Transcript Investigation of possibilities for plasma treatment of dental caries

Investigation of possibilities for plasma
treatment of dental caries
R. Walraven, R.E.J. Sladek, I.E. Kieft, E. Stoffels, P.J.A. Tielbeek
Department of Biomedical Engineering, Eindhoven University of Technology,
P.O. Box 513, 5600 MB Eindhoven, The Netherlands
E-mail: [email protected]
Dental caries
In dentistry dental cavities (Figure 1) as a result of caries are a major problem. Cavities in
teeth can be cleaned and/or sterilised by mechanically drilling or laser techniques. In both
methods heating or vibrations can take place and this can be painful for the patient
(heating and vibrations can irritate the nerve).
Goal
Our goal is to find a less destructive (no fractures) and less
painful approach to clean dental cavities. This may be done by
use of a non-thermal atmospheric plasma.
Figure 1: Dental cavity
Temperature measurements
Temperature measurements were made by use of a thermo-couple.
The thermo-couple is inserted into the box via a rubber plug (Figure 2).
Three types of temperature measurements were performed:
1) Temperature of gas (dry)
2) Temperature of PBS (wet)
3) Temperature inside tooth (inside root canal)
Effect of plasma on mineralised matrix
Tooth samples have been exposed to the plasma under various conditions (power,
exposure time).
After treatment these samples as well as untreated control samples were analysed by xray.
Results
Why plasma?
Plasma is an efficient source of various radicals, capable of bacterial decontamination,
while it operates at room temperature and does not cause bulk destruction of the tissue.
The advantage of this novel tissue-saving treatment is that it is superficial and that the
plasma can easily penetrate the cavity, which is not possible with lasers. Also the use of
plasmas is relatively cheap compared to the use of lasers.
It has been verified that there is only little temperature increase (1 – 5 °C) in the gas
(Figure 4) and even less in dental tissue.
First x-ray measurements showed no damage to the mineralised matrix. Under extreme
conditions the matrix showed cracks (Figure 5).
29
V = 300 V without PBS
vertical distance 2,6 mm
28,8
matching
network
RF amplifier
power
meter
28,6
function
generator
grounded box
glass tube
28,4
T (°C)
dual coupler
28,2
28
27,8
A
27,6
27,4
plasma
B
27,2
27
0
2
Figure 2: Experimental set-up.
Figure 3: A scheme of the experimental set-up.
Experimental set-up
Gas
RF frequency
Power dissipated in plasma
Voltage
The closed box (not vacuum-tight) shown in Figure 2 is filled with Helium
at a flow rate of 2 l/min.
8
10
12
Figure 4:
Typical temperature measurement of gas (dry).
Figure 5: X-ray of crack formed in mineralised
matrix. A = root canal; B = mineralised matrix.
Conclusions
RF-driven ‘plasma needle’
Tungsten wire (0,3 mm ) in a glass tube (Figure 2 and 3).
Because of the glass tube, the plasma stays at the tip of the needle.
Experimental parameters
6
horizontal distance (mm)
tungsten wire
gas inlet
4
• little temperature increase
• mineralised matrix not damaged
• ‘So far so good’
He
9-14 MHz
< 0.2 W
 350 V
Future plans
Dental plaque experiments
In the near future we will investigate the efficiency of plasma-aided destruction of
bacteria present in dental plaque using a standard bacterial viability kit.