragingivally delivered agents such as chlorhexidine may be questioned for value in the pre-treatment hygiene phase but have well-established efficacy immediately preoperatively and during the post-operative weeks. Long-term maintenance use of chlorhexidine is problematic due to local side effects. Antiplaque toothpastes show modest benefits to gingivitis but are not proven to prevent recurrence of periodontitis. Chemotherapy may be directed at subgingival plaque, using antimicrobials, or at the host response using anti-inflammatory agents. Antimicrobials can be locally or systemically delivered. In most cases antimicrobial chemotherapy should be considered adjunctive to mechanical debridement. The advantages of local and systemic chemotherapy must be balanced against the disadvantages and potential side effects of agents. Antimicrobial chemotherapy offers little or no benefit to the treatment of most chronic adult periodontitis patients and should be reserved for the more rapid or refractory types of disease, and after the debridement phase. Despite the large number of studies there are insufficient comparative data to support any one local delivery system or systemic regimen as superior to another. Systemic versus local antimicrobials have not been compared to date. Host response modifying drugs such as non-steriodal anti-inflammatory drugs (NSAIDS) offer the potential to reduce breakdown and promote healing, including bone regeneration. However until more data are available, NSAIDs should not be used in the management of chronic periodontal diseases, there being no specific agent(s) or regimen established for use. Chemotherapy has an important place in the management of chronic periodontal diseases but routine use must be considered as an over prescription of these valuable agents.

Principles of pharmacologic intervention

Compared to studies with conventional maintenance, relatively few studies have been conducted that have tested pharmacologic intervention as a means for supportive periodontal care. Despite the scarcity of data, several principles have begun to emerge. First, it is clear that removal of subgingival calculus is necessary for the highest level of a long-term effectiveness. Hence, pharmacologic intervention appears best suited as an adjunctive therapy directed toward "problem sites"; sites that fail to respond adequately to conventional maintenance procedures. Intrapocket drug delivery systems appear to offer particular promise since therapy can be directed to selected sites that appear to be failing. Additional effectiveness may also be obtained by use of chlorhexidine mouth rinses for short periods of time during healing to control re-infection. Eradication of reservoirs of infection throughout the mouth also appears to be an important principle related to long-term stabilization. Studies to date suggest that superior clinical response can be obtained by intrapocket delivery systems. Furthermore, up to 2 years of periodontal stabilization can be achieved by these means and longer disease-free maintenance intervals can be established. Additional clinical trials will be necessary to fully optimize and understand this therapeutic approach, but initial studies have reported promising results.

Refractory periodontitis: critical questions in clinical management

Refractory periodontitis appears to be a patient phenomenon with a clinical pattern that may be the result of different influences including genetic factors and exogenous factors that alter the host response to the bacterial challenge. Different patients may have different mechanisms involved in their disease and therefore may show different response patterns following therapy. Although localized non-responsive sites in otherwise responsive patients should not be considered refractory periodontitis, such sites do present substantial therapeutic problems. Initial evidence suggests that local delivery tetracycline provides significant advantages in the management of such sites. Although refractory periodontitis cases appear to be primarily the result of host alterations, the most predictable approach to therapy at present involves systemic antibiotics in conjunction with local therapy. The goal of antibiotic therapy should be to eliminate from detection the target bacteria that were present prior to therapy. Good plaque control, regular professional maintenance therapy, regular microbial monitoring, and control of risk factors are important aspects of the long term maintenance of these cases.

Clinical significance of bacterial resistance to tetracyclines in the treatment of periodontal diseases

Tetracyclines are frequently employed during the treatment of clinical infections in medicine and dentistry, however, emergence of resistant bacterial strains has decreased the utility of these drugs. Accordingly, there is concern that indiscriminant administration of tetracyclines during periodontal therapy will further contribute to the development of additional resistant microorganisms which can complicate infectious disease therapy. This review paper briefly discusses the utility of tetracyclines as an antimicrobial agent in the treatment of periodontal diseases. It then focuses on the clinical significance of bacterial resistance to tetracyclines. Patterns of resistance that may be associated with the following scenarios are addressed: short- and long-term antibiotic therapy, individuals with a history of prior tetracycline therapy, patients with refractory periodontitis, and following controlled local drug delivery. It appears that selection and development of bacterial resistant strains is an inevitable consequence of antibiotic therapy. Nevertheless, prudent administration of tetracyclines may help delay or prevent the emergence of resistant microorganisms.

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)

Clinical and microbiological effects of controlled-release locally delivered minocycline in periodontitis

The clinical efficacy of minocycline in a subgingival local delivery system was evaluated alone (M) or as an adjunct to scaling and root planing (M + SRP), in comparison to scaling and root planing (SRP) or to no subgingival treatment (NoTx) in adult periodontitis. Fifty-one adult patients with > or = 7 mm periodontal pockets demonstrating the presence by culture of Porphyromonas gingivalis (Pg), Prevotella intermedia (P(i)), or Actinobacillus actinomycetemcomitans (Aa) were randomized into one of the above 4 treatment groups. All sites > or = 5 mm in the most diseased quadrant in each patient received the therapy. Other quadrants were not treated. All patients received standardized oral hygiene instructions at the beginning of the study. At 0, 1, 3 and 6 months following therapy the 7 mm experimental sites were evaluated for selected periodontal pathogens by DNA probe analysis. At these same time points, the plaque index, gingival index, and bleeding on probing were evaluated as well as probing depth and relative clinical attachment level which were assessed by means of an automated probe. Probing depth reduction with M + SRP was significantly greater than all other groups at one month and significantly greater than NoTx and SRP at 3 months. There were no differences in probing depth reduction among groups at 6 months. At 6 months the gain in clinical attachment level was significantly greater for SRP than for either the NoTx or M groups. The prevalence of Pg decreased significantly in the M and M + SRP groups at one month.(ABSTRACT TRUNCATED AT 250 WORDS)