International Journal of Computerized Dentistry, 01/2017

The primary objective of implant insertion is optimal prosthetic implant positioning while simultaneously protecting sensitive anatomical structures. In this context, navigated implants show significantly better results than freehand-inserted implants. Computer-assisted navigation, in combination with three-dimensional (3D) imaging by cone beam computed tomography (CBCT), is an ideal way to achieve higher predictability for successful implant therapy. Basically, one can distinguish between static navigation using templates, and direct dynamic navigation using optical transmission systems. Both options demonstrate comparably good results as far as the precision of implant positioning is concerned. Today, the gold standard is digital manufacturing of the template. Direct navigation is the more attractive option, provided acquisition costs can be reduced by simplifying the system. This article presents patient cases that demonstrate different variants of navigated implantology. Keywords: static navigation, dynamic navigation, digital manufacturing, template, CAD/CAM, reference marker

Objective: To measure the deviations of four different cone beam computed tomography (CBCT) devices in three dimensions by means of a three-dimensional (3D) implant-planning program. Materials and methods: A master radiographic template with two vertical, two transverse, and two sagittal radiopaque markers was fabricated for a human dry skull. The lengths of the markers were measured with a high-precision caliper. The skull and the template were scanned in each of the four CBCT devices (1. Gendex GXCB-500; 2. Sirona Galileos Comfort; 3. Sirona Orthophos XG 3D; 4. Carestream CS 9300) 19 times (10 scans without moving the skull, and 9 scans with repeated repositioning of the skull in the device, according to the manufacturers' instructions). A 3D implant-planning program was used to measure the lengths of the six markers digitally. Actual and digital measurements were compared to determine device-specific errors. The repositioning of the skull examined the reproducibility of the CBCT devices. Linear measurements were analyzed statistically (P < 0.05). Results: Mean deviations without moving the skull (vertical/sagittal/transverse) for device 1 were 0.023 mm/0.000 mm/0.025 mm (0.07%/0.19%/0.24%), for device 2 were 0.410 mm/0.115 mm/0.080 mm (-1.75%/0.32%/0.88%), for device 3 were -0.665 mm/-0.215 mm/-0.675 mm (-2.71%/-1.82%/-4.42%), and for device 4 were -0.045 mm/-0.135 mm/-0.410 mm (-0.45%/-1.54%/-2.57%). The overall mean deviation for device 1 was 0.028 mm (0.16%), for device 2 was 0.072 mm (-0.95%), for device 3 was 0.518 mm (-2.97%), and for device 4 was -0.197 mm (-1.53%). The mean deviation after repositioning for device 1 was 0.004 mm (-0.65%), for device 2 was -0.250 mm (0.95%), for device 3 was 0.496 mm (-2.66%), and for device 4 was -0.265 mm (-1.92%). Thus, apart from device 3, the deviations increased. Conclusion: Deviations from the actual measurements were detected with each device. Therefore, respecting safety distances when placing implants is crucial. Keywords: implant planning, 3D planning, CBCT, 3D imaging, radiographic reproducibility, radiographic accuracy

This article describes the computer-aided design/computer-aided manufacture (CAD/CAM) accuracy of dental drill guides for application in guided surgery. Today, the availability of three-dimensional (3D) desktop printers allows for the cost-effective production of drill guides by dental laboratories. Our investigations show the accuracy of produced guides by eliminating influencing factors that exist in the guided surgery workflow. To investigate this accuracy, a method was developed to evaluate the CAD/CAM production technology apart from sources of error from cone beam computed tomography (CBCT) scans, intraoral scans, software or human error. By using a CAD/CAM-milled idealized reference model, as well as CAD data from a scanned dental model with integrated reference spheres, drill guides with different offset values were designed using the coDiagnostiX^® implant-planning software. The Bone Level Roxolid^® SLActive^® implant system (length 8 mm, diameter 3.3 mm) was chosen. The virtual position in relation to both the drill guide and the reference model was determined based on the planning data and exported STL files, respectively. Virtual and physical measurements were performed through the center coordinates of the used drill sleeves (T-sleeve: 5 mm), by applying a defined reference coordinate system (RCS) of the dental model. Drill guide templates were printed using a FotoDent^® guide on a dental desktop printer (D30), based on a defined digital workflow. After insertion of the respective drill sleeves, surgical guides were secured on the reference models using quadrangular fixation, thus allowing a tactile measurement by applying a coordinate measurement device for determination of physical position relation. Through the central points of the drill sleeves, both the coronal and apical points of the planned implant drilling as well as angular deviation were calculated and reviewed against the CAD measurements. On average, a deviation of 0.25 degrees of the planned implant was detected. Keywords: stereolithography, digital light processing, 3D printing, CAD/CAM, guided surgery, drill guide

Objective: To test the mechanical properties of three different restorative materials for implant abutments supporting all-ceramic single crowns. Materials and methods: Thirty implants with butt-joint connections were distributed into three test groups: Group A with 10 one-piece zirconia abutments, Group U with 10 titanium abutments, and Group T with 10 titanium-zirconia hybrid abutments. Monolithic zirconia single crowns were cemented and artificially aged. The crowns were loaded at a 30-degree angle in a universal testing machine until fracture or bending. Additionally, after removal of the restorations, the implant-abutment interface of the fixtures was inspected using a scanning electron microscope (SEM). Results: In Group A, the abutments failed on average at 336.78 N, in Group U at 1000.12 N, and in Group T at 1296.55 N. The mean values between Groups T and U (P = 0.009), and between Group A and Groups T and U (P < 0.001) were significantly different. The abutments in Group A failed early due to fractures of the internal parts and parts close to the implant neck. In Groups T and U, failures occurred due to bending of the implant neck. Conclusion: This experimental study proves that hybrid and titanium abutments have similar mechanical properties. One-piece abutments made of zirconia showed significantly lower fracture resistance. Keywords: implant-supported restorations, single tooth implant, CAD/CAM abutments, hybrid abutment, abutment material, implant shoulder, zirconia

Objective: The objective of the present study was to compare and evaluate the accuracy of three-dimensional (3D) image data acquired from cone beam computed tomography (CBCT) and a dental scanner using 3D software. Materials and methods: After selecting the full-arch forms of the maxilla and mandible as the master cast, the master cast was scanned via a high-precision optical scanner for use as master model data. The model was scanned 12 times each using CBCT and a dental scanner. Scanned data were superimposed onto the master cast data for evaluation of accuracy and repeatability. Results: Although significant differences in both accuracy and repeatability were seen between CBCT and dental scanner (P < 0.05), repeatability of the maxillary arch showed little difference, with CBCT and scanner having values of 17 ± 2 µm and 22 ± 5 µm, respectively. Meanwhile, repeatability of the mandibular arch with CBCT and scanner was 15 ± 0 µm and 19 ± 3 µm, respectively. Since good repeatability was shown, this demonstrated that data can be stably acquired. Conclusions: The present study demonstrated the feasibility of using a dental scanner to create a digital model as a substitute for a plaster model for use in orthodontic diagnosis and device fabrication. Keywords: cone beam computed tomography, dental scanner, accuracy, repeatability, digital model, 3D software

The incorporation of virtual engineering into our profession and the digitalization of information are allowing us new perspectives and innovative alternatives for dental treatment modalities. The use of computer-guided implant-planning software allows the radiographic, prosthetic, surgical, and laboratory fields to be combined under a common virtual scenario, permitting complete virtual treatment planning. Different alternatives for the digital workflow have been described for computer-guided implant placement. In this article, we present a recommendation for selecting the appropriate digital workflow depending on the clinical situation to achieve precise computer-guided implant planning and a predictable treatment outcome. Keywords: computer-guided implant surgery, digital planning

This case report describes the three-dimensional (3D) endodontic treatment planning of a complex mandibular incisor using the 3D Endo software (Dentsply Sirona, Bensheim, Germany). Apart from a step-by-step description of the planning, the actual endodontic treatment is shown, and possible indications for the 3D Endo software are discussed. Keywords: cone beam computed tomography, CBCT, endodontics, 3D Endo

Computer-assisted technologies open up new possibilities for significantly improving the planning and realization of implant-supported dental restorations. Three-dimensional (3D) data acquired with an intraoral sensor can be merged with comparable data acquired by various radiographic imaging techniques. Implant planning with this type of support can generate data for the manufacture of surgical guides for dental implants. The guides can then be fabricated either by a third-party provider or by the implantologist directly, by using time- and cost-saving in-office systems. The use of surgical guides can improve the surgical implantation procedure considerably, and successful and reliable outcomes can be achieved more quickly. Keywords: dental implantology, CAD/CAM, guided surgery, surgical guide, cone beam computed tomography (CBCT), implant planning