[Testing dental implants with an in vivo finite element model]

An implant-retained auricular prosthesis complicated by a modified temporal bone resection

A patient underwent a modified temporal bone resection and total auriculectomy to remove a sebaceous carcinoma arising from the tragus of the right auricle that extended into the external auditory meatus. Because the tumor extended into the temporal bone, the osseous sites originally selected for immediate placement of the craniofacial implants were resected and no longer available. Subsequently, after an appropriate period of healing, implants were placed into the residual temporal bone, considerably more superior and posterior to the external auditory meatus such that they emerged through hair-bearing skin. The purpose of this report was to describe the fabrication of an implant-retained auricular prosthesis with implants in suboptimal positions. Challenges included optimization of the stability and retention of the prosthesis, effectively managing the prosthetic space without compromising the esthetic outcome, providing adequate hygiene access for the implant connecting bar, and maintaining the health of the peri-implant tissues when the implant emerged through hair-bearing skin.

3D Reconstruction of dental specimens from 2D histological images and μCT-Scans

Direct comparison of experimental and theoretical results in biomechanical studies requires a careful reconstruction of specimen surfaces to achieve a satisfactory congruence for validation. In this paper a semi-automatic approach is described to reconstruct triangular boundary representations from images originating from, either histological sections or microCT-, CT- or MRI-data, respectively. In a user-guided first step, planar 2D contours were extracted for every material of interest, using image segmentation techniques. In a second step, standard 2D triangulation algorithms were used to derive high quality mesh representations of the underlying surfaces. This was accomplished by converting the 2D meshes into 3D meshes by a novel lifting procedure. The meshes can be imported as is into finite element programme packages such as Marc/Mentat or COSMOS/M. Accuracy and feasibility of the algorithm is demonstrated by reconstructing several specimens as examples and comparing simulated results with available measurements performed on the original objects.