Assessing the Reliability of Miller's Classification and Cairo's Classification in Classifying Gingival Recession Defects: A Comparison Study

Background and Objectives: Gingival recession results in adverse aesthetics and root sensitivity, and there is a need to treat and prevent its further progression. To overcome these problems, various advances have been made by clinicians in treating gingival recession based on the type of gingival recession. Miller's classification has been used for a long time to classify the type of recession. However, certain limitations have been found with use of Miller's classification such as a lack of clarity in the method for measuring soft and hard tissue loss in the interproximal area. Cairo classification was proposed to overcome limitations of Miller's classification to classify gingival recession. Cairo's classification is a treatment-oriented classification based on buccal and interproximal attachment loss. Therefore, the study was conducted to assess and compare the reliability of Miller's and Cairo's classifications in determining gingival recession. Material and methods: A total of 220 buccal gingival recession defects were included in the study based on the inclusion and exclusion criteria. Four examiners were included in the study. Two examiners classified the recession defects according to Miller's classification and the other two examiners classified recession defects according to Cairo's classification at baseline and at a 1-week interval. Statistical analysis was conducted using SPSS software version 25.0 using Cohen's kappa correlation coefficient and Chi-square test statistics to determine the intra- and inter-rater agreement among the examiners for the two gingival recession classification systems. A p value of <0.05 was considered statistically significant. Results: The intra-rater agreement for Cairo's classification was 0.86 and 0.82, whereas for Miller's classification, it was found to be 0.68. The inter-rater reliability agreement for Cairo's classification was 0.82 and 0.8, whereas for the Miller's classification, it was 0.56 and 0.67. Conclusions: Within the limitations of the study, it was found that Cairo's classification is clearer and more reliable than Miller's classification in the assessment of gingival recession.