cone beam international magazine of cone beam dentistry

I overview _ implant planning Fig. 1_Planned implant with full-guided drill sleeve; gingiva line set by the clinician according to X-ray image (pink); by matching obtained with the situation model – real – gingiva line (yellow). Fig. 2a_ Virtual matching in 3-D X-ray; planned implants with a situation model (red). Image cut: orthogonal ridge section with gingiva line (yellow) from the situation model. Fig. 2b_Virtual matching in 3-D X-ray, implants planned with aesthetics wax up (green); image: orthogonal ridge section with tooth line (yellow) of aesthetic wax-up. _Introduction On the basis of three-dimensional X-ray images, inthe1990sthefirstsoftwareprogrammesallowed a navigated insertion of dental implants. But the digitisation of dental processes started even earlier, namely in the mid-1980’s. Imaging techniques al- lowed the production of components based on vir- tualconstruction.Today,thisprincipleiswellestab- lishedbothinthedental-clinicalfieldandespecially inthedentallaboratory.Meanwhile,3-Ddatasetsof objectsarecreatednotonlybynormalcamerashots, buttherearealsospecial3-Dscannersinuse.Inpar- ticular, today’s desktop scanners are so precise in their resolution accuracy that they are able to ex- actly reflect the real model or oral situation. Simul- taneously with the capturing process, different methods have been developed to transfer the ac- quired 3-D data sets back to reality. While initially thiswasamillingandprototypingprocess,currently the sintering and printing processes are favoured. For a long time, navigated implantology and 3-D scanning has been developed in parallel, where at best surgical templates were fabricated by proto- typing on basis of X-ray data sets. Goal:optimalimplantposition In recent years, the matching of 3-D X-ray data sets (DICOM) and 3-D model data sets (STL) has be- gun. The goal was and still is to find the optimal sur- gical and prosthetic implant positions for navigated insertion to provide an optimal solution for the pa- tient. In addition, the production of temporary den- turesandinindividualcasesanimmediatetreatment is so much better and much more reliable and pre- dictable. At the same time, an objective quality con- trolofboththeplanningandtheresultispracticable through matching of DICOM and STL data sets. By means of some case studies, we show which diag- nostic and technical possibilities have been feasible since the establishment of the diagnostics and nav- igation system CTV in 2005 in the following article. _Implant planning with CTV X-rays are subject to the laws of physics. There- fore, all the resulting images are generally afflicted with an error regarding distortion, diffraction and interference. Because these errors have their origin in the radiological density changes of the object, some areas cannot be represented or are misrepre- sented. Particularly critical are movement-induced distortions in CBCT images. They cannot be com- pletelyavoidedorevenpredicted.Afurtherincrease in accuracy solely from radiological data does not seem to be possible currently. The solution is to col- lect additional data by using independent methods to achieve a "rectification" and detail enhancement throughcombinationwiththeradiologicaldata.For example, the line of the gingiva and other surface structures in the 3-D X-ray image cannot be traced precisely. The solution here is the correct matching Optimized implant planning: DICOM-STL matching Author_Drs Frank Schaefer, Dagmar Schaefer & Mike Zäuner, Germany 10 I cone beam2_2014 Fig. 1 Fig. 2b Fig. 2a