Pilot in vivo image spectro-photometric evaluation of optical properties of pure enamel and enamel-dentin complex

Objectives

The aim of this in vivo study is to investigate the L*a*b*and the opacity (CR) of front teeth by means of an image spectrophotometer and to evaluate the eventual influence of the background color on the results. The second aim is to investigate if there is a relationship between tea, coffee, red wine drinking habits or smoking habits of the test subjects and tooth color.
Methods

A novel image based spectro-photometric approach was developed and applied on a Swiss Army recruits group quantifying L*a*b* of pure enamel as well as of enamel-dentin complex against black and white background together with CR.
Results

When 2 mm thick pure enamel was considered, the values obtained were (mean (SD)) L*(76.3 (3.4)), a*(3.4 (1.2)) and b*(17.2 (2.45)) against white background and L*(63.5 (4.2)), a*(0.8 (1.3)) and b*(10.7 (2.7)) against black background. The opacity (CR) of 2 mm thick pure enamel was (64.4 (0.1)).

When 3 mm thick enamel-dentin complex was considered, the values obtained were L*(79.0 (2.6)), a*(3.9 (1.3)) and b*(20.4 (3.0)) against a white background and L*(74.9 (3.0)), a*(1.8 (1.2)) and b*(16.7 (3.1)) against a black background. The opacity (CR) of 3 mm thick enamel-dentin complex was (87.4 (0.1)).
Significance

The application of this method on a larger group of subjects of different ages may serve as a database for a more exact characterization of optical properties of natural enamel and dentin.