Challenges and practical approaches to blinding in dental clinical trials: a narrative methodological review

This narrative methodological review aims to critically examine the role of blinding (masking) in minimizing bias in randomized clinical trials (RCTs), with particular attention to the methodological challenges associated with its implementation. Dental research is used as a field of application to illustrate how general principles of blinding operate in complex, non-pharmacological clinical settings. A narrative synthesis was conducted based on methodological and empirical literature addressing blinding in RCTs. Classical and contemporary publications from biomedical and dental research were examined to identify key concepts, recurring challenges, and methodological strategies related to blinding. The evidence was analyzed from a conceptual and methodological perspective, integrating insights from the literature with the authors’ experience in clinical dental research. The reviewed literature indicates that, although blinding is a central strategy for reducing performance and detection bias, its feasibility in dental RCTs is frequently constrained by the procedural and operator-dependent nature of interventions. Ethical considerations, perceptible differences between treatment arms, and the assessment of subjective outcomes were identified as common barriers. When full blinding is not achievable, alternative methodological approaches—such as blinded outcome assessment, standardized protocols, and transparent reporting—emerge as important strategies to mitigate bias. Blinding presents distinct methodological challenges in dental randomized clinical trials, reflecting broader difficulties encountered in non-pharmacological research. While complete masking is often unattainable, careful trial design, explicit acknowledgment of limitations, and appropriate compensatory strategies can substantially strengthen internal validity. This review provides a methodological reflection on blinding that may inform the design and reporting of RCTs in dentistry and other complex clinical fields.