A New Index for Assessment of Severity and Extent of Gingival Pigmentation; A Diagnostic Cross-Sectional Study According to Inter and Intra-Observer Variability.

Background: Classification of gingival pigmentation (GP) is often performed using gingival pigmentation index (GPI), melanin pigmentation index (MPI), oral pigmentation index (DOPI), melanin index (MI), or physiologic/pathologic GPI. However, the internal and external reproducibility of these indexes have not been evaluated. This study aimed to introduce a new simple and applicable GPI and assess its internal and external reproducibility.

Materials and methods: This diagnostic cross-sectional study was conducted on 40 patients with maxillary and mandibular GP. Patients were in the age range of 12-60 years, and degree of GP was determined by four periodontists using DOPI, MI, MPI, GPI and the new index namely the severity and extension of gingival melanotic pigmentation index (SEMPI) under similar environmental and lighting conditions. The inclusion criteria were in the age range of 12-60 years and presence of melanin pigmentation (physiologic or pathologic) in the gingival margin, papilla, or attached gingiva. The exclusion criteria were systemic diseases, vascular lesions, hemochromatosis, amalgam tattoo, hyperbilirubinemia, or use of medications causing nonmelanotic pigmentation (hemoglobin, iron, and amalgam).

Results: The Fleiss kappa between all examiners for all indexes at 0, 7, and 14 days was higher than 0.8, indicating high agreement among the examiners. The Spearman's correlation coefficient for all indexes was positive and high at 0, 7, and 14 days (P < 0.001).

Conclusion: Considering the high agreement among the examiners for all indexes and at all-time points as well as the positive, strong correlations among them, it seems that the new index is useful for classification of GP.