Effect of sodium hypochlorite gel on bacteria associated with periodontal disease.

OBJECTIVES: An adjunct in non-surgical periodontal therapy might be sodium hypochlorite (NaOCl)-based agents. The purpose of the present in vitro study was to get deeper knowledge on the influence of different parameters as time after mixing, pH, and chemical composition of an amino acid 0.475% NaOCl (AA-NaOCl) gel consisting of two components on its anti-biofilm activity. MATERIALS AND METHODS: Six-species biofilms were cultured for 5 days, before AA-NaOCl gel was applied. In the different series, the influence of the time after mixing of the two components before application, of the concentration of NaOCl in the gel mixture, of the pH of the gel mixture, and of an exchange of the amino acid component by hyaluronic acid (HA), was analyzed. RESULTS: Mixing time point experiments showed that the AA-NaOCl gel is capable of statistically significantly reducing colony-forming unit (cfu) counts up to 30 min after mixing, but only up to 20 min after mixing the reduction was more than 2 log10 cfu. The pH experiments indicate that a reduced pH results in a reduced activity of the NaOCl formulation. NaOCl concentrations in the formulation in the range from 0.475 to 0.2% provide adequate activity on biofilms. A HA/NaOCl gel was equally active against the biofilm as the AA-NaOCl gel. CONCLUSION: Mixing of the components should be made in a timeframe of 20 min before applications. An optimization of the composition of the NaOCl formulation might be possible and should be a topic in further in vitro studies. CLINICAL RELEVANCE: The AA-NaOCl gel formulation can be mixed up to 20 min before application. Further, the study indicates that the composition of the NaOCl gel formulation can be optimized.

The In-Vitro Activity of a Cold Atmospheric Plasma Device Utilizing Ambient Air against Bacteria and Biofilms Associated with Periodontal or Peri-Implant Diseases.

Due to its antimicrobial and healing-promoting effects, the application of cold atmospheric plasma (CAP) appears to be a promising modality in various fields of general medicine and dentistry. The aim of the present study was to evaluate the antibacterial and anti-biofilm activity of a handheld device utilizing ambient air for plasma generation. Suspensions of 11 oral bacteria (among them Fusobacterium nucleatum, Porphyromonas gingivalis, Parvimonas micra, Streptococcus gordonii, and Tannerella forsythia) were exposed to CAP for 10, 30, 60, and 120 s. Before and after treatment, colony forming unit (CFU) counts were determined. Then, 12-species biofilms were cultured on dentin and titanium specimens, and CAP was applied for 30, 60, and 120 s before quantifying CFU counts, biofilm mass, and metabolic activity. A reduction of ≥3 log10 CFU, was found for ten out of the eleven tested species at 30 s (except for T. forsythia) and for all species at 60 s. For biofilm grown on dentin and titanium specimens, the log10 reductions were 2.43 log10 CFU/specimen and by about 4 log10 CFU/specimen after 120 s of CAP. The CAP application did not reduce the biomass significantly, the metabolic activity of the biofilms on dentin and titanium decreased by 98% and 95% after 120 s of CAP. An application of 120 s of CAP had no cytotoxic effect on gingival fibroblasts and significantly increased the adhesion of gingival fibroblasts to the titanium surface. These results are promising and underline the potential of CAP for implementation in periodontal and peri-implantitis therapy.

Periodontal microorganisms and Alzheimer disease - A causative relationship?

In the initiation or exacerbation of Alzheimer disease, the dissemination of oral microorganisms into the brain tissue or the low-level systemic inflammation have been speculated to play a role. However, the impact of oral microorganisms, such as Porphyromonas gingivalis, on the pathogenesis of Alzheimer disease and the potential causative relationship is still unclear. The present review has critically reviewed the literature by examining the following aspects: (a) the oral microbiome and the immune response in the elderly population, (b) human studies on the association between periodontal and gut microorganisms and Alzheimer disease, (c) animal and in vitro studies on microorganisms and Alzheimer disease, and (d) preventive and therapeutic approaches. Factors contributing to microbial dysbiosis seem to be aging, local inflammation, systemic diseases, wearing of dentures, living in nursing homes and no access to adequate oral hygiene measures. Porphyromonas gingivalis was detectable in post-mortem brain samples. Microbiome analyses of saliva samples or oral biofilms showed a decreased microbial diversity and a different composition in Alzheimer disease compared to cognitively healthy subjects. Many in-vitro and animal studies underline the potential of P gingivalis to induce Alzheimer disease-related alterations. In animal models, recurring applications of P gingivalis or its components increased pro-inflammatory mediators and ß-amyloid in the brain and deteriorated the animals' cognitive performance. Since periodontitis is the result of a disturbed microbial homoeostasis, an effect of periodontal therapy on the oral microbiome and host response related to cognitive parameters may be suggested and should be elucidated in further clinical trials.

The Antimicrobial Effect of Cold Atmospheric Plasma against Dental Pathogens-A Systematic Review of In-Vitro Studies.

Interest in the application of cold atmospheric plasma (CAP) in the medical field has been increasing. Indications in dentistry are surface modifications and antimicrobial interventions. The antimicrobial effect of CAP is mainly attributed to the generation of reactive oxygen and reactive nitrogen species. The aim of this article is to systematically review the available evidence from in-vitro studies on the antimicrobial effect of CAP on dental pathogens. A database search was performed (PubMed, Embase, Scopus). Data concerning the device parameters, experimental set-ups and microbial cultivation were extracted. The quality of the studies was evaluated using a newly designed assessment tool. 55 studies were included (quality score 31-92%). The reduction factors varied strongly among the publications although clusters could be identified between groups of set pathogen, working gases, and treatment time intervals. A time-dependent increase of the antimicrobial effect was observed throughout the studies. CAP may be a promising alternative for antimicrobial treatment in a clinically feasible application time. The introduced standardized protocol is able to compare the outcome and quality of in-vitro studies. Further studies, including multi-species biofilm models, are needed to specify the application parameters of CAP before CAP should be tested in randomized clinical trials.

Biofilm and Orthodontic Therapy.

Dental biofilms can cause major oral diseases like gingivitis, periodontitis, and caries. Orthodontic appliances promote supra- and subgingival biofilm accumulation, alter the oral microbiome, and hamper oral hygiene. Orthodontic treatment can be associated with adverse effects, such as enamel decalcification, gingivitis, and periodontal disease. The aim of this review is to summarize the changes in supra- and subgingival biofilm and periodontal tissues during and after orthodontic treatment. Studies have reported elevated levels of Streptococcus mutans and periodontopathogenic bacteria in patients undergoing orthodontic treatment. In general, the microbial changes and periodontal parameters decreased to pretreatment levels after appliance removal. Nevertheless, some adverse effects associated with orthodontic treatment are not reversible, such as enamel decalcifications caused by metabolic products of high levels of cariogenic bacteria. The evidence suggests that the roughness and constituents of the orthodontic materials influence the bacterial colonization. Therefore, several antibacterial orthodontic bonding systems, which show antibacterial effects in vitro, have been developed. The importance of adequate oral hygiene should be emphasized to all orthodontic patients. They should be frequently reminded and motivated to obtain a good oral hygiene. The evidence from the current literature suggests the safest way for orthodontic treatment in periodontally diseased patients may be after successful completion of the periodontal therapy. However, the exact time point needs to be better clarified in future studies.