Differences between the human eye and the spectrophotometer in the shade matching of tooth colour Cristina Go´ mez-Polo a, *, Miguel Go´ mez-Polo b , Alicia Celemin-Vin˜ uela b , Juan Antonio Martı´nez Va´ zquez De Parga b a Department of Dentistry, School of Medicine, University of Salamanca, Spain b Department of Orofacial Prosthesis, Faculty of Dentistry, University Complutense of Madrid, Spain 1. Introduction The study of colour is a fundamental part of aesthetic dentistry. Colour is undoubtedly one of the parameters with the greatest weight when patients judge the quality of the restoration, above all in the anterior region. Achieving perfect mimicry of the surrounding natural teeth thus becomes a crucial objective for dental practitioners and for patients. In this respect, it is therefore important to know and understand all aspects related to tooth colour and the restoration materials used, both ceramics and compound resins. There are two ways of measuring colour, one of them subjective, through the use of shade guides, and the other objective, mainly through the use of a spectrophotometer. Shade guides generally consist of colour tabs that are compared successively with the tooth to be restored under identical conditions of lighting until the tab with the greatest chromatic similarity to the natural tooth is found. The use of guides to measure shades in dentistry is a subjective process j o u r n a l o f d e n t i s t r y 4 2 ( 2 0 1 4 ) 7 4 2 – 7 4 5 a r t i c l e i n f o Article history: Received 17 February 2013 Received in revised form 5 October 2013 Accepted 7 October 2013 Keywords: Spectrophotometer Tooth colour Visual shade match Shade guide a b s t r a c t Objectives: The aim of this work was to assess the agreement between instrumental and visual colour matching. Methods: Shade selection with the 3DMaster Toothguide (Vita-Zahnfabrik) was performed for 1361 maxillary central incisors and compared with the shade obtained with the Easy- Shade Compact (Vita-Zahnfabrik) spectrophotometer. Results: We observed a greater correlation between the objective method and the subjective one in the colour dimension of lightness (Kappa 0.6587), followed by hue (Kappa 0.4337) and finally chroma (Kappa 0.3578). Conclusion: The colour dimension in which the greatest agreement is seen between the operator and the spectrophotometer is value or lightness. Clinical significance: This study reveals differences between the measurement of colour via spectrophotometry and the visual shade selection method. According to our results, there is better agreement in the value or lightness colour dimension, which is the most important one in the choice of tooth colour. # 2014 Elsevier Ltd. All rights reserved. * Corresponding author at: Department of Dentistry, School of Medicine, Campus Miguel de Unamuno s/n, University of Salamanca, 37007 Salamanca, Spain. Tel.: +34 636402669; fax: +34 923294868. E-mail addresses: crisgodent@usal.es, crisgodent@hotmail.com (C. Go´ mez-Polo), miguelodon@hotmail.com (M. Go´ mez-Polo), acelemin@odon.ucm.es (A. Celemin-Vin˜ uela), mtzvdep@odont.ucm.es (J.A. Martı´nez Va´ zquez De Parga). Available online at www.sciencedirect.com ScienceDirect journal homepage: www.intl.elsevierhealth.com/journals/jden http://dx.doi.org/10.1016/j.jdent.2013.10.006 0300-5712/# 2014 Elsevier Ltd. All rights reserved.