Method and device for quantitatively determining the surface optical characteristics of a reference object comprised by a plurality of optically differentiable layers

A device for lighting and capturing images of a sample comprising

• a digital means for the capture of images, diffusing translucent means, lighting sequence means, and an annular lighting means,
• where the digital means for the capture of images has an optical axis,
• where the annular lighting means is arranged such that its light will not fall directly on such digital means for the capture of images, where such annular lighting means has a symmetry axis that is coincident with the normal of a plane of the sample where the sample will be placed and coincident with the optical axis of said digital means for the capture of images;
• where the annular lighting means comprises light sources, where the light sources comprise red (R), green (G), blue (B), and ultraviolet (UV) channels, where the light sources are lined with a reflecting surface which prevents the emitted light from falling on the plane of the sample;
• where the diffusing translucent means is interposed between the plane of the sample and the annular lighting means,
• where the lighting sequence means commands the turning on an off of the different light sources to select individually or in combination the R,G,B, and UV channels, where the lighting sequence means also captures four types of images, where each of the four types of images corresponds to the R, G, B, and UV channels, respectively.

A method to quantitatively determine the surface optical characteristics of a tooth comprising the following steps:

• (a) lighting the tooth with one or more light sources, where the light sources comprise, jointly or separately, the red (R), green (G), blue (B), and ultraviolet (UV) channels;
• (b) obtaining images of the tooth, where the images are capable of containing information to generate six matrices with light data;
• with three of said six matrices containing respective R, G, and B components obtained when the tooth is lit with the R, G, and B light channels, respectively and the other three of the said six matrices containing respective R, G, and B, components obtained when the tooth is lit with the UV light channel;
• (c) generating a catalogue of restoring or constituent material, by using one or more laminar samples of a material to be catalogued, such samples having pre-established area;
• where each pre-established area has different pre-established thicknesses;
• obtaining thus a cataloguing of such restoration or constituent material from the quantification of corresponding six matrices with light data, obtained from said sample;
• where such quantification includes the extraction of the color values, provided by the RGB and UV lights of each one of such areas of such six matrices of said laminar samples;
• applying to said color values and adjustments to obtain a function of color versus thickness which is stored in a restoration or constituent materials catalogue;
• (d) acquiring the R, G, B and UV color of the tooth;
• (e) determining a combination of restoration or constituent materials layers, previously catalogued in step (c) above, which will behave in a manner optically equivalent to the colors (R, G, B and UV) of the tooth, acquired in step (d) above, in which a materials layer determination is carried out by:
• e1. determining the arithmetic minimum of the arithmetic differences, weighted, between the colors of the tooth, considering the background color in which said colors of the tooth were obtained, and the colors of each catalogued material, selected from those the optic nature of which is typical of the first layer of the tooth, designating as a new background color that obtained for the catalogued material which has the minimum value of said arithmetic differences;
• e2. repeating the previous sub stage of minimizing the arithmetic differences, weighted, between the same colors of the tooth, considering the new background color obtained in the previous sub stage, and the colors of each catalogued materials selected, this time, from among those the optical nature of which is typical of the next layer of the tooth;
• designating as a new background color that obtained for the catalogued material having the minimum value of said arithmetic differences of this stage;
• and
• e3. applying the previous stage iteratively, with the corresponding background color substitutions and inspecting the relevant catalogued materials sub sets, corresponding to the optical nature of the layer under determination, until completing all the layers that will make up the combination of restoration or constituent materials layers.