1212 /mhj Introduction The plasma needle: A non-thermal atmospheric plasma for treatment of biological tissue Ingrid Kieft, Raymond Sladek, Eva Stoffels Department of Biomedical Engineering, Eindhoven University of Technology P.O.Box 513, 5600 MB Eindhoven, The Netherlands Cells and tissues (Ingrid Kieft) Dental cavities (Raymond Sladek) Plasma needle Cells: -lipids -proteins -DNA Teeth: -Bacteria -Heat and pain for pulp chamber -Hand-operated tool -Atmospheric glow discharge -Effects studied in biomedical field [1]  cells and tissues  dental cavities -No thermal damage Plasma parameters Plasma power < 100 mW Voltage peak to peak ~600 V Helium flow 2 l/min frequency13.56 MHz Detached cells followed in time. 1) control sample, 2) 15 min. after treatment, 3) 1 hour after treatment, 4) 4 hours after treatment Cross section of tissue engineered skin. Control sample (left) and sample treated for 5 min (right) Conclusions Cells detach after plasma treatment, and remain alive. They are capable of reattachment and cytokinesis. Radicals reach the liquid in fysiological concentrations. More molecules in plasma leads to less radicals. The high precision plasma treatment can have applications in wound healing and cancer treatment. Conclusions Little temperature increase (1-5 o C) in the gas Even less in dental tissue Teeth can be safely exposed to the plasma No pain is experienced Plasma treatment is a promising technique in dental care Colony forming units of E. coli as function of time of treatment by He plasma Colony forming units of E. coli References: [1] Stoffels,E., Kieft, I.E., Sladek, R.E.J., “Superficial treatment of mammalian cells using plasma needle”, J.Phys.D: Appl. Phys. 36 (2003) [2] Kieft, I.E., Broers, J.L.V., Caubet-Hilloutou, V., Slaaf, D.W., Ramaekers, F.C.S., Stoffels, E., “Electric discharge plasmas influence attachment of cultured CHO K1 cells”, accepted for publication in Bioelectromagnetics [3] Zach, L. and Cohen, G., “Pulp response to externally applied heat”, Oral Surgery, Oral Medicine, Oral Pathology, 19, no. 4, (1965) Research divided in 2 parts: -1. Cells and tissues: understanding of cell reactions and tissue damage -2. Dental cavities: Investigation of non-destructive and less painful tool to clean cavities - Use of cultured fibroblast cells as model system [2] - Cell detachment observed within 30 s - Radicals are expected to play major role in process:  Detected with fluorescent probe CM-H 2 DCFDA  Concentration in µM range ~ fysiological concentration - Air admixture to helium <1% (Raman scattering) -First experiments on tissue engineered skin (by D. Bronneberg)  vacuole formation and detachment Temperature measurements inside pulp chamber  Plasma can be safely applied for 60s:  T < 2.2 o C [3]  Temperature increases after plasma off - Time to kill 90 % of bacteria is about 40s. - After plasma treatment bacteria are plated on Agar culture dishes, colony forming units are counted - Bacterial cleaning: no need for 100 % decontamination - Decontamination efficiency tested on E. coli Temperature recorded by a PT-100 inserted in the root channel. From bottom to top: setting at 200, 230, 270, 300,340 mV Plasma switched off at t=60 s