International Journal of Computerized Dentistry, 04/2020

Aim: The aim of the present study was to compare six different methods of in vivo color matching: visual shade matching (3D-Master Linearguide shade guide) performed by 1) a novice practitioner, 2) an expert practitioner, 3) the new Rayplicker spectrometer, 4) the Trios III intraoral scanner, and 5) the Omnicam intraoral scanner compared with 6) the Easyshade V spectrophotometer, which was considered as the reference. Materials and methods: Color matching was performed using the 3D-Master references on the sound maxillary right central incisors of 40 subjects. The study first compared the number of colors found using each of the six methods. The references were then converted to the Commission Internationale de l’Eclairage (CIE) L*a*b* values, from which the difference ΔE between either two methods was derived. Finally, the L* value was used to compare the luminosity measured by each of the six methods. Results: The Rayplicker showed the smallest ΔE compared with the Easyshade V. The expert found a closer color to the Easyshade V than did the novice, and both were closer to the Easyshade V than the two intraoral scanners. The intraoral scanners showed notable differences compared with the Easyshade V. The intraoral scanners also offered a reduced choice of colors and recorded the highest luminosities compared with the other methods. Conclusion: Within the limitations of this study, the color matching by the Rayplicker was closest to that of the Easyshade V. The good performance of this new device means that it is a challenging competitor for the Easyshade V. Finally, the new methods based on intraoral scanners were less reliable than the spectrophotometers and the visual shade matching. Keywords: spectrophotometers, intraoral scanners, shade matching, Rayplicker, Easyshade V, tooth color, color measurements, Trios III, Omnicam

Aim: The goal of this case series was to evaluate the clinical outcome at the 2-year follow-up of immediately loaded combined screw- and conometric-retained implant-supported full-arch restorations virtually planned using digital scanning technology. Materials and methods: This series included 12 patients presenting hopeless teeth in the maxilla treated with computer-guided flapless implant placement. A total of 72 implants were inserted. All implants were immediately loaded with a complete-arch restoration supported by an intraorally welded framework. Digital scanning technology was used to virtually plan a combined screw and conometric retention of the frameworks. Clinical parameters were assessed at 1 week and at 1, 3, 6, 12, and 24 months follow-up. Results: The survival rate after 2 years was 98.6%, as one implant failed during the osseointegration period. No major prosthetic complications were observed such as issues with mobility, unscrewed abutments, disconnected conometric copings, and prosthetic fracture. Only one patient registered the chipping of a prosthesis. Conclusion: Based on the results of the present study, the use of combined screw and conometric retention for fixed immediate restorations properly planned using digital scanning technology seems to be a viable treatment alternative to screw or conometric retention alone for immediately loaded rehabilitations. Keywords: conometric retention, screw-retained, fixed dental prostheses, computer-guided surgery, computer-aided implantology, 3D optical scanning

Aim: Currently, there is no reliable methodology to evaluate the dimensional conformity of dental prostheses manufactured through a digital shaping process. In the CAD/CAM method, the digital design of the prosthesis is considered as a reference, and it is crucial to reproduce it perfectly during the manufacturing process. Therefore, the aim of this study was to offer a comparison between a CAM prosthesis and its design model by superimposing the CAD model with the digitization of the manufactured prosthesis. Materials and methods: The metrological inspection developed in this study and presented in this article involved a comparison of the points cloud obtained by micro-computed tomography (micro-CT) and the CAD model of the prosthesis. First, an estimation of all inspection-method induced measurement errors was carried out, in which the measurement errors were assessed by proceeding to the dimensional inspection of a reference object of known dimensions. Then, the metrological inspection was extrapolated to a dental prosthesis. Results: The estimation of measurement errors presented satisfying results compared with the usual metrological protocols developed by the dentistry research community. The dimensional deviation was estimated at 0.31% and the form deviation at 0.165 µm between the Gaussian sphere and the certified ball. The inspection of the manufactured surfaces revealed under-milled areas on the occlusal face, particularly on the anatomical fossae, and an irregular margin limit compared with its smooth design. Conclusion: A reliable micro-CT evaluation of the dimensional accuracy of a manufactured dental prosthesis compared with the CAD model demonstrated the performance level of CAD/CAM systems. The evaluation reliability was confirmed by the estimation of prior measurement errors. This estimation is essential for the metrological analysis. Keywords: CAD/CAM, dental prosthesis, dental marginal adaptation, 3D imaging, dimensional measurement accuracy, micro-CT

Aim: To evaluate surface roughness (SR), color stability (CS), and color masking as assessed through the relative translucency parameter (RTP) of different provisional restoration materials before and after water thermocycling (TC). Materials and methods: Four different provisional materials were selected: acrylic resin, bis-acryl resin, polymethyl methacrylate (PMMA) CAD/CAM blocks, and 3D-printed provisional resin. Samples of 0.6- and 1.3-mm thickness were obtained, and SR, CS, and RTP were determined before and after the samples were submitted to 6000 cycles of TC. A rugosimeter was used to assess SR. Color was determined on white and black backgrounds before and after TC, and color masking was assessed through RTP. CS was determined using a spectrophotometer with the CIEDE2000 formula, before and after TC. Results: SR values before and after TC ranged from -0.01 to 0.28 for 1.3 mm, and from 0.00 to 0.38 for 0.6 mm, respectively. CS (∆E00 values) ranged from 0.53 to 4.38 for 1.3 mm, and from 0.70 to 5.66 for 0.6 mm, respectively. The highest value was obtained for 3D-printed resin. Finally, for RTP values, the difference before and after TC ranged from -0.036 to 2.66 for 1.3 mm, and from 0.52 to 2.57 for 0.6 mm, respectively, with the PMMA CAD/CAM block being the material with the lowest values in both cases. Conclusion: Values of SR, CS, and RTP varied among different materials and thicknesses. The overall performance of 3D-printed resin was inferior to that of the other materials. The PMMA CAD/CAM block obtained the overall best values for the conditions tested. Keywords: CAD/CAM, color science, dental materials, digital dentistry

This article introduces a new, fully digital workflow for the preparation of a guiding template and the procedure of the clinical operation in which it is put to use. A step-by-step technique is described including the virtual CAD of the preparation, the design of the template, the restoration based on the contours of the virtual preparation, the tooth preparation guided by the template, and the bonding of the predesigned restoration. The design and manufacture of all the templates and restorations are completed before the clinical operation. Keywords: tooth preparation template, 3D printing, immediate restoration, virtual preparation plan

A hands-on method for instrument-based occlusal analysis with digital technology is presented using a patient case example. The method is based on new software for digital occlusal analysis that includes a new measuring system for recording mandibular function (Jaw Motion Analyser Optic System/oJMA). With the new system, occlusal contact patterns in the real movement function of the mandible are captured and analyzed digitally with regard to occlusal interferences or a suitable therapeutic position of the mandible. For this purpose, scans of both jaws are brought together with the movement recordings by means of a special coupling tray and then visualized together as one complete image. Since the movement paths of the temporomandibular joints (TMJs) are also captured, the new system makes it possible to define a suitable therapeutic position specifically aimed at relieving the TMJs, and a therapeutic change in the jaw relation can be adjusted, for instance, by using an occlusal splint. Dedicated software modules provide a layer-by-layer analysis of the intercuspation relationship and the generation of ‘envelopes’ for occlusal gliding movements. This system is used to gain a deeper and more comprehensive understanding of the relationship between the structure and function of the occlusion. Interfaces to CAD software have also been established. Keywords: instrumental analysis of occlusion, digital occlusion, CAD/CAM

Aim: Sinus lift is a common procedure to achieve bone height in the maxillary posterior region. This surgery can be performed through either a lateral or crestal approach. Preoperative planning usually entails CBCT and intraoperative evaluation at the time of surgery. This article presents a case in which a surgical guide was made by digitally planning for the performance of a sinus lift procedure through a lateral approach. Case presentation: A 59-year-old partially edentulous female patient underwent sinus lift surgery using a stereolithographic guide designed in NemoStudio software and printed using clear, biocompatible MED610. On the day of surgery, the bone guide was fixed with pins, and the lateral window was made by piezoelectric surgery. There were no intraoperative or postoperative incidents. Discussion: There are very few descriptions in the literature of the use of surgical guides for sinus lift. In this case, the advantages of its use were the precision in the performance of the window, the speed and comfort of access, and the retractor effect of the guide on the flap. The main drawback was the need to raise a wide flap to achieve good settlement of the guide. Conclusion: The present case, which presents an innovative technique for the opening of the lateral window in a sinus lift procedure, is interesting for the advancement of computer-guided surgery. Keywords: oral surgery, sinus floor augmentation, computer-assisted surgery, case report

Aim: Granuloma gravidarum (GG) is a benign lesion of the soft tissue. The aim of this technical note is the volumetric assessment and follow-up 3D measurement of a GG in the anterior maxilla. Materials and methods: A 35-year-old female patient who was 7 months pregnant was referred due to a soft tissue tumor in the papilla of tooth 21. A biopsy verified a pyogenic granuloma gravidarum. Initial and consecutive volumetric measurements were made with an intraoral scanner during the patient’s pregnancy and until 16 months postpartum. Results: The volumetric assessment showed a continuous growth of the tumor and a consecutive volume reduction 16 months postpartum. In comparison with the level of the papilla of the contralateral incisor, there was an almost complete remission at the last follow-up. Conclusion: Intraoral scans can serve for the volumetric assessment of soft tissue tumors of the alveolar crest. Image superimposition enables the quantification of changes in morphology. This supports clinical follow-ups and enables the quantification of clinical observations. Keywords: epulis gravidarum, granuloma gravidarum, pyogenic granuloma, pregnancy, intraoral scanner, volumetric measurement

Smile reconstruction is achieved using rigorous and detailed methodologies that are technically demanding and both time and cost intensive. These methodologies do not include the patient during the primary conception phase. New digital technologies using augmented reality (AR) offer the option of immediate diagnosis and pre-visualization of the potential outcome before the start of treatment. A 22-year-old patient with a congenitally missing maxillary right canine, peg-shaped maxillary lateral incisors, and multiple visible diastemas required an esthetic rehabilitation. An AR virtual mock-up using specialized software was used to preview and modify the restoration proposal in real time. Using the novel ‘CAD-link’ workflow, the final AR proposal could be imported into CAD software and transformed into a digital wax-up with the new virtual wax copy function. After a minimally invasive preparation, the final veneer reconstructions were precisely planned according to the previously developed design proposal and bonded according to the well-known adhesive protocol. The workflow described in this article links AR with CAD/CAM technology and is expected to be time and cost efficient. This patient-centered approach involves the patient from the very beginning and is therefore an excellent communication tool between the patient and the restorative team. Keywords: augmented reality, virtual reality, CAD/CAM, CAD-link, esthetics, smile design, patient communication, dynamic planning, diagnostics