Temperature variations’ effects on the accuracy of an intraoral scanner
Joós-Kovács Gellért Levente PhD, Vitai Viktória, Hermann Péter Miklós PhD, Borbély Judit PhD
Purpose: To evaluate the CEREC Primescan’s accuracy at both the lowest and highest operating temperatures.
Methods: A printed PMMA maxillary model was used as reference. To capture the surface temperature, a thermal camera FLIR TG267 (FLIR Systems, Wilsonville, Oregon, USA) was used. A CEREC Primescan (Dentsply Sirona, Charlotte, North Carolina, USA) maintained at 21°C was used to create 15 digital impressions. 15 digital impressions were also taken at the highest working temperature. Differences were registered with full-arch superimpositions. The data were analyzed with the statistical program SPSS. Non-parametric tests were performed to assess how true the two groups were, as well as how different they were from one another. The precision of the two temperatures’ data was described using descriptive statistics. The difference between the two groups was determined by comparing the difference between the two variabilities.
Results: The scanner’s temperature ranges from 22±1 °C to 41.5±0.5 °C. There were no significant differences from the reference to the minimum (0,23mm) or maximum (0,12mm) temperatures. Significant difference was shown between the two temperature data. The lowest temperature data distortion surpasses, but the maximum temperature distortions are within the clinically acceptable range. Comparable levels of precision were observed at the two temperatures. Analysis of the variability of the two groups revealed no differences.
Conclusion: The manufacturer’s instructions indicate that the scanner operates reliably when used properly. The observed low temperature may have a minor impact on the scanner’s accuracy. At high temperatures, work performance may be noticeably impacted.
Comparison of Additive and Subtractive Manufacturing for Fixed Dental Restorations – Systematic Review and Meta-Analysis
Anna Németh1,2, Brigitta Teutsch2, Bence Szabó2, Judit Borbély1,2
1Department of Prosthodontics, Semmelweis University, Budapest, Hungary
2Centre for Translational Medicine, Semmelweis University, Budapest, Hungary
Objects of Investigation: Numerous studies have been conducted about the accuracy of fixed dental restorations manufactured by additive (AM) and subtractive (SM) technologies, however, the results are conflicting. The aim of this systematic review and meta-analysis was to evaluate the internal and marginal fit of fixed dental restorations made by AM in comparison with SM.
Methods Used: Studies investigating internal and marginal fit of fixed dental restoriations (crown, bridge, veneer, inlay/onlay), which were manufactured by additive and subtractive techniques, were involved. The study was registered in PROSPERO (CRD42022323090). An electronic search was performed across four databases: in May 2022, and it was restricted to English language.A systematic search was conducted based on a pre-specified search query. After duplicate removal 2515 articles were pooled. Study selection and data extraction was performed individually by two investigators, and a third independent reviewer resolved disagreements. After study selection and data extraction, 38 eligible studies were included and subgrouped by material type (metal, ceramic, interim). The outcomes were specified as internal fit and marginal fit expressed in mean difference (µm). QUIN tool and GRADE tool were used to evaluate the risk of bias and certainty of the evidence.
Results: Fabricating interim crowns, SM showed significantly higher mean difference with 25.95 µm in internal fit and 4.45 µm in marginal fit compared to AM. In the metal group, AM provided higher mean difference in internal fit with 5.69 µm, however in marginal fit SM showed higher mean difference with 7.04 µm. In case of ceramics, AM showed higher mean difference in marginal fit with 18.91 µm compared to SM with no statistically significant difference.
Conclusion: The findings of the systematic review and meta-analysis suggest that fixed restorations manufactured with AM are favourable alternatives in the digital workflow compared to SM.
Keywords: digital dentistry, CAD/CAM, 3d printing, additive manufacturing, subtractive manufacturing, fixed restoration
Trueness of 3Shape Trios 5 on full arch implant impressions
Judit Schmalzl1, Ivett Róth1, Judit Borbély1, Bálint Vecsei1
1Department of Prosthodontics, Semmelweis University, Budapest Hungary
Purpose: The aim of this present study is to determine the trueness of Trios 5 for implant restorations in cases of multiple implant positions on full arch.
Methods Used: A fully edentulous maxillary model, with implant analogs in 16, 14, 11, 21, 24, 26 positions, was used in this study (NC/RC Repositionable Implant Analog, Straumann). The PMMA models were digitized by the 3Shape E3 laboratory scanner (7 μm). For trueness comparison, 10 digital impressions were taken with the 3Shape Trios 5 intraoral scanner using Cares® NC Mono Scanbodies (Straumann). The STL files were imported into the Geomagic Control X program for the trueness measurement. The measured parameters were the following: average deviation of the scan bodies (as a group and separately) and distance measurements between the scan bodies (16-14 distance; 16-24 distance and 24-26 distance).
Results: In the case of average deviation the measured data were the following: scan bodies as a group – 155.7 µm; 16 – 42.2 µm; 14 – 33.2 µm; 11 – 133.3 µm; 21 – 158.3 µm; 24 – 175.0 µm; 26 – 280.7 µm. In the case of the distance measurements, we found the following: 16-14 distance – 39.6 µm; 16-24 distance – 140.0 µm and 24-26 distance – 47.4 µm.
Conclusion: Within the limitations of this current study, we can conclude that the trueness of the Trios 5, in the case of short-span ridges, is satisfactory, but in the case of full arch implant impressions, it is inadequate.
Keywords: accuracy, implant impression, full arch, Trios 5
Complex rehabilitation of erosive tooth wear with digital workflows
Péter Tajti1, Gábor Gerber1, Péter Hermann1, Péter Schmidt1
1Department of Prosthodontics, Semmelweis University
Introduction: Erosive tooth wear, caused by a combination of exogenous and endogenous factors, affects both the appearance and function of the entire dentition. Early diagnosis and treatment are crucial as the condition affects 30-45% of the population and can result in the destruction of teeth, necessitating complex prosthetic rehabilitation.
Case report: The 39-year-old patient visited Semmelweis University’s Prosthodontics Department to address substantial tooth wear causing notable psychosocial decline. The pre-prosthetic plan involved patient education, motivation, professional oral hygiene, and initial Michigan splint therapy, adapting the neuromuscular system to the increased occlusal vertical dimension. A chairside Michigan splint was fabricated using self-curing acrylic resin. After three months, definitive restoration began with a gothic-arch device determining jawbone relationships. A digital face bow established upper jaw relationships and individual angle values. Intraoral scanning captured both jawbones, aiding a digital smile design for a digital wax-up. The satisfactory mock-up of self-curing acrylic allowed tooth preparation. Subsequent digital impressions were taken after teeth preparation. A newly created mock-up that fits the prepared teeth held the bite height while the jaw relation was scanned. To ensure that the final restoration was an exact copy of the accepted mock-up, the “copy-paste dentistry” concept was used. Polymethyl methacrylate long-term temporary restorations were worn for a month, followed by zirconia restoration milling and luting with self-adhesive resin cement.
Summary: Rising erosive tooth wear affects function, aesthetics, and psychosocial well-being, prompting consideration of gnathological aspects during complex prosthetic rehabilitation, wherein digital technologies enhance predictability and satisfaction.
Comparison between intraoral scanner and spectrophotometer shade matching: A systematic review and meta-analysis
Viktória Vitai1,2, Brigitta Teutsch1,3, Anna Németh1, Judit Borbély1,2
1Centre for Translational Medicine, Semmelweis University, Budapest, Hungary
2Department of Prosthodontics, Semmelweis University, Budapest, Hungary
3Institute for Translational Medicine, Medical School, University of Pécs, Pécs, Hungary
Purpose: This systematic review (SR) and meta-analysis (MA) aimed to compare the accuracy of shade selection of intraoral scanners (IOSs) to spectrophotometers (SPs) as reference standards.
Methods: Studies comparing the trueness (percentage of the correct match and ΔE) and precision (repeatability, percentage of the same match) of IOS and SP determination were included in this study. An electronic search of five databases was conducted in May 2022. A total of 112 studies were identified from the databases, of which 22 articles were eligible for inclusion. After study selection and data extraction, MA was performed to define the accuracy of IOS in subgroups using four outcomes: the percentage of the correct match in Vita Classical shade guide system (VC), the percentage of the correct match in 3D master shade guide system (3D), the percentage of the correct match in VC, and the percentage of the same match in 3D. Cochrane guidelines, Joanna Briggs Institute (JBI) Checklist, and GARDE were used for the risk of bias and certainty assessment.
Results: From the 22 articles, 10 articles were included for the MA. The percentage of the correct shade matching with IOS was 20% [Confidence Interval (CI): 0.05-0.52] with VC and 23% (CI: 0.06-0.59) with 3D shade guide systems. The repeatability of shade matching by IOSs was between 81% (CI: 0.64-0.91) with VC and 81% (CI: 0.65-0.91) with 3D master shade guide systems.
Conclusions: The trueness of shade matching with IOS is low compared to SPs, although the precision is considered high. Shade determination with IOS only is not recommended.
Keywords: digital dentistry, tooth color, shade determination tool, accuracy, repeatability
The compensatory effect of cement spacing on intraoral scanner inaccuracy
Daniel Borbola1, Janos Vag1
1Semmelweis University, Budapest, Hungary e-mail: email@example.com
Objects of Investigation: During computer-aided design, a space is created between the inner surface of the prosthesis and the prepared tooth. The cement space has three distinct functions: to accommodate cement, to compensate for scanner inaccuracies, and to compensate for fabric inaccuracies. This study investigated the effect of cement space on intraoral scanner (IOS) inaccuracy compensation.
Methods used: 24 complete-arch scans were taken on models with dental abutments using an industrial scanner and two IOSs. Complete-arch frameworks were designed using Exocad with two cement gap settings for each IOS scan. In group A, a 70μm gap was set in the internal surface, excluding the marginal area. In group B, a 90μm gap was set in the internal surface with 20μm in the marginal area. The designs were digitally superimposed on the reference scan to measure the marginal and internal gaps by a non- interwoven closest-point algorithm for simulating the seating of a physical restoration. The internal error was calculated by subtracting the set space from the measured gap. The mean gaps were compared by the Wilcoxon test. An arbitrary threshold of 120μm was used to identify suboptimal scans.
Results: In group A, the gaps ranged from 53 to 393μm in the margin and from 27 to 184μm in the internal surface. In group B, the gaps ranged from 24 to 105μm in the margin and from 52 to 162μm in the internal surface. There were six outliers in group A and three in group B. The marginal gap was significantly(p<0.05) lower in group B (104 μm) than in group A (85μm). The internal error was not significantly different between the two groups (57 vs. 50μm).
Conclusions: A slight increase in cement spacing could effectively compensate for the suboptimal scan in complete-arch prosthesis.
Advancing Computer Aided Implant Surgery: Dynamic Navigation and Precision Assessment
Gabor Tamas Pinter1, Roland Decker1, Tamas Huszar1, Zsolt Nemeth1, Sandor Bogdan1
1Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Budapest, Hungary
Introduction: The first step in the development of digital implantology was the use of static, template-based implantation. This was followed by dynamic navigation, which allows real-time control of the surgery.
Objectives: To assess the accuracy of surgery performed with a dynamic navigation implantation system and to compare its calibration methods in terms of accuracy.
Methods: 44 implants were placed in 14 patients by 1 surgeon. Based on pre-operative CBCT, a planning software was used to determine the position of the implants, implant placement was performed under real-time control of dynamic navigation. A postoperative CBCT scan was performed after surgery. Measurements were taken based on the difference of planned implant position on virtual images and control CBCT images made after surgery. were superimposed. Parameters tested: angular deviation; platform deviation, apical deviation. Calibration was performed with tracer technic in 3 cases and with clip technic in 11 cases.
Conclusions: Dynamic navigation system makes high precision implant placement possible. Tracer calibration method does not require marked CBCT scan, and it has a similar accuracy as the one based on clip calibration. The accuracy of implant placement by dynamic navigation can be improved by trenching.
Key words: digital implantology, dynamic navigation, calibration methods, implant placement, calibration
Computer Aided Diagnostics and Local Drug Treatment (Case Reports)
Gabor Tamas Pinter1, Zoltan Fabian2, Peter Hermann3, Tamas Huszar1, Zsolt Nemeth1 Sandor Bogdan1
1Department of Oro-Maxillofacial Surgery and Stomatology, Semmelweis University, Budapest, Hungary
2Head and Neck Surgery Department, Dr. Kristof Fogolyan County Emergency Hospital, Sfântu Gheorghe, Romania
3Department of Prosthodontics, Semmelweis University, Budapest, Hungary
The surgical use of navigation procedures is widely spread, which can be static or dynamic interventions. Little is known about the use of navigation procedures in diagnostic and locoregional drug therapy.
Objective: Demonstrate the methods used during computer aided surgery (CAS) that can be applied for diagnostic and therapeutic purposes based on two clinical cases.
1: 34-year-old female patient who had received radio-chemotherapy for adenoid cystic carcinoma of soft palate 12 years previously. MRI showed a slowly growing terime next to the foramen rotundum close to the pterygopalatine fossa, suggesting the presence of tumor recidiva. CT based surgical template with dental support was prepared using stereolithographic technique to successfully perform biopsy from a difficult to reach anatomical region. Template guided aspiration cytology was performed from the lesion described by MRI, which was positive (adenocystic carcinoma). Based on the result surgical excision was performed.
2: 15-year-old male patient with a history of swelling and pain on the right side of the nasal cavity, detected one year earlier. CT scans showed a cyst-like lesion extending into the sinus and partially into the lower frontal part of the nasal cavity, and extending from the vestibule of the frontal region to the level of the right molar in the mouth, with a fluid-filled cyst that also involved the palate. Histologic examination confirmed a central giant cell granuloma. Reduction of the right benign maxillary tumor was performed. Based on the results of histopathological examination, local steroid therapy was applied. A CT based stereolithographic surgical template with dental support was used for precise targeting. 40mg Kenalog (Triamcinolone acetonide) infiltration was performed under local anesthesia using the template for one year postoperatively, with monthly recurrence.
Conclusions: The digital methods used in navigated surgical procedures can also be used to design and implement diagnostic and drug treatment procedures.
Key words: CAS, surgical template, histological examination, adenoid cystic carcinoma, giant central cell granuloma, steroid therapy, radiological guidance.
Development of Subperiosteal Implants Using In Silico Simulations
Dániel Petrovszki1, Zsolt Pásztor1, Lajos Bozsányi1, János Kónya1
1PREMET, Budapest, Hungary
Objects of Investigation: Purpose of the research was to develop a design and implantation guidence for subperiosteal implants using in silico simulations.
Methods Used: In the design of a subperiosteal implant multiple aspects has to be taken into consideration. First the size and thickness of the implant should preferably be small, and be fixed with a limited number of screws to the bone to minimise the seriousness of the surgery. Second the implant should be „robust”, strong and fixed in a stable way to the bone in order to avoid its fracture or deformation, as well as loosening or falling out of the screw. In order to identify key design and implantation considerations a series of subperiosteal implant designs were prepared and investigated using in silico simulations. During the research impact of size, shape and thickness of the implant, size, number of screws, as well as position of fixation were investigated.
Results: Results of simulations included stresses and deformations of the implant, the bone and the denture, as well as the generated forces on the screws. Numerical results – that can not be be obtained by in vitro and in vivo experiments – allows to better investigate and understand the impact of different design characteristics and to determine implant design rules. Results of simulations can also serve as a guidance for the dentist making the surgery.
Conclusions: In silico simulation can successfully be used in the development and design of subperiosteal implants, as well as for the planning of surgeries.