International Journal of Computerized Dentistry, Pre-Print

Aim: The aim is to record the surface roughness of monolithic chairside CAD/CAM zirconia materials to evaluate the influence of milling speed on the ability to achieve a clinically desirable surface. The null hypothesis is that there is no significant difference in the surface roughness of different zirconia materials based on the speed of subtractive milling. Materials and Methods: All test samples were milled from four different monolithic CAD/CAM zirconia blocks including CEREC Zirconia (Dentsply Sirona), CEREC Zirconia+ (Dentsply Sirona), CEREC MTL Zirconia (Dentsply Sirona), and Katana Zirconia (Kuraray Noritake). Four different dry milling speeds, Super Fast/Good, Super Fast/Very Good, Fast, and Fine were used to dry mill the specimens in a CEREC Primemill (Dentsply Sirona). A 3D measuring laser microscope (OLS4100 LEXT by Olympus) was used to measure surface roughness. Results: An Analysis of Variance (ANOVA) was used to analyze the surface roughness data for each material and milling speed. There was a significant difference for milling speed (p < 0.05) but not between zirconia materials (p > 0.05). Conclusion: Based on the limitations of this study, the milling speed influenced the surface roughness of dry milled and sintered zirconia with slower speeds resulting in smoother surfaces. The largest improvement in surface roughness occurred between Super Fast and Fast milling with a smaller incremental improvement in surface roughness with Fine milling for the Primemill. All recorded surface roughness values are within the expected range of values to be able to efficiently hand polish a clinically acceptable surface finish. Schlagwörter: CAD/CAM, CEREC, mill speed, Surface Roughness, zirconia

Aim: To evaluate the failure rate of palatal computer-guided miniscrews, placed in paramedian and parapalatal regions for orthodontic purposes. In addition, to investigate the presence of a learning curve using computer guided miniscrew insertion, and to evaluate the peri-implant soft tissues response at 2-, 6- and 12- month follow-ups. Materials and Methods: 202 palatal computer-guided miniscrews were inserted in 78 subjects for orthodontic purposes. A surgical guide was designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. The devices were disassembled monthly to perform the percussion test and to evaluate the mobility of each miniscrew. To determine the presence of a learning curve, the time of miniscrew failures and the number of surgeries were evaluated. Bleeding on probing (BOP) and probing pocket depth (PPD) were recorded for each miniscrew, at 2- (T0), 6- (T1), and 12-month follow ups (T2). Results: An immediate failure rate of 4.95%, due to lack of primary stability immediately following miniscrew insertion, was recorded, with statistically significant higher failure rate of parapalatal miniscrews (P= 0.00). Miniscrew failure occurred at random time, with an absence of a learning curve. The BOP (mean: 3.13%) and PPD (mean: 1.68mm) measurements remained stable over time. Conclusions: Computer-guided miniscrew insertion in the palatal vault showed a low failure rate without a determined learning curve to obtain predictable results and with long-term stability of peri-implant soft tissues indexes. Schlagwörter: computer-guided surgery, failure rate, Orthodontics, skeletal anchorage, TADs

Aim: To evaluate the accuracy and reproducibility of real and virtual occlusal contact points in implant-supported, fixed complete dentures. Materials and methods: The study included 19 participants using mandibular interim complete-arch fixed prosthesis supported by 3 or 4 implants as opposed to conventional removable complete dentures. At installation, an examiner installed the prostheses and verified the occlusal contact points through 2 methods: recording the real contact points with carbon paper (RC) followed by occlusal photography and intraoral scanning (VC) to record the virtual contact points to obtain a screen print of the software. Then, the two images were randomized to determine the order to be inserted into Microsoft PowerPoint for blind and paired evaluation. The independent variables consisted of the distribution of occlusal contacts points (qualification through pre-defined scores based on the position of the contact points on the surfaces of the teeth) and the reproducibility of the methods by verifying the number of occlusal points. For this, a descriptive analysis was used to evaluate the distribution of occlusal contacts points and the Wilcoxon test for the reproducibility of the occlusal contact points between the methods (p<0.05). Results: The methods had 100% and 73.6% real and virtual occlusal contact points, respectively, which is considered clinically excellent. There was no significant difference regarding the reproducibility of the methods by the number of occlusal contact points (RC: x̅13.32; VC: x̅13.68; p=0.715). Conclusion: The use of the tested intraoral scanner can be an easy and fast tool for studying and mapping the occlusion, and storing data for future treatment, with the conventional method being the preferred method for performing the occlusal adjustment. Schlagwörter: implant-fixed dental prosthesis, dental occlusion, edentulous, jaw, Occlusal adjustment, three-dimensional imaging

Learning tooth preparation techniques and the finesse required is an important part of preclinical dental education. Being able to practice surgical skills without loss of Frasaco® teeth while being provided with performance analysis data is a boon to students and educators. We investigated the combination of haptics-enhanced virtual reality (Simodont®) and conventional phantom head practice in a preclinical dental course, evaluating the students’ performances and perceptions. Forty students were randomized into two groups: Group One began within a VR-haptic setting while Group Two worked with Frasaco® teeth. Halfway through the course the scenarios were switched. A crown preparation test on Frasaco® teeth was conducted at the end of the course. Students’ performances and satisfaction were assessed anonymously. Analysis of the students’ performances included clinical metrics (occlusal and axial reduction, convergence angle, damage to adjacent teeth). The perceived usefulness of VR-haptic and phantom head simulations was assessed. In Group One, the tooth preparation metrics were more in line with the requested parameters compared to Group Two. All students ranked VR-haptics highly regarding manual dexterity improvement. In conclusion, this study shows that by combining VR-haptics with conventional dental procedures, it is possible to improve important preparation metrics in fixed prosthodontics tooth preparation. Schlagwörter: dental training, manual dexterity, practice-based learning and improvement, survey, VR-haptic simulation

Aim: The adjustment and transfer of a stable occlusion can be a major challenge in prosthetic rehabilitations. The aim of this study was to assess a non-invasive treatment option for complex prosthetic rehabilitations and occlusal analyses using 3D-printed restorations clinically. Materials and Methods: Eleven patients received a partial or complete rehabilitation with the aid of 3D-printed restorations (n=171). After 12 months of clinical service, all restorations were analyzed using the United States Public Health Service (USPHS) criteria. Results: The 12-month clinical data revealed that 3D-printed restorations showed a survival rate of 84.4%. Complications occurred mostly regarding the anatomical form (7%) or marginal integrity (6AC%) and were consequently rated “Charlie” or “Delta.” Color stability and color match of 3D-printed restorations were rated “Alpha” in 83% and 73%, respectively, of all restorations. Marginal inflammation was rated “Alpha” in 89% of all restorations. An excellent surface texture and no secondary caries or postoperative sensitivities (100%) were observed. Conclusions: 3D-printed restorations might be an alternative treatment option for initiating complex prosthetic rehabilitations. Technical complications rarely occurred. Biological complications did not occur at all. The color stability showed promising results after 12 months of clinical service. However, the results should be interpreted with caution. Long-term results with a high number of restorations should be awaited. Schlagwörter: 3D-printing, additive manufacturing, CAD/CAM, color stability, in vivo, wear behavior

Aim: To evaluate and compare the marginal adaptation and fracture resistance of resin matrix ceramic crowns fabricated using 3-dimensional (3D) printing and computer aided design/computer aided manufacturing (CAD/CAM) milling technology. Materials and Methods: Thirty extracted human maxillary first premolars were prepared to receive crown restorations and grouped into 3 groups according to 3 different crown materials (n = 10): VE: teeth restored with milled Vita Enamic, CS: teeth restored with milled Cerasmart 270 and VSC: teeth restored with 3D-printed VarseoSmile Crown Plus. Marginal analysis was performed with the aid of a digital microscope at (230x) magnification, both before and after cementation with self-adhesive resin cement and analyzed with Image J analysis software. The fracture loads for each sample were then recorded using a universal testing machine in a single load-to-failure test up until the crowns failed. Results: The lowest marginal gap values were recorded for VSC before (8.03 μm) and after (15.07 μm) cementation with significant difference compared to the other crown materials (p <0.05), while the differences between the milled groups were non-significant both before, (CS (11.35 μm) and VE (11.86 μm)), and after cementation, (CS (20.01 μm) and VE (21.08 μm)). In terms of fracture resistance, VE recorded significantly lower fracture load values (727.8 N) (p <0.05) than the crowns fabricated from CS (1213.8 N) and VSC (1181.5 N), which showed no statistically significant differences between each other. Conclusion: 3D printed definitive crowns outperformed CAD/CAM milled crowns in terms of marginal adaptation, along with comparable fracture resistance values. Schlagwörter: 3D printing, CAD/CAM milling, Fracture resistance , Marginal adaptation , Resin matrix ceramics

Aim: This randomized controlled clinical study focused on graft volume alterations after sinus floor augmentation with a deproteinized bovine bone mineral (DBBM, Geistlich Bio-Oss®), deproteinized porcine bone mineral (DPBM, THE GRAFT®) or a biphasic calcium phosphate (BCP, OSOPIA®). Material and Methods: 28 patients with edentulous situations in the posterior maxilla with less or equal to 5 mm of residual bone height received a two- staged external sinus grafting procedure with DBBM, DPBM or BCP. CBCT scans were performed prior surgery (CBCT1), directly after surgery (CBCT2) and after a healing period of 4-6 months prior implant placement (CBCT3). CBCT scans were used to analyze volumetric alterations of the sinus grafts by virtual 3D model matching of CBCT1- CBCT2 (situation after sinus grafting) and CBCT1 and CBCT2 (situation prior implant placement). Results: The volume of the bone graft in the maxillary sinus (volume (VOL%) directly after grafting rated as 100%) was stable after the healing period in the DBBM (VOL%: 103±4%) and the PBBM groups (VOL%: 112± 23) with no statistically significant differences concerning 3D measurements. In the BCP group, the grafted volume declined to 66± 25% (VOL%), statistically inferior to the DBBM and DPBM groups. Conclusion: Concerning bone graft stability/ 25 volume DBBM and DPBM show comparable outcomes. Due to resorption, BCP showed inferior bone graft volume after healing (statistically significant) compared to DBBM and DPBM. Schlagwörter: 3D evaluation, Bone substitute, CBCT, Sinus grafting, volumetric stability

Aim: There is an ongoing debate about the benefits of the facebow and individual articulator settings in prosthodontics when compared to simpler methods. This study aims to determine whether the implementation of novel algorithmic articulator concepts may be an alternative to avoid dynamic interference contacts during the design process of fixed posterior restorations and to which extent the occlusal morphology of the restoration is affected. Materials and methods: From a chairside CAD database, a total of 50 clinical patient cases documenting 61 planned fixed restorations in the posterior tooth region were selected. A common CAD software was used for the automated knowledge-based design process. When designing the restorations, functional concepts including the pure static occlusion, average articulation, 3 different articulator settings as a control, and a combination of a broad range of articulation parameters (full range dynamic articulation) were applied. The resulting dynamic contact points were both compared visually and metrically with a monitoring software. Results: There is a highly significant difference in avoiding dynamic interference contacts when applying the full range dynamic articulation in comparison to the pure static occlusion (p<0.001) and the average articulation (p<0.001). Furthermore, the superimposition revealed that the surface of the restorations showed nearly no visual morphologic changes after virtually grinding-in the interpenetrating contact points. Conclusion: The full range dynamic articulation can be used for the design of small fixed posterior restorations to avoid most dynamic interference contacts, without the need for determining individual parameters for each patient. Schlagwörter: average articulation, CAD/CAM, facebow, full range dynamic articulation, virtual articulation, virtual FGP

Aim: Even though today, many fields in dentistry allow digital processes, analogue procedures are still widely used. This cross-sectional pilot study aimed to survey insights on the digitalisation of dental practices using the example of Hesse. Materials and Methods: Between April and June 2022, 4840 active practicing dentists registered by the State Dental Association of Hesse were invited via e-mail to fill out an online questionnaire regarding their technical requirements in dental practice, dental treatment procedures, and attitude towards digitalisation in dentistry. Demographic questions were asked. Besides descriptive statistics, correlations were analyzed (P < 0.05). Result: Questionnaires of 937 dentists (279 female, 410 male, four inter/divers, 244 no answer; mean age of 51.4 ± 10.4 years) were examined representing a respond rate of 19.36%. In the area of practice administration and dental radiography, the majority of the dentists surveyed is already working digitally, which is predominantly assessed as a positive development. Already one third of the respondents state that they use an intraoral scanner for dental treatments, but the indication is mainly limited to smaller restorations. However, many dentists rate the use of social media accounts and telemedicine rather negative. Conclusion: Within the limitation of this pilot study, many processes especially in dental treatments are still analogue. However, 60% of the participants plan digitalisation of their dental practices within the next five years, which indicates a clear shift from analogue to digital dentistry. Schlagwörter: Analog-Digital Conversion, CAD/CAM, Dental Practice Pattern, Digital Technology, Intraoral Scanner, Organisation and Administration, Real World Data on Dentistry, Surveys and Questionnaires

Aim: The purpose of this systematic review and meta-analysis is to evaluate the marginal adaptation of single unit full coverage lithium disilicate fixed dental restorations fabricated with the conventional heat pressed technique and the digital CAD/CAM workflow. Materials and Methods: This study is according to the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) statement. study research was conducted in MEDLINE via PubMed and Cochrane Library databases together with a hand search of studies published until June 2022. The search terms were combining suitable Medical Subject Headings (MeSH terms) together with free text words in single or multiple conjunctions. A modified methodological index was used to assess the risk of bias of the included studies. A random effect model was applied to pool the effect estimates, and further assessment of the heterogeneity across studies using the Q test and the I2 metric was conducted. All statistical analyses were performed using Rstudio software, version 4.1.2, using the “meta” package. Results: The electronic search and hand search identified 51 articles. Eighteen met the inclusion criteria and were included in the systematic review, 17 of which were in vitro and only one was an in vivo study. However, 17 of the initial 18 could be included in the meta-analysis, due to lack of statistical data in one of the in vitro studies. Statistical analyses were conducted by using the Rstudio software program. Meta-analysis was performed with the random effects model (α=.05). No statistical difference was found between the two fabrication methods (p-value=0.49). Conclusions: Although the mean marginal adaptation of lithium disilicate single crowns was found to be better with the heat-pressed technique, there was no statistical significance with the CAD/CAM fabricated restorations and both resulted in a clinically acceptable result. Nonetheless, more clinical studies are needed for safer conclusions. Schlagwörter: all-ceramic restoration, CAD/CAM, dental ceramics, glass-ceramics, lithium disilicate crown, marginal fit, single crown

Aim: New technologies such as tactile robots and artificial intelligence are about to find their way into clinical practice in dentistry and may contribute to the improvement of oral health care in the future. In this study we hypothesized that a collaborative, tactile robot programmed by a dental student removes interproximal artificial plaque as effectively as a human operator in an in vitro pilot trial. Material and Methods: Model teeth were fully covered with artificial plaque and set into phantom jaws. First, a robot was programmed by a dental student to perform interproximal cleaning with an interproximal brush. Second, teeth were covered with artificial plaque again and the dental student performed the interproximal cleaning manually. Both experiments were repeated five times. Residual plaque was measured with binary pictures. Surface coverage was reported and comparison of methods was performed with significance defined at a= 0.05. Results: No statistically significant difference was found in the cleaning result between the robot and the human operator. Conclusion: The results of this in vitro pilot study indicate that a tactile robot with integrated artificial intelligence programmed by a dental student can perform interproximal cleaning as effectively as the dental student. Practical lmplications: In the future, the use of robot assistants to support oral hygiene, e.g., in patients with reduced motor skills or impaired vision may be further investigated. Schlagwörter: Dental robots, Dentistry, Dentronics, Human-machine-interaction, Interdental brush, Interdental cleaning, Interproximal, Oral hygiene, Robotics

Objectives: Virtual Reality (VR) technologies can be used as a content-delivery system for the purposes of both entertainment and education. Remote and digital education has become ever so important in a world where global disruptive events such as pandemics and natural disasters can define access to a face-to-face learning environment. An important aspect of VR technologies for dentistry is the creation of digital 3D models. The primary of this review was to answer the focused research question, “What software techniques are used in the creation of digital 3D models for use in dental education.” Methods: This study systematically evaluates current software and techniques used for creating digital 3D models in dental education using the Preferred Reporting Items for Systematic Reviews (PRIMSA). Results: The search strategies did not find any studies specific to the creation of dental-related 3D models. Therefore, this study for the first time provided an overview of common techniques of 3D model fabrication is discussed. Further some examples of methods of creating 3D models relevant to dentistry such armamentarium and anatomical oral structures have been discussed in considerable detail. Conclusion: The creation of 3D modelling is a rapidly evolving field with software updates and new programs being continually released. This work highlights fundamental lack of published work in the creation of 3D dental models for educational applications. Schlagwörter: 3D modelling, dental education; , dentistry, digital modelling, Virtual Reality

Artificial intelligence (AI) based systems are used in dentistry to make the diagnostic process more accurate and efficient. The objective of this study was to evaluate the performance of a deep learning program for detection and classification of dental structures and treatments on panoramic radiographs of pediatric patients. In total, 4821 anonymized panoramic radiographs of children aged between 5 and 13 years old were analyzed by YOLO V4, a CNN (Convolutional Neural Networks) based object detection model. The ability to make a correct diagnosis was tested samples from pediatric patients examined within the scope of the study. All statistical analyses were performed using SPSS 26.0 (IBM, Chicago, IL, USA). The YOLOV4 model diagnosed the immature teeth, permanent tooth germs and brackets successfully with the high F1 scores like 0.95, 0.90 and 0.76 respectively. Although this model achieved promising results, there were certain limitations for some dental structures and treatments including the filling, root canal treatment, supernumerary tooth. Our architecture achieved reliable results with some specific limitations for detecting dental structures and treatments. Detection of certain dental structures and previous dental treatments on pediatric panoramic x-rays by using a deep learning-based approach may provide early diagnosis of some dental anomalies and help dental practitioners to find more accurate treatment options by saving time and effort. Schlagwörter: artificial intelligence, deep learning, oral diagnosis, panoramic radiography, pediatric dentistry

Aim: To investigate the effect of using different materials for the fabrication of implant abutments and crowns on the mechanical behavior of implant-supported single crowns after artificial aging. The materials were tested in different combinations to reveal whether using stiff or resilient materials as an abutment or a crown material might influence the fracture strength of the whole structure. Materials and Methods: A total of 40 implants (blueSKY, bredent GmbH & Co. KG) were restored with identical custom-made CAD/CAM abutments milled out of lithium disilicate or ceramic-reinforced PEEK and were divided into 5 test groups (n = 8 each). Forty crowns made of three different materials (zirconia, lithium disilicate, and ceramic-reinforced PEEK) were used to restore the abutments. Specimens were subjected to mechanical load up to 1,200,000 cycles in a chewing simulator (Kausimulator, Willytech) with additional thermal cycling. The surviving specimens were subjected to quasi-static loading using a universal testing machine (Z010, Zwick). Results: PEEK abutments with zirconia crowns showed the highest median failure load (3890.5 N), while PEEK abutments with lithium disilicate crowns exhibited the lowest (1920 N). Fracture and deformation occurred in both crowns and abutments. Conclusion: The failure load of the restorations was influenced by the material of the abutment and the crown. Restoring PEEK abutments with zirconia crowns showed a high failure load and no screw loosening. Schlagwörter: CAD/CAM, Custom-made implant abutment, implant abutment, Lithium disilicate, PEEK, Zirconia

Aim: To determine the 3-year clinical and dimensional change of the soft tissue following implant placement in healed sites before and after loading with either customized or conventional healing abutments. Materials and Methods: Premolar/molar implants were immediately loaded with either provisional and customized abutments without finishing lines according to principles of the Biologically Oriented Preparation Technique (BOPT), test group, or conventional healing abutments, control group. Three months later, the definitive crowns were fabricated. Primary outcomes (changes in the soft tissue) and secondary outcomes (adverse events) had been registered. Result: Fifty out of 87 subjects originally included were finally selected for this retrospective analysis: 23 in the test and 27 in the control group. During the first days after surgery 2 adverse events of mucositis, one for each group, occurred. A Few technical complications such as unscrewing 4 screw-retained crowns were recorded. A significant increase in the alveolar width was observed in both groups (test = +2.5±0.5mm, and control = +1.0±0.9mm). The widths appeared to not be merely changed from 3 months to 3 years in both groups. There were no significant differences regarding the width of the keratinized mucosa measured at baseline and after follow-up. Jemt papilla index showed a higher increase in the test group compared with that of the control group. Conclusion: Within 3 years of the follow-up period, peri-implant soft tissue outcomes of single, immediately loaded implants with customized healing abutments showed better results in terms of thickness and width when they were compared with those of the conventional group. Side effects count (mucositis and dehiscence) appeared to be very similar between the two groups. In addition, customized healing abutments led to significant augmentation of the alveolar width more than twice that registered in the conventional group. Schlagwörter: anatomical cap, customized abutment, dental abutment, dental implant, implant placement

Die Okklusionsschiene ist ein häufig eingesetztes Mittel in der Zahnarztpraxis, welches zur Behandlung von Bruxismus oder Kiefergelenkserkrankungen eingesetzt wird. Die Verwendung digitaler CAD/CAM gestützter Zahntechnik erleichtert den Herstellungsprozess (Herstellung mittels 3D Druck möglich) und verbessert die Qualität der Schiene. Somit kann eine bessere Präzision, damit eine erhöhte Passgenauigkeit, sowie eine Optimierung des Herstellungsprozesses in Bezug auf Zeitaufwand und Material erreicht werden. Außerdem ist die Duplikation der Schiene unkompliziert möglich, da die 3D-Datensätze patientenbezogen als STL-Datei gespeichert und zu jeder Zeit erneut herangezogen werden können. Dieser technische Bericht beschreibt die notwendigen Arbeitsschritte des digitalen Workflows zur Herstellung einer Okklusionsschiene über ein vollständig digitales Protokoll. Die Scans von Ober -und Unterkiefer werden in zentrischer Relation erfasst und ein virtuelles Aufbissbehelf wird mit einer kostenlosen Open-Source-Modellierungssoftware entworfen.

Ziel: Der digitale Workflow zur Erstellung einer adjustierten Schiene soll anhand eines Patientenfalls dargestellt werden. Material and Methoden: Eine 25-jährige Patientin stellte sich zum Management ihres Bruxismus vor. Zu diesem Zweck sollte eine adjustierte Schiene hergestellt werden. Eine instrumentelle Bewegungsanalyse der Patientin wurde durchgeführt (JMA Optic, Amann Girrbach) sowie Ganzkieferscans der Ober- und Unterkiefers, eine Biokopie des Oberkiefers mit Kopplungslöffel sowie Bukkalscans der zentrischen Kieferrelation (Primescan, Dentsply Sirona). Die Kieferrelation wurde zuvor durch ballistisches Schließen auf einem chairside gefertigten anterioren Jig bestimmt. Im Labor erfolgte die digitale Konstruktion der Schiene im Sinne einer Michiganschiene. Die Konstruktion wurde genestet und aus einem Polymethylmethacrylat (PMMA)-haltigen Blank gefräst (CLEARsplint Disc, Astron Dental Corporation). Ergebnisse: Die Schiene wurde bei der Patientin einprobiert, ein spannungsfreier Sitz geprüft und die Statik und Dynamik kontrolliert. Bei der Nachkontrolle gab die Patientin eine Verbesserung der Verspannungen im Bereich der Kaumuskulatur an. Schlussfolgerung: Der dargestellte Vorgehen ermöglicht die Anfertigung ein adjustierten Schiene in einem rein digitalen Workflow.

Aim: An in-vitro study was performed to investigate the overall and regional accuracy and precision of digital three-dimensional facial scans obtained from four tablet-based applications (Bellus Dental Pro, Capture: 3D scan anything, Heges, and Scandy Pro 3D scanner) on an iPad Pro® (Apple Store, Cupertino, CA, USA), equipped with LiDAR and TrueDepth technology, compared to the validated manual measurements using a digital vernier caliper (DVC). Materials and Methods: The accuracy of the various applications was determined through multiple scans of a three-dimensional (3D) printed mannequin face using iPad Pro®. For precision evaluation, the mannequin’s face was scanned five times with each application, and these models were compared using the coefficient of variation (CV). The descriptive statistics were done from SPSS version 23 (IBM Company, Chicago, USA). One-sample t-test was used to analyze the difference between the control and the various scans. Results: While the applications Capture, Heges, and Scandy tended to overestimate the measured values compared to DVC, the Bellus application underestimated these values. Scandy showed the highest mean difference in the Go - Ch (R) measurement, with a value of 2.19 mm. All the others average differences were less than 1.60mm. The assessment of precision showed that the coefficient of variation ranged from 0.16% and 6.34%. Conclusion: The iPad Pro® (2020) showed good precision and reasonable reliability, and it appears to be an interesting and favorable technology for the acquisition of surface images of facial-like structures. Moreover, further clinical investigations should be conducted. Schlagwörter: precision, accuracy, face analysis, Imaging, structured light scanning, three-dimensional

Aim: Aim of this study comprised the software-supported evaluation of measurement accuracy between cone-beam computed tomography (CBCT) and panoramic radiographs in the assessment of the periodontal bone level in patients with periodontitis and comparison with clinical periodontal parameters. Material and methods: Twenty patients with severe periodontitis (stage III-IV) were evaluated clinically and radiographically (panoramic and CBCT). Diagnostic interpretation comprised three blinded investigators with different levels of experience. Specific software-basing measurement procedure evaluated radiological distances for the mesial, central, and distal bone levels on the oral and vestibular sides of the teeth investigated and furcation upper and lower boundary. Jaw localization, anatomical region-of-interest, the number of roots and experience of the observers were evaluated. All measurements were carried out twice by the same observers within a 6-week interval. Results: Slightly higher measurement deviations (SD) in the range of 0.47 (0.40) mm were found for CBCT evaluation compared to panoramic imaging. Pearson correlation analysis showed statistically strong positive correlation for the mesial and distal aspects, moderate positive correlation was found for the investigated furcations between both radiographic modalities. Compared to the clinical reference, the mean total error of measurement (SD) was larger for panoramic imaging (0.66 (0.48) mm) than CBCT (0.27 (0.08) mm) for all three observers. Conclusions: Software-supported CBCT analysis delivers better diagnostic information about the bony periodontal conditions of the patient compared to two-dimensional radiographs. However, it remains unclear if these additional information lead to better periodontal outcomes. Schlagwörter: alveolar bone losses , cone-beam CT, diagnostic imaging, dimensional measurement accuracy, Periodontitis, radiography

Die Anzahl der im zahnärztlichen Bereich verfügbaren Technologien wächst jedes Jahr weiter, wodurch nun vollständig digitale Abläufe möglich sind, die vorhersehbare ästhetische und funktionelle Ergebnisse liefern können. Dieser klinische Bericht dokumentiert schrittweise eine umfassende Mundrehabilitation, die mit einem vollständig digitalen Ansatz und einer adhäsiven und präparationsfreien Methode geplant und durchgeführt wurde. Nachdem wir die Bedürfnisse des Patienten bewertet hatten, erstellten wir einen Behandlungsplan, der die funktionellen und ästhetischen Wünsche des Patienten berücksichtigte. Die Überlagerung von 2D-Bildern und 3D-Modellen sowie Gesichtsscans des Patienten ermöglichte die digitale Vorschau des ästhetischen Ergebnisses durch die Anwendung des "Copy-Paste"-Ansatzes zur Wiederherstellung des oberen vorderen Sextanten.

Aim: The aim of this study was to evaluate the segmentation accuracy of dentition testing four free-source semi-automatic software. Materials and methods: A total of 20 cone-beam computed tomography (CBCT) were selected to perform semi-automatic segmentation of maxillary and mandibular dentition. The software tested were Invesalius, ITK-Snap, 3D Slicer and Seg3D. Each tooth model was also manually segmented (Mimics software) and set as the gold standard (GS) reference of the investigation. A specific 3D imaging technology was used to perform the superimposition between the teeth models obtained with semi-automatic software and the GS model, and to perform the surface-to-surface matching analysis. The accuracy of semi-automatic segmentation was evaluated calculating the volumetric mean differences (mean bias and limits of agreement) and the percentage of matching of the tooth models compared to the manual segmentation (GS). Qualitative assessments were performed using color-coded maps. All data were statistically analysed to perform software comparisons. Result: Statistically significant differences were found in the volumetric and matching percentage data (p < 0,05). Invesalius was the most accurate software for 3D rendering of the dentition with a volumetric bias (Mimics) ranging from 4,59 mm3 to 85,79 mm3; instead, ITK-SNAP showed the higher volumetric bias, ranging from 30,22 mm3 to 319,83 mm3. The dis-matched area was mainly located at the radicular region of the teeth. Volumetric data showed excellent inter-software reliability with coefficient values ranging from 0,951 to 0,997. Conclusio: Different semi-automatic software algorithms could generate different patterns of inaccuracy error in the segmentation of teeth. Schlagwörter: 3D rendering, CBCT, cone-beam computed tomography, digital dentistry, digital orthodontics, oral surgery, orthodontics, segmentation

Aim: A total occlusal convergence angle φ of 6° is a typical crown preparation requirement. It was shown that it is hard to achieve clinically. The present study aimed to compare ability of students to judge different steepnesses including a -1° undercut of prepared canines and molars under clinical conditions with different analogue tools. Materials and methods: The complete dentures of a patient were duplicated without the teeth 16, 23, 33, 46. For each of these gaps, 6 crown stumps were milled with φ/2 = -1°, 3°, 6°, 9°, 12° and 15°, each of which was insertable using mini-magnets. 48 students each from the 1st, 6th and 9th semester estimated these angles intraorally with various aiding tools: In addition to basic dental instruments, a parallelometer mirror, an analogue clock dial with a 6° visualization and a scale of tooth stumps with φ/2 between -1° and 15°. Results: The widely demanded 3° were hardly recognized, but assumed to be steeper or even undercut. In contrast, the -1° divergent stump walls were predominantly estimated as parallel-walled or slightly conical. With increasing taper, the stumps tended to be classified as steeper, i.e. "better". The additional tools did not result in a general improvement of the estimation performance. Students from higher semesters did not achieve better results. Conclusion: We question the objectivity of an exclusively visual assessment of crown stump taper. It appears, that dental training should at least focus on avoiding undercuts as minimal prerequisite for an accurate intraoral scanning procedure. Digital control of the preparation angle by an intraoral scan and immediate clinical implementation of these results could help to produce appropriate preparations. Schlagwörter: crown stumps, dental students, intraoral estimation, preparation angle, visualization tools

Aim: Quantitative dental plaque evaluation is necessary for clinical and scientific work. This study aimed to examine the reliability of this 3D image analysis method by digitally analysing the colour 3D images obtained from an intraoral scanner, and then detecting and quantifying the plaque information and comparing it with the clinical examination results. Materials and methods: A total of 140 teeth from 5 subjects with a standard dentition were enrolled in this study, and plaque examination was performed at two different stages: after 24 hours without oral hygiene (T1) and after habitual brushing (T2). At each time point, the Quigley-Hein plaque index of each tooth surface was recorded separately, followed by colour 3D images obtained using an intraoral scanner, and image analysis and calculation using Geomagic Wrap 2021. Results: It was found that the percentage of plaque staining area calculated from the 3D image analysis correlated well with the plaque index recorded during the clinical examination: the Spearman correlation coefficients were 0.9136 and 0.9061 (p<0.001) for all tooth surfaces at T1 and T2, respectively. The measurements of the three investigators were in good agreement, with intraclass correlation coefficients of 0.989 and 0.992 (P<0.001) for the vestibular and lingual surfaces at T1, and 0.964 and 0.983 (P<0.001) for the vestibular and lingual surfaces at T2. Conclusion: In this study, we initially developed a digital 3D evaluation system of dental plaque suitable for research and clinical practice and demonstrated its reliability. Schlagwörter: 3D image processing, dental plaque, intraoral scanner, plaque index, quantitative evaluation

Statement of the Problem: Occlusion is associated with all disciplines of dentistry and plays a major role in the longevity of both implant and tooth borne restorations. Achieving occlusal harmony ensures balance is established between the dental and myofascial structures, which can be measurably established to high numerical tolerances with the T-Scan digital occlusal analysis system. Purpose: To describe and evaluate the known and proven applications of T-Scan digital occlusal analysis in various dental practice disciplines, with a systematic review of the literature. Materials and Methods: An electronic English language Medline/PubMed and Cochrane central library database search using key words “T-Scan”, “TMD”, “Occlusion”, “Implant Protected Occlusion”, “Orthodontics”, was conducted without any date restrictions. The related journal findings were hand searched to determine studies that met a systematic review’s inclusion. Results: The PubMed/MEDLINE identified 423 articles. After removing duplicates the titles and abstracts of the 421 studies were screened. 274 ineligible articles were excluded leaving 147 articles. Of those, 33 articles were not in English, 27 full text articles were not available, 4 were comments and Letter to the Editors, and 2 articles described techniques. 86 articles total met the eligibility criteria for inclusion. Conclusion: Much scientific evidence supports the use of T-Scan, as it measures relative occlusal contact forces and occlusal contacts time-sequence durations objectively, accurately, and repeatedly for improved treatment outcomes. It’s hardware, sensor, and software evolution from T-Scan I up to today’s T-Scan10 Novus system, has overcome early sensor and system drawbacks to improve T-Scan’s clinical performance in many disciplines of Dental Medicine. Schlagwörter: digital, occlusal Equilibrium, occlusion, Quantitative analysis, T-scan

Aim: This in vitro study aimed to evaluate the depth of reading of intraoral scanners (IOSs) inside the gingival sulcus. Materials and methods: A knife-edge preparation for a full crown was performed on a Frasaco model. The gingival sulcus of the scanned model was modified using a dedicated software (Model Creator, Exocad DentalCAD 2.4 Plovdiv) by setting the coronal (CW) and apical (AW) widths and sulcus depths (D). Two dental models with different sulcus depths (1 mm or 2 mm) were printed using the digital light processing (DLP) technique. Each model was scanned ten times with seven IOSs: Emerald, Trios3, Carestrem 3600, Dentalwings, Condor, True Definition Scanner (TDS), and Omnicam. Measurements of D values were performed using 3Shape 3D viewer software. The normality of the data distribution was evaluated using the Shapiro–Wilk test (P<.05). A nonparametric Levene test was performed to check for homoscedasticity. The data were statistically analyzed with Kruskal–Wallis test (α=.05) and Nemenyi’s test. Result: All IOSs were able to read within the 1 mm-deep gingival sulcus, albeit with some statistically significant differences (P<.001). Only Trios3 was able to read the 2 mm-deep gingival sulcus (P<.001). Conclusion: The depth of reading of different IOSs can vary significantly. In the model with a 2-mm sulcus, even in the absence of oral fluids, the depth of reading is incomplete, suggesting that deep preparations into the sulcus are difficult to detect with IOSs. Schlagwörter: Depth of reading, Digital light processing, Gingival sulcus, IOS, Knife-edge preparation

Purpose: Endodontically treated teeth are more susceptible to fractures than vital teeth because of significant coronal and radicular dentin loss during endodontic therapeutic procedures. The objective of this study was to estimate and compare the influence of length and post type on the fracture strength of endodontically treated maxillary central incisors. Material and methods: In this in vitro study, sixty extracted human maxillary central incisors were decoronated 2 mm above the cemento-enamel junction.They were selected and subjected to standard endodontic treatment ,resulting in preparation with lengths of 5 mm (group 5mm),7,5 mm (group 7,5 mm) and 10 mm (group 10mm). Each group was randomly divided into 2 subgroups according to the post type , zirconia and fiber post. After appropriate surface treatment,they were cementet with resin adhesive cement and restored with zirconia crowns. Thermocycling (5 -55°C, 60 seconds, 1500 cycles) was performed after cementing the zirconia crowns on each tooth. Prepared samples were subjected to compresive static load of 0.5mm / min, at an angle of 130° to the long axis of the roots, using Universal Testing Machine (Matest ) at an cross head speed of 0.5 mm / min, until fracture.The significance of the results was assessed using 2-way ANOVA and the Tukey-Kramer test (α=0.05) Results:The ANOVA analysis indicated significant differences (P<0.05) between the groups. Tukey test revealed no significant difference among the zirconia posts of 5-mm length (26.5 N ±13.4) 7,5-mm length (25.2 N ±13.9), and 10-mm length (17.1 N ±5.2). Also, in the fiber post group, there was no significant difference when posts of 7.5-mm length (13.4 N ±11.0) were compared with the 5-mm (6.9 N ±4.6) and 10-mm (31.7 N ±13.1) groups. The 10-mm long post displayed superior fracture strength, and the 5mm-long post showed significantly lower mean values (P<0.001). Conclusion: The fracture strength of zirconia posts (5-mm and 7,5- mm length)was found to be significantly higher than those of fiber posts (5-mm and 7,5- mm length). The 10-mm long fiberpost group demonstrated significantly higher values of fracture strengths and the 5-mm long fiberpost group showed the lowest values for the force resulting in root fracture; these groups were significantly different from each other (P<.001).The fracture strength analysis with Universal Testing Machine is the only method that enables us to estimate the differences between zirconia and fiber posts with different lengths on endodontically treated teeth. Schlagwörter: Endodontically treated teeth, fiber post, fiberpost, fracture strength, universal testing machine, zirconia post

Purpose: A reference method for quantifying contaminations on two-piece abutments manufactured using CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) has not yet been established. In this in vitro study, a pixel-based machine learning method for detecting contamination on customised two-piece abutments was investigated and embedded in a semi-automated quantification pipeline. Material and Methods: Forty-nine CAD/CAM zirconia abutments were fabricated and bonded to a prefabricated titanium base. All samples were analysed for contamination by scanning electron microscopy (SEM) imaging followed by pixel-based machine learning (ML) and thresholding (SW) for contamination detection; quantification was performed in the post-processing pipeline. Wilcoxon signed-rank test and Bland-Altmann plot were applied to compare both methods. The contaminated area fraction was recorded as a percentage. Results: There was no statistically significant difference between the percentages of contamination areas (median = 0.004) measured with ML (median = 0.008) and with SW (median = 0.012), asymptotic Wilcoxon-test: p = 0.22. The Bland-Altmann plot demonstrated a mean difference of -0,006% (95% confidence interval, CI from -0.011% to 0.0001%) with increased values from a contamination area fraction > 0.03% for ML. Conclusion: Both segmentation methods showed comparable results in evaluating surface cleanliness; pixel based machine learning is a promising assessment tool for detecting external contaminations on zirconia abutments; Further studies must investigate its clinical performance. Schlagwörter: Computer-Aided Design, Dental Implant Abutments, Hygiene, Machine Learning, Scanning Electron Microscopy, Ultrasonics

Aim: To summarize the features of condylar kinematics in patients with condylar reconstruction using a mandibular motion simulation method based on intraoral scanning registration. Materials and methods: Patients undergoing unilateral segmental mandibulectomy and autogenous bone reconstruction, as well as healthy volunteers were enrolled in the study. Patients were grouped based on whether the condyles were reconstructed. Mandibular movements were recorded using a jaw-tracking system and kinematic models were simulated after registration. The path inclination of the condyle point, margin of border movement, deviation and chewing cycle were analyzed. A t-test and one-way analysis of variation were carried out. Results: Twenty patients, including six patients with condylar reconstruction, fourteen patients with condylar preservation, and ten healthy volunteers were included. The patients with condylar reconstruction showed flatter movement paths of the condyle points. The mean inclination angle of the condylar movement paths of the patients with condylar reconstruction (0.57°  12.54°) was significantly smaller than that of the patients with condylar preservation (24.70° ± 3.90°, P= 0.014) during maximum opening, as well as protrusion (7.04°  12.21° and 31.12°  6.79°, P= 0.022). Healthy volunteers’ inclination angle of the condylar movement paths was 16.81±3.97° during maximum opening and 21.54±2.80° during protrusion, no significant difference compared to patients. The condyles of the affected-side tended to deviate laterally in all patients during mouth opening and protrusion. Patients with condylar reconstruction showed more severe symptoms of mouth opening limitation and mandibular movement deviation, and showed shorter chewing cycles than patients with condylar preservation. Conclusion: Patients with condylar reconstruction showed flatter movement paths of the condyle points, greater lateral motion range, and shorter chewing cycles than patients with condylar preservation. The method of mandibular motion stimulation based on intraoral scanning registration was feasible to simulate condylar movement. Schlagwörter: Digital technology, Electromyography, Joint range of motion, Mandibular condyle, Mandibular neoplasms, Patient-Specific modeling

Aim: The aim of this in vivo study was to compare the clinical trueness of primary mucostatic impressions obtained either by a classical alginate technique or by an optical intraoral scanner of fully maxilla edentulous patients. Materials and methods: 30 patients with fully edentulous maxilla were included and underwent conventional impressions as well as intraoral optical impressions (TRIOS 3®, 3Shape®). The conventional impressions were casted and the resulting stone models were digitized using a desktop scanner (Iscan D104i®, Imetric®). These digitized impressions were superimposed over the optical impressions to compare differences between the two datasets. Statistical analyses were performed to identify relevant deviations. Result: For the 30 intraoral impressions, 80.88% of the surface areas were below the tolerance threshold of 25 μm and thus considered similar to the area scanned with the desktop scanner from the reference stone model. Interestingly, the differences (19.12% of the surfaces) were localized in depressible areas like vestibule, soft palate, incisal papilla and flabby ridge. These locations were coherent with the positive mean of differences of +22.8μm, indicating deformation or less compression using the intraoral scanner. Conclusion: Digital primary impression of the fully edentulous maxilla can be considered as similar to the conventional alginate impression, except in the depressible areas. Considering the mucostatic objective of such a primary impression, one may consider optical impression as more accurate than the conventional one. Schlagwörter: clinical trial, conventional impression, digital impression, edentulous patients, intraoral scanner, maxilla

Aim: This study aimed to evaluate the intaglio surface trueness and fit of zirconia crowns depending on the different machining strategies used with the CEREC system. Materials and methods: Thirty duplicate tooth models for a single zirconia crown were randomly assigned to the three groups (n = 10) according to the machining mode used for fabrication: grinding, wet milling, and dry milling. The scan data of the final crowns were compared to their design data to evaluate the intaglio surface trueness. The marginal and internal fits were evaluated using the cross-sectional method. The time required for the machining and sintering processes was measured for each group. Result: The wet milling group showed better trueness (RMS, 13.8 ± 1.0 μm) than the grinding and dry milling groups (p < 0.001). The marginal gap was greater in the grinding group (58.6 ± 28.9 μm) than that in the wet milling and dry milling groups (p < 0.001). The dry milling group required the shortest time for the manufacturing process. Conclusion: All machining modes fabricated crowns with a clinically acceptable trueness and fit. However, the dry milling mode was advantageous for the chairside CAD/CAM system with respect to time efficiency. Schlagwörter: 3D printing, CEREC, comparative 3D analysis, dry milling, grinding, marginal gap

Aim: To compare the accuracy of three impression methods by comparing the distance between the reference points of the implant fixture, especially in curved maxillary anterior teeth. Materials and methods: Implant fixtures were placed on the maxillary central incisor and canine areas. A maxillary master cast was made using a model scanner and 3D printer. Ten impressions were taken from the three experimental groups constructed (group P: pick-up impression coping; group I: scan body with an intraoral scanner; and group B: bite impression coping). The distance between the reference points, the angle between the scan bodies, and displacement of the 3D surface area were measured. Results: The distance between reference points were significantly different between group I and group B in the maxillary incisors and between group P and the other two groups in the maxillary canines. Group P had the least amount of displacement in both fixtures. Both fixtures showed the highest displacement in group B. Displacement of the 3D surface area in the maxillary incisors showed no significant difference between the groups. There was a significant difference in the maxillary canines between groups P and I. Conclusions: All three implant impression methods showed changes in the position and angle of the fixture compared with the master cast. In this study, the impression method using the pick-up impression coping showed the highest accuracy, but the impression method using the intraoral scanner also showed clinically acceptable accuracy. It should be noted that errors may occur when taking impressions using bite coping. Schlagwörter: bite impression coping, implant angulation, implant impression, intraoral scanner, scan body

Aim: The accuracy and reproducibility of occlusal contact points visualized by articulation foil (AF) should be investigated and then compared with contact points calculated by three different intraoral scanners (IOS). Materials and Methods: Occlusal contact points were visualized on a standardized resin dental tooth model using AF 50 times with maximum intercuspidation and constant biting force. The points were photographed from a vertical position above the model and superimposed on a screen in order to test the reproducibility of the model. This was followed by fifty-fold repetition by scans and computation of the occlusal contact points by the respective IOS CS3600 (CS ScanFlow v.1 4th version), TRIOS 3 (Basic 2019), and CEREC Omnicam (Software version 5.1). The results of computation were captured with screenshots, and were then overlaid with the photographs of the AF. The image overlays were classified into five categories: category 1 = total overlapping of contact points, category 2 = partly overlapping, category 3 = adjacent contact points without overlapping, category 4 = contact points identified only by IOS, category 5 = contact points identified only by AF. All data were statistically evaluated (95% CI). Results: In total, the visualisation of the occlusal contact points by the IOS were significantly less accurate and less reproducible compared to the AF (p < 0.05). In the combination of sensitivity and accuracy, the TRIOS3 by 3Shape showed significantly better results than the other IOS tested (p < 0.05). Conclusion: In vitro, AF displayed a significantly more accurate visualisation of the occlusal contact points than IOS. Schlagwörter: articulating foil, digital intraoral scanners, occlusion, occlusal contact point, reproducibility, visualisation