International Journal of Computerized Dentistry, 04/2007

In this in vitro investigation, we studied the static strength of three-unit all-ceramic bridge frameworks with rigid positioning of the abutments. The materials used were Vita InCeram® Alumina, Vita InCeram® Zirkonia, and zirconium oxide (Vita InCeram (X YZ Cubes for Cerec®). A finite element calculation was performed for numerical comparison of the load-bearing capacity of two main normal tensions. The purpose of the investigation was to design a framework made from hard core material, that offers the greatest possible resistance in static fracture loading tests. In a model, the 2nd maxillary right premolar and 2nd maxillary right molar served as bridge abutments and were provided with a chamfer preparation. On this base, two different bridge frameworks were constructed using CAD/CAM technology after an impression had been taken. One bridge connector was designed heart-shaped, with contact to the gingiva, while the other was designed as a "free-connector" at a distance of 1.2 mm from the gingiva. In this framework design, the radius in the cervical connector area is larger. We were uncertain as to whether it would be possible to further increase the strength of the ceramic material by the use of the differently designed pontic, independent of the hard core ceramic used. The least fracture strength was registered for the "heartshaped connector" constructed from InCeram® Alumina, with a mean fracture load of about 1089 Newton (N). The connector designed as a "free connector", made from the same material, was stronger by 10%. With the materials InCeram® Zirkonia and zirconium dioxide as well, the "free-connector" design achieved a 10% higher breakage limit than the heart-shaped design. InCeram® Zirkonia was 25% more stable in the static load tests than In- Ceram® Alumina. Zirconium dioxide demonstrated a 2.3-fold greater strength than InCeram® Alumina, while the free-connector design showed the greatest mean static loading capacity of 2808 N. Keywords: CAD/CAM technology, strength behavior, framework design, hard core materials, static load test, all-ceramic bridge framework

Based on an exclusively virtual implant planning and positioning concept, the fit of surgical-guide-like workpieces was evaluated in an in-vitro pilot study, manufactured with the InLab 3D system. From 85 maxillary casts, 8 were randomly selected. The first right maxillary incisor was removed. After optical impression of the maxillary anterior teeth, a drilling template was designed by the use of the InLab software, version 3.0. The mode "bridge" "dental database" was applied. The guidance was milled from a methacrylate block and braced on the adjacent teeth. After milling, they were checked for proper seat (without rocking). The discrepancies between the inner surface of the template and the opposing tooth surface was shown with a silcone based material, which rested on the casts after removing the template. The difference between the thickness of the silicone layer and the subjacent tooth surface was measured with a high resolution scanner. In order to characterize the fit of the 8 workpieces the average mean, average maximum and average minimum values of the fit were calculated in the buccal, incisal and palatinal area using the program Match 3D (W. Gloger, LMU): average mean: buccal: 65 µm; incisal: 116 µm; palatinal: 94 µm average maximum: buccal: 162 µm; incisal: 202 µm; palatinal:190 µm average minimum: buccal: 5 µm; incisal: 14 µm; palatinal: 15 µm In the present study it was possible to produce drilling templates with the already commercially available InLab system. The results were presented at the Annual Meeting of the German Society of Computerized Dentistry 2007 as a short presentation.

Currently, methods of modern imaging are increasingly assuming a predominant position in diagnostics and therapy. Larger and larger amounts of sensitive data and information are generated, processed and - frequently with inadequate protection - transmitted through generally accessible networks. The Internet is used especially intensively as a medium for transporting digital data; at the same time, protection of sensitive data is frequently neglected to a high degree by medical professionals. The present contribution is therefore intended to provide an overview of currently valid standards and legal regulations, as well as suitable encoding methods relevant for the dental practice. Keywords: risks of data misuse, safety gaps in e-mail communication, legal background of patient data processing, encoding methods for use in the practice and clinic