Effect of the enamel matrix derivative Emdogain on the growth of periodontal pathogens in vitro

OBJECTIVES

The aim of this study was to evaluate the effect of Emdogain (EMD), used for periodontal regeneration, on the growth of periodontal pathogens like Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia. For comparison, we studied the effect of EMD on several microbes associated with other oral diseases as well as its effect on non-pathogenic oral inhabitants.

METHODS

Freshly prepared EMD or its vehicle propylene glycol alginate (PGA) alone were added to calibrated suspensions of microbes. As a control, imitating the post-surgical subgingival situation after flap closure, a serum/NaCl-solution mixture was used. Aliquots for growth assays were taken at scheduled times for calculation of colony-forming units and cell densities over an observation period of 24 h. Additionally, EMD was spotted onto selected, newly seeded microbes growing on agar plates to see if growth inhibition zones could be produced.

RESULTS

The study revealed a marked inhibitory effect of EMD on the growth of the gram-negative periodontal pathogens. A. actinomycetemcomitans showed a significant decrease (p=0.012) in viable counts after 24 h when EMD was added at baseline. P. gingivalis and P. intermedia also showed a marked growth reduction in the presence of EMD and in these cultures no viable microbes could be detected anymore after 24 h. In contrast, no significant growth inhibition was observed in gram-positive bacteria.

CONCLUSIONS

The results suggest that EMD has a positive effect on the composition of bacterial species in the post-surgical periodontal wound, by selectively restricting growth of periopathogens that could hamper the wound healing and reduce the outcome of regenerative procedures.

Clinical and microbial evaluation of a histatin-containing mouthrinse in humans with experimental gingivitis

OBJECTIVE

P-113, a 12 amino acid histatin-based peptide, was evaluated in a mouthrinse formulation for safety, prevention of the development of experimental gingivitis, and for its effects on periodontal flora.

METHOD

159 periodontally healthy subjects abstained from oral hygiene procedures and self-administered either 0.005%, 0.01%, 0.05% P-113 or placebo mouthrinse formulations twice daily over a four week treatment period. During this time, the safety, anti-plaque, and anti-gingivitis effects of P-113 were evaluated.

RESULTS

There was a significant reduction in plaque (p=0.046) and a reduction in gingivitis (p=0.086) for subjects using 0.01% P-113 mouthrinse. Significantly more subjects in the 0.01% and 0.05% treatment groups showed a small increase in plaque index of <0.25 as compared to the placebo group (p<0.05). Similar trends were noted for changes in the % of sites with bleeding on probing in the 0.01% P-113 group. There were no treatment-related adverse events, and there were no adverse shifts in supragingival microflora during the study.

CONCLUSION

These data suggest that P-113 mouthrinse is safe and reduces plaque, gingivitis and gingival bleeding in the human experimental gingivitis model.

Antimicrobial activity of four root canal sealers against endodontic pathogens

The antibacterial effects of various types of widely used endodontic sealers have not been compared systematically on facultative or obligate anaerobic endodontic pathogens. The aim of this study was to evaluate the antimicrobial properties of four commonly used endodontic sealers: two epoxy-resin-based sealers (AH26, AH plus), one zinc-oxide eugenol-based sealer (N2), and one calcium hydroxide-based sealer (Sealapex). The testing microbes were four facultative anaerobic species (Streptococcus mutans, Streptococcus sanguis, Escherichia coli, and Staphylococcus aureus) and four obligate anaerobic species (Porphyromonas gingivalis, Porphyromonas endodontalis, Fusobacterium nucleatum, and Prevotella intermedia). The freshly mixed sealers were placed into the prepared wells of agar plates inoculated with the test microorganisms. After varying periods of incubation (2 days for facultative anaerobic species and 7 days for obligate anaerobic species), the zones of growth inhibition were observed and measured. All the sealers were distinctly different from each other in their antimicrobial activity. The sealers showed different inhibitory effects depending on the types and bacterial strains. N2 containing formaldehyde and eugenol proved to be the most effective against the microorganisms. The extreme antimicrobial potency of this root canal sealer must be weighted against its pronounced tissue toxic effect.

Susceptibilities of Eikenella corrodens, Prevotella intermedia, and Prevotella nigrescens clinical isolates to amoxicillin and tetracycline

The AB Biodisk Etest showed that 106 (100%) and 98 (92%) isolates of Eikenella corrodens were susceptible to amoxicillin and tetracycline, respectively. Twenty-three (68%) Prevotella intermedia isolates and 14 (67%) Prevotella nigrescens isolates were susceptible to amoxicillin. Seventy-nine percent of the P. intermedia isolates and 67% of the P. nigrescens isolates were susceptible to tetracycline. A higher percentage of beta-lactamase-producing isolates of P. intermedia and P. nigrescens were identified with selective agar containing amoxicillin than with nonselective agar.

Comparative clinical and microbiological effects of subgingival metronidazole application in adult periodontitis; 12-months results

The aim of the present study was to evaluate the clinical and microbiological effects of subgingival application of 25% metronidazole dental gel as an adjunct to scaling and root planing (SRP) in the treatment of adult periodontitis. Eighty teeth in 18 patients were evaluated using a split mouth design. The test teeth received SRP and a 25% metronidazole gel applied subgingivally on days 0 and 7. The control teeth received SRP only. Clinical and microbiological examinations were carried out before treatment and on weeks 1, 3, 7, 13, 26, 38 and 52 of the experimental period. Colony forming units of Porphyromonas gingivalis and Prevotella intermedia / Prevotella nigrescens were determined. Both treatments provided significant improvements in all the clinical and microbiological parameters (P<0.05). However, none of the differences between the study groups were statistically significant (P > 0.05). As a conclusion, the present study does not provide evidence in favour of the routine use of adjunctive metronidazole dental gel in the treatment of adult periodontitis.

A microbiological and clinical study of the safety and efficacy of baking-soda dentifrices

This article reports the results of a study that examined the clinical and microbiological changes associated with regular use of baking-soda dentifrices. Two dentifrice formulations were examined in a 6-month longitudinal study of 101 adult subjects with assessments for plaque, gingival inflammation, and stain at baseline and 3 and 6 months during the active phase of the study, and at 3 months after cessation of product use. One dentifrice contained 52% baking soda and 3% sodium percarbonate (Arm & Hammer PeroxiCare) while the other dentifrice contained 65% baking soda (Arm & Hammer Dental Care). Both dentifrices resulted in statistically significant reductions in dental plaque, gingival inflammation, and stain at all time periods compared to baseline. Dental plaque and buccal soft-tissue samples were obtained for microbiological analysis from a 50-subject subset. Microbiological assays, including bacterial culture, phase-contrast microscopy, and immunofluorescence microscopy, confirmed the safety of both formulations. Beneficial alterations in dental plaque bacteria were noted, including significant reductions in the levels of Actinomyces species. The data from this study indicate that dentifrices containing high levels of baking soda are clinically effective and microbiologically safe.

[A comparative study of various evaluation methods of the antibiotic sensitivity of strict anaerobic bacteria of the subgingival flora]

The study on the sensitiveness of slow-growing anaerobes bacteria to antibiotics is delicate when you consider the technical motives that make it difficult to transpose the standard methods frequently used in microbiological laboratories. The three main methods used to determine susceptibility to antibiotics are: disk-diffusion test, antibiotics containing microdilution plates and ATB ANA (bioMérieux). The aim of this study is to compare the effectiveness of each of these methods on severe anaerobes bacteria isolated in sub-gingival flora of patients suffering from developing periodontitis (rapidly progressive periodontitis, refractory periodontitis, active stage of adult chronic periodontitis). The observed bacteria are: Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum, Campylobacter rectus, Peptostreptococcus micros. Antibiotics used are: ampicilline, amoxicilline, tetracycline, erythromycine, metronidazole. The comparison of the minimal inhibitory concentrations (M.I.C) of each of these methods has permitted to show a strict correlation in the results observed with these three methods, if only the growth of the severe anaerobes bacteria on agar medium does not exceed 72 hours.

The clinical relevance of microbiologic testing: a comparative analysis of microbiologic samples secured from the same sites and cultured in two independent laboratories

A field study using five different private periodontal practices was conducted; it compared two microbiologic culture samples simultaneously secured from the same sites within 23 individual patients and submitted for bacterial identification and antibiotic sensitivity testing to two separate laboratories. The results from the two laboratories were often different. In no instance did both laboratories agree on the presence of identical bacterial species. When only bacteria above threshold levels were compared, agreement was found in only nine of 23 cases. When examining antibiotic sensitivity, using 100% kill of all tested pathogens as the ideal, agreement between the two laboratories was poor. The laboratories agreed on the use of amoxicillin 17% of the time, tetracycline 26% of the time, and metronidazole 48% of the time. The use of amoxicillin and metronidazole in combination yielded a 78% agreement when the results of both laboratories were combined. It would appear from the data that the empirical use of amoxicillin-metronidazole combination therapy may be more clinically sound and cost effective than culturing and antibiotic selection based on the results of culture from any single microbiologic testing laboratory.

An in vitro evaluation of the antimicrobial efficacy of irrigants on biofilms of root canal isolates

AIM

The bactericidal effect of four antimicrobial agents was investigated against single-species biofilms derived from a range of root canal isolates.

METHODOLOGY

Single-species biofilms of Prevotella intermedia, Peptostreptococcus micros, Streptococcus intermedius, Fusobacterium nucleatum and Enterococcus faecalis were generated on membrane filter discs and subjected to 15 min or 1 h incubation with 5 p.p.m. colloidal silver, 2.25% sodium hypochlorite (NaOCl), 0.2% chlorhexidine, 10% iodine or phosphate buffered saline (PBS) as a control. The antimicrobial activity of the agents was neutralized and the bacterial cells were harvested from the discs by vortexing, serially diluted in reduced transport fluid, plated on fastidious anaerobe agar containing 5% horse blood, incubated anaerobically and colony-forming units calculated.

RESULTS

Iodine and NaOCl were more effective than chlorhexidine except against P. micros and P. intermedia where they were all 100% effective. Iodine and NaOCl elicited a 100% kill after 1 h incubation for all strains used. However, after 15 min, they showed differing bactericidal effects depending on the strain. None of the agents were effective against F. nucleatum after 15 min but NaOCl, iodine and chlorhexidine were all effective after 1 h. Colloidal silver was generally ineffective.

CONCLUSIONS

The effectiveness of a particular agent was dependent on the nature of the organism in the biofilm and on the contact time. NaOCl was generally the most effective agent tested, followed by iodine. However the clinical efficacy of these agents must be considered in light of the complex root canal anatomy and polymicrobial nature of root canal infections.

Amoxicillin plus metronidazole in the treatment of adult periodontitis patients. A double-blind placebo-controlled study

BACKGROUND, AIMS

The aim of this double-blind, parallel study was to evaluate the adjunctive effects of systemically administered amoxicillin and metronidazole in a group of adult periodontitis patients who also received supra- and subgingival debridement.

METHODS

49 patients with a diagnosis of generalised severe periodontitis participated in the study. Random assignment resulted in 26 patients in the placebo (P) group with a mean age of 40 years and 23 patients in the test (T) group which had a mean age of 45 years. Clinical measurements and microbiological assessments were taken at baseline and 3 months after completion of initial periodontal therapy with additional placebo or antibiotic treatment. Patients received coded study medication of either 375 mg amoxicillin in combination with 250 mg metronidazole or identical placebo tablets, every 8 hours for the following 7 days.

RESULTS

At baseline, no statistically significant differences between groups were found for any of the clinical parameters. Except for the plaque, there was a significantly larger change in the bleeding, probing pocket depth (PPD) and clinical attachment level (CAL) in the T-group as compared to the P-group after therapy. The greatest reduction in PPD was found at sites with initial PPD of > or = 7 mm, 2.5 mm in the P-group and 3.2 mm in the T-group. The improvement in CAL was most pronounced in the PPD category > or = 7 mm and amounted to 1.5 mm and 2.0 mm in the P- and T-groups, respectively. No significant decrease was found in the number of patients positive for any of the test species in the P-group. The number of patients positive for Porphyromonas gingivalis, Bacteroides forsythus and Prevotella intermedia in the T-group showed a significant decrease. After therapy there was a significant difference between the P- and the T- group in the remaining number of patients positive for P. gingivalis, B. forsythus and Peptostreptococcus micros. 4 subgroups were created on the basis of the initial microbiological status for P. gingivalis positive (Pg-pos) and negative patients (Pg-neg) in the P- and the T-groups. The difference in reduction of PPD between Pg-pos and Pg-neg patients was particularly evident with respect to the changes in % of sites with a probing pocket depth > or = 5 mm. This % decreased from 45% at baseline to 23% after treatment in the Pg-pos placebo subgroup and decreased from 46% to 11% in the Pg-pos test subgroup (p < or = 0.005). In contrast, the changes in the proportions of sites with a probing pocket depth > or = 5 mm in the Pg-neg placebo and Pg-neg test subgroup were similar, from 43% at baseline to 18% after treatment versus 40% to 12% respectively.

CONCLUSIONS

This study has shown that systemic usage of metronidazole and amoxicillin, when used in conjunction with initial periodontal treatment in adult periodontitis patients, achieves significantly better clinical and microbiological results than initial periodontal treatment alone. Moreover, this research suggests that especially patients diagnosed with P. gingivalis benefit from antibiotic treatment.

Antimicrobial effectiveness of electro-chemically activated water as an endodontic irrigation solution

AIM

The aim of this in vitro study was to evaluate the antimicrobial effectiveness of electro-chemically activated water (ECA) as an endodontic irrigation solution.

METHODOLOGY

The root canals of 60 caries-free, single-rooted, adult, maxillary, anterior human teeth were instrumented and irrigated in a similar method to that used for in vivo root canal treatment. The external root surface of each tooth was sealed, maintaining the access cavities patent and the root canals were inoculated with a suspension containing four bacteria. The teeth were randomly divided into four groups (n = 15). Each group was irrigated ultrasonically with one of the following solutions: distilled water (control), NaOCl (3.5%), and ECA, the latter at pHs 7.0 and 9.0. Antimicrobial effectiveness was established directly after irrigation and again 7 days later, by counting colony-forming units on blood agar plates and by spectrophotometric analysis.

RESULTS

Large numbers of bacteria were present in the canals of teeth irrigated with distilled water. No bacteria were observed following irrigation with NaOCl. Neither of the ECA solutions were found to be effective against all the bacteria. Although some reduction in the number of bacteria was evident in the ECA groups, this was not statistically significant (P > 0.05) when compared to sodium hypochlorite.

CONCLUSION

Within the confines of this study ECA did not demonstrate antimicrobial effectiveness.

Antimicrobial activity of silver nitrate against periodontal pathogens

Metal ions were evaluated as potential antimicrobial agents suitable for local delivery in the oral cavity for the treatment of periodontitis. Silver nitrate, copper chloride, and zinc chloride were tested for antimicrobial activity in in vitro killing assays conducted in phosphate buffered saline with a series of oral bacteria including gram-negative periodontal pathogens and gram-positive streptococci. Copper and zinc salts failed to exhibit strong and consistent activity against periodontal pathogens. In contrast, silver at a concentration of 0.5 microg/mL produced a 3 log10 reduction in colony forming units (CFU)/mL or greater against all periodontal pathogens tested including Porphyromonas gingivalis, Prevotella intermedia, Prevotella denticola, Bacteroides forsythus, Fusobacterium nucleatum vincentii, Campylobacter gracilis, Campylobacter rectus, Eikenella corrodens, and Actinobacillus actinomycetemcomitans. In comparison, substantially higher concentrations of silver nitrate failed to kill oral streptococci. A silver nitrate concentration of 25 microg/mL produced log10 reductions in CFU/mL of 3.5-5 in killing assays performed in human serum against P. gingivalis, demonstrating the ability of silver to retain activity in a biological medium similar to that encountered in vivo in the periodontal pocket. These results identify silver nitrate, an antimicrobial that may possess advantages over traditional antibiotics, as a potential agent for controlled release local delivery in the oral cavity for the treatment of periodontitis.

Antimicrobial activity of tannin components from Vaccinium vitis-idaea L

Reactive oxygen species have been implicated as important pathological mediators in many clinical disorders, including periodontal disease. As a possible alternative for the treatment of periodontal disease, the antimicrobial activity of six tannins isolated from Vaccinium vitis-idaea L., with confirmed antioxidant activity, were assayed by the agar dilution method against selected periodontal pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia. The results showed that epicatechin-(4beta-->8)-epicatechin-(4beta-->8, 2beta-->O-->7)-catechin had strong antimicrobial activity against P. gingivalis and P. intermedia, but not A. actinomycetemcomitans. The other tannins tested did not show antimicrobial activity. We conclude that tannins isolated from V. vitis-idaea L. with antimicrobial activity could potentially be used for the treatment of periodontal disease.

The clinical and microbiological effects of systemic ornidazole in sites with and without subgingival debridement in early-onset periodontitis patients

BACKGROUND

The purpose of this study was to evaluate the clinical and microbiological effects of systemic ornidazole (ORN) in sites with or without subgingival debridement in early-onset periodontitis (EOP) patients.

METHODS

Two pooled bacterial samples consisting of 4 sites each (scaled and non-scaled sites) were obtained from 30 individuals exhibiting EOP. All patients received oral hygiene instruction (OHI), supragingival scaling and ORN. Subgingival scaling and root planing (SRP) was carried out only in scaled sites. Bacterial samples were taken at baseline (BL) and 1 week and 2, 6, and 12 months after systemic ornidazole administration (500 mg/bid for 7 days). One more sample was taken at scaled sites, one week after SRP.

RESULTS

One week following SRP (scaled sites) Gram-negative facultative and anaerobic rods were significantly reduced while Gram-positive facultative cocci were significantly increased. After ORN administration, P. gingivalis, P. denticola, P. intermedia, B. forsythus, C. rectus, and S. sputigena were no longer detectable in either scaled or non-scaled sites. A statistically significant long-term (2, 6, and 12 months) reduction of P. gingivalis, P. intermedia, P. loescheii, B. forsythus, and C. rectus and a pronounced increase of S. milleri, S. oralis, and S. sanguis counts in both scaled and non-scaled sites were detected in comparison to baseline. A sustained reduction of bleeding tendency and of probing depth was also observed in both scaled and non-scaled sites.

CONCLUSIONS

ORN combined with SRP effects beneficial shifts in the bacterial population associated with substantial clinical improvement, thereby indicating that ORN is effective adjunct in the treatment of EOP deep periodontal pockets where anaerobic bacteria are predominant.

Coptidis rhizoma inhibits growth and proteases of oral bacteria

OBJECTIVE

The aim of this study was to investigate the antibacterial effect of Coptidis Rhizoma (CR), a traditional medicinal plant, on oral bacteria.

MATERIALS AND METHODS

CR extract was prepared by boiling CR in water for 2 h. Alkaloids contained in CR extract were assayed by high performance liquid chromatography (HPLC). Antibacterial activity of CR extract was estimated from the lowest concentration that did not permit bacterial growth (minimum inhibitory concentration, MIC) and the concentrations that inhibited 50% of bacterial proteolytic activity (IC50).

RESULTS

CR extract inhibited the growth of Actinomyces naeslundii, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens and Actinobacillus actinomycetemcomitans at MIC of 0.031-0.25 mg ml(-1), whereas it had less inhibitory effect (MIC: 0.5-2 mg ml(-1)) on the growth of Streptococcus and Lactobacillus. The major active component of CR extract was berberine (Ber), an alkaloid, and its inhibiting specificity to bacterial growth was similar to that of CR extract. CR extract and Ber were bacteriostatic at the MICs against most of the bacteria, and bacteriocidal at the concentrations higher than the MICs. Ber inhibited the activities of collagenase from P. gingivalis and A. actinomycetemcomitans.

CONCLUSION

CR extract and Ber had an inhibitory effect on periodontopathogenic bacteria. These results suggest the possibility of their clinical application for the treatment of periodontal diseases.

Mouthrinses: a comparative microbiological study

This study was performed in order to evaluate the efficacy of different mouthrinses whose use is extended in Spain. Six different antiseptic mouthrinses were studied by means of determination of Minimal Inhibitory Concentration (MIC) values against Klebsiella pneumoniae, Serratia marcescens, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhimurium, Bacillus subtilis, Streptococcus mutans, Prevotella intermedia, Porphyromonas gingivalis and Actinobacillus actinomycetemcomitans. Also in vivo experiments were carried out in volunteers by the use of mouthrinses and evaluation of bacterial populations before and after the treatment. Finally, the kinetics of bacterial death was determined. Results suggested that the determination of MIC values is not a reliable method to evaluate the antibacterial effect of such products. On the other hand those rinsing solutions based on the effect of oxygen, such as those containing carbamide peroxide have a greater efficacy against anaerobic bacteria compared with rinses whose active molecule is a disinfectant. Finally, the kinetics of bacterial death demonstrates that the essential oil rinse kills bacteria much faster. All tested mouthrinses were active as antibacterial although those based on oxygen production or essential oils were more active than solutions based on chlorhexidine and Triclosan.

Development of a clindamycin-impregnated fiber as an intracanal medication in endodontic therapy

The effectiveness of traditional endodontic intracanal medications in reducing bacterial numbers and preventing acute flare-ups and pain continues to be questioned. In the present study, a new local delivery device was developed that releases a substantive dose of clindamycin into root canals. Clindamycin-impregnated ethylene vinyl acetate (EVA) fibers were produced, and the sensitivity of common endodontic microbes to the fibers were established. An in vitro model was developed to persistently infect 32 extracted human teeth with endodontic pathogens to test the efficacy of the clindamycin/EVA fibers in reducing the number of colony-forming units. The clindamycin/EVA fibers were shown to be effective in reducing growth of common endodontic microbes on blood agar plates, and in significantly reducing growth of Prevotella intermedia, Fusobacterium nucleatum, and Streptococcus intermedius in extracted human teeth, thus indicating merit in further exploring the potential of these fibers as intracanal medications.

Repeated local metronidazole-therapy as adjunct to scaling and root planing in maintenance patients

The purpose of this investigation was to evaluate the effect of local antibiotic therapy with metronidazole adjunctively to scaling and root planing (SRP) versus mechanical treatment alone. 30 maintenance-patients were included in this single-blind study. The subjects had to comply with the following criteria: 2 non-adjacent sites with a probing depth > or =6 mm with bleeding on probing in separate quadrants, no periodontal therapy within the last 3 months, and no antibiotic therapy within the last 6 months. After randomization, the study sites were assigned to one of the following 2 treatments: SRP plus subgingival application of metronidazole 25% dental gel (Elyzol) 5x during 10 days (test site) or SRP alone (control site). Subgingival microbiological samples were taken prior to, and 21 days and 3 months after scaling. The samples were analyzed with a commercial chair-side ELISA (Evalusite) for Porphyromonas gingivalis, Prevotella intermedia and Actinobacillus actinomycetemcomitans. Probing pocket depth (PPD), attachment level (AL) and bleeding on probing (BOP) were recorded at baseline and 3 months later. PPD reduction and AL-gain were statistically significant (p<0.001) after both treatments. However, there were no statistically significant differences between them. The same observation was made for BOP. P. gingivalis was reduced significantly after both treatments without statistically significant differences. P. intermedia was reduced significantly only after SRP. A. actinomycetemcomitans was not reduced significantly after either treatment. In conclusion, the repeated local application of metronidazole as an adjunct to SRP and the mechanical treatment alone showed similar clinical and microbiological effects without statistically significant differences with the exception of P. intermedia.

Beta-lactamase production in Prevotella intermedia, Prevotella nigrescens, and Prevotella pallens genotypes and in vitro susceptibilities to selected antimicrobial agents

The present study investigated the beta-lactamase production of 73 Prevotella intermedia, 84 Prevotella nigrescens, and 14 Prevotella pallens isolates and their in vitro susceptibilities to six antimicrobial agents. The P. intermedia and P. nigrescens isolates were recovered from oral and extraoral samples obtained from subjects in two geographic locations from 1985 to 1995. The clonality of the beta-lactamase-positive and beta-lactamase-negative isolates and the clustering of the genotypes were studied by arbitrarily primed-PCR fingerprinting. beta-Lactamase production was detected in 29% of P. intermedia isolates, 29% of P. nigrescens isolates, and 57% of P. pallens isolates. No difference in the frequencies of beta-lactamase production by P. intermedia and P. nigrescens between isolates from oral and extraoral sites, between isolates obtained at different time periods, or between P. intermedia isolates from different geographic locations was observed. However, the P. nigrescens isolates from the United States were significantly more frequently (P = 0.015) beta-lactamase positive than those from Finland. No association between the genotypes and beta-lactamase production or between the genotypes and the sources of the isolates was found. The penicillin G MICs at which 90% of the isolates were inhibited were 8 microg/ml for P. intermedia, 8 microg/ml for P. nigrescens, and 16 microg/ml for P. pallens. For the beta-lactamase-negative isolates, the corresponding values were 0.031, 0.031, and 0.125 microg/ml, and for the beta-lactamase-positive isolates, the corresponding values were 16, 8, and 32 microg/ml. All isolates were susceptible to amoxicillin-clavulanate, cefoxitin, metronidazole, azithromycin, and trovafloxacin. The MICs of amoxicillin-clavulanate and cefoxitin were relatively higher for the beta-lactamase-positive population than for the beta-lactamase-negative population.

Microbiological response of localized sites with recurrent periodontitis in maintenance patients treated with tetracycline fibers

BACKGROUND

Whether adjunctive tetracycline fibers can provide an additive effect to scaling and root planing in treating non-responsive sites in maintenance subjects is still controversial. Recolonization of the bacteria from untreated sites or from the extracrevicular region may explain the insignificant response to local therapy. The purpose of the present study was to evaluate the microbiological response of sites treated with tetracycline fibers combined with scaling and root planing.

METHODS

The study was conducted in a split-mouth design. Thirty patients on maintenance therapy having at least 2 non-adjacent sites in separate quadrants with probing depths between 4 to 8 mm with bleeding on probing, or aspartate aminotransferase enzyme levels > 800 microIU in the gingival crevicular fluid, were treated with scaling and root planing plus tetracycline fibers or with scaling and root planing only. Subgingival plaque samples were collected at baseline, and 1, 3, and 6 months following treatment. A. actino-mycetemcomitans, C. rectus, B. forsythus, E. corrodens, F. nucleatum, P. gingivalis, and P. intermedia were detected by culture, immunofluorescence, or PCR technique.

RESULTS

There was a reduction of total bacterial cell count, as well as of certain periodontal pathogens, following treatment. The prevalence of A. actinomycetemcomitans, B. forsythus, and P. gingivalis and the mean proportions of C. rectus, P. intermedia, F. nucleatum, and P. gingivalis decreased after therapy, but there was no statistically significant difference between the 2 treatment groups with respect to bacterial proportions or the number of positive sites. Besides, the pathogens could not be eliminated from the periodontal pocket, and recolonization of the pocket was noted at 3 months post-treatment.

CONCLUSIONS

Bacteria located within the cheek, tongue mucosa, saliva, or untreated sites may contribute to reinfection of the pockets and explain the insignificant response to local tetracycline therapy.

Clinical and microbiological effects of initial periodontal therapy in conjunction with amoxicillin and clavulanic acid in patients with adult periodontitis. A randomised double-blind, placebo-controlled study

The aim of the present study was to investigate the clinical and microbiological effects of initial periodontal therapy in conjunction with systemic amoxicillin plus clavulanic acid in adult periodontitis patients using a double-blind, parallel-group, and placebo-controlled protocol. 21 patients with a clinical diagnosis of generalised adult periodontitis were recruited. Clinical measurements and microbiological assessments were carried out at baseline, 3, and 12 months post-treatment. Approximately 6 weeks after initial periodontal treatment (3-6 h), patients were randomly assigned to receive coded study medication of 500 mg amoxicillin plus 125 mg clavulanic acid (Augmentin) or placebo, every 8 h for 10 days. Patients returned for follow-up visits 3, 6, 9, and 12 months after completion of the medication. The mean plaque index (PI) at baseline was 1.1 for placebo group and 0.9 for the test group. At 3 months, the PI had dropped to 0.3 in both groups, and was maintained during the rest of the study. The changes in bleeding on probing (BOP) and gingival index (GI) in the course of the study were similar in both groups. The mean whole mouth probing pocket depth (PPD) in the placebo group was 3.8 mm at baseline and 3.9 mm in the test group. A mean reduction of 1.0 mm in the placebo group and 0.9 mm in the test group was observed during the first 3 months. No further reduction in PPD was noticed during the study period in either group. There was no statistically significant difference in the PPD reduction between the 2 groups. The change in clinical attachment level (CAL) from baseline to 3 months amounted to 0.5 mm in both groups. Between 3 and 12 months, the CAL changed in neither group. In both groups, treatment resulted in a decrease in the number of spirochetes and motile rods in positive patients, but no significant differences between either group were noted in any of the dark field microscopy observations. At baseline, 1 patient in the placebo group and 2 patients in the test group were culture positive for Actinobacillus actinomycetemcomitans (Aa). After therapy, Aa was not detectable in the placebo group and 1 patient remained positive in the test group. In the placebo group, the number of patients positive for Porphyromonas gingivalis (Pg) decreased from 7 to 2 after therapy. In the test group, the 4 patients positive for Pg at baseline remained positive after therapy. In both groups, all subjects were positive for Prevotella intermedia (Pi) and Fusobacterium nucleatum (Fn) at baseline. At 12 months, all subjects had detectable subgingival Fn. 9 out of the 11 placebo and 8 of the 10 test patients remained positive for Pi. There were no differences in detection frequency of Peptostreptococcus micros (Pm) and Bacteroides forsythus (Bf) in both groups between baseline, 3, and 12 months post-treatment. The findings demonstrated that, in comparison to placebo, systemic amoxicillin plus clavulanic acid provided no additional clinical and microbiological effects in the treatment of adult periodontitis patients.

Comparative antimicrobial activity of an essential oil and an amine fluoride/stannous fluoride mouthrinse in vitro

Although laboratory studies are not necessarily predictive of clinical activity; they can help to elucidate mechanisms underlying clinical activity when the latter has been established. In a recent clinical study, an essential oil mouthrinse (Listerine Antiseptic) was shown to be significantly more effective than an amine fluoride/stannous fluoride mouthrinse (Meridol) in inhibiting supragingival plaque formation. This paper reports the results of laboratory studies comparing the antimicrobial effectiveness of these 2 mouthrinses using a kill kinetics assay and a plaque biofilm kill assay. In both assays, the essential oil mouthrinse was considerably more effective than the amine fluoride/stannous fluoride mouthrinse. These findings are consistent with the results of the clinical trial and may help to explain the observed differences in clinical activity.

A 15-month evaluation of the effects of repeated subgingival minocycline in chronic adult periodontitis

BACKGROUND

A double-blind, randomized, parallel, comparative study was designed to evaluate the long-term safety and efficacy of subgingivally administered minocycline ointment versus a vehicle control.

METHODS

One hundred four patients (104) with moderate to severe adult periodontitis (34 to 64 years of age; mean 46 years) were enrolled in the study. Following scaling and root planing, patients were randomized to receive either 2% minocycline ointment or a matched vehicle control. Study medication was administered directly into the periodontal pocket with a specially designed, graduated, disposable applicator at baseline; week 2; and at months 1, 3, 6, 9, and 12. Scaling and root planing was repeated at months 6 and 12. Standard clinical variables (including probing depth and attachment level) were evaluated at baseline and at months 1, 3, 6, 9, 12, and 15. Microbiological sampling using DNA probes was done at baseline; at week 2; and at months 1, 3, 6, 9, 12, and 15.

RESULTS

Both treatment groups showed significant and clinically relevant reductions in the numbers of each of the 7 microorganisms measured during the entire 15-month study period. When differences were detected, sites treated with minocycline ointment always produced statistically significantly greater reductions than sites which received the vehicle control. For initial pockets > or =5 mm, a mean reduction in probing depth of 1.9 mm was seen in the test sites, versus 1.2 mm in the control sites. Sites with a baseline probing depth > or =7 mm and bleeding index >2 showed an average of 2.5 mm reduction with minocycline versus 1.5 mm with the vehicle. Gains in attachment (0.9 mm and 1.1 mm) were observed in minocycline-treated sites, with baseline probing depth > or =5 mm and > or =7 mm, respectively, compared with 0.5 mm and 0.7 mm gain at control sites. Subgingival administration of minocycline ointment was well tolerated.

CONCLUSIONS

Overall, the results demonstrate that repeated subgingival administration of minocycline ointment in the treatment of adult periodontitis is safe and leads to significant adjunctive improvement after subgingival instrumentation in both clinical and microbiologic variables over a 15-month period.

Metronidazole susceptibility testing of anaerobic bacteria associated with periodontal disease

The aim of the present investigation was to determine the susceptibility of Prevotella intermedia, Porphyromonas gingivalis, Fusobacterium and Peptostreptococcus micros to metronidazole in vitro. Two methods were applied on each isolated strain: agar dilution and epsilometer Etest. A total of fifty three wild test strains (13 P.intermedia, 14 P. gingivalis, 14 F.spp and 12 P.micros) were isolated from patients with periodontitis. The Etest appears to be a simple, rapid and reliable method for the metronidazole susceptibility testing. The results show that all P.intermedia, P.gingivalis and F.spp strains were susceptible to metronidazole. The mean values of minimal inhibitory concentration obtained with the agar dilution method were, respectively, 0.98 microg/ml, 0.122 microg/ml and 0.242 microg/ml. For P.micros, the minimal inhibitory concentration was of 12.14 microg/ml. Comparatively to break points, only 60% of P.micros strains seem to be susceptible, in vitro, to metronidazole. This study demonstrated the excellent activity of metronidazole against P.intermedia, P.gingivalis, F.spp except perhaps for P.micros.

Modulation of antibacterial peptide activity by products of Porphyromonas gingivalis and Prevotella spp

This study investigated the ability of anaerobic periodontal bacteria to inactivate and resist killing by antimicrobial peptides through production of extracellular proteases. Antibacterial activities of peptides were assessed in a double-layer agarose diffusion assay, and MICs and MBCs were determined in broth microdilution assays. Culture supernates of Porphyromonas gingivalis and Prevotella spp. inactivated mastoparan, magainin II and cecropin B whilst Gram-positive oral supragingival bacteria had no effect. Inactivation was prevented by protease inhibitors and was unaffected by 45% human serum. Purified proteases from the periodontopathogen Porph. gingivalis inactivated peptides [cecropin B, brevinin, CAMEL (cecropin A 1-7 + melittin 2-9), mastoparan] as would be predicted from the amino acid sequences of the peptides and the known bond specificities of these Arg-x and Lys-x enzymes. MALDI-TOF MS revealed that inactivation of cecropin B by Porph. gingivalis protease was due to specific cleavage of the molecule. Inactivation of cecropin B by proteases took 10-15 min. Paradoxically, MICs of cecropin B against Porph. gingivalis and Prevotella intermedia were low, while Prevotella nigrescens was resistant, suggesting that production of proteases alone is insufficient to protect Porph. gingivalis and Prev. intermedia from the action of antimicrobial peptides. Thus, antimicrobial peptides could be developed as therapeutic agents targeted against specific periodontal pathogens.