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ABSTRACT
Utilization of impedance measuring methods in dental researches makes the determination of electrical properties of human tooth possible. Although impedance measurement forms the basis of numerous oral diagnostic methods, limited studies are available about the impedance of human dentin. In this paper the thickness dependency of the impedance of human dentin is investigated.
Dentin disks were prepared from dentin layer of the crown between the top of pulp and below dentin-enamel junction of five human wisdom teeth. Separated and isolated round shaped measurement areas were created on the surface of the specimens with diameter of 1 mm. The samples were thinned sequentially while the thickness and the complex impedance of each measurement area was recorded.
Investigation of the impedance of human dentin in the thickness range of 0.3 -2.3 mm allowed us to define the thickness-impedance coefficient of human dentin, as the absolute impedance value divided by the thickness and multiplied by the area of the examined dentin. The average of the thickness-impedance coefficient is equal to 8.356 Om at 1 kHz measurement frequency.
Approximately linear correlation between the thickness and the impedance of human dentin was revealed. These results may have significance in the field of clinical dentistry.
Keywords: bioengineering, electrical impedance spectrum, dentin thickness, human dentin
INTRODUCTION
Dentin is one of the major hard tissue components of teeth. It can be found under the enamel and it surrounds the entire pulp. This tissue contains micro channels projecting radially from the pulp to the enamel called dentin tubules. The density of dentin tubules near the pulp on the inner dentin is 55000 - 75000 mm2, near the enamel on the outer dentin it is 15000 - 20000 mm2. The diameter of the tubules is different as well, near the pulp they are approximately 3 - 4 pm, on the border of the dentin-enamel it is approximately 1 pm [1-5]. The dentin tubules are filled with ionized dentinal fluid therefore the bioelectrical activity of the pulp becomes measurable on the surface of the dentin. This method is called dentin recording.
Dentin recording methods allow us to observe the process of dental pain and pulp inflammation. These techniques also let the fluid flow through the tubules to be inspected and facilitate the examination of...