Impact of Presentation Sequence on Patient Tooth Shade Selection

This is a prospective, single-center, three-arm parallel-group Randomized Controlled Trial (RCT) designed to rigorously investigate the cognitive bias known as the "order effect" in patient-driven tooth shade selection. The study aims to quantify the influence of sequential versus simultaneous shade guide presentation on final aesthetic preference and to correlate this choice with the patient's underlying psychosocial perception of their dental aesthetics.

Methodology: Participants seeking aesthetic dental treatment will be randomized (1:1:1) into three intervention groups:

• Group A (Natural -> Bleached): Sequential presentation of natural shades followed by the introduction of bleached shades.
• Group B (Bleached -> Natural): Sequential presentation of bleached shades followed by the introduction of natural shades.
• Group C (Simultaneous): Single presentation of the full VITA 3D-Master shade guide (natural and bleached tabs combined).

Outcome Measures: The primary outcomes are the switching frequency and the magnitude of change (Delta L*) between initial and final selections in the sequential groups (A and B), and the comparison of the final proportion of bleached shade selections across all three groups. Secondary outcomes include the correlation between the Psychosocial Impact of Dental Aesthetics Questionnaire (PIDAQ) total score and the final selected shade's L* value, and the quantification of the Patient-Clinician Discrepancy using CIE Delta E00 between the patient's choice and an independent clinician's recommendation.

Significance: This study will provide evidence-based guidelines for clinical practice, moving beyond anecdotal preference recording to a structured, bias-mitigating approach to shared aesthetic decision-making. The integration of the PIDAQ and objective colorimetric analysis (Lab*) and Delta E00 will provide a novel, high-impact explanation for the observed preference for lighter shades.

Inclusion criteria

• Adult patients aged 18 years or older.
• Seeking aesthetic dental treatment (e.g., anterior restorations, veneers, or tooth bleaching).
• Possessing at least one sound, non-restored maxillary central incisor (tooth #8 or #9) to serve as a reference for objective shade measurement.
• Ability to understand the study procedures and provide written informed consent.
• Fluent in the language of the study (Arabic/English) to complete the psychosocial questionnaire (PIDAQ).

Exclusion criteria

• Congenital or acquired color vision deficiencies (screened using the Ishihara test).
• Cognitive impairments or psychological conditions that may affect decision-making or the ability to complete questionnaires.
• Extensive existing restorations, crowns, or severe intrinsic staining (e.g., tetracycline staining) on the maxillary anterior teeth.
• Active periodontal disease or poor oral hygiene that may interfere with accurate shade assessment.
• Previous history of professional tooth bleaching within the last 6 months.