Transgingival probing: a clinical gold standard for assessing gingival thickness

Transgingival probing is often used in the clinic to assess gingival thickness. However, what is not completely known is how well this method represents the true value of soft tissue thickness. The aim of this study was to assess differences and variation in gingival thickness when measured with transgingival probing or scanned with an intraoral device.

This ex vivo study evaluated gingival thickness on 20 porcine cadavers. Gingival thickness was assessed at both central and lateral mandibular incisors through transgingival probing with a standard metal periodontal probe and also using intraoral scanning, which was considered as the method providing the 'true value' of soft tissue thickness. Intra-examiner repeatability and method error were evaluated.

No evidence of systematic difference for any of the mandibular central or lateral incisors (mandibular right incisors: mean difference -0.17 to -0.01 mm, and mandibular left incisors: mean difference -0.11 to 0.04 mm) was observed between the periodontal probe and intraoral scanning methods. The absolute differences between the repeated measurements with intraoral scanning for each tooth type (n = 30) were calculated: the overall median was 0.089 mm and the interquartile range was 0.080 mm.

Transgingival probing with a standard metal periodontal probe for assessing gingival thickness is a reliable method, with values very close to the true gingival thickness, and it can thus be considered as the clinical gold standard.