Measurement of thermophysical properties of human dentin: Effect of open porosity

Magalhães, Manoelita Figueiredo de; Ferreira, Ricardo Alberto Neto; Grossi, Pablo Andrade; Andrade, Roberto Márcio de

doi:10.1016/j.jdent.2008.04.006

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Volume 36, Issue 8 , Pages 588-594, August 2008

Measurement of thermophysical properties of human dentin: Effect of open porosity

Manoelita Figueiredo de Magalhães
- Departamento de Engenharia Mecânica, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos 6627, CEP: 31.270-901 Campus da UFMG, Pampulha, Belo Horizonte, Minas Gerais, Brazil
- Corresponding author. Tel.: +55 31 3337 9242; fax: +55 31 3337 2831.
Ricardo Alberto Neto Ferreira
- Comissão Nacional de Energia Nuclear (CNEN), Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Avenida Presidente Antônio Carlos 6627, CEP: 31.270-901 Campus da UFMG, Pampulha, Caixa Postal 941, CEP: 30.123-970 Belo Horizonte, Minas Gerais, Brazil
- Tel.: +55 31 3069 3150; fax: +55 31 3069 3390.
Pablo Andrade Grossi
- Comissão Nacional de Energia Nuclear (CNEN), Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Avenida Presidente Antônio Carlos 6627, CEP: 31.270-901 Campus da UFMG, Pampulha, Caixa Postal 941, CEP: 30.123-970 Belo Horizonte, Minas Gerais, Brazil
- Tel.: +55 31 3069 3248; fax: +55 31 3069 3311.
Roberto Márcio de Andrade
- Departamento de Engenharia Mecânica, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos 6627, CEP: 31.270-901 Campus da UFMG, Pampulha, Belo Horizonte, Minas Gerais, Brazil
- Tel.: +55 31 3409 3510; fax: +55 31 3409 3526.

Received 20 October 2007; received in revised form 5 April 2008; accepted 8 April 2008.

Abstract

In dentistry caries removal can be performed with rotatory instruments or high intensity laser. Both techniques can heat the tooth and harm the pulp. The literature review about the measurement of human dentin thermophysical properties revealed a great variation of the values obtained by several authors, and most of the studies are outdated. Most of these studies have not directly measured the thermal diffusivity of human dentin, and the reported values are calculated values based on measurements of conductivity, density and specific heat.

Objective

The aim of the present study was to measure human dentin thermal diffusivity, density, open porosity and specific heat, and then to calculate its thermal conductivity and analyze the influence of open porosity in these properties.

Method

The methods used were: flash laser method for measuring thermal diffusivity, method of penetration and immersion with xylol for density and open porosity and differential scanning calorimetry for measuring specific heat. Calculated results of the thermal conductivity are shown as well.

Result

Results of diffusivity, density, open porosity, specific heat and thermal conductivity of measurements performed on five samples are presented and compared with results of other authors. The open porosity of the samples varied between 1.11% and 3.08% of the sample volume, corresponding to densities ranging between 2090 and 2400kgm⁻³, thermal diffusivity: 0.199 and 0.265×10⁻⁶m²s⁻¹, specific heat: 872.5 and 1181.0Jkg⁻¹K⁻¹, thermal conductivity: 0.363 and 0.666Wm⁻¹K⁻¹.

Conclusion

It has been found that there exist a strong correlation between the open porosity of human dentin and its thermal conductivity and density. Both human dentin thermal conductivity and density decrease with the increasing of open porosity, with a confidence of at least 98% and 96.6%, respectively.

Keywords: Human dentin, Thermal diffusivity, Flash laser method, Density, Open porosity, Xylol penetration and immersion method, Specific heat, Thermal conductivity