Discriminant analysis for the thin periodontal biotype based on the data acquired from three-dimensional virtual...

There have been no objective criteria for classifying the periodontal biotype. The purpose of this study is to suggest clinical guidelines for discriminating the thin biotype, which might be susceptible to gingival recession, using statistical analyses based on the measurement of the dento-gingival complex on three-dimensional virtual models.

From canine to canine, the area of the facial papilla, the facial surface area of the anterior tooth, the proportion of the dento-papillary complex, clinical papillary length, and the clinical papillary angle were measured on a three-dimensional virtual model of 133 young participants. In the clinical exam, the gingival transparency when probing was evaluated, and the classification into thin and non-thin biotype groups was used as the gold standard. The data were analyzed by discriminant analysis.

Twenty-nine participants (17 males and 12 females) belonged to the "thin group" according to the clinical evaluation. All variables were significantly different between groups (P <0.001). The results of discriminant function analysis showed that the sum of the area between each canine and lateral incisor, each lateral and central incisor, and the two central incisors was the best single determinant of biotype, and the sum of the papillary lengths between each canine and lateral incisor, each lateral and central incisor, and the two central incisors (PLSum5) was the next best choice. The cutoff value of PLSum5 was calculated to be 23.73 mm.

PLSum5 >24 mm is the suggested criterion for identifying high-risk thin biotype patients based on the comparison with the results from gingival transparency inspection. A clinical reevaluation of this criterion should be examined in additional studies for application in real clinical situations.