Training in the use of the water jet and cold atmospheric plasma jet for the decontamination of dental implants.

OBJECTIVES: Clinical trials testing new devices require prior training on dummies to minimize the "learning curve" for patients. Dentists were trained using a novel water jet device for mechanical cleaning of dental implants and with a novel cold plasma device for surface functionalisation during a simulated open flap peri-implantitis therapy. The hypothesis was that there would be a learning curve for both devices. MATERIALS AND METHODS: 11 dentists instrumented 44 implants in a dummy-fixed jaw model. The effect of the water jet treatment was assessed as stain removal and the effect of cold plasma treatment as surface wettability. Both results were analysed using photographs. To improve treatment skills, each dentist treated four implants and checked the results immediately after the treatment as feedback. RESULTS: Water jet treatment significantly improved from the first to the second implant from 62.7% to 75.3% stain removal, with no further improvement up to the fourth implant. The wettability with cold plasma application reached immediately a high level at the first implant and was unchanged to the 4th implant (mean scores 2.7 out of 3). CONCLUSION: A moderate learning curve was found for handling of the water jet but none for handling of the cold plasma. CLINICAL RELEVANCE: Scientific rational for study: Two new devices were developed for peri-implantitis treatment (Dental water jet, cold plasma). Dentists were trained in the use of these devices prior to the trial to minimize learning effects. PRINCIPAL FINDINGS: Experienced dentists learn the handling of the water jet very rapidly and for cold plasma they do not need much training. PRACTICAL IMPLICATIONS: A clinical study is in process. When the planned clinical study will be finished, we will find out, if this dummy head exercise really minimised the learning curve for these devices.

In-vitro biofilm removal from TiUnite® implant surface with an air polishing and two different plasma devices.

BACKGROUND: We investigated the efficacy of two different cold atmospheric pressure jet plasma devices (CAP09 and CAPmed) and an air polishing device with glycine powder (AP) either applied as monotherapies or combined therapies (AP + CAP09; AP + CAPmed), in microbial biofilm removal from discs with anodised titanium surface. METHODS: Discs covered with 7-day-old microbial biofilm were treated either with CAP09, CAPmed, AP, AP + CAP09 or AP + CAPmed and compared with negative and positive controls. Biofilm removal was assessed with flourescence and electron microscopy immediately after treatment and after 5 days of reincubation of the treated discs. RESULTS: Treatment with CAP09 or CAPmed did not lead to an effective biofilm removal, whereas treatment with AP detached the complete biofilm, which however regrew to baseline magnitude after 5 days of reincubation. Both combination therapies (AP + CAP09 and AP + CAPmed) achieved a complete biofilm removal immediately after cleaning. However, biofilm regrew after 5 days on 50% of the discs treated with the combination therapy. CONCLUSION: AP treatment alone can remove gross biofilm immediately from anodised titanium surfaces. However, it did not impede regrowth after 5 days, because microorganisms were probably hidden in holes and troughs, from which they could regrow, and which were inaccessible to AP. The combination of AP and plasma treatment probably removed or inactivated microorganisms also from these hard to access spots. These results were independent of the choice of plasma device.

In-Vitro Biofilm Removal Efficacy Using Water Jet in Combination with Cold Plasma Technology on Dental Titanium Implants.

Peri-implantitis-associated inflammation can lead to bone loss and implant failure. Current decontamination measures are ineffective due to the implants' complex geometry and rough surfaces providing niches for microbial biofilms. A modified water jet system (WaterJet) was combined with cold plasma technology (CAP) to achieve superior antimicrobial efficacy compared to cotton gauze treatment. Seven-day-old multi-species-contaminated titanium discs and implants were investigated as model systems. The efficacy of decontamination on implants was determined by rolling the implants over agar and determining colony-forming units supported by scanning electron microscopy image quantification of implant surface features. The inflammatory consequences of mono and combination treatments were investigated with peripheral blood mononuclear cell surface marker expression and chemokine and cytokine release profiles on titanium discs. In addition, titanium discs were assayed using fluorescence microscopy. Cotton gauze was inferior to WaterJet treatment according to all types of analysis. In combination with the antimicrobial effect of CAP, decontamination was improved accordingly. Mono and CAP-combined treatment on titanium surfaces alone did not unleash inflammation. Simultaneously, chemokine and cytokine release was dramatically reduced in samples that had benefited from additional antimicrobial effects through CAP. The combined treatment with WaterJet and CAP potently removed biofilm and disinfected rough titanium implant surfaces. At the same time, non-favorable rendering of the surface structure or its pro-inflammatory potential through CAP was not observed.

Reliability of probing depth assessments at healthy implant sites and natural teeth.

AIM: To evaluate the intra- and inter-examiner reliability in the assessment of probing depth (PD) measurements at healthy dental implant sites and periodontally healthy natural teeth. MATERIALS AND METHODS: Five patients exhibiting 21 dental implants were enrolled in the study. Eight experienced examiners performed duplicate PD measurements at six sites of all implants and of preselected natural teeth. Intra-examiner accuracy was estimated using intra-examiner correlation coefficients (ICCs) with 95% confidence intervals (CI). A gold standard (GS) examiner was set. Inter-examiner accuracy compared to the GS examiner was assessed using pairwise inter-examiner ICCs. RESULTS: The intra-examiner ICC ranged from 0.759 (95% CI, 0.692-0.812) to 0.863 (95% CI, 0.826-0.892) for the measurements at teeth and from 0.712 (95% CI, 0.580-0.800) to 0.841 (95% CI, 0.774-0.888) for the PDs assessed at implants. The inter-examiner ICCs for tooth measurements varied from 0.197 (95% CI, - 0.280 to 0.511) to 0.791 (95% CI, 0.560-0.892). The corresponding values for the assessments at implants varied from 0.576 (95% CI, 0.286-0.734) to 0.794 (95% CI, 0.708-0.855). CONCLUSIONS: The intra- and inter-examiner reproducibility of repeated PD measurements assessed by experienced examiners tended to be higher for the measurements at periodontally healthy teeth compared to healthy dental implant sites. CLINICAL RELEVANCE: Experienced examiners demonstrated a higher degree of reliability of probing measurements around teeth compared to dental implants.

Efficiency of biofilm removal by combination of water jet and cold plasma: an in-vitro study.

BACKGROUND: Peri-implantitis therapy is a major problem in implantology. Because of challenging rough implant surface and implant geometry, microorganisms can hide and survive in implant microstructures and impede debridement. We developed a new water jet (WJ) device and a new cold atmospheric pressure plasma (CAP) device to overcome these problems and investigated aspects of efficacy in vitro and safety with the aim to create the prerequisites for a clinical pilot study with these medical devices. METHODS: We compared the efficiency of a single treatment with a WJ or curette and cotton swab (CC) without or with adjunctive use of CAP (WJ + CAP, CC + CAP) to remove biofilm in vitro from rough titanium discs. Treatment efficacy was evaluated by measuring turbidity up to 72 h for bacterial re-growth or spreading of osteoblast-like cells (MG-63) after 5 days with scanning electron microscopy. With respect to application safety, the WJ and CAP instruments were examined according to basic regulations for medical devices. RESULTS: After 96 h of incubation all WJ and CC treated disks were turbid but 67% of WJ + CAP and 46% CC + CAP treated specimens were still clear. The increase in turbidity after WJ treatment was delayed by about 20 h compared to CC treatment. In combination with CAP the cell coverage significantly increased to 82% (WJ + CAP) or 72% (CC + CAP), compared to single treatment 11% (WJ) or 10% (CC). CONCLUSION: The newly developed water jet device effectively removes biofilm from rough titanium surfaces in vitro and, in combination with the new CAP device, biologically acceptable surfaces allow osteoblasts to grow. WJ in combination with CAP leads to cleaner surfaces than the usage of curette and cotton swabs with or without subsequent plasma treatment. Our next step will be a clinical pilot study with these new devices to assess the clinical healing process.

Tooth loss in periodontally treated patients: A registry- and observation-based analysis.

AIM: According to retrospective clinical studies, periodontal treatment retains teeth. However, evidence on the effectivity of periodontal treatment stemming from the general population is lacking. MATERIALS AND METHODS: We analysed data of periodontally treated patients from routine data of a major German national health insurance (BARMER-MV; sub-sample of the Federal State of Mecklenburg-Vorpommern) and from a clinical cohort (Greifswald Approach to Individualized Medicine, GANI_MED), as well as periodontally untreated and treated participants of the Study of Health in Pomerania (SHIP-TREND) with either ≥2 or ≥4 teeth with pocket depths ≥4 mm. Yearly tooth loss (YTL) estimates and incidence rates were evaluated. RESULTS: For moderately to severely affected groups, YTL and incidence rates were higher in BARMER-MV patients (0.35 and 0.18, respectively) than in untreated SHIP-TREND controls (0.19 and 0.08, respectively). In line, treated SHIP-TREND participants exhibited higher YTL rates than untreated SHIP-TREND controls (0.26 vs. 0.19). For severely affected groups, results with respect to tooth loss were inconclusive regarding the beneficial effects of periodontal treatment conducted either in the university (GANI_MED data) or in the general practice. CONCLUSION: Until 2021, periodontal treatment performed in German general dental practices within the national health insurance system was probably not efficient in retaining more teeth in the short- to mid-term. Since reimbursement schemes were changed in 2021 and now cover periodontal treatment to a much larger extent, the future will show whether these new reimbursement codes will improve the quality of periodontal treatment and whether they will lead to more long-term tooth retainment.

Efficiency of cold atmospheric plasma, cleaning powders and their combination for biofilm removal on two different titanium implant surfaces.

OBJECTIVES: Biofilm removal is the decisive factor for the control of peri-implantitis. Cold atmospheric pressure plasma (CAP) can become an effective aid due to its ability to destroy and to inactivate bacterial biofilm residues. This study evaluated the cleaning efficiency of CAP, and air-polishing with glycine (APG) or erythritol (APE) containing powders alone or in combination with CAP (APG + CAP, APE + CAP) on sandblasted/acid etched, and anodised titanium implant surface. MATERIALS AND METHODS: On respective titanium discs, a 7-day ex vivo human biofilm was grown. Afterwards, the samples were treated with CAP, APG, APE, APG + CAP, and APE + CAP. Sterile and untreated biofilm discs were used for verification. Directly after treatment and after 5 days of incubation in medium at 37 °C, samples were prepared for examination by fluorescence microscopy. The relative biofilm fluorescence was measured for quantitative analyses. RESULTS: Air-polishing with or without CAP removed biofilms effectively. The combination of air-polishing with CAP showed the best cleaning results compared to single treatments, even on day 5. Immediately after treatment, APE + CAP showed insignificant higher cleansing efficiency than APG + CAP. CONCLUSIONS: CAP supports mechanical cleansing and disinfection to remove and inactivate microbial biofilm on implant surfaces significantly. Here, the type of the powder was not important. The highest cleansing results were obtained on sandblasted/etched surfaces. CLINICAL RELEVANCE: Microbial residuals impede wound healing and re-osseointegration after peri-implantitis treatment. Air-polishing treatment removes biofilms very effectively, but not completely. In combination with CAP, microbial free surfaces can be achieved. The tested treatment regime offers an advantage during treatment of peri-implantitis.

Enzymatic biofilm destabilisation to support mechanical cleansing of inserted dental implant surfaces: an in-vitro pilot study.

Peri-implantitis is caused by microbial contamination and biofilm formation on the implant surface. To achieve re-osseointegration, the microbes must be completely removed from the surface. Adjunctive to mechanical cleaning, chemical treatment with enzymes or other substances could optimise the treatment outcome. Therefore, we investigated the efficacy of different enzymes, a surfactant, and a chelator in destabilising dental polymicrobial biofilm. The biofilm destabilising effect of the glycosidases α-amylase, dextranase, DispersinB®, and lysozyme, as well as the proteinase subtilisin A, and the nuclease Benzonase®, the chelator EDTA, and the surfactant cocamidopropyl betaine were investigated on biofilms, inoculated with plaque on rough titanium discs. The test and the control solutions were incubated for 15 min at 36 °C on biofilms, and loosened biofilm mass was removed by shear stress with a shaker. Fluorescence-stained biofilms were microscopically analysed. Acceptable cell tolerability concentrations of test substances were determined by the MTT (tetrazolium dye) assay on the MG-63 cell line. A statistically significant biofilm destabilising effect of 10% was shown with lysozyme (2500 µg/ml).

At which bone level are implants explanted?

OBJECTIVES: Clear guidelines when to remove an implant are missing. The aim of this study was to evaluate the amount of peri-implant bone loss at explantation by specialists. MATERIAL AND METHODS: Implantology specialists were asked to provide implants explanted due to peri-implantitis with related clinical information. Early failures (survival time <12 months) were analyzed separately. Questionnaires inquired age, sex, smoking, implant location, usage of bone substitutes, and implant brand. Explants were measured and bone loss was assessed using radiographs. Covariate-adjusted mixed-effects models were evaluated for bone loss and survival time. RESULTS: Twelve dental offices provided 192 explants from 161 patients with 99 related radiographs. Thirty-three (17.2%) explants were early failures. Excluding early failures, average survival time was 9.5 ± 5.8 years with absolute and relative bone loss of 7.0 ± 2.7 mm and 66.2 ± 23.7%, respectively. Late failures were removed at mean bone loss of 57.7% in the maxilla and 73.7% in the mandible irrespective of survival time. In fully adjusted mixed-effects models, only age at implantation (B = -0.19; 95% CI: -0.27, -0.10) remained a significant factor for survival time. Implants exhibited significantly more relative bone loss if they were positioned in the mandible (B = 17.3; 95% CI: 3.91, 30.72) or if they were shorter (B = -2.79; 95% CI: -5.50, -0.08). CONCLUSIONS: Though the mean bone loss (66.2%) at which implants were explanted was in accordance with the literature, its wide variation and differentiation between jaws showed that the profession has no universally accepted threshold beyond which an implant cannot be preserved.

Effects of cold atmospheric pressure plasma and disinfecting agents on Candida albicans in root canals of extracted human teeth.

Reinfection in endodontically treated teeth is linked to the complexity of the root canal system, which is problematic to reach with conventional disinfection methods. As plasma is expected to have the ability to sanitize narrow areas, the aim of this study was to analyze the effect of cold atmospheric pressure plasma (CAP) on Candida albicans in root canals of extracted human teeth. CAP was applied as mono treatment and in combination with standard endodontic disinfectants (sodium hypochlorite, chlorhexidine and octenidine). Disinfection efficiency was evaluated as reduction of the logarithm of colony forming units per milliliter (log10 CFU/mL) supported by scanning electron microscopy as imaging technique. Plasma alone showed the highest reduction of log10 CFU, suggesting the best disinfection properties of all tested agents.

Fibroblast Growth on Zirconia Ceramic and Titanium Disks After Application with Cold Atmospheric Pressure Plasma Devices or with Antiseptics

PURPOSE: Fast wound healing after abutment connection may reduce infectious complications. Cold atmospheric pressure plasma can increase the hydrophilicity of abutment surfaces, and therefore, the cell attachment, cell density, and sealing could improve to hamper microbial penetration into the wound cavity. In this in vitro study, the effect of three different plasma devices and common antiseptics on cell growth after treatment on zircon ceramic and titanium disks was analyzed. MATERIALS AND METHODS: Specimens were treated for 5 minutes with the plasma devices kINPen 08, kINPen 09, or kINPen Chamber and for 15 minutes with the antiseptics chlorhexidine digluconate (0.2%), octenidine (0.1%), and ethanol (70%). After treatment, primary human fibroblast cells (HGF-1) were seeded and incubated for 1 and 24 hours. The cell area after 1 hour and cell density after 24 hours were analyzed by scanning electron microscopy images. RESULTS: Water contact angles of both surfaces (95/96 degrees) were significantly reduced to 26 to 36 degrees (titanium) or 9 to 28 degrees (zircon ceramic) after plasma treatment. Only on titanium, the average cell area was significantly increased after 1-hour cell incubation following kINPen 08 and kINPen 09 treatment. No significant differences between all three plasma devices and the untreated control were determined on both materials after 24 hours, whereas octenidine and chlorhexidine reduced cell surface covering. The cell density was significantly lower for all treatment regimens except octenidine on zircon ceramic compared with titanium. CONCLUSION: Plasma reduced the water contact angle and supported cell covering on titanium in the early stage. Plasma devices had no discernible influence on cell covering after 24-hour cell incubation, whereas chlorhexidine and octenidine hampered cell covering on both abutment surfaces.

Side effects by oral application of atmospheric pressure plasma on the mucosa in mice.

Cold atmospheric pressure plasma (CAP) has been investigated with promising results for peri-implant diseases treatment. However, prior to in-vivo applications of CAP sources in humans, short-term harmful mucosal damage or other unwanted side effects have to be reviewed. 180 male mice (B6C3F1) were divided into twelve treatment groups (n = 15). The right buccal cheek mucosa was treated with CAP. The first and second group each received continuous 10 sec irradiation with 2 different plasma sources (kINPen09, PS-MWM). The third group was treated with the kINPen09 for one minute. Control groups were treated with a corresponding dose of ultraviolet light for 8 seconds or 48 seconds and the other one was left untreated. The animals were weighed before and after treatment. The animals were sacrificed one day or one week after exposure. Stained tissue samples were histologically examined for tissue damage independently by two experienced pathologists. One day after CAP treatment histological analysis showed focal mucosal erosion with superficial ulceration and necrosis accompanied by a mild inflammatory reaction. One week after CAP treatment, the mucosal defects were completely re-epithelialized, associated with remnants of granulation tissue in the stroma irrespective of treatment duration. Furthermore, no cytological atypia was found and no severe weight loss occurred. The control groups did not show any alterations at all. CAP treatment led to a superficial mucosal damage that healed within few days. Nonetheless, further long-term experiments are necessary to exclude undesirable side effects after longer observation time. Particularly, potential carcinogenic effects must be ruled out prior to the application of CAP treatment in daily dental practice.

Osteoblast growth, after cleaning of biofilm-covered titanium discs with air-polishing and cold plasma.

AIM: To investigate the effects of a combined biofilm removal with an optimized air polishing and a cold plasma device on cells in vitro. MATERIALS AND METHODS: A 7-day-old biofilm was removed from rough titanium discs with an air-polishing device with erythritol powder (AP) or with a cold atmospheric pressure argon plasma (CAP) device or in combination of both (AP + CAP). The removal efficacy was evaluated by subsequent cell seeding of osteoblast-like cells (MG-63). The cell spreading was analysed after 5 days of incubation by scanning electron microscopy. Separately, the surface hydrophilicity was analysed by measuring the water contact angle (WCA) of the disc for each treatment method. RESULTS: The mechanical plaque removal with AP rendered specimen conducive for cell growth, 85% of the surface was covered with cells. An advantage of the combination of AP + CAP was not detectable compared to AP (cell coverage ranged from 57% up to 75%). After sole CAP treatment, microorganisms re-grew and destroyed all cells. The WCA was reduced by all treatment methods. CONCLUSION: An AP treatment has the potential to remove biofilm from rough implant surfaces completely. In contrast to our hypothesis, the combination of plasma and AP treatment did not enhance osteoblast spreading.

Removal of naturally grown human biofilm with an atmospheric pressure plasma jet: An in-vitro study.

The removal of biofilm is a prerequisite for a successful treatment of biofilm-associated diseases. In this study, we compared the feasibility of an atmospheric pressure plasma device with a sonic powered brush to remove naturally grown supragingival biofilm from extracted teeth. Twenty-four periodontally hopeless teeth were extracted. Argon jet plasma with an oxygen admixture of 1 vol% and a sonically driven brush were used to remove biofilm with application times of 60 s, 180 s and 300 s. The treatment efficiency was assessed with light microscopy, scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The highest biofilm removal rate was observed after an application time of 180 s/300 s with the sonic brush (80.4%/86.2%), plasma (75.5%/89.0%). These observations were confirmed by SEM. According to XPS analysis, plasma treatment decreased the amount of carbon and nitrogen, indicative of an extensive removal of proteins. Plasma treatment of naturally grown biofilm resulted in an effective cleaning of the tooth surface and was comparable to mechanical treatment. Treatment time had a significant influence on plaque reduction. These results showed that plasma could be a useful adjuvant treatment modality in cases where biofilm removal or reduction plays a decisive role, such as periodontitis and peri-implantitis. Plasma-treated biofilm on an extracted tooth.

Longitudinal effects of systemic inflammation markers on periodontitis.

AIM: Systemic low-grade inflammation represents a central hallmark of chronic diseases and has been proposed as the underlying mechanism linking factors like obesity or diabetes with periodontitis. However, the impact of inflammatory markers on periodontitis has not yet been investigated. MATERIALS AND METHODS: The study population comprised 1784 subjects from the Study of Health in Pomerania with complete 11-year follow-up. Fibrinogen and white blood cell (WBC) counts were measured as markers of inflammation. Periodontitis was assessed by probing depth (PD), clinical attachment loss (CAL) and the CDC/AAP case definition. RESULTS: Multilevel regression analyses revealed significant coefficients for the impact of both inflammation markers on the percentage of sites with PD/CAL ≥ 3 mm. Increases in fibrinogen about 1 g/l were associated with 3.0% and 2.7% more sites with PD/CAL ≥ 3 mm respectively. Consistent associations were found using mean values of PD/CAL but not using missing teeth or caries. Regarding the CDC/AAP case definition, 11-year changes in fibrinogen and WBC counts were significantly associated with ≥1 category progression (OR: 1.36 and 1.11). CONCLUSIONS: Fibrinogen levels and WBC counts showed consistent long-term associations with PD, CAL and the CDC/AAP case definition. Results indicate that systemic low-grade inflammation might indeed represent one possible pathway for effects of obesity, diabetes or other chronic inflammatory conditions on periodontitis.

In vitro treatment of Candida albicans biofilms on denture base material with volume dielectric barrier discharge plasma (VDBD) compared with common chemical antiseptics.

OBJECTIVES: To prevent oral candidiasis, it is crucial to inactivate Candida-based biofilms on dentures. Common denture cleansing solutions cannot sufficiently inactivate Candida albicans. Therefore, we investigated the anticandidal efficacy of a physical plasma against C. albicans biofilms in vitro. MATERIALS AND METHODS: Argon or argon plasma with 1 % oxygen admixture was applied on C. albicans biofilms grown for 2, 7, or 16 days on polymethylmethacrylate discs; 0.1 % chlorhexidine digluconate (CHX) and 0.6 % sodium hypochlorite (NaOCl) solutions served as positive treatment controls. In addition, these two solutions were applied in combination with plasma for 30 min to assess potential synergistic effects. The anticandidal efficacy was determined by the number of colony forming units (CFU) in log(10) and expressed as reduction factor (RF, the difference between control and treated specimen). RESULTS: On 2-day-biofilms, plasma treatment alone or combined with 30 min CHX treatment led to significant differences of means of CFU (RF = 4.2 and RF = 4.3), clearly superior to CHX treatment alone (RF = 0.6). Plasma treatment of 7-day-or 16-day-old biofilms revealed no significant CFU reduction. The treatment of 7-day-old (RF = 1.7) and 16-day-old (RF = 1.3) biofilms was slightly more effective with NaOCl alone than with the combined treatment of NaOCl and plasma (RF = 1.6/RF = 1.9). The combination of CHX and plasma increased the RF immaterially. CONCLUSION: The use of plasma alone and in combination with antiseptics is promising anticandidal regimens for daily use on dentures when biofilms are not older than 2 days. CLINICAL RELEVANCE: Plasma could help to reduce denture-associated candidiasis.

Cold atmospheric plasma in combination with mechanical treatment improves osteoblast growth on biofilm covered titanium discs.

Treatment of implants with peri-implantitis is often unsuccessful, because an instrumented implant surface and residual microbial biofilm impedes re-osseointegration. The application of cold atmospheric plasma (CAP) could be a simple and effective strategy to overcome the inherent problems of peri-implantitis treatment. CAP is able to destroy and eliminate bacterial biofilms. Additionally, it increases the wettability of titanium, which supports cellular attachment. In this study, the behaviour of osteoblasts on titanium discs was analysed after treatment of bacterial biofilms with CAP, brushing, or a combination of both. A human plaque biofilm was cultured on titanium discs. Treatment with a brush (BR), 1% oxygen/argon CAP (PL), or brushing combined with CAP (BR+PL) was used to eliminate the biofilm. Discs without biofilm (C), autoclaved biofilm (AUTO) and untreated biofilm (BIO) served as controls. Subsequently, human osteoblastic cell growth (MG-63) was observed after 1 and 24 h. Biofilm remnants on BR and PL impaired osteoblastic cell development, whereas the BR+PL provided an increased area of osteoblastic cells. A five-day cell growth was only detectable on BR+PL treated discs. The combination of established brushing and CAP application may be a promising strategy to treat peri-implantitis.

Abdominal obesity modifies long-term associations between periodontitis and markers of systemic inflammation.

OBJECTIVE: Periodontitis is considered to promote atherosclerosis and cardiovascular diseases through increased low-grade systemic inflammation. However, there is no information on the long-term impact of periodontitis on systemic inflammation from cohort studies. Thus, this study aims to assess the impact of periodontitis on systemic inflammation (fibrinogen and white blood cells (WBC)) in a population-based longitudinal survey in north-eastern Germany. METHODS: The study sample comprised 2622 subjects from the Study of Health in Pomerania with complete 5- and 11-year follow-ups. Periodontitis was assessed by probing depth and clinical attachment level. Multilevel regression analyses were applied to evaluate associations between periodontitis measures and i) fibrinogen/WBC count using 11-year follow-up data and ii) respective z-scores of fibrinogen/WBC count using 5- and 11-year follow-up data. We adjusted for common cardiovascular risk factors and stratified analyses by abdominal obesity (P for interaction <0.10). RESULTS: In lean subjects, beta-coefficients of mean probing depth were B = 0.13 (0.08-0.019; P < 0.001) for fibrinogen and B = 0.50 (0.37-0.64; P < 0.001) for WBC count using 11-year follow-up data only. For lean subjects, models using z-scores confirmed that increased mean probing depths were associated with increased fibrinogen z-scores (B = 0.14 (0.09-0.18; P < 0.001)) and increased WBC z-scores (B = 0.16 (0.11-0.20; P < 0.001)). Consistent results were found for mean clinical attachment levels. For abdominally obese subjects, relations between periodontitis measures and levels of inflammation markers were less pronounced or non-significant. CONCLUSION: Modified by abdominal obesity, periodontitis affected systemic inflammation in a significant dose-dependent manner. Results contribute to the discussion on how periodontitis is linked to atherosclerosis and cardiovascular diseases.

Synergistic Effects of Nonthermal Plasma and Disinfecting Agents against Dental Biofilms In Vitro.

Aim. Dental biofilms play a major role in the pathogenesis of many dental diseases. In this study, we evaluated the synergistic effect of atmospheric pressure plasma and different agents in dentistry on the reduction of biofilms. Methods and Results. We used monospecies (S. mutans) and multispecies dental biofilm models grown on titanium discs in vitro. After treatment with one of the agents, the biofilms were treated with plasma. Efficacy of treatment was determined by the number of colony forming units (CFU) and by live-dead staining. For S. mutans biofilms no colonies could be detected after treatment with NaOCl or H2O2. For multispecies biofilms the combination with plasma achieved a higher CFU reduction than each agent alone. We found an additive antimicrobial effect between argon plasma and agents irrespective of the treatment order with cultivation technique. For EDTA and octenidine, antimicrobial efficacy assessed by live-dead staining differed significantly between the two treatment orders (P < 0.05). Conclusions. The effective treatment of dental biofilms on titanium discs with atmospheric pressure plasma could be increased by adding agents in vitro.

Atmospheric pressure plasma: a high-performance tool for the efficient removal of biofilms.

INTRODUCTION: The medical use of non-thermal physical plasmas is intensively investigated for sterilization and surface modification of biomedical materials. A further promising application is the removal or etching of organic substances, e.g., biofilms, from surfaces, because remnants of biofilms after conventional cleaning procedures are capable to entertain inflammatory processes in the adjacent tissues. In general, contamination of surfaces by micro-organisms is a major source of problems in health care. Especially biofilms are the most common type of microbial growth in the human body and therefore, the complete removal of pathogens is mandatory for the prevention of inflammatory infiltrate. Physical plasmas offer a huge potential to inactivate micro-organisms and to remove organic materials through plasma-generated highly reactive agents. METHOD: In this study a Candida albicans biofilm, formed on polystyrene (PS) wafers, as a prototypic biofilm was used to verify the etching capability of the atmospheric pressure plasma jet operating with two different process gases (argon and argon/oxygen mixture). The capability of plasma-assisted biofilm removal was assessed by microscopic imaging. RESULTS: The Candida albicans biofilm, with a thickness of 10 to 20 µm, was removed within 300 s plasma treatment when oxygen was added to the argon gas discharge, whereas argon plasma alone was practically not sufficient in biofilm removal. The impact of plasma etching on biofilms is localized due to the limited presence of reactive plasma species validated by optical emission spectroscopy.