Reconstructing Teeth with Bite Information

We propose a method for restoring the surface of a tooth crown so that the pose and anatomical features of the tooth will work well for chewing. The system of teeth has been modeled with a 3D statistical multi-object shape model build from 3D scans of dental cast models. The restoration is carried out using the shape model statistics in a Bayesian framework to calculate the most probable tooth crown shape(s), given the fragments of one or more neighboring and opposing tooth crowns. The modeling of and reconstruction with the multi-object shape model has been realized by extending the model with a concept of elasticity that generalizes better to new teeth. The elasticity has been calculated from the surface curvature relations within and between each tooth sample, simulating a prior knowledge of the shape variation. 1 Tooth Reconstruction In the dental industry, the design and construction of restorations to be inserted in a patient’s mouth is carried out by dental technicians, that are highly trained experts in tooth anatomy and the function of the bite. The task can be to model the missing part of a broken tooth crown, model the crown of a whole missing tooth or even several missing teeth. The restorations are traditionally constructed directly from the materials by hand, but the use of software to model the construction elements of a restoration has been growing rapidly the last couple of years [1,2,3]. Other than saving money on the temporary building materials, the software solution saves time, as some of the traditional production steps can be skipped and proper customized 3D modeling tools and automatic routines can speed up the construction work. The existing dental software systems combines the software with a scanning device to produce a 3D surface model of the patients remaining teeth, on which the restoration is to be designed. The modeled restoration can then be exported as a 3D surface model and milled or printed directly in the final material. One of the most challenging steps towards an automation of dental restoration modeling software is the anatomical deformations of the tooth crowns to be reconstructed. An anatomical correct deformation of a tooth crown surface cannot be calculated exclusively from the size and location of the surrounding surfaces of the scanned data. Some prior knowledge must be added to the system, which describes the shapes and legal deformations of the teeth. It is our goal to develop a system that can learn and describe the complex shape system of the bite, and with this knowledge reconstruct the surfaces of missing tooth crown parts, whole teeth, or several teeth from information extracted from scanned data. The work reported in this article is based on [4], and the plaster casts have been scanned by the 3Shape laser scanner, some shown in Figure 1.