Integration of 3D anatomical data obtained by CT imaging and 3D optical scanning for computer aided implant surgery

<p>Abstract</p> <p>Background</p> <p>A precise placement of dental implants is a crucial step to optimize both prosthetic aspects and functional constraints. In this context, the use of virtual guiding systems has been recognized as a fundamental tool to control the ideal implant position. In particular, complex periodontal surgeries can be performed using preoperative planning based on CT data. The critical point of the procedure relies on the lack of accuracy in transferring CT planning information to surgical field through custom-made stereo-lithographic surgical guides.</p> <p>Methods</p> <p>In this work, a novel methodology is proposed for monitoring loss of accuracy in transferring CT dental information into periodontal surgical field. The methodology is based on integrating 3D data of anatomical (impression and cast) and preoperative (radiographic template) models, obtained by both CT and optical scanning processes.</p> <p>Results</p> <p>A clinical case, relative to a fully edentulous jaw patient, has been used as test case to assess the accuracy of the various steps concurring in manufacturing surgical guides. In particular, a surgical guide has been designed to place implants in the bone structure of the patient. The analysis of the results has allowed the clinician to monitor all the errors, which have been occurring step by step manufacturing the physical templates.</p> <p>Conclusions</p> <p>The use of an optical scanner, which has a higher resolution and accuracy than CT scanning, has demonstrated to be a valid support to control the precision of the various physical models adopted and to point out possible error sources. A case study regarding a fully edentulous patient has confirmed the feasibility of the proposed methodology.</p

Effect of smoking habits on accuracy of implant placement using mucosally supported stereolithographic surgical guides

Background: Smoking is considered as a factor for implant survival and peri-implant bone loss of dental implants. Several studies revealed the negative effect of smoking on osseointegration, and its dose-related effect. Aim: To evaluate the effect of smoking habits on accuracy of implant placement using mucosally supported stereolithographic surgical guides. Material and Methods: Six OsseoSpeed™ implants (Astra Tech AB) were inserted into the maxilla in 13 patients. Patients were excluded if they suffered from any systemic disease or if they were actually taking any kind of medication. Software (Mimics 9.0) was used to fuse images of the virtually planned and actually placed implants, and locations and axes were compared between the nonsmoking and smoking subgroups. As the mucosal biotype could probably influence accuracy data, twelve reference points were defined within each patient to define a mean mucosal thickness value. Results: In the smoking subgroup, 36 implants were placed compared to 42 in the nonsmoking subgroup. Mean coronal deviation was 1.04 mm (range: 0.29-2.45 mm) in smokers compared to 0.80 mm in the nonsmokers (range: 0.29-1.67 mm). At apical point mean deviation was 1.26 mm (range: 0.39-3.01 mm) in smokers compared to 1.02 mm in the nonsmokers (range: 0.32-2.59 mm). Mean angular deviation was 2.64° (range: 0.41°-6.81°) in smokers compared to 2.57° in the nonsmokers (range: 0.16°-8.86°). Significant differences were found when comparing global coronal and apical deviation between smokers and nonsmokers (P<0,05). Evaluating mucosal thickness, mean value was 3.19 mm (range: 2.39-4.01 mm) in smokers compared to 2.43 mm in the nonsmokers (range: 1.44-3.03 mm) Conclusions: Statistically significant differences were found when comparing the accuracy of dental implant placement in smokers to nonsmokers. Smokers have significant thicker supporting mucosal tissues compared to nonsmokers which may explain inaccuracy due to less stability of the surgical guide or the scanning prosthesis

Diseño de un prototipo de prótesis mandibular, a partir de modelos anatómicos 3d, caso de estudio

Este proyecto propone el diseño de una prótesis de mandíbula para tratar una alteración congénita denominada Microsomia Hemifacial (MH), en cuya deformidad se ve comprometida la integridad de la Articulación Temporomandibular (ATM), ya sea de uno de los lados de la mandíbula o incluso ambos, que afecta la simetría facial del usuario que la padece. Para el desarrollo del proyecto se investigó sobre esta anomalía congénita con el fin de entender mejor la problemática del caso de estudio de este proyecto. Para el desarrollo del prototipo de prótesis de mandíbula a partir de modelos anatómicos 3D, primero se investigó los programas que existen en el mercado y que permitieron realizar la reconstrucción tridimensional a partir de imágenes médicas en formato Dicom, las cuales provienen de equipos de Tomografía Computarizada y/o Resonancia Magnética. Además se diseñó un Phantom para validar experimentalmente el funcionamiento y la interacción de cada software con el diseñador, igualmente, esta herramienta sirvió para evaluar la eficiencia y la precisión de cada uno de los programas, ya que se generó una tabla comparativa que permitió detectar las ventajas y desventajas de cada uno. El proceso incluyó la consulta de materiales que se utilizan para la fabricación de los Phantom, los cuales están muy ligados a que sus características simulen la densidad de los tejidos humanos. La selección de medidas y geometría de cada material también fue referenciada y se utilizó para verificar cada valor con cada uno de los software previamente seleccionados. Con dicha actividad se generó una tabla comparativa con la cual se logró evidenciar que el programa con los mejores resultados es Invesalius, programa que se usó para procesar y generar el modelo tridimensional a partir de las imágenes tomográficas del caso de estudio de este proyecto. Al concluir con la reconstrucción 3D, se encontró zonas afectadas por ruidos provenientes de diferentes fuentes. Por esta razón el modelo tridimensional fue exportado a otro software, para eliminar el ruido de la malla, con lo cual se pudo limpiar y reducir las zonas afectadas, lo cual permitió realizar el diseño del prototipo de prótesis de mandíbula con base en la anatomía del usuario. Además se realizó una tabla comparativa la cual permitió observar el cambio de las diferentes propiedades de malla según el tipo de filtro aplicado. Con base en estos datos se seleccionó el número de iteraciones y el tipo de filtro que requiere ser implementado teniendo en cuenta los tipos de ruido que contienen los datos del caso de estudio. Finalmente se pudo desarrollar un modelo 3D adecuado (sin ruido) para continuar con las otras fases de diseño. Como el tipo de MH del caso de estudio, solo afecta un lado de la mandíbula del usuario, al tener un modelo tridimensional libre de zonas de ruido, se generó un conjunto de superficies de la parte anatómica que no es afectada por la MH, con las cuales se generó el sólido de los componentes que van a ser empleados para reemplazar el cóndilo y la fosa, dos componentes esenciales de la articulación temporomandibular y recuperar con esto la simetría facial. Una vez obtenido el prototipo de prótesis de mandíbula, se procedió a realizar un análisis computacional FEA con el cual se verificó el comportamiento y se logró concluir que el esfuerzo Von Mises máximo registrado en el modelo es de 124,8 MPa, por otro lado el desplazamiento máximo registrado fue de 0,02 mm. Datos similares a lo reportado en la literatura. Igualmente se pudo otorgar un factor de seguridad global del prototipo de 1,4PregradoIngeniero(a) Biomédico(a

Desarrollo de un Módulo de Tratamiento de Imagen para Sistemas de Imagen Dental

Este trabajo resume los desarrollos llevados a cabo sobre reducción de artefactos metálicos y de segmentación de tejidos mandibulares que salen al paso de las limitaciones de los sistemas de imagen dental actuales. Los métodos propuestos han sido evaluados analíticamente obteniendo resultados satisfactorios respecto al estado del arte actual, hecho que ha dado lugar a un número considerable de publicaciones científicas.Lloréns Rodríguez, R. (2011). Desarrollo de un Módulo de Tratamiento de Imagen para Sistemas de Imagen Dental. http://hdl.handle.net/10251/28047.Archivo delegad

Accuracy of intraoral real-time navigation versus static, CAD/CAM manufactured pilot drilling template in dental implant surgery – an in vitro study

Nach Zahnverlust gelingt heutzutage die Wiederherstellung des Kauapparates mit Implantaten zunehmend unterstützt durch dreidimensionale Planung und statische oder dynamische Hilfsmittel für den Transfer in die OP. Hierfür verwendete Bohrschablonen oder echtzeitnavigierende Systeme liefern verlässliche, präzise Ergebnisse, um durch die Implantation weder anatomische Strukturen des Patienten zu verletzen, noch das spätere Zahnersatzkonzept zu beeinträchtigen. Unsere Studie vergleicht die Genauigkeiten zwischen Pilotbohrschablonen, die den ersten Teil der Implantatbohrung unterstützen, und echtzeitnavigierter dynamischer Navigation mit dem DENACAM®-System der Firma mininavident. Die DENACAM® ist in ihrer Bauweise handlicher, als herkömmliche Systeme. Zwei Behandler mit unterschiedlicher klinischer Erfahrung haben an zwölf teilbezahnten Unterkiefermodellen aus Kunststoff insgesamt 60 Implantate gesetzt. Die prä- und postoperative Analyse erfolgte dabei durch digitale Volumentomographie. Zur Auswertung wurde das Treatment Evaluation Tool, eine in das Implantatplanungsprogramm coDiagnostiX® integrierte Software, genutzt. Im direkten Vergleich erhielten wir bei Nutzung der Bohrschablone signifikant genauere Ergebnisse im Versatz der Implantatbasis und -spitze in den einzelnen räumlichen Ebenen (p = 0,0079; 0,003; 0,0341; 0,0006; 0,0044). Hinsichtlich der Angulation war das Navigationssystem präziser (p = 0,0016). Die Differenz im Winkel zur Planung lag bei 3°. Die mediane horizontale Abweichung lag echtzeitnavigiert bei 0,52 mm an der Basis und 0,75 mm an der Spitze. Das Navigationssystem implantierte hinsichtlich der Angulation genauer, je näher die Bohrung am Erkennungsmarker des Systems lag (p = 0,0043). Die Bohrschablone zeigte diese Tendenz nicht und war den Winkel betrachtet präziser (p = 0,0022). Analog zur Literatur profitierten beide Behandler vor allem bei der Angulation des Implantats von der Echtzeitnavigation (p = 0,0337; 0,0355). Über die Versuchsdauer sahen wir lediglich eine subjektive Verbesserung der Implantationsleistung. Für zukünftige In-vivo-Untersuchungen könnte die Auswertung anstatt über ein postoperatives dreidimensionales Röntgenbild strahlenschonender mit digitalen intraoralen Scans durchgeführt werden. Für eine evidenzbasierte Empfehlung zur Anwendung des DENACAM®-Systems in vivo, sollten zusätzlich weitere klinische Studien folgen.Objectives: Nowadays, rehabilitation of the masticatory apparatus with implants is increasingly successful using 3D planning and static or dynamic aids. Aim of this study is to compare accuracy between pilot drilling templates and intraoral real-time dynamic navigation with DENACAM® system from mininavident. Methods: A total of 60 implants were placed on 12 partially edentulous lower jaw models by two practitioners with different clinical experience. One half were placed with pilot drilling templates, other half with dynamic navigation. In addition, implant placement in switching gaps and free-end situations was investigated. Accuracy was assessed by re-evaluation of postoperative cone-beam computed tomography. Results: In direct comparison, we obtained significantly more accurate results in offset of implant base and tip in particular spatial dimensions when using drilling templates (p = 0.0079; = 0.003; =0.0341; =0.0006; =0.0044). With regard to angulation, real-time navigation was more precise (p = 0.0016). Its inaccuracy was 3°. Median horizontal deviation was 0.52 mm at base and 0.75 mm at tip using DENACAM®. Regarding angulation, it was found that the closer the drill hole was to the system's marker, the better navigation performed. The template did not show this trend (p = 0.0043; = 0.0022). Analogous to the literature, both practitioners mainly benefited from real-time navigation regarding angulation of the implant (p = 0.0337; 0.0355). Over the trial period, we only saw a subjective improvement in implant placement performance. Conclusion: Considering limitations of an in-vitro study, dynamic navigation may be a tool for reliable and accurate implantation. At implant positions planned far from marker, inaccuracies should be expected and taken into consideration. However, further clinical studies need to follow in order to provide an evidence-based recommendation for use in-vivo. Clinical significance: The compact design of DENACAM® enables real-time navigation in practice.2021-08-3

A 3D environment for surgical planning and simulation

The use of Computed Tomography (CT) images and their three-dimensional (3D) reconstruction has spread in the last decade for implantology and surgery. A common use of acquired CT datasets is to be handled by dedicated software that provide a work context to accomplish preoperative planning upon. These software are able to exploit image processing techniques and computer graphics to provide fundamental information needed to work in safety, in order to minimize the surgeon possible error during the surgical operation. However, most of them carry on lacks and flaws, that compromise the precision and additional safety that their use should provide. The research accomplished during my PhD career has concerned the development of an optimized software for surgical preoperative planning. With this purpose, the state of the art has been analyzed, and main deficiencies have been identified. Then, in order to produce practical solutions, those lacks and defects have been contextualized in a medical field in particular: it has been opted for oral implantology, due to the available support of a pool of implantologists. It has emerged that most software systems for oral implantology, that are based on a multi-view approach, often accompanied with a 3D rendered model, are affected by the following problems: unreliability of measurements computed upon misleading views (panoramic one), as well as a not optimized use of the 3D environment, significant planning errors implied by the software work context (incorrect cross-sectional planes), and absence of automatic recognition of fundamental anatomies (as the mandibular canal). Thus, it has been defined a fully 3D approach, and a planning software system in particular, where image processing and computer graphic techniques have been used to create a smooth and user-friendly completely-3D environment to work upon for oral implant planning and simulation. Interpolation of the axial slices is used to produce a continuous radiographic volume and to get an isotropic voxel, in order to achieve a correct work context. Freedom of choosing, arbitrarily, during the planning phase, the best cross-sectional plane for achieving correct measurements is obtained through interpolation and texture generation. Correct orientation of the planned implants is also easily computed, by exploiting a radiological mask with radio-opaque markers, worn by the patient during the CT scan, and reconstructing the cross-sectional images along the preferred directions. The mandibular canal is automatically recognised through an adaptive surface-extracting statistical-segmentation based algorithm developed on purpose. Then, aiming at completing the overall approach, interfacing between the software and an anthropomorphic robot, in order to being able to transfer the planning on a surgical guide, has been achieved through proper coordinates change and exploiting a physical reference frame in the radiological stent. Finally, every software feature has been evaluated and validated, statistically or clinically, and it has resulted that the precision achieved outperforms the one in literature

Contribution à l'assurance qualité des dispositifs médicaux en implantologie orale : à propos de la précision du placement implantaire

The quality assurance is a recent discipline in the medical domain, all the more in odontology. Its implementation passes in our discipline essentially by the application of rules of requirements towards medical devices used within dental surgeries. Implants, abutments, implant’s prosthesis but also the surgical guides are examples applied to the domain. This surgico-prosthetic technique owes be executed in the best conditions with an optimal requirement: every act which can have consequences on the patient and/or the future of the treatment. To meet the requirements of quality assurance of the treatment, it seems that the static surgical guides can be a way to improve the placement of implants thus impacting on the quality of the organized therapeutics. At first, the notions of quality assurance and medical devices are handed in light, in particular through the filter of the oral implantology. Then, the quality of the treatment is discussed: historic bases until the knowledge of today. It is important to master the evolution of this technique and tools associated to understand and thus use tools diagnoses and therapeutic at our disposal today. The last time of this work establishes) the evaluation of the current tools implantologie (CAD-CAM, stereolithography, surgery guides static, IT) through a study on anatomical subjects. This study estimates the precision of the implant’s positioning with conventional said guides and guides of static guided surgery. This precision is estimated by comparison of the preliminary images of planning and the post operative threedimensional examinationsL'assurance qualité est une discipline récente dans le domaine médical, d'autant plus en odontologie. Sa mise en oeuvre passe dans notre discipline essentiellement par l'application de règles d'exigences vis-à-vis des dispositifs médicaux utilisés au sein des cabinets dentaires. Les implants, les piliers, les prothèses implantaires mais également les guides chirurgicaux sont des exemples appliqués au domaine implantaire. Cette technique chirurgico-prothétique se doit d'être exécutée dans les meilleurs conditions avec une exigence optimale : chaque acte pouvant avoir des conséquences sur le patient et/ou l'avenir du traitement. Afin de répondre aux exigences d'assurance qualité du traitement implantaire, il semble que les guides chirurgicaux statiques puissent être un moyen afin d'améliorer le placement implantaire impactant donc la qualité de la thérapeutique mise en place. Dans un premier temps, les notions d'assurance qualité et des dispositifs médicaux sont remis en lumière, notamment au travers du filtre de l'implantologie orale. Ensuite, la qualité du traitement implantaire est discutée : des bases historiques jusqu'aux connaissances d'aujourd'hui. Il est important de maitriser l'évolution de cette technique et des outils associées afin de comprendre et donc d'utiliser les outils diagnostics et thérapeutiques à notre disposition aujourd'hui. Le dernier temps de ce travail constitue l'évaluation des outils actuels en implantologie (CFAO, stéréolithographie, chirurgie guide statique, informatique) au travers d'une étude sur sujets anatomiques. Cette étude évalue la précision du positionnement implantaire avec des guides dits conventionnels et des guides de chirurgie guidée statique. Cette précision est évaluée par comparaison des images préalables de planification et des examens tridimensionnels post-opératoire