International Journal of Computerized Dentistry, 04/2010

Information from the opposing dentition is used to design and fabricate occlusal contacts with a reasonable level of accuracy for a given restoration. The Dental Database with the Antagonist design process utilizes a bite registration to propose the construction of a virtual opposing model. The Articulation design technique utilizes a functionally generated bite registration to control both the maximum intercuspation and excursive contacts on the restoration. Correlation design technique offers the opportunity to copy the established occlusal anatomy to the preparation. Although these techniques offer a workflow to establish occlusal contacts with the Cerec system, there is a lack of quantitative data as to the accuracy achieved. Alternative techniques to control the occlusal contacts have been suggested which rely on "user customized design techniques" that recommend altered program settings, manual override of automated features in the software, or modification of the established software design programs. The purpose of this study was to measure the occlusal vertical discrepancy for various design techniques. Full crowns made using Dental Database with the Antagonist design technique had a significantly smaller occlusal vertical discrepancy than those made with Correlation. Dental Database with the Antagonist had a significantly smaller occlusal vertical discrepancy than all suggested alternative design techniques. Use of the Dental Database with Antagonist design technique provides the most accurate technique for establishing occlusal contacts with the Cerec 3D system. Keywords: CAD/CAM, occlusion, Cerec, software design

The aim of this patient-based study was to assess the effect of fixed splinting of mandibular premolars having reduced alveolar support on load distribution in the periodontium. A patient's mandibular second premolar with considerably reduced alveolar bone height was restored using a metal-ceramic restoration splinted with the adjacent first premolar; an acceptable 3-year maintenance period was observed. A patient-based three-dimensional finite element model was constructed using the morphological measurements obtained from the diagnostic cast and radiographs. The model incorporated in vivo occlusal records and was used to analyze stress and strain in the periodontium for splinted and nonsplinted simulations. Modified models were also created to explore the effects of relative bone height on the stress and strain distributions. The maximum principal stress and strain on the periodontium of the second premolar were considerably higher before splinting than after splinting and were close to strain levels indicative of potential bone microdamage. In contrast, the stress and strain in the first premolar increased after splinting. The modified models showed that the increased vertical gap of alveolar height between the splinted teeth was another factor to increase the load in the first premolar. Since the prosthodontic procedure employed is not routinely used, the results cannot be generalized. However, it is suggested that fixed splinting can decrease the periodontal load on premolars with reduced periodontal support, but may increase the load on the splinted tooth. Keywords: prosthodontics, bite force, tooth splint, diagnosis, finite element analysis

TriLuxe ceramic blocks for chairside CAD/CAM procedures are color layered to allow natural esthetics, and only require subsequent glazing. The purpose of this study was to compare color repeatability of different batches of TriLuxe blocks. The three commercially available shades (1M2C, 2M2C, 3M2C) of TriLuxe blocks for the Cerec CAD/CAM system were examined. For each of the three colors, three different batches were tested, 5 blocks each. The measurements were made using a spectrophotometer equipped with an integrating sphere using the CIELab colorimetric system. One-way ANOVA showed that the factor "Production Batch" was not statistically significant. Regarding ΔE, none of the 315 color comparisons (neither within the same shade, nor between specimens of the same batch, nor between specimens from different batches) exceeded the proposed ΔE=3.3 threshold for clinical acceptability. All the different batches of the different shades of VITA TriLuxe blocks for the Cerec system showed the high degree of color correspondence necessary in industrially prefabricated CAD/CAM blocks. Keywords: ceramic, color, CAD/CAM, chairside, Cerec, spectrophotometer

Since May 2010, the representative of a "completely new class of devices" (statement of the manufacturer) from the Apple company has been on the market. This article describes possibilities for its use in the dental environment.

With the aid of an innovatively structured ceramic block, it is possible to achieve results at a high esthetic level with relatively simple means. In the three-dimensionally structured Vitablocs RealLife, translucent enamel ceramic is arranged around a conically structured, opaque dentin core. The virtual restoration can be positioned freely in all three dimensions with the aid of the Cerec / inLab software. The restorations are milled fully anatomically and only minimally glazed or characterized with stains. Results that otherwise can be achieved only with much more complex layering processes are possible. Keywords: CAD/CAM process, Cerec, inLab, ceramic blocks, polychromatic, esthetics, anterior tooth, crown, veneer