Periodontal antimicrobials — finding the right solutions

A Low-Cost Protocol Using the Adjunctive Action of Povidone-Iodine Irrigations and Sodium Hypochlorite Rinsing Solution in Step 2 of Periodontal Therapy for Patients with Stage III-IV Periodontitis: A Single-Blind, Randomized Controlled Trial

In severe stages of periodontitis, conventional periodontal therapy and maintenance care are usually insufficient due to the viral and bacterial etiology; thus, a mechanical approach alone may not be sufficient to eliminate a substantial portion of subgingival pathogens, especially in deep periodontal sites. Background and Objectives: This single-blind, randomized clinical trial aimed to compare the clinical and microbiological efficacy of a low-cost protocol using povidone-iodine and sodium hypochlorite formulations as adjuncts to non-surgical therapy for patients with stage IV periodontitis when compared with chlorhexidine, the most commonly employed substance to date for antimicrobial regimens in periodontal therapy. Materials and Methods: Forty-five patients were randomly divided into two groups: control (subgingival instrumentation, chlorhexidine-assisted) and test (antiviral medication, subgingival instrumentation with povidone-iodine, sodium hypochlorite rinsing solution, and antibiotics). Clinical measurements and microbiological analyses were performed at baseline and after three months. Results: After three months, notable differences were found in the bacterial detection scores for Porphyromonas gingivalis (a significant reduction in detection frequency was observed in the test compared to the control (p = 0.021)), and there were significant reductions in detection in the test group for Tannerella forsythia and Treponema denticola, showing undetectable levels (p < 0.0001 for both). In the test group, the pocket probing depth median value was reduced significantly (p = 0.0005); similarly, bleeding on probing showed a marked decrease (p < 0.0001). However, changes in clinical attachment loss and full-mouth plaque score were not statistically significant. Conclusions: Using the proposed protocol, substantial improvements in clinical and microbiological parameters were obtained when compared with the current antimicrobial recommendations.

Efficacy of a novel three-step decontamination protocol for titanium-based dental implants: An in vitro and in vivo study

AIM

The aim of the study was to evaluate several mechanical and chemical decontamination methods associated with a newly introduced biofilm matrix disruption strategy for biofilm cleaning and preservation of implant surface features.

MATERIALS AND METHODS

Titanium (Ti) discs were obtained by additive manufacturing. Polymicrobial biofilm-covered Ti disc surfaces were decontaminated with mechanical [Ti curette, Teflon curette, Ti brush, water-air jet device, and Er:YAG laser] or chemical [iodopovidone (PVPI) 0.2% to disrupt the extracellular matrix, along with amoxicillin; minocycline; tetracycline; H2 O2 3%; chlorhexidine 0.2%; NaOCl 0.95%; hydrocarbon-oxo-borate-based antiseptic] protocols. The optimal in vitro mechanical/chemical protocol was then tested in combination using an in vivo biofilm model with intra-oral devices.

RESULTS

Er:YAG laser treatment displayed optimum surface cleaning by biofilm removal with minimal deleterious damage to the surface, smaller Ti release, good corrosion stability, and improved fibroblast readhesion. NaOCl 0.95% was the most promising agent to reduce in vitro and in vivo biofilms and was even more effective when associated with PVPI 0.2% as a pre-treatment to disrupt the biofilm matrix. The combination of Er:YAG laser followed by PVPI 0.2% plus NaOCl 0.95% promoted efficient decontamination of rough Ti surfaces by disrupting the biofilm matrix and killing remnants of in vivo biofilms formed in the mouth (the only protocol to lead to ~99% biofilm eradication).

CONCLUSION

Er:YAG laser + PVPI 0.2% + NaOCl 0.95% can be a reliable decontamination protocol for Ti surfaces, eliminating microbial biofilms without damaging the implant surface.

Adjunctive dental therapies in caries-active children: Shifting the cariogenic salivary microbiome from dysbiosis towards non-cariogenic health

Background:

The oral microbiome is a complex assembly of microbial species, whose constituents can tilt the balance towards progression of oral disease or sustained health. Recently we identified sex-specific differences in the salivary microbiome contained within caries-active and caries-free children. In this study, we sought to ascertain if adjunctive dental therapies, including povidone iodine and chlorhexidine, were effective in shifting the cariogenic microbiome from dysbiosis to non-cariogenic health.

Design:

We recruited young children (ages 2–12 years) to enter five enrollment groups, with each group (N = 9–30 participants/group) receiving caries restorative and/or adjunctive therapies, either singularly or in combination (OHSU IRB #6535). Saliva specimens were collected pre- and post-treatment (4–8 weeks) of caries preventive measures, and oral microbiota were identified using next generation sequencing (HOMINGS, Forsyth Institute, Cambridge, MA).

Results:

With the use of multi-dimensional scaling plots, support vector machine learning, odds ratio analysis, and other statistical methods, we have determined that treatment with povidone iodine can shift the composition of the salivary cariogenic microbiome to include higher proportions of aerobic microorganisms, such as Stentrophomonas maltophila, as well as non-cariogenic, anaerobic microorganisms including Poryphyromonas and Fusobacterium species.

Conclusion:

We have identified microorganisms that are associated with caries-active children and have determined that povidone iodine is an effective adjunctive therapy that has the potential to shift the composition of the cariogenic microbiome to one more closely aligned with non-cariogenic health.

Detection rates of periodontal bacteria and herpesviruses in different forms of periodontal disease

The aim was to investigate the detection rates of periodontal bacteria (Porphyromonas gingivalis, Tannerella forsythia, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans) and herpesviruses (herpes simplex virus-1 [HSV-1], cytomegalovirus [CMV], and Epstein-Barr virus [EBV]) in different forms and severity of periodontal disease, and to compare them with those in periodontally healthy subjects. One hundred and twenty-nine patients participated in the study: 39 diagnosed with periodontal abscess (PA), 33 with necrotizing ulcerative periodontitis (NUP), 27 with chronic periodontitis (CP), and 30 participants with healthy periodontal tissue represented a healthy control group. All patients with periodontal disease (PA, NUP, and CP) were also divided into two groups according to the severity of their disease: moderate and severe periodontitis. The subgingival samples were collected from the periodontitis active sites and the detection of microorganisms was performed by end-point polymerase chain reaction analyses. The results revealed significantly higher detection rates of P. gingivalis, T. forsythia, and P. intermedia in all three groups of patients with periodontitis than in healthy participants. The highest detection rate of A. actinomycetemcomitans was noticed in CP, which was significantly higher than that in PA, NUP, and healthy control. The occurrence of EBV was significantly higher in NUP than in CP and healthy participants. CMV was detected significantly more frequently in PA and NUP than in CP and healthy participants. Comparisons among healthy participants and patients with moderate and severe periodontitis showed significantly higher detection rates of EBV and CMV in patients with severe forms of periodontitis than in healthy participants and those with moderate periodontitis.

Treatment with Nd:YAG Laser Irradiation Combined with Sodium Hypochlorite or Hydrogen Peroxide Irrigation on Periodontal Pathogens: An In Vitro Study

Objective: The purpose of this study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd:YAG) laser with low concentrations of hydrogen peroxide (H₂O₂) or sodium hypochlorite (NaOCl) on viability of oral bacteria. Materials and methods: Bacterial species Streptococcus gordonii, Porphyromonas gingivalis, and Fusobacterium nucleatum were grown in an anaerobic chamber at 37°C. Samples were irradiated with the Nd:YAG laser (1064 nm, 300 μm Varian tip) using parameters: 150 mJ, 20 Hz, 3 W, 50 sec, and 100 μs short pulse duration in contact mode. Treatment groups included (1) control, (2) Nd:YAG, (3) 0.5% H₂O₂, (4) Nd:YAG and 0.5% H₂O₂, (5) 0.5% NaOCl, and (6) Nd:YAG with 0.5% NaOCl. Viable colonies were counted, calculated into colony forming unit/mL, and converted into log form for statistical analysis using a two-tailed paired t-test. Results: The combined treatment with the Nd:YAG and H₂O₂ showed the greatest reduction in all bacterial viability compared with other treatment groups (p < 0.001). Antiseptic solutions and laser were most effective against P. gingivalis, least effective against S. gordonii but improved significantly in combination with laser irradiation (p < 0.001). Laser alone was effective against all of three bacterial species, however, it was not significant. Conclusions: Combination treatment with Nd:YAG laser and an oxidative disinfectant (0.5% NaOCl or H₂O₂) resulted in more effective reduction of bacterial viability than monotherapies.

Periodontal herpesvirus morbidity and treatment

Four billion individuals worldwide have a history of periodontitis, with the poorest people in society most affected. Periodontitis can lead to unsightly drifting of teeth and tooth loss that may interfere with the wellbeing of daily living and has also been linked to at least 57 medical diseases and disabilities. The etiology of severe periodontitis includes active herpesviruses, specific bacterial pathogens, and destructive immune responses, but herpesviruses seem to be the major pathogenic determinant. Periodontal herpesviruses that disseminate via the systemic circulation to nonoral sites may represent a major link between periodontitis and systemic diseases. Current treatment of periodontitis focuses almost exclusively on bacterial biofilm and will require revision. Periodontal therapy that targets both herpesviruses and bacterial pathogens can provide long-term clinical improvement and potentially reduces the risk of systemic diseases. Molecular diagnostic tests for periodontal pathogens may enable early microbial identification and preemptive therapy. This review details an efficient and reliable anti-infective treatment of severe periodontitis that can be carried out in minimal time with minimal cost.

Er:YAG Laser Irradiation Reduces Microbial Viability When Used in Combination with Irrigation with Sodium Hypochlorite, Chlorhexidine, and Hydrogen Peroxide

The erbium-doped yttrium aluminum garnet (Er:YAG) laser is used to treat periodontal disease; however, its effectiveness at killing oral bacteria is not well known. Furthermore, the compounding effect of the combination of a laser treatment and irrigation methods with antimicrobials on bacterial viability is yet to be determined. The purpose of this in vitro study was to evaluate the effect of the Er:YAG laser with irrigation using chlorhexidine (CHX), hydrogen peroxide (H₂O₂), or sodium hypochlorite (NaOCl) on the viability of oral bacteria. Three bacterial species were used in our study: Streptococcus gordonii, Fusobacterium nucleatum, and Porphyromonas gingivalis. Bacteria were grown in an anaerobic chamber in brain heart infusion broth and incubated at 37 °C. Bacterial samples with an OD of 0.5 were irradiated with the Er:YAG laser at 2940 nm using a 400-µm Varian tip. The experiment was repeated four times using these parameters: 40 mJ, 40 Hz, and 1.6 W for 20 seconds with the 300 µs short pulse duration in contact mode. Treatment groups consisted of the following: (1) no treatment, (2) 0.5% H₂O₂ alone, (3) 0.5% NaOCl alone, (4) 0.03% CHX alone, (5) Er:YAG irradiation alone, (6) Er:YAG irradiation with 0.5% H₂O₂, (7) Er:YAG irradiation with 0.5% NaOCl, and (8) Er:YAG irradiation with 0.03% CHX. Microbial viability was determined through plating and colony counts and calculated into CFU/ml. Statistical analysis was done using a two-tailed paired t-test. The use of the Er:YAG laser alone failed to show statistically significant antibacterial activity against any of bacteria. The most effective mono-treatment with irrigation solutions for all three bacteria were 0.5% H₂O₂ and 0.5% NaOCl (p < 0.001 for each solution). Irrigation with 0.03% CHX was most effective against F. nucleatum (p < 0.01) and less against P. gingivalis and S. gordonii and showed the least antibacterial action alone but improved significantly in combination therapy (p < 0.05). The combined treatment with the Er:YAG showed the greatest and most significant improvement in the reduction of bacterial viability compared to any other treatment group (p < 0.05 for each combined treatment). Irradiation with the Er:YAG laser with the addition of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX under a short working time (20 s) resulted in a significant reduction of bacterial viability for all three bacterial species compared with any single treatment option. The combination of irradiation with the Er:YAG laser with the addition of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX resulted in a larger reduction of bacterial survival when compared to monotherapies with antimicrobial solutions or laser. The combination of the Er:YAG laser with a low concentration irrigant solution of 0.5% H₂O₂, 0.5% NaOCl, or 0.03% CHX could be an effective treatment protocol for the reduction of periodontal pathogens and thus suitable treatment for non-surgical periodontal therapy.

Low Efficacy of Hypochlorous Acid Solution Compared to Povidone-iodine in Cataract Surgery Antisepsis

Background:

Hypochlorous Acid Solution (HAS) is a non-irritating, odorless and transparent, pH-neutral substance having antimicrobial activity.

Objective:

The study aimed to compare the efficacy of HAS with a 10% povidone-iodine (PVI) solution for antisepsis in Phacoemulsification Cataract Surgery (PCS).

Methods:

Consecutive patients undergoing PCS in the Elbląg City Hospital, Poland, were enrolled in this prospective trial. In the morning just before surgery a swab was taken from the inferior conjunctival fornix of the eye that was to be operated. Patients were assigned to receive conjunctival irrigation with PVI or HAS in the operating room. Three minutes after lavage with PVI or HAS, conjunctival swabs were taken. During surgery the cornea and conjunctival sac were irrigated with Ringer’s lactate. The last swab was taken before removing the eye speculum.

Results:

Overall, 110 patients completed the study; there were 59 patients in the PVI group and 51 patients in the HAS group. Conjunctival lavage with 10% PVI resulted in a decrease in bacterial load, while HAS application did not. In the HAS group a reduction in bacterial load was found after surgery. Patients after HAS irrigation reported significantly less discomfort associated with conjunctival lavage than with PVI. None of the patients developed postoperative endophthalmitis or any type of eye inflammation within the follow-up period.

Conclusions:

This study confirms the excellent antibacterial activity of a 10% povidone-iodine solution used for three minutes before cataract surgery. Conjunctival irrigation with Ringer lactate during PCS decreased the bacterial load of the conjunctival sac.

Antimicrobial Activity of a Cationic Guanidine Compound against Two Pathogenic Oral Bacteria

This study evaluated the potential antimicrobial properties of a polyguanidine (CatDex) on two oral bacteria. Chlorhexidine gluconate 1340 μmoL L-1 (CHX 0.12%) was used as control. Streptococcus mutans (S. mutans) and Porphyromonas gingivalis (P. gingivalis) were grown in BHI media. Bacterial sensitivity and antimicrobial activity were determined by the minimum inhibitory concentration (MIC) and Kirby-Bauer methods. To study side effects, that is, toxicity, dental pulp stem cells (DPSCs) were used. Fluorometric cytotoxicity and confocal microscopy assays were used in order to test cell viability. CatDex inhibited growth of S. mutans at all concentrations and growth of P. gingivalis at all concentrations except 25 μmoL L-1. The MIC of CatDex was 50 μmoL L-1 for both S. mutans and P. gingivalis. The inhibition of bacteria exposed for 8 h at 50 μmoL L-1 of CatDex exhibited increased antimicrobial activity over time, with 91% inhibition in both bacteria. The antimicrobial activities of CatDex and CHX were similar when tested on two common bacteria. CatDex was significantly less toxic to DPSCs. CatDex toxicity depended on time and not on concentration. With regard to clinical relevance, CatDex may have potential as a novel antimicrobial agent. Further studies are in progress.

Antimicrobial efficiency of mouthrinses versus and in combination with different photodynamic therapies on periodontal pathogens in an experimental study

BACKGROUND AND OBJECTIVE

In the therapy of destructive periodontal disease, chemical antimicrobial agents and increasingly photodynamic therapy (PDT) play an important adjunctive role to standard mechanical anti-infective treatment procedures. However, both antiseptic methods have their shortcomings in terms of eliminating periodontal pathogens. The aim of the study was to compare the antibacterial efficacy of different antiseptic mouthrinses, of a conventional and a new, modified PDT^plus as well as of the different antiseptic mouthrinses combined with either the conventional or the modified PDT^plus against periopathogens.

MATERIAL AND METHODS

Six representative periodontitis-associated bacterial strains were grown for 24 h under anaerobic conditions. After mixing the individual cell pellets they were exposed to 10 different antiseptic mouthrinse formulations: chlorhexidine (0.2%, 0.06%, CHX); CHX + cetylpyridinium chloride (each 0.05%); sodium hypochlorite (0.05%); polyhexanide (0.04%, PHMB1; 0.1%, PHMB2); octenidine dihydrochloride (0.1%); fluoride (250 ppm); essential oils; povidone iodine (10%); and saline (0.9%, NaCl) as control. Furthermore, the bacteria were treated with conventional PDT based on light-emitting diodes and a new modified photodisinfection combining photosensitizer with hydrogen peroxide to PDT^plus also based on light-emitting diodes. In addition to the single treatments, a combined application of antiseptic exposure followed by use of PDT or PDT^plus was performed. The microbial viability was characterized by analyzing colony growth and fluorescence-based vitality proportions.

RESULTS

Nearly all mouthrinses caused a statistically significant growth inhibition. The most effective antiseptics, CHX (0.2%), CHX/cetylpyridinium chloride and octenidine dihydrochloride, inhibited bacterial growth completely. Conventional PDT resulted in moderate reduction of colony growth. The modified PDT^plus achieved maximum antimicrobial effect. The combination of antiseptic exposure and PDT against periopathogens predominantly increased antibacterial efficacy compared to the single applications. The mouthrinse containing essential oil seemed to interfere with PDT.

CONCLUSION

A combination therapy of preceding chemotherapeutical exposure and subsequent photodisinfection may be a more effective and promising antibacterial treatment than single applications of the antiseptic methods. The modified PDT^plus using oxygen-enriched toluidine showed a superior antibacterial effect on periodontal pathogens to conventional PDT and to the majority of the investigated mouthrinses.

Low-cost periodontal therapy

Periodontitis is a complex infectious disease that affects low-income individuals disproportionately. Periodontitis is associated with specific bacterial species and herpesviruses, and successful prevention and treatment of the disease is contingent upon effective control of these pathogens. This article presents an efficacious, highly safe, minimally invasive, practical and low-cost periodontal therapy that involves professional and patient-administered mechanical therapy and antimicrobial agents. The major components are scaling for calculus removal, periodontal pocket irrigation with potent antiseptics, and treatment with systemic antibiotics for advanced disease. Povidone-iodine and sodium hypochlorite have all the characteristics for becoming the first-choice antiseptics in the management of periodontal diseases. Both agents show excellent antibacterial and antiviral properties, are readily available throughout the world, have been safely used in periodontal therapy for decades, offer significant benefits for individuals with very limited financial resources, and are well accepted by most dental professionals and patients. Four per cent chlorhexidine applied with a toothbrush to the most posterior part to the tongue dorsum can markedly reduce or eliminate halitosis in most individuals. Systemic antibiotics are used to treat periodontopathic bacteria that are not readily reached by topical therapy, such as pathogens within gingival tissue, within furcation defects, at the base of periodontal pockets, and on the tongue, tonsils and buccal mucosae. Valuable antibiotic therapies are amoxicillin-metronidazole (250 mg of amoxicillin and 250 mg of metronidazole, three times daily for 8 days) for young and middle-aged patients, and ciprofloxacin-metronidazole (500 mg of each, twice daily for 8 days) for elderly patients and for patients in developing countries who frequently harbor enteric rods subgingivally. Scaling to remove dental calculus and the prudent use of inexpensive antimicrobial agents can significantly retard or arrest progressive periodontitis in the great majority of patients.

Clinical and microbiologic results 12 months after scaling and root planing with different irrigation solutions in patients with moderate chronic periodontitis: a pilot randomized trial

BACKGROUND

The aim of this study is to determine in a randomized trial the impact on treatment outcome after 12 months of different subgingival irrigation solutions during scaling and root planing (SRP).

METHODS

Fifty-one adult volunteers with generalized chronic periodontitis were treated by full-mouth SRP using 0.9% sodium chloride, 0.12% chlorhexidine digluconate, or 7.5% povidone-iodine for subgingival irrigation during SRP. Before SRP and after 3 and 12 months, probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) were recorded. Subgingival plaque samples were analyzed for Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola.

RESULTS

PD, CAL, and BOP were significantly improved in all groups after 12 months (P <0.001 to P = 0.044). No significant differences were seen among the groups for all sites and sites with 4 to 6 mm PD at baseline. The povidone-iodine group had the highest clinical improvements. The counts of A. actinomycetemcomitans and P. gingivalis were significantly reduced after 12 months (P = 0.045 and P = 0.002) using povidone-iodine. Significant differences between the groups were seen after 3 months for A. actinomycetemcomitans and P. gingivalis, and after 12 months for T. forsythia.

CONCLUSIONS

No differences were seen among the groups in the clinical results after 12 months. Regarding the microbiologic results, a slight benefit seemed to derive from the use of povidone-iodine.

Orthodontically assisted vertical augmentation in the esthetic zone

Severe periodontal disease leading to tooth loss causes multiple challenges when treatment planning replacement of these teeth with implant-supported restorations. Provisionalization and transitioning the patient from natural dentition to implant-supported restorations without use of removable prostheses can be difficult to achieve. A detailed evaluation and comprehensive treatment plan should precede extraction of the affected teeth. Forced eruption as a method of modifying the osseous and gingival topography has been established. This clinical report illustrates the use of nonmaintainable teeth to simultaneously develop the site for future implant placement, as well as support a fixed interim restoration during treatment. Patient was classified as an American College of Prosthodontists Prosthodontic Diagnostic Index (ACP PDI) class IV patient.

A fluorescence assay to determine the viable biomass of microcosm dental plaque biofilms

Dental plaque bacteria form complex and robust cell aggregates which cannot be counted accurately using epifluorescence microscopy. This causes a significant problem for quantifying their viability. The aim of the investigation was to develop a fluorescence assay to quantify the viable biomass of dental plaque biofilms. Using an artificial mouth system, microcosm plaques were grown under a range of fluoride and mineralizing conditions, and were treated with the oral antiseptics chlorhexidine (CHX) and Listerine. Plaques were harvested, made into suspension and stained in microtitre plates with a di-chromatic fluorescent stain (Live/Dead BacLight). The percentage of viable biomass was calculated from the regression data generated from a viability standard. The standard was constructed using different proportions of viable (green fluorescence) and non-viable (red fluorescence) plaque bacteria, and growth conditions for optimizing green fluorescence were investigated. The results from the assay showed that fluoride at 1000 and 3000 ppm promoted plaque viability by at least 15%, from approximately 45 to 60%, and at 5000 ppm to approximately 87% (P<0.05). Plaques treated with Listerine and CHX from d 0 yielded insufficient biomass to be tested for viability, however 14 d post-treatment, viability was comparable to untreated plaques (approximately 55%, P>0.05). Treatment with Listerine and CHX from d 3 reduced biomass but not viability. Development of this assay enabled viability of plaque bacteria which cannot be resolved with epifluorescence microscopy to be evaluated. It offers a rapid alternative to epifluorescence microscopy and could be applied to nonoral bacteria.

Efficacy of gasiform ozone and photodynamic therapy on a multispecies oral biofilm in vitro

Ozone gas and photodynamic therapy (PDT) have been claimed to be antimicrobially effective. This study assessed their antimicrobial potential in vitro. Mature six-species oral biofilms were treated as follows (n = 9 per group): (i) a 60-s application of gasiform vacuum-ozone or vacuum alone (on wet or air-dried biofilm samples); (ii) PDT (i.e. methylene blue in combination with or without a diode soft laser, and a soft laser alone); or (iii) antimicrobial solutions: immersion of biofilms for 60 s in 0.2 and 2% chlorhexidine or in 0.5 and 5% hypochlorite solution. Treatment with chlorhexidine or hypochlorite served as a positive control, whereas untreated samples served as negative controls. Colony-forming units on blood agar were counted. Only the 5% hypochlorite solution was able to totally eliminate the microorganisms in the biofilm. The observed reduction of viable counts by vacuum-ozone application and PDT was less than one log(10) step. Under the conditions of the current study, gasiform ozone and PDT had a minimal effect on the viability of microorganisms organized in a cariogenic biofilm.

Inhibition of Porphyromonas gingivalis proteinases (gingipains) by chlorhexidine: synergistic effect of Zn(II)

BACKGROUND/AIMS

Gingipains, proteolytic enzymes produced by the periodontal pathogen Porphyromonas gingivalis, are regarded as virulence factors in the pathogenesis of periodontitis. Inhibition of gingipain activity therefore may have therapeutic potential, and it has been suggested that chlorhexidine may inhibit the activities of these enzymes. The purposes of the present study were to examine systematically the inhibitory effects of chlorhexidine on three purified gingipains and to determine the effect of Zn(II) on chlorhexidine inhibition.

METHODS

The activities of lys-gingipain (Kgp) and two forms of arg-gingipain (RgpB and HRgpA) were measured in the presence of varying concentrations of chlorhexidine and with chlorhexidine supplemented with Zn(II). Inhibition constants (K(i)'s) were determined for chlorhexidine alone and in the presence of Zn(II). Fractional inhibitory constant indices were calculated to assess the synergy of the chlorhexidine-Zn(II) inhibition.

RESULTS

RgpB, HRgpA, and Kgp were all inhibited by chlorhexidine with K(i)'s in the micromolar range. For RgpB and HRgpA, the inhibitory effects of chlorhexidine were enhanced 3-30-fold by Zn(II). The chlorhexidine-Zn(II) interaction was synergistic for inhibition of HRgpA and RgpB. For Kgp, the effect of Zn(II) on chlorhexidine inhibition was antagonistic.

CONCLUSIONS

Chlorhexidine is an effective inhibitor of gingipains, and the inhibition of R-gingipains is enhanced by Zn(II). A mixture of chlorhexidine and Zn(II) may be useful as an adjunct in the treatment of periodontitis and in the post-treatment maintenance of periodontitis patients.

Update on human cytomegalovirus in destructive periodontal disease

AIM

Human cytomegalovirus (HCMV), a herpesvirus, is discussed in this review as it relates to destructive periodontal disease in humans.

RESULTS

HCMV genomic sequences, detected by polymerase chain reaction identification, occur with elevated frequency in severe adult periodontitis, localized and generalized aggressive (juvenile) periodontitis, Papillon-Lefèvre syndrome periodontitis, acute necrotizing ulcerative gingivitis, and periodontal abscesses.

DISCUSSION

Herpesviruses establish lifelong persistent infections. HCMV infection involves an asymptomatic latent phase interrupted by periods of recrudescence where viral replication and possibly clinical disease become manifest. HCMV reactivation is triggered by a number of immunosuppressive factors, some of which have been shown also to be risk factors/indicators of periodontitis. HCMV periodontal infection may cause release of tissue-destructive cytokines, overgrowth of pathogenic periodontal bacteria, and initiation of cytotoxic or immunopathologic events.

CONCLUSIONS

A growing body of data supports the concept that HCMV contributes to severe types of periodontal disease. HCMV infection of the periodontium may alter the immune control of resident microorganisms and be important in a multistage pathogenesis of periodontitis involving viral activation, periodontopathic bacteria, and host immune responses. Understanding the significance of HCMV and other herpesviruses in the development of periodontal disease may have important therapeutic implications. Vaccines against HCMV, which are in various stages of development, need to be evaluated for their ability to decrease the incidence of destructive periodontal disease.