Gingival phenotype assessment methods and classifications revisited: a preclinical study

Abstract

Objective To compare gingival phenotype assessment methods based on soft tissue transparency on different backgrounds and assessor experience levels. Methods For this purpose, 24 gingival specimens were retrieved from pig jaws with tissue thicknesses from 0.2 to 1.25 mm. Three methods were assessed: periodontal probe PCP12 (thin/thick), double-ended periodontal probe DBS12 (thin/moderate/thick) and colour-based phenotype probe CBP (thin/moderate/thick/very thick). Each sample was photographed with each probe underneath and categorized whether the probe was visible or not using different coloured backgrounds. To measure experience level influence, dentists, dental undergraduate students and laypersons (n = 10/group) performed the evaluation. Results PCP12 probe showed a threshold between 0.4 and 0.5 mm. To distinct between thin and moderate thick gingiva, a comparable range for DBS12 was found while moderate thickness was between 0.5 and 0.8 mm and for thick above 0.8 mm. CBP also showed a comparable threshold of 0.5 mm for thin versus moderate as compared with the other methods; above 0.8 mm, predominantly a very thick tissue was measured. In general, the background colour had a minor impact on PCP12 and DBS12, and investigator experience showed no clear influence on GP assessment. Conclusion Based on probe transparency and within the limitation of a preclinical study, we suggest GP differentiation into three entities: thin (< 0.5 mm; high risk), moderate (0.5–0.8 mm; medium risk) and thick (> 0.8 mm; low risk). Clinical relevance All three GP assessment methods are easy to perform and seem to have a high predictive value with a three entities classification for DBS12 and CBP.

Are colored periodontal probes reliable to classify the gingival phenotype in terms of gingival thickness?

“…21 The rationale of having such a specific/detailed classification is that it may allow an improved detection rate of cases with very thick and very thin gingiva. 9,11 However, in the present study most cases were categorized as "medium" with CPP, i.e., six out of eight examiners judged > 85% of the cases in this category, whereas only few cases were classified to one of the other categories (i.e., "thin," "thick," and "very thick"). This clustering in the "medium" category corresponds well with what was reported in a recent study using CPP to judge GT in lower anterior teeth 22 ; therein, about 70% of the cases were classified by a single examiner as "medium."…”

“…The present study tested one of the newer devices—the CPP—consisting of a set of three probes allowing a classification into four GT groups (see Supplementary Figure 1 in online Journal of Periodontology ) 21 . The rationale of having such a specific/detailed classification is that it may allow an improved detection rate of cases with very thick and very thin gingiva 9,11 . However, in the present study most cases were categorized as “medium” with CPP, i.e., six out of eight examiners judged > 85% of the cases in this category, whereas only few cases were classified to one of the other categories (i.e., “thin,” “thick,” and “very thick”).…”

“…In perspective, there is no consensus on which GT measured at which vertical level should be considered as relevant/critical for clinical decision making. Specifically, the literature provides a range of cut-off values for a "thin" gingiva from 0.5 to 1.5 mm 11,14,16,28,32,38,39 with 1 mm-although still rather arbitrary-being most commonly used. 14,16,28,32,38 Further, GT is measured at various vertical levels, ranging from about 1 to 3 mm from to the gingival margin 14,17,22,32,33 to a level related to the probing pocket depth.…”

“…Within the last decade, new devices promising a more reliable and/or detailed GT assessment/classification have been introduced into the market. [9][10][11][12]14,16,17,22,[28][29][30][31][32][33][34][35] In this context, it is important that the accuracy, inter-examiner reproducibility, and intra-examiner repeatability of any new device is properly assessed. The present study tested one of the newer devices-the CPP-consisting of a set of three probes allowing a classification into four GT groups (see Supplementary Figure 1 in online Journal of Periodontology).…”

“…The most common method is the placement of a standard periodontal probe (SPP) into the gingival sulcus at the midfacial aspect of the tooth. [7][8][9][10][11][12][13][14][15][16][17] If the SPP is visible/shining through the tissue at the gingival margin, the gingiva is considered "thin," whereas it is judged "thick" if the probe is invisible. 13 However, the probe transparency method has a certain subjective component; in a previous study complete agreement in classifying GT as thin or thick with SPP was achieved in 80% of the cases among three evaluators.…”