Endodontic microorganism susceptibility by direct contact test

The aim of this study was to evaluate in vitro the duration of the antimicrobial effect of endodontic sealers by means of the Direct Contact Test. The sealers tested were: Endomethasone - Septodont, Endomethasone C-Septodont, Endion-Voco, Diaket-ESPE, Pulp Canal Sealer-SybronEndo, and AH26-Dentsply DeTrey. The endodontopathic microorganisms (MO) confronted were: Staphylococcus aureus (Sa), Candida albicans (Ca), Enterococcus faecalis (Ef), Prevotella intermedia (Pi), Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn). Test specimens of each sealer were prepared and placed on the surface of agar plates that had been inoculated with each MO, and after predetermined periods, transfers were made from the contact area between the test specimen and the cultured agar and from the area that had not been in contact with the test specimens (control). The results were read as presence/absence of microbial growth and analyzed statistically using the Kruskal-Wallis test. It was concluded that the structural features and virulence of endodontopathic microorganisms determine their response to the sealers, independently of the time during which sealers act and the mechanism by which the antiseptic reaches the microorganism, which in this case was by direct contact.

The influence of molecular oxygen exposure on the biology ofPrevotella intermedia, with emphasis on its antibiotic susceptibility

AIM

This study focuses on investigating the molecular and physiological characteristics of Prevotella intermedia after molecular oxygen exposure (MOE) and the effect on drug susceptibility patterns.

METHODS AND RESULTS

Samples of P. intermedia were used as parent strains: ATCC25611 and four clinical isolates. Strains adapted to oxidative stress by MOS were obtained by the enrichment technique. Drug susceptibility was evaluated by minimal inhibitory concentrations (MIC) using agar dilution. Arbitrarily primed-polymerase chain reaction (AP-PCR) was used to evaluate the genetic diversity of all strains and physiological analyses were made by sodiumdodecylsulfate-polyacrylamide gel electrophoresis and two-dimensional electrophoresis of crude, cell-free extracts. The genetic profile showed that lineages with altered MIC values were selected after MOE. Overall, we found significant decrease in drug susceptibility for the aero-strains against all tested antimicrobials (amoxicillin, amoxicillin+clavulanic acid, clindamycin, chloramphenicol, ertapenen and metronidazole). We also observed markedly different protein expression patterns between the parent and selected aero-strains.

CONCLUSIONS

MOE induces changes in the genetic profile and protein expression patterns of P. intermedia that may also be linked to its drug resistance mechanisms.

SIGNIFICANCE AND IMPACT OF THE STUDY

The effects of MOE on anaerobic bacterial physiology and behaviour may influence antimicrobial susceptibility patterns with potential consequences to antimicrobial chemotherapy.

Duration-dependent susceptibility of endodontic pathogens to calcium hydroxide and chlorhexidene gel used as intracanal medicament: an in vitro evaluation

The aim of this study was to evaluate the effective duration of antimicrobial activity of a calcium hydroxide-based medicament (Apex Cal) and 2% chlorhexidene gluconate gel against selected endodontic pathogens (Enterococcus faecalis, Candida albicans, Porphyromonas gingivalis, and Prevotella intermedia). The agar diffusion test was used to determine the antimicrobial activity. Chlorhexidene gluconate gel showed the largest inhibitory zones. The antimicrobial action of both medicaments decreased significantly with time, with calcium hydroxide showing no antimicrobial action after 72 hours. In conclusion, 2% chlorhexidene gel showed better antimicrobial activity than calcium hydroxide, and the effective antimicrobial action of both medicaments decreased after 48 hours.

Antimicrobial Effect of Triclosan and Triclosan with Gantrez on Five Common Endodontic Pathogens

Microbial control of the root canal system is one of the key objectives of root canal therapy. Triclosan is a widely accepted broad spectrum antimicrobial agent proven to be effective against many gram-positive and gram-negative bacteria. Triclosan acts by blocking bacterial fatty acid biosynthesis. The addition of Gantrez copolymer has been shown to enhance the antimicrobial activity of triclosan. The purpose of this study was to determine the minimum inhibitory and bactericidal concentrations of triclosan and triclosan with Gantrez against Prevotella intermedia, Fusobacterium nucleatum, Actinomyces naeslundii, Porphyromonas gingivalis, and Enterococcus faecalis. The minimum inhibitory concentration (MIC) of both test solutions was determined for each of the 5 microorganisms by using microtiter serial dilutions. Samples were streaked on 5% sheep blood agar plates and placed in an anaerobic incubator to determine the minimum bactericidal concentration (MBC). The MBC of triclosan ranged from 12-94 microg/mL. The MBC of triclosan with Gantrez ranged from <0.3-10.4 microg/mL. The addition of Gantrez enhanced the bactericidal activity of triclosan. Both triclosan and triclosan with Gantrez demonstrated bactericidal activity against the 5 specific endodontic pathogens.

Subgingival chlorhexidine varnish administration as an adjunct to same-day full-mouth root planing. II. Microbiological observations

BACKGROUND

Recently, the clinical additive value of a highly concentrated chlorhexidine (CHX) varnish, when applied subgingivally as an adjunct to scaling and root planing, was described. The objective of the present study was to investigate the microbiological impact of a treatment strategy for chronic periodontitis based on a combination of same-day full-mouth root planing and subgingival CHX varnish administration.

METHODS

A randomized, controlled, single-blind, parallel trial was conducted on 33 non-smoking chronic periodontitis patients. The control group received oral hygiene instructions and same-day full-mouth root planing. The test group received the same instructions and treatment; however, all pockets also were disinfected using a supersaturated CHX varnish. Subgingival plaque samples were collected from the deepest site per quadrant in each patient at baseline and after 1, 3, and 6 months. Pooled sample analysis was performed using a multiplex polymerase chain reaction-based method for the identification of Actinobacillus actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), Tannerella forsythensis (Tf), Treponema denticola (Td), and Prevotella intermedia (Pi).

RESULTS

In terms of detection frequency and bacterial levels, significant, mainly temporary, reductions from baseline were found in both groups. When a comparison was made between the control and the test group, significant differences in the detection frequency of Tf (P = 0.024) and Td (P = 0.024), which favored the test group, were found at 1 month. A similar phenomenon was seen for Td (P = 0.031) based on bacterial levels. An important trend toward lower Tf levels in the test group also was found at 1 month (P = 0.052). Compared to baseline levels, microbiological benefits in the test group seemed to be maintained, at least in part, over a 6-month period. In contrast, all microbial levels had relapsed in the control group at study termination.

CONCLUSION

The microbiological results of the present study promote the subgingival administration of a highly concentrated CHX varnish as an adjunct to same-day full-mouth root planing.

The effects of tetracycline, minocycline, doxycycline and ofloxacin on Prevotella intermedia biofilm

Prevotella intermedia, a black-pigmented, anaerobic, gram-negative bacterium, is associated with various type of periodontitis. Antibiotic treatments via a systemic or local route have been reported as being useful for treating periodontal disease. The purpose of this study was to examine the effects of four antibiotics, tetracycline (TET), minocycline (MINO), doxycycline (DOXY) and ofloxacin (OFLX) on P. intermedia biofilms at minimum inhibitory concentrations (MIC) from one-fold to 100-fold. MICs were determined for planktonic cells. Biofilm formation was determined with the crystal violet stain method and the bioactivities in the biofilms were determined with the adenosine triphosphate (ATP) -bioluminescent assay using a 96-well culture plate. At one-fold MIC, DOXY inhibited biofilm formation by P. intermedia ATCC 25611. Other antibiotics at one-fold MIC had no effects on the biofilm formation of tested bacterial strains. In P. intermedia ATCC 25611 biofilms, all the antibiotics tested showed inhibitory activities at five- to 100-fold MICs. In the biofilms of P. intermedia strains, except ATCC 25611, treated with three tetracycline antibiotics, the bioactivities were significantly increased, indicating the difficulties involved in designing antibiotic therapy for periodontal disease.

Antimicrobial activity of Mahonia aquifolium and two of its alkaloids against oral bacteria

Extracts or alkaloids isolated from Mahonia aquifolium exhibit antimicrobial activity against Gram-positive and Gram-negative bacteria, fungi, and protozoa. In this study the bacteriostatic and bacteriocidal activities of a M. aquifolium extract and two of its major alkaloids, berberine chloride and oxyacanthine sulphate, were tested in vitro against nine different oral bacteria. Minimum inhibitory concentrations were in the range from < or = 0.0031% to 0.1993% for the M. aquifolium extract, from 0.002% to > 0.125% for berberine chloride, and from 0.0156% to > 0.0625% for oxyacanthine sulphate. The values for the minimum bactericidal concentrations were in the same range, indicating that the test substances most probably acted in a bactericidal manner. The most susceptible bacterium against all three test substances was Porphyromonas gingivalis.

Antimicrobial actions of benzimidazoles against the oral anaerobes Fusobacterium nucleatum and Prevotella intermedia

BACKGROUND/OBJECTIVE

Benzimidazoles are widely used as proton-pump inhibitors to control stomach hyperacidity and have been found also to have antimicrobial actions against Helicobacter pylori and oral streptococci. Our primary aim was to determine if they are active also against oral anaerobes associated with gingivitis. Our major focus was on catabolism because it leads to production of inflammatory metabolites such as butyrate and ammonia. The benzimidazoles are effective in the protonated form at acid pH values and cause irreversible inhibition of enzymes associated with formation of drug-target disulfide bonds.

METHODS

Fusobacterium nucleatum ATCC 25586 and Prevotella intermedia ATCC 25611 were grown anaerobically in suspension cultures, harvested, washed and exposed to the benzimidazole lansoprazole at pH values of 4 or 5 before being washed and used for standard assays to detect inhibition of catabolic functions, uptake of the agent and lethality.

RESULTS

Lansoprazole was found to be a bacteriostatic, multi-target antimicrobial against F. nucleatum under anaerobic conditions inhibitory for amino acid fermentation and also for glycolysis of glucose or fructose. ID(50) values for fermentation of amino acids and dipeptides by F. nucleatum ranged from 0.05 mM for lysine to 0.25 mM for serine. Fructose catabolism was highly sensitive with an ID(50) value of 0.03 mM apparently related to high sensitivity of the phosphoenolpyruvate:fructose phosphotransferase system, while the ID(50) for glucose catabolism by intact cells was some 0.07 mM. Fermentation of aspartate or aspartylaspartate by P. intermedia was found to be lansoprazole-sensitive with ID(50) values of about 0.18 and 0.20 mM, respectively.

CONCLUSION

Catabolism of amino acids, dipeptides and sugars by oral anaerobes associated with gingivitis are sensitive to the inhibitory actions of lansoprazole. Thus, catabolic pathways are potential targets for use of benzimidazoles against bacteria involved in gingivitis.

In vitro antimicrobial activity of sodium hypochlorite and chlorhexidine against selected single-species biofilms

AIM

To investigate the antimicrobial activity of 2.5% and 5.25% sodium hypochlorite and 2.0% chlorhexidine gel and liquid as endodontic-irrigating substances against selected single-species biofilms.

METHODS

Single-species biofilms of Enterococcus faecalis, Staphylococcus aureus, Candida albicans, Prevotella intermedia, Porphyromonas gingivalis, Porphyromonas endodontalis and Fusobacterium nucleatum were generated on a cellulose nitrate membrane placed on agar medium. The biofilms were then immersed in the endodontic-irrigating substances for 30 s and also for 5, 10, 15, 30 and 60 min, with and without mechanical agitation. Sterile saline was used as control. After each time period, the membrane filters were then transferred to tubes containing 2 mL of fresh broth medium plus neutralizers (in order to prevent the residual action of the tested substances). The micro-organisms were suspended using a vortex, and the inoculum was serially diluted 10-fold. Aliquots of the dilutions were plated on 5% sheep blood agar medium, and incubated under adequate gaseous conditions. Colony-forming units were calculated. The samples were compared using the Friedman and Tukey test, when necessary, at a significance level of P < 0.05.

RESULTS

Mechanical agitation promoted the effectiveness of the antimicrobial agents, resulting in less time to eliminate the same micro-organisms, except for S. aureus with 2.5% NaOCl. Antimicrobial agents in liquid presentation, especially 5.25% NaOCl and 2% chlorhexidine, killed the tested micro-organisms more rapidly. Saline did not inhibit the growth of any of the tested micro-organisms, with or without agitation, being statistically different (P < 0.05) from NaOCl and chlorhexidine. P. intermedia, P. gingivalis, P. endodontalis and F. nucleatum were eliminated in 30 s by all antimicrobial agents, with our without agitation, in contrast with the facultative and aerobe strains.

CONCLUSIONS

Mechanical agitation improved the antimicrobial properties of the chemical substances tested using a biofilm model, favouring the agents in liquid presentation, especially 5.25% NaOCl and 2% chlorhexidine.

Photodynamic Therapy for Endodontic Disinfection

The aims of this study were to investigate the effects of photodynamic therapy (PDT) on endodontic pathogens in planktonic phase as well as on Enterococcus faecalis biofilms in experimentally infected root canals of extracted teeth. Strains of microorganisms were sensitized with methylene blue (25 microg/ml) for 5 minutes followed by exposure to red light of 665 nm with an energy fluence of 30 J/cm2. Methylene blue fully eliminated all bacterial species with the exception of E. faecalis (53% killing). The same concentration of methylene blue in combination with red light (222 J/cm2) was able to eliminate 97% of E. faecalis biofilm bacteria in root canals using an optical fiber with multiple cylindrical diffusers that uniformly distributed light at 360 degrees. We conclude that PDT may be developed as an adjunctive procedure to kill residual bacteria in the root canal system after standard endodontic treatment.

In vitro evaluation of the antimicrobial activity of calcium hydroxide combined with chlorhexidine gel used as intracanal medicament

The aim of this study was to investigate the antimicrobial activity of calcium hydroxide (Ca(OH)2) combined with 2% chlorhexidine gluconate (CHX) gel against endodontic pathogens and to compare the results with the ones achieved by Ca(OH)2 mixed with sterile water and by CHX gel alone. Two methods were used: the agar diffusion test and the direct contact test. Ca(OH)2 + 2% CHX gel produced inhibitory zones ranging from 2.84 to 6.5 mm, and required from 30 seconds to 6 hours to eliminate all tested microorganisms. However, 2% CHX gel showed the largest microbial growth zones from 4.33 to 21.67 mm, and required 1 minute or less to inhibit all tested microorganisms. A paste of Ca(OH)2 plus sterile water inhibited only the microorganisms with which it was in direct contact and required from 30 seconds to 24 hours to kill all tested microorganisms. In conclusion, 2% CHX gel + Ca(OH)2 showed better antimicrobial activity than Ca(OH)2 manipulated with sterile water.

Antibacterial effect of electrolyzed water on oral bacteria

This study investigated the antibacterial effect of electrolyzed water on oral bacteria both in vitro and in vivo. Tap water was electrolyzed in a water vessel using platinum cell technology. The electrolyzed tap water (called Puri-water) was put in contact with five major periodontopathogens or toothbrushes contaminated with these bacteria for 30 sec. In addition, Puri-water was used as a mouthwash for 30 sec in 16 subjects and the antibacterial effect on salivary bacteria was evaluated. Puri-water significantly reduced the growth of all periodontopathogens in culture and on toothbrushes, and that of aerobic and anaerobic bacteria in saliva, when compared to the effect of tap water. It also significantly reduced mutans streptococci growing on mitis salivarius-bacitracin agar. Our results demonstrate that the electrolyzed tap water is effective as a mouthwash and for toothbrush disinfection.

Selective inhibition of Porphyromonas gingivalis growth by a factor Xa inhibitor, DX-9065a

BACKGROUND

Porphyromonas gingivalis is a causative bacterium of adult periodontitis. However, there is no drug specific for P. gingivalis and for its virulence factor.

OBJECTIVES

The objective of this study was to examine the effects of a new selective inhibitor of activated factor X, DX-9065a, on growth of Porphyromonas gingivalis and other periodontopathic bacteria.

METHODS

We incubated P. gingivalis and other periodontopathic bacteria in the presence or absence of DX-9065a and examined the effect of DX-9065a on bacterial growth and trypsin-like activity in its cultures. We also examined the effects of DX9065a on amidolytic activity of purified trypsin-like proteinases (gingipains RgpA and RgpB), from P. gingivalis and on trypsin-like activity in gingival crevicular fluids from patients with adult periodontitis.

RESULTS

DX-9065a selectively inhibited the growth of P. gingivalis and Prevotella intermedia, and its effect on P. gingivalis was bactericidal. Trypsin-like proteinase activity was detected in P. gingivalis, and the activity was strongly inhibited by DX-9065a. DX-9065a even inhibited amidolytic activity of RgpA and RgpB from P. gingivalis. Furthermore, trypsin-like proteinase activity in gingival crevicular fluids was strongly inhibited by DX-9065a.

CONCLUSIONS

DX-9065a inhibits P. gingivalis growth in part through to its ability to inhibit the trypsin-like proteinase activity in P. gingivalis and may be useful for a new drug for treatment of adult periodontitis.

Antibacterial action of photoactivated disinfection {PAD} used on endodontic bacteria in planktonic suspension and in artificial and human root canals

OBJECTIVES

To measure antibacterial action of photoactivated disinfection (PAD) on endodontic bacteria in planktonic suspension and root canals.

METHODS

Four bacteria, Fusobacterium nucleatum,Peptostreptococcus micros, Prevotella intermedia and Streptococcus intermedius, were tested in suspension. After mixing equal volumes of Tolonium chloride and bacterial suspension for 60s, each 200 microL of concentration (>10(6)cfu mL(-1)) was irradiated with light at 633+/-2 nm. Each energy dose/Tolonium chloride concentration combination was tested eight times, with controls. Prepared root canals in Training Blocs and extracted human teeth were inoculated with S. intermedius followed by 10 mg L(-1) Tolonium chloride or saline. Bacteria in canals were sampled before and after light irradiation. Student t-test assessed significance of changes in viable bacteria produced by treatment of either light or Tolonium chloride alone and light/Tolonium chloride combinations.

RESULTS

In suspension, reductions in bacteria were highly significant (P<0.01) for light/Tolonium chloride combinations compared to light or Tolonium chloride alone. Maximum mean log reductions of 1.14 (P. intermedia), 2.48 (P. micros), 2.81 (F. nucleatum) and 6.73 (S. intermedius) were at 4.8 J/20 mg L(-1). Antibacterial action was increased by energy dose increase (not always significantly), but not by Tolonium chloride concentration. In control canals mean log reductions of 0.42 (Blocs) and 0.38 (teeth) from initial levels were not significant. PAD mean log reductions of 2.40 (Blocs) and 2.01 (teeth) were highly significant. Changes for PAD/energy dose combinations were not significant.

CONCLUSION

PAD killed endodontic bacteria at statistically significant levels compared to controls. Kills varied with bacterial species.

In vitro antibacterial efficacy of a new chlorhexidine slow-release device

OBJECTIVE

The aim of this study was to evaluate and compare the antibacterial effect of chlorhexidine and calcium hydroxide slow-release devices on oral bacteria.

METHOD AND MATERIALS

The agar diffusion test was used to evaluate the antibacterial effect of the slow-release devices Activ Point (chlorhexidine; Roeko) and Calcium Hydroxide Plus Point (Roeko) on 8 anaerobic and 2 facultative oral bacterial strains, as well as 2 bacterial cultures randomly sampled from necrotic root canals and incubated in anaerobic and aerobic broth for 48 hours. The efficiency of the medicaments against the various strains was evaluated using a nonparametric test (Friedman type) and a second nonparametric test (Wilcoxon's signed rank test).

RESULTS

Activ Point produced significantly larger inhibition zones (P < .001) than the calcium hydroxide slow-release device around all tested bacterial strains.

CONCLUSION

The chlorhexidine slow-release device (Activ Point) exhibited significant antibacterial activity in the agar diffusion test and merits study as an intracanal medicament.

[Bacterial spectra and antibiotics in odontogenic infections. Renaissance of the penicillins?]

BACKGROUND

The role played by odontogenic infection in dental, oral, and maxillofacial surgery is not to be underestimated even at the present time. An extensive, standardized, prospective study was performed with the intention of verifying the bacterial spectrum of odontogenic infections to evaluate antibiotic sensitivity.

MATERIAL AND METHODS

Bacterial spectra and resistograms of 65 patients with an odontogenic infection were analyzed in a prospective study under standardized conditions for specimen collection and transport.

RESULTS

A total of 226 bacterial strains were analyzed. The ratio between anaerobes and aerobes was approximately 2:1. The most frequent aerobes were members of the genera Streptococcus (46 isolates), Staphylococcus (10 isolates), and Neisseria (9 isolates), respectively. The anaerobic gram-positive spectrum was dominated by members of the genera Eubacterium (19 isolates), Peptostreptococcus (16 isolates), and Actinomyces (12 isolates). The most frequently isolated gram-negative anaerobes were Prevotella (46 isolates), and Fusobacterium (21 isolates). The overall resistance to antibiotics was very low: only 7.3% of all bacteria were resistant to penicillin G/V, and 8.8% showed resistance to ampicillin. The resistance rates to other beta-lactam antibiotics were 4.4% to piperacillin and 0.6% to imipenem, respectively. Penicillin G presented the highest antimicrobial activity among aerobes: only 4.5% of anaerobic strains were resistant of penicillin G. The other resistance rates of anaerobic bacteria to antibiotics were as follows: ampicillin 24%, doxycycline 34%, erythromycin 18%, and clindamycin 9.3%. Penicillin G was also highly antimicrobially active to anaerobes. The resistance rates were: penicillin G 8.1%, ampicillin 2.6%, doxycycline 9.2%, erythromycin 10.2%, and clindamycin 1.4%, respectively.

The Efficacy of Povidone-Iodine Products against Periodontopathic Bacteria

A total of 8 strains of 6 bacterial species, Porphyromonas gingivalis ATCC33277 and TDC286, Actinobacillus actinomycetemcomitans ATCC29523 and JP2, Fusobacterium nucleatum No. 2, Tannerella forsythensis ATCC43937, Prevotella intermedia ATCC25611 and Streptococcus anginosus ATCC33397, were treated with povidone-iodine (PVP-I) gargle (PVP-I: 0.47 and 0.23% w/v) or chlorhexidine gluconate (CHG) gargle (CHG: 0.002% w/v) for 15, 30 or 60 s, after which they were inoculated into various media, cultured and counted for residual bacteria. At both concentrations, PVP-I gargle reduced the viable cell count of all 8 bacterial strains to below the measurable limit within 15 s. By contrast, there were more than 1,000 viable colonies 60 s following treatment with the CHG gargle. The results demonstrate that povidone-iodine gargle has rapid bactericidal activity against the causative bacteria of periodontal disease.

Supportive periodontal therapy using mechanical instrumentation or 2% minocycline gel: a 12 month randomized, controlled, single masked pilot study

OBJECTIVE

To compare the short-term performance of subgingival local delivery of 2% minocycline gel and conventional subgingival debridement in supportive periodontal therapy (SPT) patients.

METHODS

Forty adult patients having completed active treatment for moderate to advanced chronic periodontitis were included in a randomized, controlled, single masked maintenance care pilot study. Sites with residual pocket probing depths > or =5 mm and bleeding on probing were treated with either minocycline gel (minocycline-group) or scaling and root planing only (debridement-group) at baseline, 3, 6, and 9 months. Clinical and microbiological examinations were performed at baseline, 3, 6, 9, and 12 months.

RESULTS

Full-mouth plaque and bleeding scores remained <10% and <20%, respectively, for both groups throughout the study. In both groups there was a persistent reduction in number of teeth and sites with probing pocket depths > or =5 mm (p<0.05) with no significant differences between the groups. The prevalence of Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Actinobacillus actinomycetemcomitans, Prevotella intermedia, and Prevotella nigrescens, remained at levels < or =10(5) in the majority of patients and sites in both groups.

CONCLUSION

This pilot study failed to show a difference between local delivery of 2% minocycline gel as mono-therapy and traditional subgingival debridement in patients on SPT.

Local Oxygen Therapy for Treating Acute Necrotizing Periodontal Disease in Smokers

BACKGROUND

The main aim of treatment for acute necrotizing periodontal disease is fast and effective reduction of anaerobic destructive microorganisms to avoid periodontal damage. The effect of adjunctive local oxygen therapy in the treatment of necrotizing periodontal disease was examined in this study.

METHODS

Thirty patients with acute necrotizing periodontal disease were treated with the systemic antibiotics amoxicillin, clavulanic acid, and metronidazole. In 15 out of 30 patients, adjunctive local oxygen therapy was administered. The patients were followed from the first to 10th day of treatment with clinical and bacteriological examinations. The clinical examination registered gingival bleeding, periodontal probing depth, and attachment loss; to follow up microbiological colonization of the periodontal sulcus, five representative bacteria were registered by a semiquantitative DNA polymerase chain reaction test.

RESULTS

In both groups of patients, colonization with Prevotella intermedia, Tannerella forsythensis, and Treponema denticola was initially positive. None of these three microorganisms were completely eradicated in any of the patients in the group without oxygen therapy within the first 10 days of treatment. In the group with adjunctive oxygen therapy, all patients either showed a reduction in or complete eradication of the microorganisms, resulting in more rapid clinical restitution with less periodontal destruction.

CONCLUSIONS

Adjunctive oxygen therapy results in early eradication of pathogenic anaerobic microorganisms in cases of acute necrotizing periodontal disease. The damage to periodontal tissue is reduced.

Effects of zinc and copper on adhesion and hemagglutination of Prevotella intermedia and Prevotella nigrescens

This study investigated the mechanism of protein attachment to the surface of the putative periodontal pathogens Prevotella intermedia and Prevotella nigrescens in artificial gingival crevicular fluid, and ways to increase protein attachment to the bacterial cells. The effects of cations on protein attachment, bacterial adhesion, and hemagglutination were examined, and cation-binding components on both bacterial species were identified. The presence of cations, especially zinc, copper and cerium, increased attachment of human serum proteins to both bacterial species. In contrast, the presence of hydrophobic inhibitors or sugars had little effect. Protein attachment was reduced by heat treatment of the bacterial cells. Pretreatment of bacteria with human serum proteins inhibited adhesion of both species to buccal epithelial cells and hemagglutination. These effects were enhanced by the presence of zinc and copper during pretreatment. Using a chelating column, specific zinc- and copper-binding proteins were identified on the surfaces of both bacterial species.

In vitro evaluation of the susceptibility of endodontic pathogens to calcium hydroxide combined with different vehicles

The aim of this study was to investigate in vitro the antimicrobial activity of calcium hydroxide [Ca(OH)2] in combination with different vehicles against endodontic pathogens. For such purpose, a broth dilution test was performed. Pastes were prepared with Ca(OH)2 powder and the following vehicles: sterile water, glycerin, camphorated monochlorophenol (CMCP), CMCP + glycerin, polyethyleneglycol and CMCP + polyethyleneglycol. The time required for the pastes to produce negative cultures against the tested microorganisms was recorded and analyzed statistically using the Kruskal Wallis test at 5% significance level. Timing for pastes to eliminate the aerobic and facultative anaerobic microorganisms ranged from 6 to 24 h, while strict anaerobic microorganisms were inhibited within 30 s to 5 min. Microbial susceptibility, ranked from weakest to strongest, can be presented as follows: Enterococcus faecalis (the most resistant microorganism), Candida albicans, Staphylococcus aureus, Porphyromonas gingivalis, Porphyromonas endodontalis and Prevotella intermedia (the last two microorganisms required the same time to be eliminated). In conclusion, calcium hydroxide pastes needed more time to eliminate facultative than anaereobic microorganisms. These findings suggest that the antimicrobial property is related both to paste formulation and to microbial susceptibility.

Antimicrobial profiles of periodontal pathogens isolated from periodontitis patients in the Netherlands and Spain

BACKGROUND AND AIM

Antimicrobial resistance of periodontal pathogens towards currently used antibiotics in periodontics has been investigated in a previous study. Microbial resistance in the periodontal microflora was more frequently observed in Spanish patients in comparison with Dutch patients. The aim of the present study was to compare antimicrobial susceptibility profiles of five periodontal bacteria isolated from periodontitis patients in Spain and in The Netherlands.

MATERIAL AND METHODS

Subgingival plaque samples from adult patients with periodontitis were collected and cultured on selective and non-selective plates. Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Micromonas micros were isolated and used for minimal inhibitory concentration tests using the Epsilometer (E-test) technique. Eight different antibiotics were tested on all bacterial isolates. MIC50 and MIC90 values for each antibiotic and each species were determined and the percentage of resistant strains was calculated.

RESULTS

Significantly higher MIC values were noted in Spanish strains of F. nucleatum for penicillin, ciprofloxacin, of P. intermedia for penicillin, amoxicillin and tetracycline, of M. micros for tetracycline, amoxicillin and azithromycin, and of P. gingivalis for tetracycline and ciprofloxacin. Based on breakpoint concentrations, a higher number of resistant strains in Spain were found in F. nucleatum for penicillin, amoxicillin and metronidazole, in Prevotella intermedia for tetracycline and amoxicillin, and in A. actinomycetemcomitans for amoxicillin and azithromycin. Resistance of P. gingivalis strains was not observed for any of the antibiotics tested both in Spain and The Netherlands.

CONCLUSIONS

Differences exist in the susceptibility profiles of periodontal pathogens isolated from periodontitis patients in Spain and in The Netherlands. This implicates that antibiotic susceptibility testing is necessary to determine efficacy of antimicrobial agents. Also, clinical studies with antibiotics should take these differences into account. The information from the present study indicates that it may not be possible to develop uniform protocols for usage of antibiotics in the treatment of severe periodontitis in the European Union.

Multi-target antimicrobial actions of zinc against oral anaerobes

OBJECTIVE

Zinc is used in oral care products as an antiplaque/antigingivitis agent. Our objective was to assess the antimicrobial actions of zinc against oral anaerobes associated with gingivitis, specifically Fusobacterium nucleatum and Prevotella intermedia, with focus on catabolism and oxidative metabolism.

METHODS

The oral anaerobes were grown in complex medium in an anaerobic chamber, harvested by centrifugation and used directly for experiments with suspensions. Biofilm growth involved super-infection by F. nucleatum of an initial biofilm formed by Streptococcus sanguis.

RESULTS

Zn(2+) inhibited catabolism of glutamate, glutamyl-glutamate, glucose and fructose by F. nucleatum cells in suspensions with ID(50) values, respectively, of 0.05, 0.005, 0.01 and 0.01 mM. The ID(50) value for inhibition of glutamate catabolism by biofilms was 0.10 mM. Inhibition of glutamate catabolism could be related to inhibition of substrate uptake and of 2-oxoglutarate reductase. Zn(2+) also inhibited catabolism of aspartate or aspartyl-aspartate by P. intermedia with ID(50) values of 0.07 and about 0.03 mM, respectively. Respiration of intact cells of F. nucleatum and NADH oxidase in cell extracts were sensitive to zinc with ID(50) values, respectively, of about 1.0 and 1.4 mM. Zinc also inhibited production of hydrogen peroxide by F. nucleatum (ID(50) = ca. 0.04 mM.) but at high concentrations acted to potentiate and enhance peroxide killing of the anaerobe.

CONCLUSION

Zn(2+) is a potent inhibitor of catabolism by F. nucleatum and P. intermedia, including catabolism of peptides, which can be degraded to yield inflammatory metabolic end products. Zn(2+) also inhibits O(2) metabolism of F. nucleatum by about 50% and hydrogen peroxide production nearly completely but also enhances killing by peroxide added to cells.

Comparison of the antimicrobial activity of six irrigants on primary endodontic pathogens

The purpose of this study was to compare the antimicrobial activities of 6% and 3% sodium hypochlorite (NaOCl), 2% and 0.12% chlorhexidine gluconate (CHX), and 0.01% and 0.005% doxycycline (Doxy) on four microorganisms associated with primary endodontic infections. The agar diffusion test was used to measure antimicrobial activities of these agents against Peptostreptococcus micros, Prevotella intermedia, Streptococcus sanguis, and Lactobacillus acidophilus. Minimum inhibitory concentration analysis was performed using the macrodilution method. For three of the four microorganisms, the general order of antimicrobial effectiveness was 0.01% Doxy >0.005% Doxy >6% NaOCl >3% NaOCl >2% CHX > 0.12% CHX. For L. acidophilus, the order of effectiveness was 6% NaOCl >3% NaOCl >2% CHX > 0.01% Doxy >0.005% Doxy >0.12% CHX. The 6% NaOCl showed significantly greater zones of inhibition than 3% NaOCl for all endopathogens tested.