Effects of a combination therapy to eliminate Porphyromonas gingivalis in refractory periodontitis

Selective Antimicrobial Therapies for Periodontitis: Win the "Battle and the War"

Traditional antimicrobial therapies for periodontitis (PD) have long focused on non-selective and direct approaches. Professional cleaning of the subgingival biofilm by instrumentation of dental root surfaces, known as scaling and root planning (SRP), is the mainstay of periodontal therapy and is indisputably effective. Non-physical approaches used as adjuncts to SRP, such as chemical and biological agents, will be the focus of this review. In this regard, traditional agents such as oral antiseptics and antibiotics, delivered either locally or systemically, were briefly reviewed as a backdrop. While generally effective in winning the “battle” against PD in the short term, by reducing its signs and symptoms, patients receiving such therapies are more susceptible to recurrence of PD. Moreover, the long-term consequences of such therapies are still in question. In particular, concern about chronic use of systemic antibiotics and their influence on the oral and gut microbiota is warranted, considering antibiotic resistance plasmids, and potential transfer between oral and non-oral microbes. In the interest of winning the “battle and the war”, new more selective and targeted antimicrobials and biologics for PD are being studied. These are principally indirect, blocking pathways involved in bacterial colonization, nutrient acquisition, inflammation or cellular invasion without directly killing the pathogens. This review will focus on current and prospective antimicrobial therapies for PD, emphasizing therapies that act indirectly on the microbiota, with clearly defined cellular and molecular targets.

A therapeutic Porphyromonas gingivalis gingipain vaccine induces neutralising IgG1 antibodies that protect against experimental periodontitis

Porphyromonas gingivalis infected mice with an established P. gingivalis-specific inflammatory immune response were protected from developing alveolar bone resorption by therapeutic vaccination with a chimera (KAS2-A1) immunogen targeting the major virulence factors of the bacterium, the gingipain proteinases. Protection was characterised by an antigen-specific IgG1 isotype antibody and Th2 cell response. Adoptive transfer of KAS2-A1-specific IgG1 or IgG2 expressing B cells confirmed that IgG1-mediated protection. Furthermore, parenteral or intraoral administration of KAS2-A1-specific polyclonal antibodies protected against the development of P. gingivalis-induced bone resorption. The KAS2-A1-specific antibodies neutralised the gingipains by inhibiting: proteolytic activity, binding to host cells/proteins and co-aggregation with other periodontal bacteria. Combining key gingipain sequences into a chimera vaccine produced an effective therapeutic intervention that protected against P. gingivalis-induced periodontitis.

Systemic anti-microbial agents used in periodontal therapy

Periodontitis is an infectious disease with marked inflammatory response, leading to destruction of underlying tissues. The aim of periodontal therapy is to eradicate the pathogens associated with the disease and attain periodontal health. This is achieved by non-surgical and surgical therapy; however, mechanical debridement and topical application of antiseptics may not be helpful in all cases. In such cases, adjunctive systemic antibiotic therapy remains the treatment of choice. It can reach micro-organisms at the base of the deep periodontal pockets and furcation areas via serum, and also affect organisms residing within gingival epithelium and connective tissue. Before advising any anti-microbial agent, it is necessary to have knowledge of that agent. The aim of this review article is to provide basic details of each systemic anti-microbial agent used in periodontal therapy. The points discussed are its mode of action, susceptible periodontal pathogens, dosage, its use in treatment of periodontal disease, and mechanism of bacterial resistance to each anti-microbial agent. It might be of some help while prescribing these drugs.

Mechanisms of action of systemic antibiotics used in periodontal treatment and mechanisms of bacterial resistance to these drugs

Antibiotics are important adjuncts in the treatment of infectious diseases, including periodontitis. The most severe criticisms to the indiscriminate use of these drugs are their side effects and, especially, the development of bacterial resistance. The knowledge of the biological mechanisms involved with the antibiotic usage would help the medical and dental communities to overcome these two problems. Therefore, the aim of this manuscript was to review the mechanisms of action of the antibiotics most commonly used in the periodontal treatment (i.e. penicillin, tetracycline, macrolide and metronidazole) and the main mechanisms of bacterial resistance to these drugs. Antimicrobial resistance can be classified into three groups: intrinsic, mutational and acquired. Penicillin, tetracycline and erythromycin are broad-spectrum drugs, effective against gram-positive and gram-negative microorganisms. Bacterial resistance to penicillin may occur due to diminished permeability of the bacterial cell to the antibiotic; alteration of the penicillin-binding proteins, or production of β-lactamases. However, a very small proportion of the subgingival microbiota is resistant to penicillins. Bacteria become resistant to tetracyclines or macrolides by limiting their access to the cell, by altering the ribosome in order to prevent effective binding of the drug, or by producing tetracycline/macrolide-inactivating enzymes. Periodontal pathogens may become resistant to these drugs. Finally, metronidazole can be considered a prodrug in the sense that it requires metabolic activation by strict anaerobe microorganisms. Acquired resistance to this drug has rarely been reported. Due to these low rates of resistance and to its high activity against the gram-negative anaerobic bacterial species, metronidazole is a promising drug for treating periodontal infections.

Impact of periodontal therapy on the subgingival microbiota of severe periodontitis: comparison between good responders and individuals with refractory periodontitis using the human oral microbe identification microarray

BACKGROUND

This study compares the changes to the subgingival microbiota of individuals with "refractory" periodontitis (RP) or treatable periodontitis (good responders [GR]) before and after periodontal therapy by using the Human Oral Microbe Identification Microarray (HOMIM) analysis.

METHODS

Individuals with chronic periodontitis were classified as RP (n = 17) based on mean attachment loss (AL) and/or >3 sites with AL ≥2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GR (n = 30) based on mean attachment gain and no sites with AL ≥2.5 mm after treatment. Subgingival plaque samples were taken at baseline and 15 months after treatment and analyzed for the presence of 300 species by HOMIM analysis. Significant differences in taxa before and post-therapy were sought using the Wilcoxon test.

RESULTS

The majority of species evaluated decreased in prevalence in both groups after treatment; however, only a small subset of organisms was significantly affected. Species that increased or persisted in high frequency in RP but were significantly reduced in GR included Bacteroidetes sp., Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella spp., Tannerella forsythia, Dialister spp., Selenomonas spp., Catonella morbi, Eubacterium spp., Filifactor alocis, Parvimonas micra, Peptostreptococcus sp. OT113, Fusobacterium sp. OT203, Pseudoramibacter alactolyticus, Streptococcus intermedius or Streptococcus constellatus, and Shuttlesworthia satelles. In contrast, Capnocytophaga sputigena, Cardiobacterium hominis, Gemella haemolysans, Haemophilus parainfluenzae, Kingella oralis, Lautropia mirabilis, Neisseria elongata, Rothia dentocariosa, Streptococcus australis, and Veillonella spp. were more associated with therapeutic success.

CONCLUSION

Persistence of putative and novel periodontal pathogens, as well as low prevalence of beneficial species was associated with chronic refractory periodontitis.

Comparisons of subgingival microbial profiles of refractory periodontitis, severe periodontitis, and periodontal health using the human oral microbe identification microarray

BACKGROUND

This study compared the subgingival microbiota of subjects with refractory periodontitis (RP) to those in subjects with treatable periodontitis (GRs = good responders) or periodontal health (PH) using the Human Oral Microbe Identification Microarray (HOMIM).

METHODS

At baseline, subgingival plaque samples were taken from 47 subjects with periodontitis and 20 individuals with PH and analyzed for the presence of 300 species by HOMIM. The subjects with periodontitis were classified as having RP (n = 17) based on mean attachment loss (AL) and/or more than three sites with AL >or=2.5 mm after scaling and root planing, surgery, and systemically administered amoxicillin and metronidazole or as GRs (n = 30) based on mean attachment gain and no sites with AL >or=2.5 mm after treatment. Significant differences in taxa among the groups were sought using the Kruskal-Wallis and chi(2) tests.

RESULTS

More species were detected in patients with disease (GR or RP) than in those without disease (PH). Subjects with RP were distinguished from GRs or those with PH by a significantly higher frequency of putative periodontal pathogens, such as Parvimonas micra (previously Peptostreptococcus micros or Micromonas micros), Campylobacter gracilis, Eubacterium nodatum, Selenomonas noxia, Tannerella forsythia (previously T. forsythensis), Porphyromonas gingivalis, Prevotella spp., Treponema spp., and Eikenella corrodens, as well as unusual species (Pseudoramibacter alactolyticus, TM7 spp. oral taxon [OT] 346/356, Bacteroidetes sp. OT 272/274, Solobacterium moorei, Desulfobulbus sp. OT 041, Brevundimonas diminuta, Sphaerocytophaga sp. OT 337, Shuttleworthia satelles, Filifactor alocis, Dialister invisus/pneumosintes, Granulicatella adiacens, Mogibacterium timidum, Veillonella atypica, Mycoplasma salivarium, Synergistes sp. cluster II, and Acidaminococcaceae [G-1] sp. OT 132/150/155/148/135) (P <0.05). Species that were more prevalent in subjects with PH than in patients with periodontitis included Actinomyces sp. OT 170, Actinomyces spp. cluster I, Capnocytophaga sputigena, Cardiobacterium hominis, Haemophilus parainfluenzae, Lautropia mirabilis, Propionibacterium propionicum, Rothia dentocariosa/mucilaginosa, and Streptococcus sanguinis (P <0.05).

CONCLUSION

As determined by HOMIM, patients with RP presented a distinct microbial profile compared to patients in the GR and PH groups.

Clinical Response of Azithromycin as an Adjunct to Non-Surgical Periodontal Therapy in Smokers

BACKGROUND

Antibiotic therapy can be used in very specific periodontal treatment situations such as in refractory cases of periodontal disease found to be more prevalent in smokers. This study was designed to determine the efficacy of azithromycin (AZM) when combined with scaling and root planing (SRP) for the treatment of moderate to severe chronic periodontitis in smokers.

METHODS

Thirty-one subjects were enrolled into a 6-month randomized, single-masked trial to evaluate clinical, microbial (using benzoyl- DL-arginine naphthylamine [BANA] assay), and gingival crevicular fluid (GCF) pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) levels in response to SRP alone or SRP + AZM. At baseline, patients who smoked > or =1 pack per day of cigarettes who presented with at least five sites with probing depths (PD) of > or =5 mm with bleeding on probing (BOP) were randomized into the test or control groups. At baseline and 3 and 6 months, clinical measurements (probing depth [PD], clinical attachment loss [CAL], and bleeding on probing [BOP]) were performed. GCF bone marker assessment (Ctelopeptide [ICTP] as well as BANA test analyses) were performed at baseline, 14 days, and 3 and 6 months.

RESULTS

The results demonstrated that both groups displayed clinical improvements in PD and CAL that were sustained for 6 months. Using a subject-based analysis, patients treated with SRP + AZM showed enhanced reductions in PD and gains in CAL at moderate (4 to 6 mm) and deep sites (>6 mm) (P <0.05). Furthermore, SRP + AZM resulted in greater reductions in BANA levels compared to SRP alone (P <0.05) while rebounds in BANA levels were noted in control group at the 6-month evaluation. No statistically significant differences between groups on mean BOP and ICTP levels during the course of the study were noted.

CONCLUSIONS

The utilization of AZM in combination with SRP improves the efficacy of non-surgical periodontal therapy in reducing probing depth and improving attachment levels in smokers with moderate to advanced attachment loss.

Clinical and microbiological changes associated with the use of combined antimicrobial therapies to treat "refractory" periodontitis

BACKGROUND

The present investigation examined clinical and microbial changes after a combined aggressive antimicrobial therapy in subjects identified as "refractory" to conventional periodontal therapy.

METHOD

Fourteen subjects were identified as "refractory" based on full-mouth mean attachment loss and/or >3 sites with attachment loss > or =3 mm following scaling and root planing (SRP), periodontal surgery and systemic antibiotics. After baseline monitoring, subjects received SRP, locally delivered tetracycline at pockets > or =4 mm, systemically administered amoxicillin (500 mg, t.i.d. for 14 days)+metronidazole (250 mg, t.i.d. for 14 days) and professional removal of supragingival plaque weekly for 3 months. Subjects were monitored clinically every 3 months post-therapy for 2 years. Subgingival plaque samples were taken at the same time points from the mesial aspect of each tooth and the levels of 40 subgingival taxa were determined using checkerboard DNA-DNA hybridization. Mean levels of each species were averaged within a subject at each visit. Significance of changes in clinical and microbiological parameters over time were evaluated using the Friedman or Wilcoxon signed ranks test.

RESULTS

On average, subjects showed significant improvements in all clinical parameters after therapy. Mean (+/-SEM) full-mouth pocket depth reduction was 0.83+/-0.13 mm and mean attachment level "gain" was 0.44+/-0.12 at 24 months. Clinical improvement was accompanied by major reductions in multiple subgingival species during the first 3 months of active therapy that were maintained for most species to the last monitoring visit. Reductions occurred for three Actinomyces species, "orange complex" species including Campylobacter showae, Eubacterium nodatum, three Fusobacterium nucleatum subspecies, Peptostreptococcus micros, Prevotella intermedia as well as the "Streptococcus milleri" group, Streptococcus anginosus, Streptococcus constellatus and Streptococcus intermedus. Subjects differed in their response to therapy; six modest response subjects exhibited less attachment level gain and were characterized by reductions in the microbiota from baseline to 3 months, but re-growth of many species thereafter.

CONCLUSIONS

The combined antibacterial therapy was successful in controlling disease progression in 14 "refractory" periodontitis subjects for 2 years.

A systematic review on the effect of systemic antimicrobials as an adjunct to scaling and root planing in periodontitis patients

BACKGROUND

Scaling and root planing (SRP) are the bases of non-surgical therapy in the treatment of periodontitis. However, results from this therapy are often unpredictable and dependable from many different factors.

OBJECTIVES

The aim of this systematic review was to evaluate the effectiveness of the adjunctive use of systemic antimicrobials with scaling and root planing (SRP) vs. SRP alone in the treatment of chronic (CP) or aggressive periodontitis (AgP).

SEARCH STRATEGY

Use of computerized databases, namely MEDLINE, the Cochrane Oral Health Group Specialty Trials Register and EMBASE; reference lists from relevant articles were hand-searched; and a hand-search of selected journals until April 2001.

SELECTION CRITERIA

Studies were selected if they were designed as controlled clinical trials in which systemically healthy patients with either AgP or CP were treated with SRP plus systemic antimicrobials in comparison with SRP alone or with placebo, for a minimum of 6 months. Main outcome measures were clinical attachment level (CAL) change and probing pocket depth (PPD) change.

DATA COLLECTION AND ANALYSIS

Two reviewers extracted independently information regarding quality and study characteristics, in duplicate. Kappa scores determined their agreement. Main results were collected and grouped by drug, disease and PPD category. For the quantitative data synthesis, the data was pooled (when mean differences and standard errors were available), and either a Fixed Effects or Random Effects meta-analysis was used for the analysis.

RESULTS

After an initial selection, 158 papers were identified by the manual and electronic searches; 25 papers were eligible for inclusion. Their quality assessment showed that randomization and allocation concealment methods were seldom reported and blindness was usually not defined clearly. In general, selected studies showed high variability and lack of relevant information for an adequate assessment. Overall, SRP plus systemic antimicrobial groups demonstrated better results in CAL and PPD change than SRP alone or with placebo groups. Only limited meta-analyses could be performed, due to the difficulties in pooling the studies and the lack of appropriate data. This analysis showed a statistically significant additional benefit for spiramycin (PPD change) and amoxicillin/metronidazole (CAL change) in deep pockets.

CONCLUSION

Systemic antimicrobials in conjunction with SRP, can offer an additional benefit over SRP alone in the treatment of periodontitis, in terms of CAL and PPD change, and reduced risk of additional CAL loss. However, differences in study methodology and lack of data precluded an adequate and complete pooling of data for a more comprehensive analyses. It was difficult to establish definitive conclusions, although patients with deep pockets, progressive or 'active' disease, or specific microbiological profile, can benefit more from this adjunctive therapy.

Povidone-iodine as a periodontal pocket disinfectant

OBJECTIVES AND BACKGROUND

Povidone-iodine [polyvinylpyrrolidone-iodine complex (PVP-iodine)] might constitute a valuable adjunct to current periodontal therapy because of its broad-spectrum antimicrobial activity, low potential for developing resistance and adverse reactions, wide availability, ease of use, and low financial cost. This investigation employed a randomized, split-mouth study design to determine the microbiological and clinical effects of 10% PVP-iodine subgingival irrigation in periodontitis lesions showing radiographic evidence of subgingival calculus.

METHODS

Sixteen adults having at least one periodontal pocket of 6 mm or more in each quadrant of the dentition and harboring one or more periodontopathic bacteria participated in the study. In each subject, a study site in each quadrant was randomly chosen to receive either subgingival irrigation with 10% PVP-iodine together with scaling and root planing, scaling and root planing alone, subgingival irrigation with 10% PVP-iodine, or subgingival irrigation with sterile saline. Prior to therapy and at 5 weeks post-treatment, microbiological culture was carried out without knowledge of the clinical status or the type of treatment rendered. A blinded clinical examiner determined presence of dental plaque, probing pocket depth, and gingival bleeding on probing. Microbiological and clinical data were analyzed using a repeated measures analysis of variance and Kruskal-Wallis rank test with the Tukey and Mann-Whitney post hoc tests.

RESULTS

At 5 weeks post-treatment, subgingival irrigation with PVP-iodine together with scaling and root planing caused a 95% or greater reduction in total pathogen counts in 44% of pockets having >/= 6 mm depth whereas scaling and root planing alone, povidone-iodine irrigation alone and water irrigation alone caused 95% reduction of total pathogens only in 6-13% of similar study sites (P = 0.02). Reduction in mean pocket depth was 1.8 mm for the PVP-iodine/scaling and root planing group, 1.6 mm for the scaling and root planing group, and 0.9 mm for the PVP-iodine and the saline monotherapy groups, with statistical significance reached for the scaling and root planing group vs. the PVP-iodine group (P = 0.04) and for the scaling and root planing group vs. the saline group (P = 0.02). Reduction in visible dental plaque, which ranged from 38% to 62%, showed no significant differences among treatment groups.

CONCLUSIONS

The addition of subgingival PVP-iodine irrigation to conventional mechanical therapy may be a cost-effective means of reducing total counts of periodontal pathogens and helping control periodontal disease. However, subgingival irrigation with PVP-iodine without concomitant mechanical debridement might not improve microbiological and clinical variables in comparison with saline irrigation, at least not in sites with radiographic evidence of subgingival calculus.

Selection of antimicrobial agents in periodontal therapy

BACKGROUND

The recognition over the past 3 decades of microbial specificity in periodontitis has afforded dental practitioners the ability to prevent and treat the disease with a variety of antimicrobial drugs. These include systemic antibiotics, topical antibiotics and topical antiseptics.

RESULTS

Systemic antibiotic therapy can be essential in eliminating pathogenic bacteria that invade gingival tissue and in helping control periodontal pathogens residing in various domains of the mouth from where they may translocate to periodontal sites. Frequently used periodontal combination antibiotic therapies are metronidazole-amoxicillin (250-375 mg of each 3 x daily for 8 days) and metronidazole-ciprofloxacin (500 mg of each 2 x daily for 8 days). Microbiological analysis helps determine the optimal antibiotic therapy and effectiveness of treatment. Topical antibiotics that are commercially available as controlled release devices suffer from several potential problems, including insufficient spectrum of antimicrobial activity in some periodontal polymicrobial infections, risks of producing an antibiotic resistant microbiota, and high acquisition costs. Topical antiseptics of relevance in periodontal treatment include 10% povidone-iodine placed subgingivally by a syringe for 5 min, and 0.1% sodium hypochlorite solution applied subgingivally by patients using an irrigation device.

CLINICAL IMPLICATIONS

The present paper recommends periodontal treatment that includes a battery of professionally and patient-administered antimicrobial agents (properly prescribed systemic antibiotics, povidone-iodine and sodium hypochlorite subgingival irrigants, and chlorhexidine mouthrinse). Available chemotherapeutics can provide effective, safe, practical and affordable means of controlling subgingival colonization of periodontal pathogens and various types of periodontal disease.

Antibiotic resistance of subgingival species during and after antibiotic therapy

AIM

The purpose of the present investigation was to determine the percentage and identity of antibiotic-resistant species in subgingival plaque and saliva samples from chronic periodontitis patients treated by scaling and root planing followed by orally administered amoxicillin or metronidazole.

METHOD

In all, 20 chronic periodontitis patients were selected for study. After clinical and microbiological monitoring, subjects were randomly assigned to receive either orally administered amoxicillin at the dosage of 500 mg, 3 times daily for 14 days or orally administered metronidazole at the dosage of 250 mg, 3 times daily for 14 days. For the antibiotic resistance determinations, subgingival plaque samples were taken from six posterior teeth at baseline, and 90 days; and from two randomly selected teeth at 3, 7 and 14 days during and after antibiotic administration. Samples were plated on enriched blood agar plates with or without either 2 micro g/mL metronidazole or 2 micro g/mL amoxicillin. Colonies were counted at 7 days. Significant differences in percentage of resistant organisms over time were determined by the Quade test. Microbial growth was washed from antibiotic-containing media and the identity of species determined using checkerboard DNA-DNA hybridization. Data were compared with those obtained in a previous study from subjects receiving SRP only or SRP followed by 14 days of orally administered doxycycline. The level of doxycycline used to determine antibiotic resistance in that study was 4 micro g/mL.

RESULTS

The mean percentage of resistant isolates increased during antibiotic administration and returned to baseline levels by 90 days post therapy. The mean percentages (+/- SEM) of isolates resistant to 2 micro g/mL metronidazole were 53 +/- 9, 65 +/- 9, 79 +/- 4 and 69 +/- 7 at baseline, 3, 7 and 14 days during antibiotic administration, and 57 +/- 4, 64 +/- 5, 62 +/- 7 and 47 +/- 6 at 3, 7, 14 and 90 days after antibiotic administration. At the same time points, the percentage of resistant isolates to amoxicillin was 0.5 +/- 0.2, 22 +/- 12, 14 +/- 5 and 37 +/- 11 during, and 31 +/- 11, 8 +/- 3, 3 +/- 2 and 3 +/- 0.6 after, administration. Antibiotic-resistant isolates of resistant species detected during or after therapy were also detected prior to therapy. The most prevalent resistant species in the metronidazole-treated group were: A. naeslundii 1, S. constellatus, A. naeslundii 2, S. mitis, S. oralis, A. odontolyticus, S. sanguis, and in the amoxicillin-treated group: S. constellatus, P. nigrescens, E. saburreum, A. naeslundii 1, S. oralis, P. melaninogenica and P. intermedia.

CONCLUSIONS

Systemic antibiotic administration transiently increased the percentage of resistant subgingival species, but a major component of subgingival plaque remained sensitive to the agents during their administration. Antibiotic-resistant isolates of resistant species could be detected in samples both prior to and after therapy. However, % antibiotic-resistant isolates returned to baseline levels 90 days after antibiotic administration.

The use of PVP-iodine as an adjunct to non-surgical treatment of chronic periodontitis

OBJECTIVE

The present study was performed to assess the effect of topically-applied PVP-iodine, used as an adjunct both during basic non-surgical therapy and at re-treatment during the long-term maintenance of patients with advanced periodontal disease.

MATERIAL AND METHODS

223 patients with advanced destructive periodontitis were recruited. The participants met the following inclusion criteria: (i) a minimum of 8 non-molar teeth, (ii) probing pocket depth of > or = 6 mm at > or = 2 teeth in each dentate quadrant, and radiographic bone loss exceeding 40% at the same teeth. A baseline I examination included assessment of plaque, gingivitis, probing pocket depth (PPD), probing attachment level (PAL) and radiographic bone height (RxBL). Following baseline I, the patients were stratified into 2 treatment groups; 2 subjects out of 3 were included in a control group and 1 in a test group. All participants, on an individual basis, received a case presentation and were instructed in proper self-performed plaque control measures. Non-surgical therapy was performed by the use of an ultrasonic device. The instrumentation in the test group was combined with the administration of 0.1% PVP-iodine. All subjects were recalled for comprehensive examinations 3, 6 and 12 months (baseline II) after baseline I and then after 3, 5 and 13 years of maintenance therapy. PAL determinations were performed annually. Subjects (losers) who at the re-examinations after 1, 2 and 3 years of maintenance demonstrated an annual further loss of PAL > or = 2 mm at > or = 4 teeth were exited from the study and referred for re-treatment. There were 9 losers in the test and 31 in the control group. In addition, 8 subjects in the test and 25 subjects in the control group withdrew from the trial for reasons unrelated to the study. These 73 subjects were not included in the data presentation from the various examinations.

RESULTS

It was demonstrated that non-surgical periodontal therapy resulted in (i) improved gingival conditions, (ii) reduced PPD, (iii) gain in PAL. It was also documented that the topical application of 0.1% PVP-iodine in conjunction with the mechanical root debridement established conditions which further improved the outcome of therapy. This was evidenced by the fact that at the 3, 6, and 12 months re-examinations after baseline I, the test group had significantly lower mean PPD values and significantly more gain of PAL than the control group. During the 12 years of SPT, it was possible for most subjects in both groups to maintain shallow pockets and to avoid marked further loss of PAL. There were, however, a larger number of losers in the control than in the test group.

CONCLUSION

PVP-iodine, topically applied during subgingival instrumentation, may improve the outcome of non-surgical periodontal therapy.

Position paper: sonic and ultrasonic scalers in periodontics. Research, Science and Therapy Committee of the American Academy of Periodontology

Ultrasonic and sonic scalers appear to attain similar results as hand instruments for removing plaque, calculus, and endotoxin. Ultrasonic scalers used at medium power seem to produce less root surface damage than hand or sonic scalers. Due to instrument width, furcations may be more accessible using ultrasonic or sonic scalers than manual scalers. It is not clear whether root surface roughness is more or less pronounced following power-driven scalers or manual scalers. It is also unclear if root surface roughness affects long-term wound healing. Periodontal scaling and root planing includes thorough calculus removal, but complete cementum removal should not be a goal of periodontal therapy. Studies have established that endotoxin is weakly adsorbed to the root surface, and can be easily removed with light, overlapping strokes with an ultrasonic scaler. A significant disadvantage of power-driven scalers is the production of contaminated aerosols. Because ultrasonics and sonics produce aerosols, additional care is required to achieve and maintain good infection control when incorporating these instrumentation techniques into dental practice. Preliminary evidence suggests that the addition of certain antimicrobials to the lavage during ultrasonic instrumentation may be of minimal clinical benefit. However, more randomized controlled clinical trials need to be conducted over longer periods of time to better understand the long-term benefits of ultrasonic and sonic debridement.

In vitro antimicrobial susceptibilities of three Porphyromonas spp and in vivo responses in the oral cavity of cats to selected antimicrobial agents

OBJECTIVES

To determine in vitro susceptibility of Porphyromonas gingivalis, P salivosa and P circumdentaria to seven antimicrobial agents by agar dilution and Epsilometer test methods and to assess the effectiveness of these antimicrobial agents in reducing the numbers of each Porphyromonas spp in the oral cavity of 16 domestic cats.

DESIGN

A two-part prospective study involving in vitro antimicro-bial studies using Porphyromonas spp obtained from naturally occurring feline infections and in vivo antimicrobial response studies using client-owned cats with naturally occurring periodontal disease.

PROCEDURE

Isolates (n = 25) of three feline Porphyromonas spp from the oral cavity and oral-associated disease were tested for their in vitro susceptibility to amoxycillin, amoxycillin-clavulanate, benzylpenicillin, clindamycin, doxycycline, erythromycin and metronidazole, using agar dilution and Epsilometer test methods. Digoxigenin-labelled whole chromosomal DNA probes directed against P gingivalis VPB 3492, P circumdentaria NCTC 12469T and P salivosa VPB 3313 were used to quantify organisms taken from two sample sites at the gingival margins of these cats prior to, and 5 days after, treatment with one of four commonly used antimicrobial products (amoxycillin-clavulanate, clindamycin, doxycycline or spiramycin-metronidazole). The response to treatment was assessed clinically for each cat.

RESULTS

All isolates were susceptible in vitro to all seven antimicrobial agents using both methods. The numbers of P gingivalis were not reduced at the gingival sample sites by administration of amoxycillin-clavulanate for 5 days, although this treatment reduced the numbers of P salivosa and P circumdentaria to below detection levels in six of eight and two of three of sample sites, respectively; clinical improvement was not observed in cats treated with amoxycillin-clavulanate. Treatment with clindamycin, doxycycline or spiramycin-metronidazole resulted in clinical improvement and a marked reduction of all Porphyromonas isolates at the sample sites.

CONCLUSION

The Epsilometer test is a simple and accurate method for determining the minimum inhibitory concentration for P gingivalis, P salivosa and P circumdentaria. All strains were susceptible in vitro to all the antimicrobial agents tested although clinical improvement of gingival disease was not noted with amoxycillin-clavulanate when given for 5 days at usual doses. This appears to be the first report of the disparity between the in vivo and in vitro susceptibility of oral bacterial strains to amoxycillin-clavulanate in the veterinary dental literature. This also appears to be the first report in which clinical and microbiological responses to commonly used antimicrobial agents for periodontal disease in cats has been documented and quantified. It was shown that treatment with clindamycin, spiramycin-metronidazole or doxycycline not only produced a substantial reduction in the number of Porphyromonas spp (in the majority of cases to below detection levels), but also resulted in substantial clinical improvement. This would indicate that these antimicrobial agents are useful adjunctive therapy to mechanical debridement in domestic cats.

Povidone-iodine's effects and role in the management of periodontal diseases: a review

This review article addresses the effects of povidone-iodine (PVP-I) and its utility in the treatment of periodontal diseases. There are data to support the following statements: PVP-I is a potent antiseptic and, when used as a component in a rinse with H202, the rinse can decrease the level of gingivitis. With regards to patients with adult periodontitis, there is some evidence to indicate that PVP-I delivered via an ultrasonic device achieves better results in deep pockets than ultrasonic debridement when water is the irrigant. The benefits of PVP-I in the treatment of refractory periodontitis are unclear. Subgingival irrigation with PVP-I may reduce the incidence of bacteremia if it is employed as a pre-procedural intrasulcular irrigant; however, this technique is not recommended for high-risk patients. PVP-I is a safe antiseptic and does not appear to impede wound healing or induce resistant bacteria. It is an approved drug whose intraoral use is an unlabeled indication. In conclusion, the literature suggests that utilization of PVP-I is potentially beneficial in the management of some periodontal diseases. However, additional clinical trials are needed to verify this assessment, since it is based upon a limited number of studies.

Differential clinical treatment outcome after systemic metronidazole and amoxicillin in patients harboring Actinobacillus actinomycetemcomitans and/or Porphyromonas gingivalis

48 adult patients with untreated periodontitis harboring subgingival Actinobacillus actinomycetemcomitans and/or Porphyromonas gingivalis as assessed by PCR were randomly assigned to receive full-mouth scaling alone (control) or scaling with systemic metronidazole plus amoxicillin and supragingival irrigation with chlorhexidine digluconate (test). In patients harboring A. actinomycetemcomitans intraorally at baseline, the adjunctive antimicrobial therapy resulted in a significantly higher incidence of probing attachment level (PAL) gain of 2 mm or more compared to scaling alone over 12 months (p<0.05). In addition, suppression of A. actinomycetemcomitans in subgingival plaque below detectable levels was associated with an increased incidence of PAL gain. In contrast, patients initially harboring P. gingivalis but not A. actinomycetemcomitans in the oral cavity showed a significantly higher incidence of PAL loss following adjunctive antimicrobial therapy compared to scaling alone (p<0.05). When the presence of pathogens at baseline was disregarded in the analysis, adjunctive antimicrobial therapy did not significantly enhance clinical treatment outcome. The results indicated that adults with untreated periodontitis harboring A. actinomycetemcomitans may benefit from the adjunctive antimicrobial therapy for a minimum of 12 months, whereas, the regimen may adversely affect the clinical treatment outcome of patients harboring P. gingivalis but not A. actinomycetemcomitans.

Clinical and microbiological features of refractory periodontitis subjects

The purpose of this investigation was to compare the clinical parameters and the site prevalence and levels of 40 subgingival species in successfully treated and refractory periodontitis subjects. 94 subjects received scaling and root planing and if needed, periodontal surgery and systemically administered tetracycline. 28 refractory subjects showed mean full mouth attachment loss and/or > 3 sites showing attachment loss > 2.5 mm within 1 year post-therapy. 66 successfully treated subjects showed mean attachment level gain and no sites with attachment loss > 2.5 mm. Baseline subgingival plaque samples were taken from the mesial aspect of each tooth and the presence and levels of 40 subgingival taxa were determined using whole genomic DNA probes and checkerboard DNA-DNA hybridization. The mean levels and % of sites colonized by each species (prevalence) was computed for each subject and differences between groups sought using the Mann-Whitney test. Most of the 40 species tested, including Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Treponema denticola and Bacteroides forsythus, were equally or less prevalent in the refractory group. Prevotella nigrescens was significantly more prevalent in successfully treated subjects, while refractory subjects harbored a larger proportion of Streptococcus species, particularly Streptococcus constellatus. The odds of a subject being refractory was 8.6 (p < 0.001) if S. constellatus constituted > or = 3.5% of the total DNA probe count. Since few microbiological differences existed between treatment outcome groups using DNA probes to known species, the predominant cultivable microbiota of 33 subgingival samples from 14 refractory subjects was examined. 85% of the 1649 isolates were identified using probes to 69 recognized subgingival species. The remaining unidentified strains were classified by analyzing 16S rRNA gene sequences. Many sequenced isolates were of taxa not considered a common part of the oral microbiota such as Acinetobacter baumanni, Gemella haemolysans, Enterococcus faecalis, Staphylococcus warneri, Pseudomonas aeruginosa and novel species in the genera Bartonella, Ralstonia, Neisseria, Eubacterium, Rothia, Gordona, Gemella, Corynebacterium, Leptotrichia, and Actinomyces. Refractory subjects constituted a heterogeneous group based on their subgingival microbiota. As a group, they did not harbor more of the "classic" periodontopathogens, although elevated proportions of S. constellatus were found.

Clinical and microbiological features of subjects with adult periodontitis who responded poorly to scaling and root planing

In a previous report, it was shown that scaling and root planing (SRP) decreased mean pocket depth and attachment level in subjects with adult periodontitis, as well as the levels and prevalence of Bacteroides forsythus, Porphyromonas gingivalis and Treponema denticola. However, a subset of subjects in that study exhibited mean loss of attachment following SRP. The purpose of the present investigation was to seek clinical and microbiological differences between subjects who responded well or poorly to SRP. 57 subjects with adult periodontitis were treated by full-mouth SRP under local anaesthetic. Clinical assessments of plaque, redness, suppuration, BOP, pocket depth and attachment level were made at 6 sites per tooth prior to and 3 months post-SRP. Attachment level measurements were repeated at each visit and differences in means between visits used to assess change. 18 subjects showed mean attachment loss 3 months post-SRP (poor response group), while 39 showed mean attachment level gain (good response group). The prevalence and levels of 40 subgingival taxa in subgingival plaque samples from the mesiobuccal site of each tooth (maximum 28 sites) in each subject prior to and 3 months post-SRP were assessed using checker-board DNA-DNA hybridization. The prevalence of each species was computed for each subject and averaged across subjects in the 2 treatment-response groups at each visit. Differences between groups were sought using the Mann-Whitney test. There were no statistically significant differences between the 2 response groups in any clinical parameter prior to therapy. Subjects in the good response group showed more attachment level gain at sites with baseline pocket depths of < 4 mm, 4-6 and > 6 mm than poor response subjects. Of 40 species evaluated, A. naeslundii genospecies 2 (A. viscosus), T. denticola, C. gracilis and C. rectus were significantly higher and more prevalent pre-therapy in the good response subjects. Mean attachment level change post SRP could be predicted using multiple linear regression with A. naeslundii genospecies 2 (A. viscosus) and T. denticola as the predictor variables (r2 = 0.373, p < 0.00001). Sites that gained > or = 2 mm of attachment post therapy showed a significant decrease in the counts of P. gingivalis (7.5 +/- 3.5 to 0.2 +/- 0.2 x 10(5)), T. denticola (8.2 +/- 3.5 to 1.8 +/- 1.1 x 10(5)) and B. forsythus (11.1 +/- 5.7 to 0.3 +/- 0.2 x 10(5)). The data of the present investigation indicate that SRP is most effective in subjects and sites with high levels of the subgingival species that this therapy affects.

beta-Lactamase producing bacteria in adult periodontitis

In 23 untreated adult periodontitis patients, the occurrence of beta-lactamase producing periodontal bacteria was determined. In addition to non-selective isolation media, selective isolation and growth of beta-lactamase positive subgingival bacterial species was carried out on blood agar plates supplemented with amoxicillin and plates with amoxicillin+clavulanic acid. Porphyromonas gingivalis, Prevotella intermedia, Actinobacillus actinomycetemcomitans, Peptostreptococcus micros, Fusobacterium nucleatum, Bacteroides forsythus and Campylobacter rectus isolates from the non-selective medium were tested for beta-lactamase activity by a nitrocefin disk method (DrySlide) and by a laboratory chromogenic nitrocefin-based test. Isolates from the amoxicillin plates that were absent on the amoxicillin/clavulanic acid plates were identified and tested for beta-lactamase production. Based on the non-selective plates, six of 23 P. intermedia isolates, 2 of 19 B. forsythus isolates and 3 of 23 F. nucleatum isolates were beta-lactamase positive. The beta-lactamase positive species Prevotella loescheii, Prevotella buccae, Prevotella buccalis and Actinomyces spp were recovered from the selective amoxicillin plates. beta-Lactamase positive subgingival species were recovered from 17 of 23 patients (74%) but usually comprised low proportions of the subgingival microbiota (range < 0.01-15%). Comparison of the DrySlide test and the nitrocefin-based laboratory test revealed full agreement of test results. beta-Lactamase activity in whole subgingival plaque was detected in 12 patient samples (52%). It was concluded that beta-lactamase activity in subgingival bacteria in adult periodontitis is a common feature. However, since the majority of the samples showed only low-level enzymatic activity, the clinical relevance of this observation with regard to therapy with unprotected enzyme-susceptible beta-lactams is uncertain, though failure on the other hand, is difficult to rule out when a mechanism of resistance is present. The majority of beta-lactamase positive strains was found among species of the Prevotella genus.

Active and alpha-1 proteinase inhibitor complexed leukocyte elastase levels in crevicular fluid from patients with periodontal diseases

Human leukocyte elastase is present in large amounts in the crevicular fluid of patients with periodontal disease and was considered as a putative biological marker of the evolution of such diseases. The aim of this work was to measure spectrophotometrically amounts of active elastase (AE) and elastase complexed to alpha 1 proteinase inhibitor (E-alpha 1-PI) in gingival crevicular fluid obtained, from patients suffering from rapidly progressive periodontitis (RPP group) or adult periodontitis (AP group) with different probing depths (3 to 5 mm and > 6 mm). AE and E-alpha 1-PI concentrations were negligible in healthy individuals. AE, but not E-alpha 1-PI, concentration appears to vary significantly with the probing depth in patients suffering either from rapidly progressive or adult periodontitis. No correlations were found between levels of AE and E-alpha 1-PI in the different groups of patients. AE concentration seems to be a marker of periodontal diseases in relation with probing depth.

Short-term responses to periodontal therapy in insulin-dependent diabetic patients

This investigation studied relative changes in periodontal conditions of 18 insulin-dependent diabetic patients. Measures of gingival inflammation, crevicular fluid aspartate aminotransferase (AST) levels, probing depth and attachment levels, the presence of three periodontal pathogens (Porphyromonas gingivalis, Bacteroides forsythus, and Actinobacillus actinomycetemcomitans) and serum antibody titers to these bacteria, and blood sugar levels (glycosylated hemoglobin, HbAlc) were studied before and 2 months after non-surgical debridement. Antibody titers to the same bacteria were also studied in sera from 18 sex- and age-matched periodontally healthy and non-diabetic subjects. Periodontal conditions showed significant improvement. The mean probing depth at 4 of the worst sites selected in each patient decreased from 5.7 mm to 4.8 mm (p < 0.0001). The mean full width probing depth changed from 2.9 mm (s.d. +/- 0.2) to 2.5 mm (s.d. +/- 0.3). A mean gain of 0.4 mm attachment level was recorded (P < 0.0001). The mean AST value decreased from 1009 microIU to 518 microIU (P < 0.006). Minimal differences in mean glycosylated hemoglobin values (HbAlc) were noticed before and after treatment. A. actinomycetemcomitans was never detected. P. gingivalis was present at 7% of the sites both before and after treatment. B. forsythus was found at 29% of sites (50% of patients) before and at 36% of sites (61% of patients) after treatment. Positive associations were found between the presence of B. forsythus and AST values, gingival index, probing depth, and attachment level (P < 0.05). Baseline serum IgG titers to P. gingivalis were significantly lower in the patients with diabetes (9.5 ELISA units vs. 28.5 ELISA units in the healthy controls). IgG titers to B. forsythus did not differ between diabetic and non-diabetic subjects. No changes in IgG titers occurred after treatment. Clinical improvements after mechanical non-surgical therapy in patients with insulin-dependent diabetes mellitus were modest after 2 months. Treatment did not eliminate B. forsythus and P. gingivalis and did not affect IgG titer responses. More intense therapy, and longer follow-up times, may be necessary to see more pronounced clinical and systemic effects.

Polymerase chain reaction detection of 8 putative periodontal pathogens in subgingival plaque of gingivitis and advanced periodontitis lesions

A 16S rRNA-based polymerase chain reaction (PCR) detection method was used to determine the prevalence of Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Campylobacter rectus, Eikenella corrodens, Porphyromonas gingivalis, Prevotella intermedia. Prevotella nigrescens and Treponema denticola in subgingival specimens of 50 advanced periodontitis, 50 adult gingivitis and 50 pediatric gingivitis subjects. The optimal PCR conditions were determined for each study species. Agarose gel electrophoresis of PCR products from each study species revealed a single band of the predicted size. Restriction enzyme digestion of amplicons confirmed the specificity of the amplification. PCR detection limits were in the range of 25-100 cells. No cross-reactivity with other oral micro-organisms or nonspecific amplification was observed. The prevalence by PCR in advanced periodontitis, adult gingivitis and pediatric gingivitis subjects was 30%, 14% and 14% for A. actinomycetemcomitans, 86%, 18% and 8% for B. forsythus, 74%, 52% and 78% for C. rectus, 80%, 70% and 66% for E. corrodens, 70%, 10% and 14% for P. gingivalis, 58%, 12% and 18% for P. intermedia, 52%, 20% and 22% for P. nigrescens, and 54%, 16% and 16% for T. denticola, respectively. The prevalence was higher in the advanced periodontitis group than in both adult gingivitis and pediatric gingivitis for A. actinomycetemcomitans, B. forsythus, P. gingivalis, P. intermedia, P. nigrescens and T. denticola at P < 0.01, and for E. corrodens at P < 0.05. The prevalence of C. rectus was significantly higher in the advanced periodontitis group than in the adult gingivitis group at P < 0.01. Matching results between PCR and culture occurred in 28% (B. forsythus) to 71% (A. actinomycetemcomitans) of the samples; the major discrepancy occurred in the PCR-positive/culture-negative category. Matching results between PCR and DNA probe methods were found in 84% of the subjects (B. forsythus) and 70% (P. gingivalis). Odds ratio analysis revealed statistically significant positive associations between 17 of the 28 possible combinations (P < 0.01). This study demonstrated the utility of a 16S rRNA-based PCR detection method for identifying important subgingival microorganisms. The results indicated a strong association between the study species and periodontitis. Several previously unreported symbiotic relationships were found between the 8 species tested.

Refractory periodontitis or recurrence of disease

Refractory periodontal disease is characterized by low plaque scores and low responsiveness to periodontal therapy. The patients often have a history of antibiotic therapy and therefore have a high incidence of resistance in the subgingival microflora. The above features are in contrast to adult chronic periodontal disease and recurrence of disease. The subgingival microflora of refractory disease may be either predominantly gram-positive with elevated levels of Streptococcus intermedius or may be gram negative and contain elevated levels of the classical periodontal pathogens. In some cases serum IgG antibodies against Porphyromonas gingivalis are elevated and seem to decrease after therapy. Smoking may be an important factor in refractory periodontal disease. Treatment with directed antibiotic therapy as an adjunct to scaling and root planing retards the progression of disease for a limited time. Many questions are still not answered and suggestions are made for future directions in research.

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.