Clinical justification of the effectiveness of the use of digital devices for determining the color of the tooth

BACKGROUND: The procedure for determining the color of teeth can be carried out visually using colors or special devices, or both methods at the same time. The visual definition of shades using popular instrumental techniques, although ubiquitous, is nevertheless very subjective. The hardware method for determining the color of teeth consists in an objective computer analysis of the image obtained under ideal optical conditions. Ambient light should not affect the color detection results obtained by spectrophotometers and colorimeters. The main advantage of the hardware method of determining the color of teeth is the elimination of subjectivity. The world scientific literature describes many studies comparing the quality of color determination by hardware and visual methods. However, these data differ, and the conclusions are not unambiguous in the choice of a particular method, therefore, the clinical effectiveness of digital technologies for determining the color of teeth, as well as the scientific justification of their use, is an urgent problem of modern dentistry.

AIM: To evaluate the accuracy of determining the color of teeth with digital dental devices in comparison with the visual assessment of color by an expert group.

MATERIAL AND METHODS: In order to achieve this goal and form the design of the study, we analyzed the sources of scientific literature. The information search was carried out in the scientific electronic databases eLibrary, Scopus, PubMed in the period from 2002 to 2020, according to the keywords of the query: methods for determining the color of teeth, comparison of methods for determining the color of teeth, hardware methods for determining the color of teeth. The results of the study of special literature on this topic have identified the most accurate and frequently used methods for determining color in practical healthcare. Of the visual methods, preference is given to determining the color of teeth using the colors VITA Toothguide 3D-Master (VITA Zahnfabrik, Germany) and VITA Classical (VITA Zahnfabrik, Germany). Of the devices, among spectrophatometers, most authors prefer VITA Easyshade (VITA Zahnfabrik, Germany) and Spectro Shade (Micro High Technologies, Italy), among hybrid devices (intraoral scanners) — 3Shape TRIOS (3Shape, Denmark). The evaluation of the accuracy of determining the color of teeth by digital dental devices was carried out on 20 natural right medial central incisors of 20 patients in a dental office. The effectiveness of these devices was determined in comparison with the teeth color indicators determined by the expert group. For each pair of the studied methods, Cohen’s kappa was determined — a statistical coefficient for determining the mutual reliability of appraisers. When calculating Cohen’s mouthguard, the results of color determination for each third of the tooth surface were compared separately by compiling multi-field tables. Statistical processing was carried out in Excel 2016.

RESULTS: According to the interpretation intervals of Cohen’s kappa values, mutual reliability of evaluators is defined as “excellent” at values from 0.75 to 1.0, “good” — from 0.6 to 0.74, “acceptable” and “bad” — from 0.4 to 0.59 and less than 0.4, respectively. The Spectra Shade device showed excellent consistency with experts in determining the color of the tooth in all three parts of the surface. Vita Easyshade V showed less consistency with the expert assessment, but its level is interpreted as good. The color detection data using the 3Shape Trios digital scanner did not agree well with the opinion of experts. The devices showed consistency between themselves in the range from acceptable to good, while mutual reliability in the Spectra Shade - Vita Easyshade V pair turned out to be better than others.

CONCLUSION: Taking into account the fact that the accuracy of the devices does not depend on the factors to which a person is exposed, such as subjectivity, illumination, time of day, eye fatigue, the color of nearby teeth, etc., it is advisable to use the Spectra Shade and Vita Easyshade V devices in clinical practice to increase the objectivity of color determination and improve patient satisfaction with dental treatment.