Plasma treatment reduced contact angle and supported spreading of osteoblastic cells. The application of cold plasma may be supportive in the treatment of peri-implant lesions and may improve the process of re-osseointegration.

IntroductionThe 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.MethodIn 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.ResultsThe 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.

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.

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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.

The medical background of these investigations is periodontal disease which involves progressive loss of the connective tissue and alveolar bone around the teeth. Increased wettability of dentin or bone replacement materials (hydroxyapatite) may be supportive for successful periodontal regeneration. In this in vitro study, we investigated if an atmospheric pressure, non-thermal plasma process is able to enhance wettability of dentin and hydroxyapatite as well as if increased wettability translates into a higher spreading capacity of osteoblasts. Surface modification was performed with an atmospheric pressure plasma jet on hydroxyapatite, mammoth ivory and human dentin discs. We used three different plasma gas compositions (argon/þ0.2%oxygen/þ1% oxygen) with 30, 60 or 120 s application time. Water contact angles and cell spreading of MG-63 osteoblasts were measured before and after plasma treatment. Contact angles of the three investigated materials (dentin, hydroxyapatite and mammoth ivory: 52.008, 36.008 and 71.008, respectively) were significantly reduced after 120 s plasma application (13.908 AE 1.70, 0.008 AE 0.00 and 0.008 AE 0.00, respectively). The most effective contact angle reduction was observed after 60 or 120 s application of Ar þ 1%O 2 plasma. The cell area of osteoblasts grown on dentin treated with Ar þ 1%O 2 plasma was larger than on untreated dentin surfaces ( p < 0.05). The application of atmospheric plasma reduces the contact angle; the altered surface chemistry translates into a superior spreading of osteoblasts on dentin. These results may offer an additional approach to optimise periodontal regeneration.Plasma Process. Polym. 2011, 8, 975-982 ß

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.

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.