Inter-observer agreement in the radiographic interpretation of Demirjian's developmental stages in the mandibular second and third molars – A comparative study

BACKGROUND: The developmental stages of the teeth in the radiographs are graded on an ordinal scale. The present study was conducted using 123 digital orthopantomograms from individuals in the age group of 5 to 22 years and to analyze and evaluate the inter-observer agreement in grading the developmental stages of second and third molars. Four observers with different levels of practical experience in age estimation participated in the study. The development stages of both the molars in the lower left quadrant (3(rd) quadrant) were assigned based on the Demirjian's 10 stage chart. The percentage agreement and Kappa statistics were used to test the agreement between the observers. The data of the observer 1 were used as the standard for the comparison. RESULTS: There was 70.0%–75.6% agreement among the observers in staging second molar and 52%–68.3% for the third molars. There was an excellent agreement (k > 080) between observer 1 and observer 2 and a good agreement (k = 060–0.79) between observer 1 and the other two observers for both the molars. The Fleiss Kappa revealed moderate to a good overall agreement for both the molars (k = 0.51–0.66). The Freidman's test revealed a significant difference in the grading of third molars between all the raters (χ(2)= 25.02, df 3, P < 0.001) and for the second molar the difference was not significant (χ(2)= 3.89, df 3, P > 0.05). The stage-wise overall agreement was fair for Stage 3 in the second molar and Stage 9 and Stage 4 in the third molar. CONCLUSIONS: In conclusion, proper training in the radiographic interpretation of developmental stages may minimize the errors during the age estimation methods.