The accuracy and reliability in tooth shade selection using different instrumental techniques : a vitro study

Abstract

This study aimed to evaluate the accuracy and reliability of tooth shade selection in the model using 30 milled crowns via five methods: 1). Digital single–lens reflex (DSLR) camera with twin flash (TF) and polarized filter (DSLR+TF), 2). DSLR camera with a ring flash (RF) and polarized filter (DSLR+RF), 3). Smart-phone camera with light corrector and polarized filter (SMART), 4). Intraoral scanner (IO), and 5). Spectrophotometer (SPEC) was compared with the control group or manufactural shade. The CIE Lab values (L, a, and b values) were obtained from five of the methods to indicate the color of the tooth. Adobe Photoshop program was used to generate CIE Lab values from the digital photographs. An intraclass correlation was applied for the reliability test based on two repetitions. (Total 18 tests per group: 9 crowns × 2 repetitions) Descriptive data of L, a, b values, and ΔE was performed. Test and control studies were analyzed by using the Kruskal-Wallis Test (total 90 tests per group: 30 crowns × 3 repetitions). The correlation test was performed between test and control using Spearman’s correlation. The reliability of the intraclass correlation of L, a, and b values obtained from five methods showed satisfactory correlation ranged from 0.732–0.996, 0.887–0.994, and 0.884–0.999, respectively. The ΔE from DSLR+TF, DSLR+RF, SMART, SPEC was significantly higher than clinical acceptance (ΔE>6.8) compared to the control group, whereas, the ΔE from IO was 5.99 and all of L, a, b values were not statistically significantly different from the manufactural shade (P<0.01). The ΔE of DSLR+RF group showed the least accuracy (ΔE=19.6), whereas ΔE of DSLR+TF, SMART, and SPEC showed similar accuracy ΔE (ΔE=10.56, 10.48, and 11.67 respectively). With the limitation of this study, the tooth shade selection various from various methods. Hence, a combination of various methods can be done for accurate tooth shade selection. A professional learning curve to establish a better outcome. THESIS IMPLICATION: The study aims to verify the high relevant instrumental techniques for a precise tooth color determination. This study shows accuracy and reliability of the updated instrumental techniques when compared to manufactural shades. It will help the clinician to decide the most suitable method with the least error in esthetic treatment. Also, it helps to avoid unnecessary costs, re-step of treatment, and time-consuming between patient and clinician. Finally, shade selection becomes an increasingly digitalized performance with the related instrument. Therefore, the evaluation may provide a further step of improvement in future digital devices.