Inter-rater agreement among multiple examiners for the assessment of plaque scores between quantitative light-induced fluorescence-digital and two-tone disclosing solution-stained digital images

Abstract Background To utilize plaque scoring indices as objective measures, a certain standard of intra-rater and inter-rater agreement must be met. Achievement of high consistency among several examiners in the assessment of images from Q-ray cam (for quantitative light-induced fluorescence-digital imaging) and digital single-lens reflex camera of stained tooth surfaces might enable more efficient undertaking of large epidemiological studies and oral tests. Methods Second-year dental hygiene students and registered dental hygienists 40 examiners were randomly selected, all of whom provided informed consent. Multiple examiners assessed plaque scoring indices from the two types of images of the same 30 patients. The images were observed on a computer monitor, and the area with dental plaque was assessed using the Patient Hygiene Performance Index. The intra-class correlation coefficient was determined to evaluate the agreement among examiners and test methods for dental plaque Q-ray cam and digital single-lens reflex camera measurements were compared using a Bland-Altman plot. The intra-class correlation coefficient was analyzed using SPSS version 24 software (SPSS Inc., Chicago, IL, USA), and the exploratory graph was analyzed with MedCalc. Results Agreement among 40 examiners was excellent with an intra-class correlation coefficient of 0.990 when the Q-ray cam was used. The intra-class correlation coefficient for the registered dental hygienists group was 0.987 and that for the dental hygiene students group was 0.980. Conclusions The study was high agreement in the assessment of Q-ray cam images and digital single-lens reflex camera images of stained dental plaque by multiple examiners, confirming that the two methods are validated both independently and with high mutual agreement.