Gingival phenotype classification by visual and probe visibility assessments: Relationship with thickness and probe design.

Background: This study investigated the agreement among dentists in classifying gingival phenotype (GP) through periodontal probe visibility (PPV) assessment with various probe types and the visual method. Additionally, the relationship between GP classifications and gingival thickness (GT) was evaluated.

Methods: Photographs were taken with standard periodontal probe (SPP), color-coded periodontal probe (CCPP) tips in white, green, and blue, as well as metal phenotype probe (MPP) tips in gray and black. Evaluators (periodontist, periodontics resident, endodontics resident, dental student) assessed the photographs and classified the GPs. GT was measured by trans gingival probing.

Results: Visual method showed poor to fair agreement to classify GP. The lowest agreement regarding PPV was noted with white-tipped CCPP. The highest agreement in singular PPV was observed with CCPP blue (κ = 0.932), followed by CCPP green (κ = 0.791), MPP black (κ = 0.783), SPP (κ = 0.730), and MPP gray (κ = 0.690). Combined PPV data revealed fair to moderate agreement with CCPP and moderate to substantial agreement with MPP in GP classification. The corresponding GT to different GP classifications based on combined PPV were comparable. The agreement between SPP and CCPP in classifying non-thin phenotypes was 89.8%, while the agreement between SPP and MPP was 75.4%. Based on PPV, no significant GT cutoff value was found to distinguish between thin and non-thin phenotypes.

Conclusion: Determining a precise GT that guarantees the visibility of a given probe can be difficult when evaluating GP. Regardless of the type of probe, the PPV method has a high potential for misclassifying GP, despite having an acceptable agreement.

Plain language summary: Gingival phenotype (GP) is constituted by thickness of the gums and width of keratinized tissue around teeth. Direct visual evaluation or evaluating a periodontal probe's visibility beneath gums are established techniques to classify gingival phenotype. This study investigated how dentists classify GP using visual assessments and different types of periodontal probes, while also exploring the relationship between GP classifications and gingival thickness. Results showed varied agreement among dentists in classifying GP, with lower agreement observed when using certain types of probes, notably the white-tipped phenotype probe. The highest agreement was found with the blue phenotype probe. Data from periodontal probe visibility assessments indicated fair to moderate agreement with certain probes, suggesting some inconsistency in classification methods. Interestingly, GP classification with visual assessments or probes did not correlate with gingival thickness, which may highlight the importance of considering both factors in clinical practice. These findings underline the need for attention when relying solely on visual assessments or specific probe types for accurate GP classification.