A reliability study of clinical tooth wear measurements

Statement of problem. Most studies examining tooth wear severity have been performed on dental casts. This indirect approach has limited applicability to dental practice because during the assessment of the casts, the identification of dentin exposure is difficult or even impossible. Purpose of study. The purpose of this study was to assess occlusal and incisal tooth wear clinically to determine the reliability of the assessment procedure and to establish the influence of selected relevant clinical variables (dental quadrant, tooth type, and severity of wear) on the reliability. Material and methods. Forty-five volunteers (17 men, 28 women; mean age 33.7 +/- 10.7 years), 32 with temporomandibular disorders and 13 free from signs and symptoms of such disorders, were evaluated on 4 occasions, Two trained observers graded tooth wear at 2 different points in time with a 5-point ordinal scale developed for use in this study. The inter-racer and intra-racer reliability of the scale was expressed as Cohen's kappa. The influence of 2 clinical variables, dental quadrant and tooth type, on the values of kappa was tested with 1-way analysis of variance and post hoc Bonferroni tests. Probability levels of P < .05 were considered statistically significant. The influence of the final clinical variable, severity of wear, was assessed qualitatively. Results. The overall values of the inter-rater and intra-rater reliability were substantial (kappa = 0.632 to 0.678). The clinical variable dental quadrant did not influence the kappa values, whereas the inter-rater reliability during tine first session was better for incisors and canines than for premolars (1-way analysis of variance: F-3,F-23=4.577, P=.012; post hoc Bonferroni tests: P=.030 and .036). Qualitative assessment of severity of wear indicated that the more advanced the tooth wear, the more reliably it could be graded. Conclusion. By means of the developed 5-point ordinal scale and within the limitations of this study, it was concluded that tooth wear can be assessed reliably in the clinical dental setting.