Three-Dimensional Topography of the Gingival Line of Young Adult Maxillary Teeth: Curve Averaging Using Reverse-Engineering Methods

Purpose: This study attempted to establish three-dimensional average curves of the gingival line of maxillary teeth using reconstructed virtual models to utilize as guides for dental implant restorations. Materials and Methods: Virtual models from 100 full-mouth dental stone cast sets were prepared with a three-dimensional scanner and special reconstruction software. Marginal gingival lines were defined by transforming the boundary points to the NURBS (nonuniform rational B-spline) curve. Using an iterative closest point algorithm, the sample models were aligned and the gingival curves were isolated. Each curve was tessellated by 200 points using a uniform interval. The 200 tessellated points of each sample model were averaged according to the index of each model. In a pilot experiment, regression and fitting analysis of one obtained average curve was performed to depict it as mathematical formulae. Results: The three-dimensional average curves of six maxillary anterior teeth, two maxillary right premolars, and a maxillary right first molar were obtained, and their dimensions were measured. Conclusions: Average curves of the gingival lines of young people were investigated. It is proposed that dentists apply these data to implant platforms or abutment designs to achieve ideal esthetics. The curves obtained in the present study may be incorporated as a basis for implant component design to improve the biologic nature and related esthetics of restorations. Keywords: cementoenamel junction, dental implants, esthetics, gingival line, scalloped design, three-dimensional scanner