Design of an optical device for endoral 3D contouring

The task of obtaining dental impression is a complicate one and it can be very uncomfortable to the patient. It is mainly based on the insertion, inside the mouth, of a formable material which is made to adhere tothe teeth and, when hardened, removed from the oral cavity. In this way a negative cast of the dental elements is obtained. This is a completely manual process, mainly based on the ability of the dentist and many errors can occur that can alter the correct shape detection of the dental elements. In this work a device to perform the 3D contouring of dental elements is designed and discussed. The device is based upon optical methods so that any direct contact with the dental elements is avoided and the discomfort is diminished. The basic principle adopted to fulfill the task is based on the fringe projection approach. A known fringe pattern is projected on the dental surface and the projected pattern is modulated by the surface itself. Demodulating the signalallows obtaining the shape of the elements. Optical fibers are used in order to keep small the dimensions of the device so that it can be introduced in the endoral environment and an innovative approach to phase hierarchical unwrapping was developed to manage area where high slopes are present.