10 February 2023

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Shade matching process: the role of intraoral scanners

By Professor Lorenzo Breschi, Annamaria Forte

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Introduction

Today, high aesthetic demand has revolutionized the treatment plans favored by the developments in materials and technique technologies. To fulfill the aesthetic requirements, it is, therefore, necessary that the final restoration replicate the optical properties of the natural dentition which is polychromatic and multilayered with intricate optical properties in nature.

The most common method used to accomplish this task is the visual shade selection using shade guides. The visual shade matching process produces highly variable results and it is influenced by multiple factors from the operator (i.e. eye fatigue, personal interpretation, clinical experience and proficiency). Environmental factors like light conditions also play a role in the outcome.

Numerous studies have reported a high percentage of color mismatches in aesthetic restorations. Consequently, the modern trend is to reduce these variables and introduce more reliable shade matching selection methods mainly based on instrumental or digital tools, such as digital cameras, spectrophotometers, spectroradiometers and colorimeters. 

Recently, high-definition cameras of intraoral scanners have also been proposed to be used in shade matching selection. The possibility to combine impression making with the color selection in one tool would be extremely advantageous to clinical practice.

A recently published systematic review and meta-analysis by Dr. Mohammed Akl et al. evaluated the available literature to provide information on the viability of using intraoral scanners for shade matching.  

Materials and methods

Researchers searched electronic databases including PubMed/MEDLINE, SCOPUS, EBSCO, Cochrane and ProQuest for articles published between January 1, 2011 and December 30, 2021 using the main search terms “intraoral scanners,” “scanners,” “TRIOS,” “CEREC,” “Planmeca,” “Medit” and “digital dentistry.” The team used these terms with one of the following keywords: “EasyShade” or “shade selection” or “shade matching” or “shade” or “tooth color” or “tooth shade” or “digital shade matching.” Both clinical and laboratory studies published in peer-review journals using the intra-oral scanners for shade matching were included in the review process. A manual search of the references completed the search. 

Results 

The search strategies yielded a total of 1,635 potential articles. After evaluation of titles and abstracts, 19 full-text articles were identified and reviewed. Four articles were further excluded as they did not meet the inclusion criteria, and 15 studies were included in the final review.

Most studies included visual shade matching in their comparison to different instruments that included intraoral scanners. The studies included in this review assessed only three intraoral scanners: TRIOS 3 (3Shape; Copenhagen, Denmark), CEREC Omnicam and CEREC Primescan (Dentsply Sirona; York, PA). 

The TRIOS 3 was the most evaluated instrument. Eleven of the 15 studies used one of the Vita EasyShade spectrophotometers (EasyShade, EasyShade V, EasyShade Advance; VITA; Bad Säckingen, Germany) as a reference device.

Accuracy varied significantly between studies, with the majority recommending the use of visual shade matching to confirm or verify the intraoral scanner results.

Intraoral scanners are highly repeatable for shade matching and outperformed visual shade matching. Setting intraoral scanners to the Vita 3D Master shade guide improved both accuracy and precision. Shade matching with intraoral scanners may be influenced by external factors such as ambient light sources and incorrect use or manipulation. 

Conclusions

Based on the findings of this systematic review and meta-analysis, researchers concluded that intraoral scanners set to the Vita 3D Master shade guide may be used for shade matching. However, due to the variability of the data, a visual shade matching confirmation is still recommended.

Mohammed A. Akl, Dina E. Mansour, Fengyuan Zheng. "The Role of Intraoral Scanners in the Shade Matching Process: A Systematic Review." Journal of Prosthodontics. 02 August 2022. https://doi.org/10.1111/jopr.13576