The 3D maxillary orientation device (3DMOD) - a novel device for measuring post-surgical three-dimensional maxillary changes

Objectives: To assess the validity and reproducibility of the 3D Maxillary Orientation Device to assess the simulated post-surgical 3D changes of the maxilla using an in vivo model. Methodology: A 3D maxillary orientation device (3DMOD) was developed based on a modified Fox’s occlusal plane guide. Equidistant points were marked on the extra-oral arms of the 3DMOD creating nine landmarks for data analysis. Reproducibility of 3DMOD insertion and removal was assessed by placing the 3DMOD onto the maxillary dentition of five volunteers and taking extra-oral facial 3D stereophotogrammetry images (Di4D SNAP system) at one-week intervals (T1 and T2). To measure the post-surgical changes of the maxilla, the 3DMOD was secured to the maxillary dentition of an in vivo skull model. The position of the 3DMOD changed a known amount using modified Lego® blocks attached to the 3DMOD, to simulate various maxillary movements. Baseline images of the 3DMOD were taken with 0mm displacement and again with the 3DMOD advanced and vertically impacted by 3mm, 6mm and 9mm. Additionally a left and right cant and 3mm advancement with posterior differential impaction were simulated. Images were re-taken one-week later (T1 and T2). Following baseline and simulated maxillary movement, the changes of the landmarks in the x, y and z direction were determined using Di3D viewing software for data analysis. Results: For 3DMOD insertion on replacement the mean differences in the x, y and z direction were all significantly less than 0.5mm. The difference between the simulated maxillary movements (advancement and impaction) and the 3DMOD derived measurements were all statistically significantly 0.5mm or less. The device was reproducible, none of the mean differences between T1 and T2 were significantly greater than 0.5mm (95% CI range 0.0mm and 1.1mm). Conclusion: The 3DMOD, coupled with stereophotogrammetry, is an acceptable method to measure 3D simulated maxillary movements. Further studies are needed to assess the validity and reproducibly of using the 3DMOD in patients undergoing maxillary osteotomies

Temporomandibular Joint Diseases: Diagnosis and Management

Temporomandibular Joint Diseases are common and dificult to treat. From diagnosis to treatment, our options are in a broad range. Keeping updated with new technologies is extremely important for researchers and health professionals

Computational design and engineering of polymeric orthodontic aligners

Transparent and removable aligners represent an effective solution to correct various orthodontic malocclusions through minimally invasive procedures. An aligner-based treatment requires patients to sequentially wear dentition-mating shells obtained by thermoforming polymeric disks on reference dental models. An aligner is shaped introducing a geometrical mismatch with respect to the actual tooth positions to induce a loading system, which moves the target teeth toward the correct positions. The common practice is based on selecting the aligner features (material, thickness, and auxiliary elements) by only considering clinician's subjective assessments. In this article, a computational design and engineering methodology has been developed to reconstruct anatomical tissues, to model parametric aligner shapes, to simulate orthodontic movements, and to enhance the aligner design. The proposed approach integrates computer-aided technologies, from tomographic imaging to optical scanning, from parametric modeling to finite element analyses, within a 3-dimensional digital framework. The anatomical modeling provides anatomies, including teeth (roots and crowns), jaw bones, and periodontal ligaments, which are the references for the down streaming parametric aligner shaping. The biomechanical interactions between anatomical models and aligner geometries are virtually reproduced using a finite element analysis software. The methodology allows numerical simulations of patient-specific conditions and the comparative analyses of different aligner configurations. In this article, the digital framework has been used to study the influence of various auxiliary elements on the loading system delivered to a maxillary and a mandibular central incisor during an orthodontic tipping movement. Numerical simulations have shown a high dependency of the orthodontic tooth movement on the auxiliary element configuration, which should then be accurately selected to maximize the aligner's effectiveness

Optical accuracy assessment of robotically assisted dental implant surgery

BACKGROUND: Static and dynamic dental implant guidance systems have established themselves as effective choices that result in predictable and relatively accurate dental implant placement. Generally, studies assess this accuracy using a postoperative CBCT, which has disadvantages such as additional radiation exposure for the patient. This pilot study proposed a scanbody-agnostic method of implant position assessment using intraoral scanning technology and applied it as an accuracy test of robotically assisted dental implant placement using the Neocis Yomi. MATERIALS AND METHODS: All of the robotically assisted dental implant surgery was performed in the Postdoctoral Periodontology clinic at Boston University Henry M. Goldman School of Dental Medicine. Completely edentulous patients were excluded. A total of eleven (11) implants were included in the study, eight (8) of which were fully guided. An optical impression of each implant position was obtained using a CEREC Omnicam (SW 5.1) intraoral scanner. Each sample used either a DESS Lab Scan Body or an Elos Accurate Scan Body as a means to indirectly index the position of the implant. A comparison of planned implant position versus executed surgical implant position was performed for each placement using Geomagic Control X software. Global positional and angular deviations were quantified using a proposed scanbody-agnostic method. Intraoral directionality of deviation was visually qualified by the author (D.K). RESULTS: Mean global positional deviations at the midpoints of the top of each scanbody were 1.7417 mm in the partially guided samples and 1.1300 mm in the fully guided samples. Mean global positional deviations at the midpoints of the restorative platforms of each implant were 1.3142 mm in the partially guided sample and 1.27045 mm in the fully guided samples. Mean global positional deviations at the midpoints of the apex of each implant were 1.455 mm in the partially guided samples and 1.574 mm in the fully guided samples. Mean angular deviations were 3.7492 degrees in the partially guided samples and 2.6432 degrees in the fully guided samples. CONCLUSION: Within the sample size limitations, robotically assisted dental implant surgery offers similar implant placement accuracy compared to published static and dynamic implant placement guidance systems. Intraoral optical assessment of dental implant position used in this study allows comparable analysis to other methods without requiring additional exposure to radiation and should be considered the default method of assessing guidance accuracy

Prediction of Root Form Using Crown Data: Mandibular Left First Premolar

Introduction: The purpose of this study was to determine if a statistical shape model (SSM) of the lower left first premolar, consisting of both crown and root data, could adequately describe the root form from a surface scan consisting of only crown data. Secondly, it tested if there were any angles or measurements on the tooth crown that correlate with any aspects of root morphology. The average orthodontist practicing today or in the near future is likely to use or own a digital intraoral scanner in their office. Yet optical scans only allow visualization of the crowns of teeth and external structures. We know that the orthodontic profession and the published literature support treatment of the teeth crowns and their roots in all three planes of space.1-7 Data acquired through CBCT imaging provides an accurate representation of the teeth and their roots, but it comes at a cost of relatively high radiation exposure.22-38 For this reason, the use of CBCT and other radiographic modalities to analyze orthodontic treatment is generally limited to the least use necessary.8 This study set out to find if statistical shape modeling could provide the practitioner with root form and/or positional data that could aid in patient care. Materials and Methods: Surface scans of 76 extracted mandibular first premolar teeth were entered into statistical software that created a statistical shape model from the population data and select landmark points. Then, using only the optical surface scans of 16 real patient crowns, the statistical model predicted a root form. Real patient roots, after being segmented from CBCT’s, were compared to the predicted roots and agreement was measured. Statistical analysis was performed using intraclass correlation tests and Euclidean Distance Matrix Analysis (EDMA), a technique used to compare biologic shapes using landmark points, to compare the 3D root shapes and dimensions. Spearman’s rho test was used to determine relationships within the 76 teeth population crown and root measurements. Results: The comparison between averaged real and predicted root forms using EDMA showed no significant differences. However, when an intraclass correlation coefficient test compared linear and angular measurements between individual real and predicted teeth forms, the agreement was weak or non-existent. For the population of 76 extracted mandibular first premolars, there were several different measurements and angles that showed moderate or weak agreement to each other. None of the tested measurements within the population showed strong, predictive correlation between crown and root measurements. Conclusions: For the mandibular first premolar, we were able to accurately predict root form from only optical crown scans when we averaged the real and predicted comparisons. On an individual level, the real and predicted teeth forms were statistically different. There were several moderate and weak agreements between measurements in the population of 76 extracted mandibular first premolars

Digital Workflows and Material Sciences in Dental Medicine

The trend of digitalization is an omnipresent phenomenon nowadays – in social life and in the dental community. Advancement in digital technology has fostered research into new dental materials for the use of these workflows, particularly in the field of prosthodontics and oral implantology.CAD/CAM-technology has been the game changer for the production of tooth-borne and implant-supported (monolithic) reconstructions: from optical scanning, to on-screen designing, and rapid prototyping using milling or 3D-printing. In this context, the continuous development and speedy progress in digital workflows and dental materials ensure new opportunities in dentistry.The objective of this Special Issue is to provide an update on the current knowledge with state-of-the-art theory and practical information on digital workflows to determine the uptake of technological innovations in dental materials science. In addition, emphasis is placed on identifying future research needs to manage the continuous increase in digitalization in combination with dental materials and to accomplish their clinical translation.This Special Issue welcomes all types of studies and reviews considering the perspectives of the various stakeholders with regard to digital dentistry and dental materials