Is measurement of the gingival biotype reliable? Agreement among different assessment methods

Background: To determine agreement among the most commonly used methods for assessing the gingival biotype. Material and Methods: An electronic survey was sent to a sample of dentists practicing in Spain. The questionnaire was based on the evaluation of 5 cases involving different gingival biotype assessment methods. Dentists were required to classify the cases as having a "thin", "thick" or "not able to classify" biotype. Each case was assessed using a frontal intraoral photo of the anterior teeth; an enlarged photo of the buccal aspect of the tooth with a periodontal probe inserted inside the sulcus; and the real thickness measured in mm with a calibrated needle. Agreement among the classifications was assessed using Cohen's kappa coefficient. Results: A total of 104 surveys were analyzed. The most commonly used assessment method was visual evaluation of the morphology of the gingiva and the teeth (62.5%). Concordance among the three different methods was weak (kappa = 0.278). Agreement among the classification methods was greater in extreme cases (thinner and thicker gingival thickness). Conclusions: The most commonly used methods for assessing gingival biotype are not reliable. The three tested methods show poor to weak agreement, which leads to non-reliable estimation of the gingival biotype.