PubMed ID (PMID): 26734665Pages 303-317, Language: English, GermanZimmermann, Moritz / Mehl, Albert
Im digitalen dentalen Zeitalter gewinnt die virtuelle Behandlungsplanung des Patienten immer mehr an Bedeutung. Aufgrund neuer technologischer Möglichkeiten im CAD/ CAM-Bereich erscheint eine interdisziplinäre vorhersagbare Patientenbehandlung im Sinne eines "backward planning" sinnvoll und realistisch. Mittels eines für den Patienten vorab erstellten virtuellen Smile Design kann bereits heutzutage ein ästhetisches virtuelles Ziel-Set-up für ein angestrebtes Behandlungsendergebnis erstellt werden. Ausgehend von diesem virtuellen Set-up können anschließend im interdisziplinären Kontext die weiteren Behandlungsschritte entschieden und mit dem Patienten kommuniziert werden. Der vorliegende Artikel stellt das Konzept des Smile Design sowie die hierfür zu beachtenden ästhetischen Analysen vor. Neben dem schrittweisen Vorgehen werden die verschiedenen Möglichkeiten und Systeme zur Erstellung eines virtuellen Smile Design dargestellt und miteinander verglichen. Nach einer Diskussion der Vorteile und Einschränkungen des virtuellen Smile Design werden die verschiedenen Möglichkeiten zur Integration eines 2-D Smile Design in den digitalen 3-D Workflow aufgezeigt. Darüber hinaus werden neue Möglichkeiten wie die Integration des Smile Design in digitale Facescans sowie die dreidimensionale Verlaufsdiagnostik unter Verwendung von Intraoralscannern vorgestellt.
Keywords: Smile Design, CAD/CAM, Gesichtsanalyse, Ästhetik, Intraoralscan, virtuelle Verlaufskontrolle
PubMed ID (PMID): 26734666Pages 319-331, Language: English, GermanMaggetti, Ivano / Bindl, Andreas / Mehl, Albert
Objectives: To address the controversy, in which indications average value articulation is suitable or to what extent individual registrations, especially using the facebow, should be applied, a quantification of the variability of relevant anatomical landmarks is necessary. The goal of this study was to investigate the mean and natural bandwidth of the parameters describing articulation.
Methods: Significant landmarks were measured on three-dimensional (3D) cone beam computed tomography (CBCT) scans of 120 arbitrarily selected individuals. The bandwidth and mean values of the anatomical relations were calculated.
Results: The mean arm length of the Bonwill triangle was 103.3 mm, with a range of 90.2 mm (minimum) to 117.9 mm (maximum), and a mean base length of 99.6 mm, with a range of 85.2 mm to 112.6 mm. There was a high correlation between the length of the left and right arms, but not between the arms and the base. The mean height of the Bonwill triangle, measured between the condyles and the occlusal plane, resulted in 34.3 mm, with a range of 21.0 mm to 47.2 mm. The mean value of the Balkwill angle was 20.4 degrees, with a range of 9.0 degrees to 27.6 degrees. The angle between the Camper's line and the occlusal plane averaged around 7 degrees.
Conclusions: This study presents the bandwidth of anatomical relations necessary for articulation systems. The results are specific for males and females. The relevant parameters offer a high symmetry between the right and left sides. Additionally, the results show that the Bonwill triangle is more likely to be isosceles than equilateral.
Clinical significance: The knowledge of the anatomical bandwidth of temporomandibular joint (TMJ) positions in relation to the dentition allows the simulation of software- controlled virtual articulators and the substitution of facebows.
Keywords: Bonwill triangle, anatomical landmarks, Camper's plane, articulator, occlusal plane
PubMed ID (PMID): 26734667Pages 333-342, Language: English, GermanKober, Cornelia / Hellmich, Christian / Stübinger, Stefan / Zeilhofer, Hans-Florian / Sader, Robert
Introduction: The load-carrying behavior of the human mandible can be described using finite element simulation, enabling investigations about physiological and pathological skeletal adaption. "Anatomical simulation" implies a stepwise approximation towards the anatomical reality.
Method: The project is structured in three steps. In Step 1, the preprocessing, the simulation model is provided. Step 2 is the numerical computation. Step 3 is dedicated to the interpretation of the results. The requirements of the preprocessing are: a) realization of the organ's individual anatomy, namely its outer shape; b) the tissue's elastic properties, thus its inner consistency; and c) the organ's mechanical loads. For physiological mandibular loading, these are due to muscles, temporomandibular joints, and tooth forces. Meanwhile, the reconstruction of the macroscopic anatomy from computed tomography data is standard. The periodontal ligament is inserted ex post using an approach developed by the authors. The bone is modeled anisotropically and inhomogeneously. By the visualization of the individual fiber course, the muscular force vectors are realized. The mandibular condyle is freely mobile in a kind of simplified joint capsule. For the realization of bite forces, several approaches are available.
Results: An extendible software tool is provided, enabling the user - by variable input of muscle and bite forces - to examine the individual patient's biomechanics, eg, the influence of the periodontal ligament, the condition of the temporomandibular joints, atrophic processes, or the biomechanical situation of dental implants.
Discussion: By stepwise approximation towards the anatomical reality, the mandibular simulation will be advanced to a valuable tool for diagnosis and prognosis.
Keywords: mandible, biomechanics, finite element method, simulation, stress/strain behavior, mechanical loading, periodontal ligament, temporomandibular joint, masticatory muscles, skeletal adaption
PubMed ID (PMID): 26734668Pages 343-367, Language: English, FrenchTapie, Laurent / Lebon, Nicolas / Mawussi, Bernardin / Fron-Chabouis, Hélène / Duret, Francois / Attal, Jean-Pierre
As is the case in the field of medicine, as well as in most areas of daily life, digital technology is increasingly being introduced into dental practice. Computer-aided design/ computer-aided manufacturing (CAD/CAM) solutions are available not only for chairside practice but also for creating inlays, crowns, fixed partial dentures (FPDs), implant abutments, and other dental prostheses. CAD/CAM dental practice can be considered as the handling of devices and software processing for the almost automatic design and creation of dental restorations. However, dentists who want to use dental CAD/CAM systems often do not have enough information to understand the variations offered by such technology practice. Knowledge of the random and systematic errors in accuracy with CAD/CAM systems can help to achieve successful restorations with this technology, and help with the purchasing of a CAD/CAM system that meets the clinical needs of restoration. This article provides a mechanical engineering viewpoint of the accuracy of CAD/ CAM systems, to help dentists understand the impact of this technology on restoration accuracy.
Keywords: accuracy, dental CAD/CAM, digital dentistry, geometric approximations, geometric defects
PubMed ID (PMID): 26734669Pages 369-379, Language: English, GermanWiedhahn, Klaus
Until now, the ability to fabricate definitive Cerec bridges for the posterior region was less a question of the capabilities of the Cerec software than the availability of ceramic materials with sufficient strength for these indications. With the launch of the somewhat translucent inCoris TZI zirconia, Sirona has made possible the computer-assisted design and computer- assisted manufacturing (CAD/CAM) of monolithic bridges using Cerec dental software. In this article, the possibilities and limitations of inCoris TZI, as well as inCoris TZI C (a recently introduced further development from Sirona), will be demonstrated, based on two clinical cases.
Keywords: Cerec bridges, zirconia, esthetics with zirconia, inCoris TZI, inCoris TZI C