Evaluation of the relationship between visual examination and loupes usage in caries detection and dentists' fatigue levels: an in-vitro study.

backgroundThe aim of this study is to evaluate the effect of visual and general fatigue on intra- and inter-observer reliability in caries assessment using the ICDAS II system, and to investigate the role of magnification in maintaining examiner consistency under different fatigue conditions.

methodsExtracted teeth without decay or with early enamel lesions were embedded in silicone impression material. Dentists' visual and physical fatigue levels were assessed twice daily-before morning practice and after afternoon sessions-using the Visual Fatigue Questionnaire and the Chalder Fatigue Scale. Three restorative dentistry research assistants with similar clinical experience examined the teeth using visual inspection and loupe magnification based on the ICDAS II criteria. Histological evaluation was performed under 10× magnification using the ERK (Ekstrand, Ricketts and Kidd) Histological Scoring System. ICDAS II scores were compared with histological scores. Histological evaluation was used as a reference framework rather than a direct measure of diagnostic accuracy. Examiners repeated measurements one week apart to calculate Intraclass Correlation Coefficient (ICC) values for intra-observer reliability. Weighted Cohen's Kappa analysis assessed inter-observer agreement, the relationship between diagnostic methods, and the effect of fatigue.

resultsLoupe use significantly increased ICC values for all observers (≈ 0.22; p < 0.001). In visual examination, ICC values ranged from 0.39 to 0.86, whereas loupe-assisted evaluations yielded ICC values of 0.81-0.95, indicating substantially improved intra-observer reliability. Weighted Cohen's Kappa revealed significant morning-afternoon intra-observer agreement (p < 0.001), with Kappa values of 0.62-0.84 in the morning and 0.54-0.73 in the afternoon. Loupe-assisted examinations consistently showed higher diagnostic agreement, while decreased examiner consistency in the afternoon was associated with visual fatigue and reduced attention. Inter-observer agreement was also significant and high for both methods (p < 0.001). Morning Kappa values were 0.66 for visual examination and 0.69 for loupe-assisted examination; afternoon values were 0.59 and 0.61, respectively. Overall, loupe use was associated with improved examiner consistency and agreement and afternoon declines reflected the impact of fatigue.

conclusionWithin the limitations of this study, the use of loupes significantly improved intra-observer reliability and observer consistency in caries detection. Additionally, fatigue accumulated during the day negatively affected examiner reliability, as reflected by decreased agreement levels in afternoon assessments. These findings emphasize the role of visual support tools and operator-related factors in maintaining diagnostic consistency.