DOI: 10.3290/j.ijcd.b2599841, PubMed-ID: 3507242724.01.2022, Sprache: Englisch
Aims: To evaluate the accuracy of tridimensional (3D) printed guide assisted flapless cortical bone micro-osteoperforations in the anterior mandible on a cadaver model.
Materials and Methods: Five human cadaver heads with complete dentition in the anterior mandible were used in this study. Pre-planning cone beam computed tomography (CBCT) and intraoral surface scans were obtained. After alignment, drilling sites in the interradicular areas were planned from canine to canine, and a surgical guide was printed. The drilling was performed and a post-procedure CBCT scan was obtained in order to assess the accuracy of the procedure in relation to the virtual planning.
Results: The mean±SD mesiodistal interradicular space was 2.67±0.84 mm. The mean±SD error of the actual drilled hole in comparison to the planned position of the mesial drill site was 0.66±0.33 mm and to the distal drill site 0.56±0.33 mm. There was a statistically significant difference between the number of times the teeth were hit mesially (10 out of 64 holes) and distally (none).
Conclusions: The technique proposed in the current study, limited to ex vivo scenario, provides a valid and reliable method for mandibular micro-osteoperforations using a 3D generated surgical guide. However, risk of damaging adjacent radicular surfaces, particularly in areas with limited mesiodistal interradicular bone needs to be considered. Further studies should focus on using thinner drills, adding other methods to stabilize the guide. Additionally, by and selecting individuals and perforation sites with more mesiodistal interradicular bone less damage is likely.
Schlagwörter: 3D printing, Accuracy, Corticotomy, Guided surgery, Microosteoperforations, Pre-orthodontic surgery
DOI: 10.3290/j.ijcd.b2599791, PubMed-ID: 3507241624.01.2022, Sprache: Englisch
Aim: We conducted a prospective study to evaluate the accuracy and complications of 3D-printed patient-specific surgical guides and plates that were designed and finished in-house.
Materials and Methods: Eighteen patients who required advancement genioplasty, with or without concomitant orthognathic surgery, were enrolled in the study. Virtual surgical movements were simulated using the patients’ cone-beam computed tomography (CBCT) scans, and computer-aided designing of patient-specific surgical guides and fixation plates were performed in our department. CBCT scans were taken at 1 month postoperatively, stereolithographic models of the preoperative virtual plan and the postoperative CBCT were registered. Part comparisons were done to assess the accuracy of the movements. The median, minimum and maximum differences were measured. Two landmarks, the Menton and Pogonion, were also used to compare the differences locally.
Results: The median deviations for the 18 cases was 0.19mm. The median deviation at the Menton and Pogonion were 0.67mm and 0.41mm respectively. There was no significant correlation between the surgical movement of less than 7mm advancement and the transfer accuracy (p = 0.77). No adverse events or complications were reported within post-operative 6 months.
Conclusions: Our protocol of self-designed 3D-printed patient-specific surgical guides and plates provided an accurate method to transfer the virtual surgical plan to the operating theatre.
Schlagwörter: 3D printing, chin, computer planning, genioplasty, patient specific implants, patient specific plates
DOI: 10.3290/j.ijcd.b2599775, PubMed-ID: 3507241724.01.2022, Sprache: Englisch
Aim: To present an image-processing measurement algorithm to evaluate the transfer accuracy of indirect bonding (IDB) trays, exemplified by a CAD/CAD-based IDB tray integrated into a digital orthodontic workflow.
Materials and Methods: Plaster models of 24 patients with full dentition and different malocclusions were scanned with an intraoral scanner (TRIOS®, 3Shape, Copenhagen, Denmark) to receive digital models, which served for the virtual placement of orthodontic brackets in a simulation software (OnyxCeph³™, Image Instruments, Chemnitz, Germany).
The resulting STL-files were sent to CA Digital for production of INDIVIDUA® IDB trays (CA Digital, Hilden, Germany). Upon receipt, the brackets were transferred to the respective plaster models using these trays. Finally, a second scan was performed to record the actual bracket position. The transfer accuracy was then analysed by a measurement algorithm scripted to automation, which calculated the deviations of the planned and the real bracket positions with a local best-fit alignment resulting in three linear and three angular measurements for each bracket.
Results: In total, 622 brackets and tubes were transferred successfully. The presented algorithm analysed the transfer accuracy and demonstrated that the linear measurements were in 98.3% within the range of the American Board of Orthodontics standard. The angular measurements were in 86.7% within this range when using the INDIVIDUA® IDB tray.
Conclusion: Scripted measurement algorithms facilitate the evaluation of present and future materials and designs for IDB trays to find an efficient solution for the orthodontic practice. The INDIVIDUA® IDB tray is a digital alternative to conventional indirect bonding trays.
Schlagwörter: 3D automation, 3D superimposition, Best-fit alignment, Digital orthodontics, Digital workflow, Indirect bonding tray, Intraoral scan, Measurement algorithm , Transfer accuracy
DOI: 10.3290/j.ijcd.b2599749, PubMed-ID: 3507241824.01.2022, Sprache: Englisch
Aim: The aim of this prospective study is to evaluate the accuracy of 3-dimensional (3D) orthognathic surgical planning and CAD/CAM splints by comparing planned versus actual postoperative outcomes. Methods: Ten patients scheduled for bimaxillary orthognathic surgery to correct a Skeletal III dentofacial deformity were recruited for this prospective "proof of concept" study. All subjects had cone beam computed tomography (CBCT) taken not more than 2 months preoperatively and within the 1-week postoperative period. The distance between 6 dental landmarks (midpoint of maxillary and mandibular incisors, mesio-buccal cusps of the first maxillary and mandibular molars) and 3 intersecting symmetry planes [Frankfurt horizontal plane (FHP), mid-sagittal plane (MSP) and coronal plane (CP)] were measured and the differences between the virtually simulated and actual post-operative models were computed. The threshold for accuracy was set at 2mm.
Results: Differences between planned and actual outcomes were analyzed via Chi-square tests and two-tailed paired student t-tests. The overall mean linear difference for all 6 landmarks was 0.98mm. The overall mean linear differences for both maxillary and mandibular landmarks relative to FHP, MSP and CP were 1.3mm, 0.7mm and 0.9mm respectively. Four cases had all linear differences of the 6 landmarks <2.0mm while the other 6 cases had at least 1 linear difference >2.0mm, the majority of which were in the superior-inferior direction. There were statistically significantly greater inaccuracies in the FHP as compared to MSP and CP (p<0.05).
Conclusion: Most of the linear differences between the simulated and actual outcomes were clinically acceptable. However, greater linear differences were seen in the superior-inferior direction, indicating a greater surgical error in achieving the desired vertical position of the maxilla-mandibular complex.
Schlagwörter: CAD/CAM, Digital dentistry, Orthognathic surgery, Virtual planning
DOI: 10.3290/j.ijcd.b2599735, PubMed-ID: 3507241924.01.2022, Sprache: Englisch
Aim: The purpose of the present study was to report early surgical template-related and postoperative complications, as well as to evaluate the accuracy of computer-guided implant placement.
Materials and methods: Data were collected retrospectively from records of patients who had undergone computer-guided implant surgery between 2016 and 2018. Incidence of early surgical template-related and postoperative complications was recorded. Accuracy of implant placement was evaluated by comparing the data from postoperative CBCT records with the data from the preoperative virtual implant planning by using appropriate image registration software. Depth, coronal, apical and depth deviations were measured.
Results: Twenty-seven partially edentulous patients who received 52 implants with 31 static surgical templates were finally included in the study. All implants had been inserted fully-guided by using flapless technique and following one-stage approach. All implants had been successfully osseointegrated. Except of one template fracture, no other complication had been recorded. The mean angulation deviation was 2.74 ± 1.8 degrees (95% CI 2.29-3.26 degrees), the mean coronal deviation was 0.89 ± 0.7 mm (95% CI 0.73-1.07 mm), the mean apical deviation was 1.4 ± 1 mm (95% CI 1.16-1.71 mm) and the mean depth deviation was 0.57 ± 0.4 mm (95% CI 0.48-0.71 mm).
Conclusion: The use of static surgical templates for fully guided implant placement demonstrated acceptable clinical performance. However, there are some factors affecting accuracy, which should be considered during implant planning and surgery for further improvement of the technique.
Schlagwörter: dental implant, guided surgery, accuracy, implant studio, 3Shape, MGuide, 3D printing
DOI: 10.3290/j.ijcd.b2599709, PubMed-ID: 3507242024.01.2022, Sprache: Englisch
Purpose: This study aimed to evaluate the stress distribution patterns, resistance to fracture, and failure modes of endodontically treated molars restored with different cuspal coverage options.
Materials and methods: Three-dimensional models of mandibular first molars with six kinds of typical cuspal coverage were generated: T1, mesiobuccal cuspal coverage; T2, coverage of all buccal cusps; T3, mesiolingual cuspal coverage; T4, coverage of all lingual cusps; T5, mesiobuccal and mesiolingual cuspal coverage; and T6, coverage of all cusps. All restorations were fabricated with zirconia-reinforced lithium silicate ceramic. The stress and its distributions under axial and oblique loading were analysed by finite element analysis (FEA). Sixty human mandibular molar samples were randomly allocated into 6 groups (n = 10) to simulate the application of six types of restorations with different cuspal coverage as in the FEA analysis and then subjected to a compressive test. All fractured specimens were subjected to fractography. Data were analysed by one-way ANOVA, Tukey’s post hoc test, and Fisher’s exact test (α = 0.05).
Results: The T2 and T6 groups presented superior stress distribution patterns under both axial and oblique loading compared to the other models. The fracture loads in the T2 (1627 ±358 N) and T6 (1639 ±355 N) groups were significantly higher than those in the other groups (P < 0.05). The T2 and T6 groups exhibited more restorable failure modes. Fractography showed more cracks below the cement-enamel junction in the T3, T4, and T5 groups.
Conclusions: Onlay restoration with whole functional cuspal coverage provided comparable effects to coverage of all cusps in endodontically treated molars, and both methods exhibited a more even stress distribution and fracture resistance and better mechanical performance in high occlusal areas than other types of cuspal coverage.
Schlagwörter: endodontically treated teeth, CAD/CAM, cuspal coverage, endocrown, FEA, onlay
DOI: 10.3290/j.ijcd.b2599691, PubMed-ID: 3507242124.01.2022, Sprache: Englisch
Aim: This study aimed to determine the impact of different degrees of salivary contamination and variations in occlusal force during intraoral scanning of inlay and onlay cavities on the accuracy of fine structure reconstruction and occlusal records.
Material and Methods: Digital data of inlay/onlay models, collected using an intraoral scanner, were divided into 40 groups according to the restoration type (onlay or inlay), salivary contamination level (none, completely dry; mild, moist but not visually apparent; moderate, half-filled cavity; severe, filled-up cavity), and simulated occlusal force (0, 2, 4, 6, or 8 kg). The acquired 120 datasets were used to measure the average interocclusal space and cavity buccolingual internal angle.
Results: Salivary contamination and occlusal force affected the occlusal contact (p < 0.001), but the restoration type did not (p > 0.05). We found an interaction between inlay type (p < 0.001), but not occlusal force (p > 0.05) and salivary contamination. Salivary contamination also affected the fine structure accuracy (p < 0.001), but the restoration type did not (p > 0.05), and no interaction between the two factors was found (p > 0.05). The difference in the measured internal angle increased with the increase in salivary contamination.
Conclusions: Intraoral optical scanning of inlay/onlay preparations was reliable for recording occlusal contact but showed uncertainty in cavity fine structure reconstruction when moderate or severe salivary contamination was present in the cavity. 21 Nevertheless, a moist cavity surface with no visually apparent salivary contamination is acceptable.
Schlagwörter: CAD/CAM, digital impression, internal angle measure, intraoral optical scanning, occlusal contact, occlusal force simulation, salivary contamination, three-dimensional reconstruction
DOI: 10.3290/j.ijcd.b2599661, PubMed-ID: 3507242224.01.2022, Sprache: Englisch
Objective: To assess the clinical status of monolithic zirconia CAD/CAM endocrown and crowns on post and core build-ups of endodontically treated molars after 5 years of clinical service.
Material and Methods: 670 patients who received restoration for excessive defects in Ansteel Group Hospital from 2012 to 2015 were selected and divided randomly into 2 groups: 334 patients in the endocrown group and 336 cases in crown with post and core group. All the treatment accepted digital CAD/CAM system. The restoration of the prosthesis at 1 year, 3years and 5years after treatment was evaluated by the USPHS (United States Public Health Service) criteria and satisfaction questionnaire. Besides, the cost time of tooth preparation was recorded by the dentists.
Results: Most of the patients in both groups reported a grade ‘A’ after treatment. Compared with the crown with post and core, the gingival health, food impact, marginal accuracy and general satisfaction of 3 years and 5 years after treatment in endocrown group had higher rated (P < 0.05). There was no statistical difference in other indicators between 2 groups at all observational time points after treatment (P > 0.05). The cost time of tooth preparation of crown with post and core was significantly higher than that of the endocrown group.
Conclusion: The CAD/CAM scanning system combined with monolithic zirconia has remarkable effects on dental restoration. Endocrown is a significant superior choice in clinical application compared with the crown with post and core.
Schlagwörter: monolithic zirconia endocrowns, crowns on post and core build-up, CAD/CAM fabrication
DOI: 10.3290/j.ijcd.b2599445, PubMed-ID: 3507242324.01.2022, Sprache: Englisch
Aim: The aim of this study was to present the different stages of prosthetic treatment planning involved in the design of an esthetic smile and improving masticatory function using CAD/CAM technology.
Materials and methods: The patient underwent the following tests and procedures: CBCT cone beam computed tomography (CS9300, Carestream, USA), intraoral scans and occlusal detection (CS3600, Carestream, USA), a portrait session (Nikon D610, Tokyo, Japan), a face scan (Bellus 3D FaceApp, iPhone XS, Apple ) and registration of individual TMJ angles and mandibular movements with a Zebris for Ceramill device (Amman Girrbach, Germany). All the data were transferred to a Ceramill Mind software (Amman Girrbach, Germany) where they were integrated. The face scan and photos were superimposed on the CBCT. Scans of the dental arches were combined with the CBCT. On this CBCT basis, position of the condyles in the articular fossae was determined.. A Virtual Artex CR articulator (Amann Girrbach, Germany) was attached to the 3D object. Individual TMJ angles and mandibular movements were then introduced.
Result: A virtual patient was created in the Ceramil Mind software. The optimal shape and position of each tooth were designed into the programme The wax-up was printed using a 3D printer and a temporary mock-up and final restoration were made for the patient. In te same time, the aesthetics of the smile was improved and a harmonious central occlusion and articulation were obtained on virtual models and in in the patient's oral cavity.
Conclusion: The presented digital planning protocol allows to work out an optimal solution in complicated patient cases from a functional and aesthetic point of view.
Schlagwörter: CAD/CAM, CBCT, computerized dentistry, digital dentistry, digital occlusion and articulation, esthetic digital planning, Zebris for Ceramill
DOI: 10.3290/j.ijcd.b2599407, PubMed-ID: 3507242424.01.2022, Sprache: Englisch
Purpose: Creating wax-ups of missing teeth for backward-planning in implant surgery is a complex and time-consuming process. To facilitate implant-planning procedures, the automatic generation of a virtual wax-up would be useful. In this study, the reconstruction of missing teeth in partially edentulous patients was performed automatically using a newly developed software. The accuracy was investigated in order to test its clinical applicability.
Material and Methods: This study presents a new method for creating an automatic virtual wax-up, which could serve as a basic tool in modern implant planning procedures. First, a statistical shape model (SSM) based on 76 lower and upper arch scans from dentally healthy individuals was generated. Then artificially generated tooth gaps were reconstructed. The accuracy of the workflow was calculated using a Leave-One Out cross validation (LOOCV) and was given as median deviation (mm). Scans of three clinical cases with partial edentulism were equally reconstructed using the SSM and compared to the final prosthodontic work.
Results: The reconstruction of the artificial tooth gaps could be performed with the following median reconstruction accuracy: gap 21 with 0.15mm; gap 27 with 0.20mm; gap 34 with 0.22mm: gap 36 with 0.22mm; gap 12-22 with 0.22mm; gap 34-36 with 0.22mm. A scenario for a close to edentulous lower jaw with all teeth missing except teeth 33 and 43 could be reconstructed with a median reconstruction accuracy of 0.37mm. The median tooth gap deviation of the SSM-based reconstruction in clinical cases differed from the final inserted prosthodontic teeth by 0.49mm-0.86mm in median.
Conclusion: A first feasibility of creating virtual wax-26 ups using a SSM could be shown. Artificially generated tooth gaps could be reconstructed close to original with the proposed workflow. In the clinical cases the SSM proposes an anatomical reconstruction, which does not yet consider prosthodontic aspects. To obtain clinical use contact to antagonist teeth must be considered and more training data must be implemented. However, the presented method offers a fast and viable way for the approximate placement of missing crowns. This could be used in a digital planning workflow when implant position must be determined.
DOI: 10.3290/j.ijcd.b2599297, PubMed-ID: 3507242524.01.2022, Sprache: Englisch
Aim: to evaluate the trueness of seven different intra-oral scanners (IOSs) in making a completearch digital scan with and without splinting the scan bodies.
Material and methods: A polyurethane model of an edentulous mandible with 4 dental implant analogues was prepared. Reference scan was made using a laboratory scanner. The reference model was scanned with each of the seven investigated IOSs (control groups, n=10 per scanner) and scanned again after splinting the scan bodies (study groups, n=10 per scanner). Each scan was exported as standard tessellation language (STL) file and transferred to a comprehensive metrology program (Geomagic Control X). In order to measure the trueness, four points (A, B, C and D) were determined on the scan bodies and the distance between point A and other points (DAB, DAC, DAD) was measured. The measurements were tested for normality using Kolmogrov- Smirnov test and probability plots. Trueness was compared using Three-way ANOVA and pairwise comparisons were performed using post-hoc Tukey and paired sample T-test. Statistical analyses were two sided, and the significance level was set at 5%.
Results: Splinting the scan bodies improved the trueness of the digital scans while increasing the inter-implant distance decreased the trueness values. Significant association was found between the trueness values and all three tested variables including splinting the scan bodies, type of IOS, and inter-implant distance (P<0.001).
Conclusion: Based on the present findings, splinting the scan bodies can improve the trueness of digital complete arch implant scans due to the improvement in morphological landmarks do the stitching process regardless of the type of the IOS or the inter-implant distance.
Schlagwörter: Dental Implant, Digital Scan, Intraoral Scanner, Scan Body, Splinting, Trueness
DOI: 10.3290/j.ijcd.b2599279, PubMed-ID: 3507242624.01.2022, Sprache: Englisch
Aim: The aim of this ex vivo study was to examine the accuracy of apicoectomies performed by means of augmented reality-assisted (AR-A) versus template-guided apicoectomies (TG-A).
Material and Methods: In total, 40 apicoectomies were performed in 10 cadaver pig mandibles. Every pig mandible underwent two template-guided apicoectomies (TG-A) and two AR-assisted apicoectomies (AR-A) in molar and premolar teeth. A crossed experimental design was applied. AR-A was performed using the Microsoft Hololens 2. TG-A was performed using the SMOP software. Postoperative cone beam CT scans were superimposed with the presurgical planning data. The deviation between the virtually planned apicoectomy and the surgically performed apicoectomy was measured. The angular deviation (primary outcome; [degree]) and the depth deviation (secondary outcome; [mm]) was measured.
Results: Overall 36 out of 40 apicoectomies could be included in the study. Regarding the primary outcome parameter, angle deviation, there was no significant difference between AR-A and TG-A. The mean values were 5.33° (± 2.96°) in the AR-assisted group and 5.23° (± 2.48°) in the template-guided group. The secondary outcome parameter depth deviation showed no significant difference between the AR-assisted group of 0.27mm (± 2.32mm) and the template-guided group of 0.90mm (± 1.84mm). In this crossed experimental design, both techniques showed to overshoot the target depth in posterior sites versus not reaching target depth in anterior sites (p<0.001).
Conclusion: AR technology has the potential to be introduced 27 into apicoectomy surgery, in case further development is implemented.
Schlagwörter: augmented reality, augmented reality in dentistry, augmented reality in oral surgery, AR-assisted apicoectomy, template-guided apicoectomy, ex vivo study
DOI: 10.3290/j.ijcd.b2588207, PubMed-ID: 3506037421.01.2022, Sprache: Englisch
Aim: To evaluate the accuracy of dynamic navigation-guided surgery (DNGS) for implant positioning performed by a novice operator. Secondary objectives were to analyze the operator’s learning curve and to identify possible complications deriving from the technique.
Material & Methods: Twenty-five implants were placed in eight partially edentulous human heads. Preoperative cone beam computed tomography (CBCT) scans were imported to planning software to determine the implant positions. Implants were placed using a dynamic navigation system. Postoperative CBCTs were superimposed onto the implant planning images. Discrepancies between virtual planned implant positions and post-surgical positions were evaluated by measuring horizontal platform deviation, apex deviation, apico-coronal (vertical) deviation, and angular deviation.
Results: Mean platform, apex, vertical and angle deviations were 1.55 ± 0.81 mm, 2.45 ± 0.84 mm, 1.59 ± 0.70 mm, and 5.56 ± 4.03º, respectively. No significant differences were found between maxilla and mandible or between anterior and posterior sites. A flat learning curve was observed with the exception of the implant platform that a tendency toward improvement in accuracy was observed between the eighth implant placed and the seventeenth. No complications were reported.
Conclusions: Based on the results of a study performed by a novice operator on a cadaveric model, The DNGS allows accurate implant placement within a 2 mm safety margin in terms of implant platform and vertical positions, and a 3 mm margin in apical vicinities. The technique requires practice to learn the required hand-eye coordination.
Schlagwörter: Computer-assisted surgery, computer guided surgery, dynamic navigation, accuracy, dental implant, dental navigation
DOI: 10.3290/j.ijcd.b2588203, PubMed-ID: 3506037321.01.2022, Sprache: Englisch
Aim. The full-contact model has been widely used in tooth preparation and prosthesis fabrication. However, it is rarely used in denture tests. The purpose of this study was to design a suitable full-contact dental model for denture tests.
Materials and Methods. A standard dental model with the complete teeth morphology was raster scanned and 3D reconstructed. Then, the positioning and fixing surfaces of the dental model were reshaped. The dental model was digitally trimmed into two parts: a fundamental part and a replaceable part. The modular design was presented according to dentition defects around the first molar. The prepared tooth replicas were designed through preparation/scanning/registration/separation sequences. The dental models were fabricated by SLA 3D printing rapid prototype technology. The static fracture force of the dental model was predicted using the finite element method. The effects of the four design methods on the suitability of the five testing operations (abutment fabrication, prosthesis fabrication, assembling, loading, and observation) were quantitatively analyzed. The static tests of three fixed partial dentures (FPDs), including tooth-supported, implant-supported, and tooth-tooth17 supported prosthesis, were conducted to investigate the fracture feature. The dynamic test of a removable partial denture (RPD) was undertaken to study the wear characteristic.
Result. The dental model could bear the maximum fracture strength 4268.3 N. Seven positive and two negative effects of the design methods were produced. The maximum fracture strength of the FPDs were 1331.2 N, 1356.7 N, and 1987.7 N. The wear facets of the RPD in the dynamic denture test were distributed in three regions.
Conclusion. The force capacity of the full-contact dental model allows the application of static denture tests. The dental model provides improvements in fixture design, removable design, and replica design for the testing operations. The dental model is more recommended in the dynamic test than the static test.
Schlagwörter: dental model, denture test, computer-assisted design, 3D printing, computer assisted analysis
DOI: 10.3290/j.ijcd.b2588185, PubMed-ID: 3506037221.01.2022, Sprache: Englisch
Aim: Increased vertical growth of maxilla is a condition that affects a large part of the population, which reveals a skeletal alteration of the cranio-masticatory system. One of the effects generated by excessive vertical growth of maxilla is a gingival smile pattern that, in addition to affecting aesthetic patterns, can alter the masticatory biomechanics, which is a primary etiological factor in temporomandibular dysfunction. Contemporary imaging aids help optimize diagnostic analysis, apply treatment, and make an evaluation before, during and after treatment. This study aims to compare the clinical diagnosis of gingival smile with the dimensions of the dentoalveolar square, digitally calculated in the panoramic projection of the cone beam tomography.
Materials and methods: a sample of 37 patients, an analysis of the correlation between the dimensions of the dentoalveolar square of Tatis panoramic cephalometry and clinical photometry was performed, applying Tjan’s gingival smile analysis.
Results: Results show that the cephalometric measurement method of the dentoalveolar square and Tjan’s photometric measurement method have high correlation and agreement. Both methods can be used to classify the smile type in high, medium, or low.
Conclusions: analysis of the dentoalveolar square of the panoramic cephalometry provides an accurate diagnosis of the anterior vertical dimension of the maxilla related to the clinical diagnosis of smile.
Schlagwörter: gingival smile, panoramic radiography, maxillary height, smile analysis, maxillary vertical dimension
DOI: 10.3290/j.ijcd.b2588175, PubMed-ID: 3506037121.01.2022, Sprache: Englisch
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
DOI: 10.3290/j.ijcd.b2588153, PubMed-ID: 3506037021.01.2022, Sprache: Englisch
Aim: This study is aimed to evaluate the effect of milling mode and margin defining method on marginal and internal adaptation of digitally designed and fabricated ceramic veneers.
Materials and Methods: Forty extracted central incisors were prepared for ceramic veneers. Veneers were categorized into 4 groups (#10) based on designing (automatic or manual defining of cervical and incisal margins) and milling mode (fine or extra-fine). Veneers were cemented to teeth using resin cement and then polished. After cementation, the teeth were embedded in clear polyester resin. Then the teeth cut into three section, absolute marginal gap at the cervical margins (AMGC), marginal gap at incisal (MGI) and cervical margins (MGC), and internal gap (IG) at axial wall were evaluated using a scanning electron microscope. Two-way ANOVA and t-tests were used (α=.05).
Result: Margin defining method affected adaptation of internal and incisal margin; automatic software margin defining resulted in less IMG (P=.038) and IG (P=.009) than manual.
Conclusion: Selection of milling mode didn’t affect marginal gap. Margin defining method affected marginal gap at incisal margin and internal gaps.
Schlagwörter: veneer, margin defining, SEM, CAD-CAM, marginal adaptation, ceramic
DOI: 10.3290/j.ijcd.b2588131, PubMed-ID: 3506036921.01.2022, Sprache: Englisch
Aim: Milling-based, subtractive fabrication of digital complete dentures represents the computer-engineered manufacturing method of choice, but efficient additive manufacturing technologies might prove beneficial for the indication as well. The aim of this study is to evaluate the accuracy of surface adaptation of complete denture bases fabricated using subtractive, additive, and conventional manufacturing techniques.
Materials and methods: A standardized edentulous maxillary model was digitally designed and milled. 12 duplicated plaster casts were scanned, and virtual denture bases were designed accordingly. Physical complete denture bases (n=12/technique) were manufactured applying different digital and conventional fabrication strategies. 1) CNC milling (MIL), 2) material jetting (MJ), 3) selective laser sintering (SLS), and 4) digital light processing technology (DLP). 12 denture bases produced by injection molding (INJ) served as control. The intaglio surfaces of the denture bases were digitized, superposed with the surface data of the casts using a best-fit algorithm, and accuracy of surface adaptation was assessed examining deviations. Statistical analysis was conducted using SPSS (p < 0.05).
Result: 23 Milling of denture bases lead to significantly better surface adaptation compared to all other technologies (p < 0.001). The remaining fabrication methods, including conventional manufacturing of denture bases, revealed no considerable overall differences.
Conclusions: All technologies investigated are adequate to produce complete denture bases regarding surface adaption, whereas milled denture bases present superior surface adaptation.
Schlagwörter: 3D printing, additive manufacturing, CAD-CAM, digital complete denture, digital light processing, denture fit, material jetting, milling, PolyJet technology, selective laser sintering
DOI: 10.3290/j.ijcd.b2585503, PubMed-ID: 3506036821.01.2022, Sprache: Englisch
Aim: The purpose of this study was to investigate the effectiveness of digital impressions made by 3rd and 4th year dental students using a retrospective record review at one US dental school during a one-year period.
Materials and Methods: One hundred and twenty-five (125) digital impressions and the produced restorations were evaluated after reviewing patient records related to quality assurance. Effectiveness and acceptability of digital impressions and restorations were associated with the students educational level, number of prepared teeth scanned, the type of produced restoration, and the restorative material, using Fisher's Exact Chi-square tests. All dental students had previous education in the digital curriculum in their preclinical education.
Results: Ninety-one percent (91%) of the digital impressions were acceptable and eighty percent (80%) of the produced restorations had clinically acceptable margins. Impression approval and restoration acceptance were not affected by student's educational level, number of preparations, or restoration type. Restoration acceptance was significantly affected by restorative material (p=0.039), with higher rates of acceptable marginal integrity found with glass ceramic and zirconia materials.
Conclusions: Within the parameters of this study, 3rd and 4th year dental students after having extensive education in the preclinical curriculum, can utilize digital impressions effectively for clinical practice. Dental schools can and should educate students in digital dentistry and the results of this study show that with adequate educational experiences, dental students can use digital impressions effectively for clinically acceptable restorations.
Schlagwörter: digital dentistry, digital imagining, digital impressions, CAD/CAM, intraoral scanners