Comparative Clinical Assessment Of Gingival Thickness Using Different Methods And Its Relation To Various Levels Of Gingival Pigmentation – An Observational Study

Abstract

AIM: It’s hypothesized that the probe visibility (PV) method, as recommended by current guidelines, may not effectively differentiate between thick and thin gingiva in individuals with gingival pigmentation. Hence, the aim of this study is to compare the effectiveness of the Probe Visibility (PV) method using the UNC-15 probe and Colorvue Biotype Probe (CBP) with calliper and transgingival probing measurements for assessing gingival thickness in individuals with varying degrees of gingival pigmentation.

MATERIALS AND METHODS: This observational study included 80 participants over a 3-month period. The buccal gingiva adjacent to the right maxillary central incisor was assessed. Gingival thickness was measured using four methods: direct measurement with a calliper (gold standard), transgingival probing with an endodontic spreader, and probe visibility using both the Colorvue Biotype Probe (CBP) and UNC-15 probe. Gingival pigmentation was assessed subjectively using the Dummett–Gupta Oral Pigmentation Index (DOPI).

RESULTS: Among the 80 participants, the UNC-15 probe was visible in 38 cases and not visible in 42. For the CBP, the green tip was most commonly visible (44 participants), followed by equal frequencies for white tip visible, blue tip visible, and blue tip not visible (12 each). DOPI index classifications were predominantly Class 0 and 1, with no cases in Class 3.

Direct measurement using a calliper (mean: 0.53 mm) was significantly lower than transgingival probing (mean: 0.66 mm), with a statistically significant difference between the two (p = 0.000). A significant positive correlation was observed between calliper measurements and both PV methods (UNC-15 and CBP), indicating that greater gingival thickness was associated with lower probe visibility. However, correlations between gingival pigmentation (DOPI index) and gingival thickness or probe visibility were weak and not statistically significant.

Kruskal-Wallis tests revealed significant differences in gingival thickness measurements across CBP visibility categories and DOPI classes, with the "blue tip not visible" group and DOPI Class 2 showing the highest gingival thickness. Despite trends, DOPI index did not significantly predict probe transparency in regression analysis (p > 0.05).

CONCLUSION: Probe visibility significantly correlates with gingival thickness measurements, while gingival pigmentation (DOPI Index) does not significantly influence probe transparency or transgingival measurements. Although DOPI affects direct calliper measurements, it is not a reliable predictor of probe visibility using UNC-15 or CBP probes.