Gingival landmarks, cutoff values, and related variables for determining gingival phenotypes: A scoping review

Statement of problem: Accurate assessment of the gingival phenotype (GP) is essential for achieving predictable esthetic integration and functional success. However, inconsistencies persist in the methods and variables used to establish gingival landmarks and cutoff values for GP determination. Purpose: The purpose of this study was to perform a comprehensive review of the gingival landmarks, cutoff values, and related variables used in determining gingival phenotypes (GPs), with particular attention to the reported area under the curve (AUC) values. Material and methods: A scoping review was conducted in accordance with the PRISMA-ScR guidelines. Searches were performed in the PubMed, Web of Science, Scopus, and Embase databases up to June 2025. Inclusion criteria comprised observational cross-sectional studies comparing periodontal probe visibility (PPV) with transgingival probing (TGP), an ultrasound device (USD), soft tissue cone beam computed tomography (ST-CBCT), or other methods that report AUC values. Results: Nine articles met the inclusion criteria and were analyzed based on the cutoff values of gingival thickness (GT) or related variables for GP determination. Seven studies reported the cutoff values obtained after the protocol execution; among these, 5 differentiated between thin and thick categories using standard periodontal probes, and 2 categorized thin, medium, thick, and very thick phenotypes using color-coded probes. These studies assessed one or more gingival landmarks. Only 2 studies reported preselected cutoff values. Conclusions: The cutoff values for GP determination can be classified into those obtained after the protocol execution and those preselected before study initiation. The most used gingival landmark was 2 mm apical to the mid-facial gingival margin for both thin and thick categories.The identified studies examined the gingival thickness, gingival angle, papilla width, papilla height, probing depth, keratinized tissue width, and crown width/crown length ratio, as variables of interest in the GP determination.