Diagnostic Accuracy of the Gingival Phenotype by the Transparency of the Periodontal Probe Through the Gingival Sulcus: A Systematic Review and Meta-Analysis

This study aimed to investigate the accuracy of diagnosing thin and thick gingival phenotypes (GPs) by the transparency of the periodontal probe (TRAN) through the gingival sulcus. Eligible studies comparing TRAN to direct methods for gingival thickness (GT) measurement (reference tests) were searched in four databases (including MEDLINE and EMBASE) up to 2024. Quality assessment was carried out using QUADAS-2. A latent class meta-analysis for imperfect gold-standard model was conducted considering the multiple thresholds (TSs) and landmarks adopted by the reference tests. The 10 included studies presented a low risk of bias and low applicability concerns. The summary sensitivity (SSe) ranged from 49% (95% CI: 25.8% to 68%) with a TS of 0.8 mm to approximately 53% (TSs of 1 and 1.2 mm); the summary specificity (SSp) ranged from 60% (95% CI: 42.4% to 82.6%) with a TS of 1 mm to 68% (95% CI: 46.4% to 82.5%) with a TS of 0.8 mm. The highest SSe (67%) and SSp (76%) were found in the analysis grouping the same TS (0.8 mm) and landmark (1 mm from the gingival margin). The assessment of GP using TRAN could lead to inadequate diagnoses, especially in determining a thin phenotype. Its accuracy is highly dependent on the TSs used to differentiate between thin and thick GPs and the apicocoronal landmark where the GT was obtained.