The PRECISE protocol: intra-oral photogrammetry-led digital workflow for full-arch immediate implant loading

With respect to the European Union 2017 amendment of the Medical Device Regulations (MDR), this overview article presents recommendations concerning medical 3D printing in oral and maxillofacial surgery (OMFS). The MDR were screened for applicability of the rules to medical in-house 3D printing. Applicable regulations were summarized and compared to the status of medical use of 3D printing in OMFS in Germany. Recommendations were made for MDR concerning medical 3D printing. In-house printed models, surgical guides, and implants fall under the category of Class I-III, depending on their invasive and active properties. In-house medical 3D printing for custom-made medical devices is possible under certain prerogatives: (1) the product is not being used in another facility, (2) appropriate quality systems are applied, (3) the reason for omitting commercial products is documented, (4) information about its use is supplied to the responsible authority, (5) there is a publicly accessible declaration of origin, identification, and conformity to the MDR, (6) there are records of manufacturing site, process and performance data, (7) all products are produced according to the requirements proclaimed before, and (8) there is an evaluation of clinical use and correction of possible issues. Several aspects must be addressed for in house medical 3D printing, according to the MDR. Devising MDR related to medical 3D printing is a growing challenge. The implementation of recommendations in OMFS could help practitioners to overcome the challenges and become aware of the in-house production and application of 3D printed devices.

This study aimed to introduce 3D printing in a municipal hospital to improve the treatment of craniomaxillofacial patients and optimize costs and operating time. Thus we describe the implementation of low-cost in-house 3D printing to facilitate orbital- and mandible reconstruction in CMF surgery. Moreover, we address legal requirements, safety at work, fire- and data protection. Finally, we want to share our experiences using 3D printing and point out its advantages in providing better patient care. We outline the setup of in-house 3D printing and focus on obeying German health care regulations. We based our approach on a fused deposition modeling 3D printer and free software. As proof of concept, we treated 4 cases of severe orbital trauma and 1 case of mandibular reconstruction. We printed a 3D patient-specific model for each case and adapted a titanium mesh implant, respectively, a titanium reconstruction plate before performing the surgery. Our approach reduced costs, duration of anesthesia, operating time, recovery time, and postoperative swelling and increased the revenue. Functional outcome in orbital reconstruction like eye movement and double vision, was improved compared to the conventional technique. No severe complications like loss-of-vision or surgical revision occurred. Likewise, mandibular reconstruction showed no plate loosening or plate fracture. The implementation of cost-efficient 3D printing resulted in successful patient treatment with excellent outcomes. Our practice guide offers a 3D printing workflow and could be adapted to fit the needs of other specialties like neurosurgery, orthopedic surgery as well.

Reconstructing 3D cone beam computed tomography (CBCT) images from a limited set of projections is an important inverse problem in many imaging applications from medicine to Inertial Confinement Fusion (ICF). The performance of traditional methods such as filtered back projection (FBP) and model-based regularization is sub-optimal when the number of available projections is limited. In the past decade, deep learning (DL) has gained great popularity for solving CT inverse problems. A typical DL-based method for CBCT image reconstruction is to learn an end-to-end mapping by training a 2D or 3D network. However, 2D networks fail to fully use global information. While 3D networks are desirable, they become impractical as image sizes increase because of the high memory cost. This paper proposes Swap-Net, a memory-efficient 2.5D network for sparse-view 3D CBCT image reconstruction. Swap-Net uses a sequence of novel axes-swapping operations to reconstruct 3D volumes in an end-to-end fashion without using full 3D convolutions. Simulation results on ICF show that Swap-Net consistently outperforms baseline methods both quantitatively and qualitatively in terms of reducing artifacts and preserving details of complex hydrodynamic simulations of relevance to the ICF community.

Evaluation of Differences Between Estimated Delivered Dose and Planned Dose in Nasopharynx Patients Using Deformable Image Registration and Dose Accumulation

This paper aims to elucidate how three-dimensional (3D) printing technology has greatly impacted orthodontic practice, marking a significant advancement in planning treatment, fabricating appliances, and patient care. The integration of digital technologies, such as digital cephalogram, digital photography, intraoral and facial scanners, desktop scanners, cone-beam computed tomography (CBCT), and 3D printing, has significantly enhanced the efficiency, accuracy, consistency, and predictability of treatment outcomes. The advent of 3D printing in dental and orthodontic treatment has introduced a new era marked by precision, efficiency, and customised appliances, empowering practitioners to achieve superior results for their patients. Some of its applications in orthodontics include manufacturing clear aligner trays, surgical guides for miniscrew insertion and corticotomy, splints for orthognathic surgery, and retainers.

Endoscopic endonasal anterior skull base surgery is currently applied for the treatment of olfactory neuroblastoma, and other skull base lesions. In the surgical approach to the anterior skull base, one of the important step is extended frontal sinus surgery, including modified endoscopic Lothrop procedure (MELP). Surgical simulation using artificial three dimensional (3D) models is known to a useful training method to learn the surgical steps and to gain the surgical skills. In this study, we investigated the usefulness of a 3D head model with the detailed CT information in the surgical simulation for extended frontal sinus surgeries and anterior skull base resections. 3D head models (KEZLEX, Ohno, Japan) were used as a surgical simulator. This model is exactly reconstructed and made as a human head including sinonasal structure and anterior/posterior skull base by 3D printer. In this model, we made the first olfactory nerve with a steel wire at the skull base as the posterior limit of the frontal sinus flour to the skull base. In addition, the head model was examined for surgical anatomy by using the cone-beam CT (Accuitomo, Morita, Japan). Then, endoscopic endonasal surgery was performed using a high speed bur (M5, Medtronic, Japan) for the bone resection guided with a navigation system (Fusion, Medtronic, Japan). MELP was performed according to the surgical steps of the outside-in frontal drill-out technique. In results, MELP and the anterior skull base resection including crista galli were successfully performed for 3D model with CT and the navigation. These findings suggest that surgical simulation using artificial 3D head model and cone beam CT combined with a navigation system is useful in the surgical training for endoscopic endonasal anterior skull base surgery.

Fabrication of three-dimensional (3D) items is of utmost importance in oral surgery, dental prosthodontics, and maxillofacial implants. Computer-aided design (CAD) and computer-aided manufacturing (CAM) are promising technologies that can create structures of interest with acceptable efficiency, accuracy, and reproducibility. Among the different CAD/CAM technologies, 3D printing is well-received by dental professionals because of its capability for unlimited designs and ease of manufacturing. Using 3D printing, researchers may design combined cells and biomaterial constructs that closely mimic the complicated structures of natural tissues and organs to be employed in regenerative dentistry. Along with advances in image processing techniques, such as cone beam computed tomography (CBCT), 3D printing is expected to be used in clinical settings. In this chapter, we describe the 3D printing methods and applications, with primary focus on dental tissue engineering and oral/maxillofacial implants. The chapter also explores the importance of biomolecules and vasculature in 3D-printed constructs.

A descriptive and exploratory study was carried out with the aim of proposing and validating an open protocol for making 3D impressions of stereolithographic models, which is available to professionals in the area of Dentistry. Nine operators (senior students of the Dentistry degree), without previous experience in the use of software and hardware for 3D printing, divided into two groups were trained through theoretical and practical sessions. The A worked with three helical tomographies (TAC) and the B with three cone beam computed tomography (CBCT), all in DICOM format, converted to STL files. In total, 99 bone structures corresponding to 33 jaws, 33 axis and 33 facial masses-skull bases were analyzed, and a total of 33 jaws were printed in PLA (polylactic acid filament). At the end of the study, no statistically significant difference was found in the implementation of the proposed protocol between the operators, the measurements of the pieces printed by each of them, the gold standard, the TAC and the CBCT, with which not only validated the protocol, but it was possible to determine the resources necessary to carry out this type of 3D printing.

The use of high-fidelity stereolithographic models that accurately reflect patient-specific pathology has become commonplace in craniofacial surgery. Multiple studies have reported the use of commercially available three-dimensional (3D) printers that allow medical centers with limited resources to reconstruct 3D models comparable to industry-made counterparts. However, most models are printed using only a single filament, which portrays the surface craniofacial anatomy, but fails to highlight relevant intraosseous structures. This presents a significant limitation when used for preoperative planning and intraoperative guidance in surgical procedures requiring osteotomies, where knowledge of the precise location of critical structures is paramount to avoid injury. The authors report a novel technique for creating transparent 3D models of relevant intraosseous craniofacial anatomy at a cost that mitigates the financial burden of industrial 3D model or industrial 3D printer acquisition. Cases are presented to demonstrate the diverse applications of this technique, with accurate display of the tooth roots, the inferior alveolar nerve, and the optic nerve, to aid in preoperative planning of osteotomies. This technique enables production of low-cost, high-fidelity transparent 3D models with applications in preoperative planning for craniofacial surgery.

To analyze the indications and frequency for three-dimensional (3D) imaging for implant treatment planning in a pool of patients referred to a specialty clinic over a 3-year period. All patients who received dental implants between 2008 and 2010 at the Department of Oral Surgery and Stomatology at the University of Bern were included in the study. The influence of age, gender, and time of treatment (2008 to 2010) on the frequency of use of two-dimensional (2D) radiographic imaging modalities alone or in combination with 3D cone beam computed tomography (CBCT) scans was analyzed. Furthermore, the influence of the indication, location, and need for bone augmentation on the frequency of use of 2D imaging modalities alone or in combination with CBCT was evaluated. In all, 1,568 patients (792 women and 776 men) received 2,279 implants. Overall, 633 patients (40.4%) were analyzed with 2D imaging procedures alone. CBCT was performed in 935 patients (59.6%). There was a statistically significant increase in CBCT between 2008 and 2010. Patients older than 55 years received a CBCT scan in addition to 2D radiographic imaging statistically significantly more often. Additional 3D imaging was most frequently performed in the posterior maxilla, whereas 2D radiographs alone exhibited the highest frequency in the anterior mandible. The combination of 2D with CBCT was used predominantly for implant placement with simultaneous or staged guided bone regeneration or sinus elevation. Based on these findings from a specialty clinic, the use of additional CBCT imaging for implant treatment planning is influenced by the indication, location, local anatomy (including the need for bone augmentation), and the age of the patient.

Three-dimensional (3D) printed models can improve the understanding of the structural anatomic changes in cases of temporomandibular joint ankylosis and pseudoankylosis leading to closed jaw locking. Their use in pre-surgical planning and intraoperative guidance has been reported, contributing to the predictability and success of these surgery procedures, which can be quite complex, especially in small animal patients. The use and production of 3D tools and models remain challenging and are so far limited to institutions with high (economical and human) resources. This study aims to propose simplified workflows using open-source software to facilitate an in-house 3D printing process. To illustrate this, three cases of temporomandibular joint ankylosis and one of pseudoankylosis were reviewed, where in-house 3D printed models were used for client communication and surgical management. The 3D models were segmented from computed tomography and printed via stereolithography. They were used to support discussion with clients (n = 4), to allow surgeons to pre-surgical plan and practice (n = 4) and for intraoperative guidance during surgery (n = 2). Surgical cutting guides were produced in one case to improve precision and define more accurately osteotomy lines. It is essential to consider the initial time and financial investment required for establishing an in-house 3D printing production, particularly when there is a need to produce biocompatible tools, such as surgical cutting guides. However, efficient and streamlined workflows encourage the integration of this technology, by accelerating the printing process and reducing the steep learning curves, while open-source software enhances accessibility to these resources.

Background: Several factors must be considered when selecting the appropriate field of view (FOV) and voxel size for good image quality on Cone Beam Computed-Tomography (CBCT). The purpose of this study is to determine the factors that must be considered in selecting the appropriate FOV and voxel size to achieve good image quality according to the purpose of the examination. Method: Articles in Q1 and Q2 journals published within the period from January 2016 to September 2021 were searched from Scopus and PubMed online using the keywords field of view/FOV in CBCT, voxel size in CBCT, and FOV and voxel size in CBCT. On the basis of the article selection criteria, 13 journals were included in the study. Also included in the study were several types of three-dimensional (3D) CBCT machines: Planmeca ProMax® 3D ProFaceTM, i-Cat Cone Beam 3D, Picasso Trio CBCT: Carestream unit® CS 9300 CBCT, and Accuitomo F17D 3D CBCT. Result: It is generally recommended that a 0.2 mm voxel size be used to detect periodontal disease, secondary caries, fractures, external resorption, and endodontic complications. Meanwhile, for root fractures with an intracanal metallic post and an anatomic isthmus in the root canal, a 0.1 mm voxel size is recommended to be used, and for evaluating the implant, 0.3 mm and 0.4 mm voxel sizes are recommended. Conclusion: It was found in the review that most of the selected studies recommended using the smallest FOV available in the CBCT unit to detect pathological conditions and important anatomical structures.

Background This study aims to evaluate the accuracy of volumetric measurements of three-dimensional (3D)-printed human condyles from cone-beam computed tomography (CBCT) in comparison to physical condyles using a water displacement test. Methodology A sample of 22 dry condyles was separated from the mandibular body by disc, mounted on a base made of casting wax, and scanned using the SCANORA (Scanora 3DX, Soredex, Finland) CBCT scanner. Subsequently, the projection data were reconstructed with the machine-dedicated OnDemand 3D (Cybermed Co., Seoul, Korea). The Standard Tessellation Language file was prepared for 3D printing using chitubox slicing software v1.9.1. Frozen water-washable gray resin was used for 3D printing. All condyles were printed using the same parameters and the same resin. The volumetric measurements were then performed using a customized modified pycnometer based on water volume and weight displacement. Volumetric measures were performed for both the physical human condyles and the 3D-printed replicas and the measurements were then compared. Results The volume of dry condyles using the water displacement method showed an average (±SD) of 1.925 ± 0.40 cm3. However, the volume of 3D-printed replicas using the water displacement method showed an average (±SD) of 2.109 ± 0.40 cm3. The differences in measurements were insignificant (p > 0.05), as revealed by an independent t-test. Conclusions Highly precise, accurate, and reliable CBCT for volumetric mandibular condyle was applied for measurements of a human condyle and 3D-printed replica. The modified pycnometer for volumetric measurements presented an excellent volumetric measure based on a simple water displacement device. The tested modified pycnometer can be applied in volumetric measurements in both 3D-printed and mandibular condyle.For best accuracy, the highest scanning resolution possible should be used.As it directly handles irregularly shaped solid objects in a non-destructive manner with a high level of precision and reliability, this 3D scanning approach may be seen as a superior alternative to the current measurement methods.

Purpose: Compare the localization accuracy of 3D cone beam computed tomography (CBCT) and 4D CBCT for a dynamic respiratory phantom, considering cases with and without respiratory variations between planning and treatment. Methods and Materials: A respiratory phantom was imaged using 3D CBCT and 4D CBCT. Measurements of the amplitude of motion in 3D CBCT and 4D CBCT and size of the sphere at its exhale position in 4D CBCT were acquired. The phantom was then misaligned by known distances relative to a reference position. 3D CBCT and 4D CBCT were used to re-align the phantom by comparing localization images to reference images. Because the ideal 4D CBCT registration approach was to be determined, multiple localization-reference pairs of images were examined. Comparison was performed for multiple respiratory waveforms at two amplitudes as well as for waveforms where amplitudes were increased or decreased by 30%, simulating changes in respiratory behavior between simulation and localization. Error of localization trials was defined as the difference between the recommended table shifts and the known displacement. Results: Measurements of the respiratory amplitude were underestimated for all cases. Measurement of the sphere diameter exhibited < 2 mm error. Localization errors were less than 2.6 mm for all cases. When the motion amplitude was the same during localization as planning, automatic registration of the exhale frame from the 4D CBCT to the reference exhale frame had the smallest error in localization of 0.54 ± 0.03 mm. However, automatic registration of the 4D CBCT AIP to the reference AIP had the smallest errors when the motion amplitude changed between planning and localization, 1.59 ± 0.12 mm for the +30% amplitude change and 0.69 ± 0.02 mm for the -30% amplitude change. Conclusion: Because lung tumor motion amplitude throughout treatment may vary between planning and treatment, the use of 4D CBCT AIP registered to reference AIP was recommended for localization. 4D CBCT provided additional benefits compared to 3D CBCT of substantial reduction in target blurring and verification of respiratory motion characteristics prior to treatment.

Accuracy and precision of 3D-printed implant surgical guides with different implant systems: An in vitro study