International Journal of Computerized Dentistry, 02/2019

Aim: For orthodontic aligner treatment, excellent full-arch impressions with correctly displayed interdental areas (IAs) are required. To analyze the ability of impression taking of the IAs in periodontally compromised dentitions, two intraoral scanning systems and one conventional impression technique were investigated in vitro under standardized testing conditions. Materials and methods: A total of 60 impressions of the maxilla and mandible were taken from a periodontally compromised test model (A-PB) with three different techniques (n = 20): One conventional impression (EXA'lence) (CVI) and two digital impressions with the intraoral scanners Trios III (3Shape) (TIO) and True Definition (3M ESPE) (TRU). Standard tessellation language (STL) datasets were generated for TIO and TRU, whereas type IV dental stone casts were manufactured for CVI. The casts were then digitized with a laboratory scanner (ATOS). The percentage of displayed IAs in relation to the complete IA was calculated for each IA using evaluation software (GOM Inspect). Finally, the data were subjected to the median test. Result: TRU showed a significantly higher percentage of displayed IAs compared with the other two methods (P < 0.05). Only a few IAs were shown in CVI. TIO showed significantly better results compared with CVI, although the results were not as good as those of TRU. Conclusion: Within the limitations of this in vitro study, intraoral scanners - and especially the one based on active wavefront sampling (AWS) technology (as for TRU) - can be recommended for the reproduction of wide IAs (undercuts) in periodontally compromised patients. Keywords: intraoral scanners, periodontally compromised dentition, full-arch impression, aligner treatment, orthodontics, digital dentistry

Aim: The objective of this prospective pilot clinical study was to evaluate the accuracy of a new dynamic navigation system and postoperative clinical outcomes. Materials and methods: Ten patients were recruited and 18 implants were placed. The surgery was performed with the navigation system and according to the virtual planning. Ten implants were placed using a flapless technique and eight implant sites were prepared with a combined piezo-drill method. The deviation between the real implant position obtained from the postoperative cone beam computed tomography (CBCT) scan and the planned implant position was measured. Result: The average deviation was 1.19 ± 0.54 mm. The mean deviation measured at the insertion point was 1.04 ± 0.47 mm and at the apical point it was 1.35 ± 0.56 mm. The depth error was 0.43 ± 0.34 mm. The axis deviation was 6.46 ± 3.95 degrees. No significant differences were found between the flapless and the open-flap approaches and between the conventional and piezoelectric techniques. No complications occurred. Conclusion: The accuracy values reported in this study are comparable, although not superior, to the literature data regarding dynamic and static computer-guided surgery. Dynamic navigation could increase the quality and safety of interventions and may reduce morbidity when compared with freehand insertion techniques. Deviation at the entry point (mm) Deviation at the apex (mm) Depth deviation (mm) Angular deviation (degrees) Mean 1.04 1.35 0.43 6.46 SD 0.47 0.56 0.34 3.95 Maximum 2.21 2.28 1.41 6.46 Minimum 0.45 0.59 0.03 3.95 Deviation at the entry point (mm)Deviation at the apex (mm)Depth deviation (mm)Angular deviation (degrees)OF0.96 ± 0.331.45 ± 0.600.35 ± 0.227.93 ± 5.15FL1.10 ± 0.581.27 ± 0.570.49 ± 0.425.28 ± 2.60Data are shown as mean ± SDOF = open-flap surgery; FL = flapless surgery Deviation at the entry point (mm)Deviation at the apex (mm)Depth deviation (mm)Angular deviation (degrees)P1.01 ± 0.251.37 ± 0.480.44 ± 0.267.63 ± 4.30C1.06 ± 0.621.34 ± 0.660.42 ± 0.415.52 ± 3.81Data are shown as mean ± SDP = piezoelectric tips; C = conventional burs Keywords: computer-assisted surgery, image-guided surgery, implantology, navigation system, real-time tracking, implant placement accuracy

Purpose: Cone beam computed tomography (CBCT) in orthodontics is increasingly used for detecting impacted or ectopic teeth or for orthognathic and cleft lip and palate treatment. Incidental findings (IFs) are frequently encountered and often relevant. The aim of this study was to detect the prevalence of relevant pathologies on CBCT scans of orthodontic patients. Methods: Over a 6-year period, incidental imaging findings were analyzed in 345 CBCT scans (181 men; 164 women; age 16.3 ± 8.4 years), and subdivided into dental (Group 1), skeletal (Group 2), sinunasal (Group 3), and infrequent other pathologies (Group 4). Results: A total of 502 IFs were detected in 345 patients (1.4 IFs per patient, on average). Most IFs were found in Group 1 (358 IFs; 71.3%), followed by Group 2 (129 IFs; 25.7%), Group 3 (14 IFs; 2.8%), and Group 4 (1 IF; 0.2%). There were 119 (34.5%) patients with a missing wisdom tooth, 94 (27.3%) with dental aplasia, 71 (20.6%) with dislocations, 33 (9.6%) with partial opacifications, and 27 (7.8%) with signs of sinusitis. Conclusions: This study found that IFs in orthodontic CBCT scans are frequently encountered, even in younger orthodontic patients. When interpreting CBCT scans, orthodontists should be aware of potential relevant IFs that may require further investigation, change patients' treatment or affect their quality of life. Keywords: cone beam computed tomography, incidental findings, orthodontics, craniomaxillofacial, 3D imaging, field of view

Aim: Atherosclerotic carotid plaques (ACPs) constitute the main etiological factor in about 15% of strokes. ACPs can be detected on routine dental panoramic radiographs. As these are one of the most commonly performed dental images, they can be used as a source of available data for computerized methods of automatic detection of ACPs in order to significantly increase their timely diagnosis. The aim of this study was to present the potential of applying deep learning methodology to detect ACPs on routine panoramic radiographs with the ultimate goal of preventing strokes. Methods: The Faster Region-based Convolutional Neural Network (Faster R-CNN) for deep learning was used. The operation of the algorithm was assessed on a small dataset of 65 panoramic images. As the available training data was limited, data augmentation was performed by changing the brightness and randomly flipping and rotating cropped regions of interest in multiple angles. Receiver operating characteristic (ROC) analysis was performed to calculate the accuracy of detection. Results: ACPs were detected with a sensitivity of 75%, a specificity of 80%, and an accuracy of 83%. The ROC analysis showed a significant area under curve (AUC), different from 0.5. Conclusions: The novelty of the study lies in showing the efficiency of a deep learning method for the detection of ACPs on routine panoramic images based on a small dataset. Further improvement is needed as regards the application of the algorithm to the level of introducing this methodology in routine dental practice for stroke prevention. Keywords: stroke, deep learning, panoramic imaging, panoramic radiograph, neural network, atheroma, dentist, atherosclerotic carotid plaques (ACPs)

Aim: This study evaluated the stress distribution of implant-supported prostheses, varying the different combinations of computer-aided design/computer-aided manufacturing (CAD/CAM) materials between the hybrid abutment and the monolithic crown by three-dimensional (3D) finite element analysis (FEA). Materials and methods: Nine models were designed with Rhinoceros 3D and Ansys software. Each model contained a bone block of the molar area, including an implant (IH; Ø 3.75 × 11 mm) supporting a hybrid abutment (ceramic mesostructure (MS) cemented onto a titanium [Ti] base) and a monolithic crown. The occlusal load was applied to the fossa bottom (300 N; 30 degrees). The results were analyzed using the von Mises stress for each separated prosthetic structure and microstrain for the bone tissue. Result: Von Mises maps of the crown, ceramic MS, implant, screw, and cement layers showed a decreased stress concentration as the elastic modulus (E modulus) of the ceramic crown (CR) associated with a rigid ceramic MS decreased. No differences in bone tissue regarding microstrain were observed. Conclusion: Implant-supported crowns present less stress concentration when a rigid abutment is associated with resilient crowns. Keywords: ceramics, finite element analysis (FEA), dental implants, material testing, dental implant-abutment design, dental materials

Aim: The purpose of this study was to evaluate the effectiveness of several methods of disinfection and sterilization of computer-aided design/computer-aided manufacturing (CAD/CAM) camera mirror sleeves (Omnicam; Dentsply Sirona). Materials and methods: The outer surface of seven groups of mirror sleeves were inoculated by submerging them in suspensions of Staphylococcus aureus and Pseudomonas aeruginosa. Post inoculation, the groups were decontaminated as follows: Group A: no decontamination or sterilization following inoculation (positive control); Group B: surface cleaning with a neutral soap (Dawn Dish Soap, Procter & Gamble) and water only; Group C: surface disinfection with 17% isopropanol (CaviWipes; Metrex). Groups D to F received a different high-level disinfection (HLD) solution in an HLD container (Dentsply Sirona) as follows: Group D: 0.55% ortho-phthalaldehyde (OPA) (Cidex OPA; Johnson & Johnson); Group E: 7.5% hydrogen peroxide (H2O2) (Sporox II; Sultan); Group F: 7.35% H2O2 and 0.23% peracetic acid (PAA) (Compliance; Metrex). Group G received dry-heat sterilization (Rapid Heat Sterilizer; Cox). Also, dry-heat sterilized mirror sleeves that were not exposed to bacteria and not disinfected served as a negative control. The presence of bacteria was tested on the inside and outside of the sleeves by plating samples on TSA II. A percent reduction in CFU/ml from the positive control group was determined per group. Results: All methods of disinfection except Dawn Dish Soap resulted in greater than 99.99% reduction in CFU/ml compared with the positive control group. Conclusions: Both HLD or dry-heat sterilization resulted in no growth of microorganisms in cultures taken from both the outside and inside surfaces of the bacteria-contaminated mirror sleeves. Keywords: bacteria, decontamination, CAD/CAM, mirror sleeves

Immediate implant placement in molar sites has the potential to improve patient treatment experience by reducing overall treatment time and the number of appointments. However, primary closure remains a technical challenge. Aim: The objective of this case series was to assess the final clinical outcome at the 2-year follow-up of immediate implant therapy in molar sites using a digitally fabricated sealing socket abutment (SSA) at the time of extraction. Materials and methods: This case series included 29 patients who received immediate implant placement in molar sites. A digital impression was taken at the time of placement, and a chairside CAD/CAM healing abutment was fabricated and delivered in situ to close the alveolar socket. Clinical assessments were reported with a minimum of 2 years of follow-up. Results: All patients reported uneventful postoperative recovery after 1 week of healing. No implant failures were observed. The assessment by an experienced clinician showed healthy and stable periimplant tissue. Conclusion: Based on the results of this study, the combination of an immediate implant placement protocol and a customized SSA seems to be a viable treatment alternative, although this needs to be confirmed by future prospective randomized studies. Keywords: CAD/CAM healing abutment, digital workflow, immediate implant placement, soft tissue healing, emergence profile, digital impression