The i3d Shade Matching Technique: A Case Report

Abstract

Objectives: In direct composite restorations, successful shade matching is considered as one of the most difficult task to accomplish. It is based on a subjective comparison between a shade tab and the natural tooth and as direct composite restorations are realized within one single appointment, no try-in is possible. Therefore the search for a reliable shade matching procedure is still going on. Materials and Methods: Based on the fact that composite shade is thickness-dependent and that a natural tooth is built up of enamel and dentin with individual 3D thicknesses, a novel shade matching technique was developed respecting the natural three-dimensional structure of the tooth to be reproduced by the restorative composite material. CBCT data of an upper central incisor were converted into stl 3D files and a pair of 3D printed molds was acquired. One represented the negative of the root and the dentin core and the other one represented the negative of the enamel complex. By using these molds, an individual 3D shade tab perfectly reproducing the natural tooth morphology was fabricated out of pre-selected composite materials and used for shade comparison with a fractured upper central incisor. Results: The preoperative ΔE value of approximately 3.46 of the custom shade tab-tooth has decreased into a postoperative ΔE value of 1.96. The vertical L* axis represented by Lightness made a significant positive difference (-3.07 to -1.78) when dentin material was modified while maintaining the same initial three-dimensional structure of the tooth to be reproduced, in both the custom shade tab-tooth and in the final restoration. Conclusions: The proposed method significantly improved the shade matching of a direct composite restoration within one appointment. In the future, the i3D technique may be also used for 3D printed composite restorations and for the development of more aesthetic composite materials as well.