Correlational Research on the 3D Digital Models Based Measurement for Periodontal Biotypes of Crown and Gingival Morphology

Background This paper aims to quantitatively study the clinical parameters of crown and gingival morphology (CGM) of the maxillary anterior teeth (MAT), and analyze the correlation of parameters between periodontal biotype(PB) and CGM, with a view to providing objective standards for periodontal biotyping.Methods The 3D maxillary digital models of 56 experimental subjects were obtained through an intra-oral scanner, and an array of parameters measued with the SpaceClaim software, such as gingival angle (GA), papilla width (PW), papilla height (PH), crown length (CL), crown width (CW), crown width/crown length ratio (CW/CL), bucco-lingual width of the crown (BLW), contact surface width (CSW), and contact surface height/crown length ratio (CS/CL). Then, the PBs were judged through the transparency method of the periodontal probe through the gingival sulcus. Logistic regression was adopted to analyze the independent influence factors of PB, and the receiver operating characteristic curve (ROC curve) used to analyze the optimal cutoff value of independent influence factors.Results There is statistical difference to the parameters of CGM of the MAT at left and right side. The thick biotype accounts for 69.6%, and the parameters of gender, GA, PW, PH, CW and CW/CL are significantly correlated with PBs (P≤0.043). GA (OR=1.206) and PW (OR=5.048) are the independent predictive factors of PBs, their areas under the ROC curve (AUC) are 0.807 and 0.881, respectively, and their optimal cutoff values are 95.95° and 10.01mm, respectively.Conclusion The CGMs of the MAT at the left and right side is symmetrical. The thin biotype accounts for a small portion, and GA and PW are the independent influence factors of PBs. When GA is 95.95° and PW is 10.01mm, it is the optimal cutoff value to categorize experimental subjects into thick biotype.