title: Measurement of the thermal diffusivity of dental filling materials using modified Angström's method.
abstract: OBJECTIVE
  A new measuring technique for the determination of thermal diffusivity is proposed. Using this technique, the thermal properties of a few different dental filling materials were measured.
  
  
  METHODS
  The proposed method for measurement of thermal diffusivity is based on the classical Angström's method. The method exploits the propagation of a plane thermal wave generated by a Peltier's device in a cylindrical sample along its axis. The thermal diffusivity of the sample is calculated from the phase difference between harmonic components of temperatures measured at sample surfaces, perpendicular to the direction of thermal wave propagation. The estimated accuracy of measurement is typically about 10% for samples with low thermal diffusivity. The proposed method was used for the determination of thermal diffusivities of Achatit Bichromatic, Charisma and Dentimet dental filling materials.
  
  
  RESULTS
  The measured thermal diffusivities were: 0.295(0.020)x10(-6)m(2)s(-1) for Achatit Bichromatic, 0.321(0.015)x10(-6)m(2)s(-1) for Charisma and 1.70(0.12)x10(-6)m(2)s(-1) for Dentimet. The thermal conductivities of these materials were also estimated. The results were compared with values obtained from independent constant flux measurements with marble as a reference material.
  
  
  CONCLUSIONS
  There are no standard techniques for the determination of the thermal properties of dental filling materials. Moreover, it is difficult to find the thermal diffusivity and the thermal conductivity of many of them. The method proposed in this paper allows the simple and accurate measurement of thermal diffusivity. Thermal parameters of dental filling materials should be compatible with the parameters of human teeth. Lack of thermal compatibility can cause not only patient discomfort but also mechanical stresses leading to microcracks.
authors.affiliation: Institute of Physics, Silesian University of Technology, Krzywoustego 2, 44-100 Gliwice, Poland. jerzy.bodzenta@polsl.pl
authors.forename: Jerzy
authors.initials: J
authors.lastname: Bodzenta
authors.forename: Bogusław
authors.initials: B
authors.lastname: Burak
authors.forename: Marian
authors.initials: M
authors.lastname: Nowak
authors.forename: Monika
authors.initials: M
authors.lastname: Pyka
authors.forename: Maria
authors.initials: M
authors.lastname: Szałajko
authors.forename: Marta
authors.initials: M
authors.lastname: Tanasiewicz
mesh_terms: D003188:Composite Resins; D003723:Dental Amalgam; D003793:Dental Restoration, Permanent; D012823:Silicate Cement; D013814:Thermal Conductivity; D013816:Thermodynamics
chemical_list: C084111:Charisma composite resin; D003188:Composite Resins; D012823:Silicate Cement; D003723:Dental Amalgam