Reliability of Dental Shade Selection Methods: Agreement Among Spectrophotometer, Intraoral Scanner, and Cross-Polarization Photography

Objective

The study aimed to evaluate the reliability and agreement of dental shade selection methods—spectrophotometry, intraoral scanning, and cross-polarized digital photography (CP photography)—using VITA Classical (VC) and VITA 3D-MASTER (V3M) shade guides.

Materials and Methods

The shade of the central area of the right maxillary central incisor was assessed in 56 subjects using three methods: SpectroShade spectrophotometer, 3Shape TRIOS intraoral scanner, and CP photography. All measurements were standardized, performed in triplicate, and conducted under controlled conditions. Fleiss' Kappa was used to evaluate intra-instrument reliability, while Cohen's weighted Kappa assessed inter-instrument agreement. CIEDE2000 (ΔE ₀₀) values were calculated to evaluate the magnitude of color differences between methods.

Results

Intra-instrument reliability was highest for the spectrophotometer across both shade guides, followed by CP photography and the intraoral scanner. Inter-instrument agreement revealed substantial agreement between CP photography and the spectrophotometer for the VC guide (κ = 0.736) and moderate agreement for the V3M guide (κ = 0.553). The intraoral scanner showed moderate to substantial agreement with the spectrophotometer for the V3M guide (κ = 0.607). Additionally, CP photography yielded fewer cases exceeding the acceptability threshold than the intraoral scanner.

Conclusions

CP photography demonstrated high intra-instrument reliability and substantial agreement with the spectrophotometer, particularly when using the VC guide.

Clinical Significance

This study supports the use of accessible methods, such as CP photography, for accurate shade selection, which could potentially enhance clinical outcomes and patient satisfaction in restorative dentistry.