Desktop Scanner Research Articles

Accuracy of occlusal splints printed in different orientations by liquid crystal display technology: an in vitro study.

To evaluate the accuracy of occlusal splints printed in different orientations by liquid crystal display technology. An occlusal splint was digitally designed, and additive manufactured using an LCD printer (Phrozen Sonic 4k, Phrozen) at three orientations relative to the printer bed: 0, 45, and 70 degrees (n=10). The 3D-printed occlusal splints were digitised using a desktop scanner, resulting in experimental meshes. The meshes were analysed in a metrology software program, comparing the experimental ones with the initially designed occlusal splint (trueness) and each other within the same group (precision). The discrepancies were shown in a colour map and the root mean square indicated the magnitude of the total discrepancy between the meshes. Kruskal-Wallis test was used (α=0.05) followed by post-hoc Dunn's test. There was no statistical difference in trueness among the groups (P=0.086); however, splints printed at 70 degrees showed better precision compared to those printed at 0 (P<0.001) and 45 degrees (P<0.001). The splints printed at 0 and 45 degrees exhibited a similar discrepancy pattern, with higher values in the posterior segment-positive on the buccal surface and negative on the lingual surface of molars. In contrast, splints printed at 70 degrees had higher discrepancy values in both anterior and posterior segments, with an inverted pattern on molars. The accuracy of occlusal splints was affected by the different orientation in terms of precision, with 70 degrees resulted in highest precision compared to 0 and 45 degrees. No difference was found in terms of trueness. Higher discrepancies were found located in molars and incisal edge of anterior teeth. 3D-printing using LCD technology stands out for its affordability and good resolution, however the optimal printing angle remains unclear. Vertical positioning allows more objects to fit on the print bed, while horizontal positioning reduces print time. For DLP printers, a 0-degree angle provides good accuracy for occlusal splints, whereas a 90-degree angle results in lower accuracy. This study found that for LCD printers, 0, 45, and 70 degrees had similar trueness, with 70 degrees offering the highest precision. Thus, vertical positioning at 70 degrees can be a safe choice for the accuracy of occlusal splints printed on LCD technology.

Accuracy of intraoral versus desktop scanners used in digitizing polyvinyl siloxane impression for fabricating a CAD-CAM customized post and core.

This in vitro study aimed to compare the 3-dimensional (3D) accuracy of intraoral and desktop scanners when digitizing the post and core polyvinyl siloxane impressions. Ten extracted human teeth were prepared to build a post space in the root canal. Each tooth was scanned using a micro-computed tomography device (MCT), and the slice data were reconstructed as controls. A conventional quadrant polyvinyl siloxane impression was made and scanned thrice using an intraoral scanner (IOS) and a desktop blue-light scanner (IMS), with one of the scans randomly selected as the definitive cast. Precision was assessed by comparing the deviations among repeated scans. Trueness was evaluated by analyzing the deviations between the MCT and each definitive cast (MCT-IOS and MCT-IMS). The clinically acceptable root mean square (RMS) value was set to 50 µm. The mean RMS values of the repeated scans of IOS and IMS were 18.3 ± 3.9 µm and 13.9 ± 6.2 µm (P < 0.05), and the difference between them was 4.4 ± 5.9 µm. The mean RMS values of MCT-IOS and MCT-IMS were 28.3 ±3.0 µm and 31.3 ± 4.2 µm (P < 0.05), with a difference of 3.0 ± 2.9 µm. The RMS values were significantly lower than 50 µm (P < 0.05). The IOS showed slightly better trueness than the IMS but slightly lower precision. The precision and trueness of the two scanners for digitizing post and core impressions were acceptable for clinical application.

Effectiveness of 2 Lip Taping Techniques in Infants With Bilateral Cleft Lip and Palate: A Randomized Clinical Trial.

This trial was designed to test the efficacy of 2 lip taping methods in modifying the maxillary arch dimensions (MADs) of infants with bilateral cleft lip and palate (BCLP) before lip repair surgery. Parallel-group randomized clinical trial. The trial was conducted at 3 centers in Baghdad city. Thirty-six nonsyndromic infants with BCLP. The eligible infants were randomly assigned to either the first experimental group that received a conventional horizontal tape (3 M Steri strip-1/4 inch) or the second experimental group that received a custom-made tape made of Steri strips and orthodontic extra oral elastics. All of the included infants in both groups had rubber base impressions taken for them at the start of treatment (T1) and right before surgical lip repair (T2). A desktop scanner was used to scan each of the generated models, creating digital models that could be used for outcome evaluation. Virtual MAD measurements were performed by a blinded assessor on the generated digital models both before (T1) and after (T2) treatment. At T2, both groups showed statistically significant changes in all measured MADs, with a mean difference ranging from 1.36 to 2.95 mm for the conventional taping group and from 1.46 to 7.96 mm for the custom-made one. The comparison of the 2 groups revealed both statistically and clinically significant differences with a P value <.05. The custom-made taping demonstrated more constriction in maxillary arch in terms of changes, which could provide easier surgical manipulation for the cleft parts. Lip taping appears to be an efficient technique for modifying the MADs in infants with BCLP.

The Accuracy of Intraoral Scanners in Maxillary Defects with Different Model Variations.

Background: Advances in digital technology and intraoral scanners (IOSs) have the potential to enable accurate digital impressions for patients with maxillary defects. This study aimed to compare the accuracy of IOSs in completely and partially edentulous models with maxillary defects. Methods: Three polyurethane models-one completely edentulous (CE) and two partially edentulous, following Aramany classifications I (ACI) and II (ACII)-were created using stereolithography. These models were scanned with a desktop scanner to create reference models. Ten scans were performed using three different intraoral scanners (TRIOS 3, Primescan, and Virtuo Vivo). The IOS datasets were analyzed to assess trueness and precision using a two-way ANOVA and multiple-comparison tests with Bonferroni corrections (α = 0.05). Results: Both the model type and the IOS significantly influenced trueness and precision. The interaction between the model type and the IOS was found to be statistically significant (trueness: p = 0.001; precision: p = 0.005). The highest trueness was observed in the ACII model scanned with TRIOS 3 and Primescan. TRIOS 3 and Primescan also exhibited the highest precision in the ACII model. For Virtuo Vivo, there were no significant differences among the models (p = 0.48). Conclusions: Although intraoral scanners (IOSs) demonstrated significant differences in trueness when used in completely and partially edentulous models with maxillary defects, these differences may be considered clinically insignificant.

Effects of Operator Experience and Scanning Distance on Intraoral Scanner Accuracy

Aim: This study aimed to evaluate the effect of operator experience and scanning distance on the accuracy of the intraoral scanner in terms of trueness and precision. Material and Methods: Reference data were obtained by scanning a partially edentulous gypsum model with implant analogs in regions 15, 16, 26, and 27 using a desktop scanner. Two expert dentists, one experienced and one inexperienced, performed test scans using the Trios 5 scanner. All data were transferred to analysis software. The scan bodies in the test scans were superimposed with the reference scan bodies for trueness measurement using a best-fit algorithm, calculating the deviation between the datasets. Precision measurement involves aligning the test scan data with each other using the same method. The effect of operator experience and scanning distance on scanner accuracy was evaluated using independent-sample t-tests. Results: Full-arch scans exhibited higher trueness and precision deviations than partial-arch scans. For partial-arch scans by the experienced operator, the mean trueness deviation was 7.45µm, compared to 55.56µm for full-arch scans (p&lt;0.001). Inexperienced operator results were 7.60µm and 58.90µm, respectively (p&lt;0.001). Operator experience had no significant effect on trueness. For partial-arch scans performed by the experienced operator, the mean precision deviation was 2.73µm, compared to 33.87µm for full-arch scans (p&lt;0.001). Inexperienced operator results were 3.36µm and 39.79µm, respectively (p&lt;0.001). Operator experience significantly affected precision in partial-arch scans (p=0.044) but not in full-arch scans (p=0.563). Conclusion: Scanner accuracy decreased with increasing scanning distance. The effect of operator experience on scanner accuracy was insignificant.

Effect of Virtual Casts Superimposition Strategies on the Estimation of IOS Accuracy in Complete-Arch Scans.

This study aims to assess the impact of three different strategies of best-fit (BF) alignments of virtual casts on the estimation of the accuracy of intraoral scanner (IOS) in complete-arch scans. A maxillary typodont, modified with an Implant Scan Body (ISB) in the retroincisive area, was digitized using a desktop scanner (SW Optor Lab) to obtain a reference STL file. The typodont was then scanned 10 times using two IOSs (Trios4, Itero). Each STL file obtained from the IOS was superimposed onto the reference cast using three methods in CloudCompare: full-arch BF (BF-full), BF at the starting tooth (BF-tooth), and BF at the ISB (BF-ISB). Discrepancies from the reference were recorded, and trueness and precision were compared for each method. Statistical analysis with the Kruskall-Wallis nonparametric test was performed (α = 0.05). The Kruskall-Wallis test (p ⟨0.05) revealed statistically significant differences in trueness and precision among the alignment methods. Post Hoc multiple comparison test p-values were all below the critical alpha value. Differences in BF methods lead to significantly different accuracy values of IOS complete-arch scans as different virtual casts' alignment discrepancy. BF-full had the highest accuracy followed by BF-ISB and BF-tooth.

B-083 Sensitivity of the Sebia Hydragel 6 electrophoresis/immunofixation assay for detection of beta-2 transferrin in dilute cerebrospinal fluid (CSF): assessment by image analysis

Abstract Background Beta-2 transferrin (asialo transferrin) greater than 2-sialo transferrin is characteristic of cerebrospinal fluid (CSF). Our neurosurgery department recently requested availability of an in-house assay to evaluate post-surgical drainage fluids for presence of CSF. The Sebia Hydragel 6 beta-2 transferrin electrophoresis/immunofixation profile can be used as a qualitative (positive/negative) assay for this purpose. As a starting point for evaluation of the assay, we examined the sensitivity of the assay for detection of the beta-2 transferrin band in dilute CSF. This was performed by quantitative image analysis. Methods Assays were conducted according to manufacturer's instructions. Our proband sample was pooled CSF. Successive dilutions were by factors of 2 (1, 1/2, 1/4, 1/8, 1/16, 1/32). Electrophoresis/ immunofixation was performed simultaneously for these samples across lanes in 6-lane gels. We performed quantitative assessment of the electrophoretic bands for beta-2 transferrin by image analysis. The gel image was scanned to an electronic file (600 dpi png) using a desktop scanner. Grayscale pixel data were obtained using Python and the Python Image Library (PIL). Total grayscale integrals for staining of beta-2 transferrin bands were computed and compared across dilutions of the proband sample. Results For CSF dilutions, the assay was invariably visually positive down to dilutions of 1/16. By image analysis, this cutoff had signal/noise ratio (S/N) of 3.5. Across dilutions, band integrals were dependent on dilutions according to a simple hyperbola (representative example: see Figure). Conclusions The Sebia Hydragel 6 electrophoresis/immunofixation assay for qualitative assessment of presence of beta-2 transferrin was found to be suitable for unambiguous detection of beta-2 transferrin in CSF down to 1/16 dilution of CSF. By image analysis, the dose vs. response curve (density of staining for beta-2 transferrin across dilutions of CSF) was non-linear.

3D printing: Changing the landscape of orthodontics

This paper aims to elucidate how three-dimensional (3D) printing technology has greatly impacted orthodontic practice, marking a significant advancement in planning treatment, fabricating appliances, and patient care. The integration of digital technologies, such as digital cephalogram, digital photography, intraoral and facial scanners, desktop scanners, cone-beam computed tomography (CBCT), and 3D printing, has significantly enhanced the efficiency, accuracy, consistency, and predictability of treatment outcomes. The advent of 3D printing in dental and orthodontic treatment has introduced a new era marked by precision, efficiency, and customised appliances, empowering practitioners to achieve superior results for their patients. Some of its applications in orthodontics include manufacturing clear aligner trays, surgical guides for miniscrew insertion and corticotomy, splints for orthognathic surgery, and retainers.

Deviation parameters of intraoral scanning with and without artificial markers versus conventional impression of total, partial and congenital nasal defects: A pilot non-randomized clinical trial

PurposeThis pilot clinical trial aimed to investigate accuracy of intra-oral scanning (IOS) with and without artificial reference markers in capturing total, subtotal and congenital nasal defects. Basic proceduresThirteen patients with 3 types of nasal defects were selected and digitally scanned using an IOS with (ScM) and without artificial markers (Sc). Patients were grouped as follows; Group T (total nasal defect), Group P (partial/subtotal nasal defect), Group C (congenital defect). Silicone impressions of the defects were made and poured to get a model that was scanned using a Desktop scanner (Imp). The standard tessellation language (STL) files obtained from IOS were registered and compared to each other using a processing software. RMS, positive and negative average values were used to report deviations between the scans. Kruskal Wallis test was used to study the effect of defect type, while Friedmann was used to study the effect of impression technique. Results were considered significant at P≤.05. Main findingsAll deviation values showed statistically significant differences among the 3 studied nasal defects and among the 3 investigated impression techniques. The smallest deviation values were recorded in Sc-ScM of congenital defects (RMS= 0.13±0.04, +average=0.08±0.01, -average=-0.09±0.02), while the largest deviation values were recorded in IMP-Sc in the total defects (RMS= 0.38±0.05, +average=0.29±0.04, -average=-0.29±0.04). ConclusionsWithin the limitations of this study, it was concluded that the nasal defect type and the use of artificial markers during scanning affect the deviation parameters of the obtained scan. The combined effect of the studied parameters calls for the use of markers in when scanning total nasal defects.

Comparisons of precision and trueness of digital dental casts produced by desktop scanners and intraoral scanners

Background/purposeDifferent types of scanners are gradually used to produce digital dental casts in the current dental practice. This study tested the accuracy of the three desktop scanners and two intraoral scanners and evaluated whether the desktop scanners had higher precision than the intraoral scanners. Materials and methodsThis study used the three desktop and two intraoral scanners to scan a standard dental cast 5 times. The 5 digital casts produced by the same scanner were compared each other to study the precision errors of each scanner. Moreover, 5 sets of the 5 digital casts produced by the 5 different scanners were compared each other to investigate the trueness errors among these 5 different scanners. ResultsThis study showed a significant difference in the precision error of produced digital casts made by the 5 different scanners (P < 0.0001). The two intraoral scanners had significantly higher precision errors of produced digital casts than the three desktop scanners. However, there were no significant differences in the precision errors among the three desktop scanners and between the two intraoral scanners. The results of the whole cast or particular tooth surface trueness analyses demonstrated that the trueness errors were concentrated at the molar regions of produced digital casts when comparisons were performed between the intraoral and desktop scanners. ConclusionWe conclude that the desktop scanners can achieve a better precision than the intraoral scanners. When the intraoral scanner is used, the dentist should notice the possible model errors at the molar regions.

Effect of print orientation on the dimensional accuracy and cost-effectiveness of rapid-prototyped dental models using a PolyJet photopolymerization printer: An in vitro study

The purpose of this study was to evaluate the accuracy and cost-effectiveness of the dental models 3D printed in vertical and horizontal orientation as compared to the conventional plaster and digital models. This study involved scanning 50 plaster models using Maestro 3D Desktop Scanner (AGE Solutions, Pisa, Italy). The STL file obtained from the scanner was processed and three-dimensionally (3D) printed in the horizontal and vertical orientation using a PolyJet 3D printer (Objet 30 prime, Stratasys Ltd., Eden Prairie, Minnesota, United States). The accuracy of the rapid-prototyped (3D printed) models was measured from the pre-determined landmarks and was compared among the groups. In addition, determining the cost-effectiveness of the 3D printed models in different orientations was based on the amount of material (resin) utilized during the 3D printing process. ANOVA was used to determine the accuracy of the models. There were statistically insignificant differences (P>0.05) among rapid-prototyped models (≤0.06mm) compared to plaster models and digital models for the linear measurements made in all three planes of space. The dental models printed in the horizontal orientation were found to be more cost-effective than those printed in a vertical orientation in terms of the amount of material (resin) utilized and printing time during the 3D printing process. The accuracy of rapid-prototyped models 3D printed in the horizontal and vertical orientations was comparable to the plaster models and digital models for clinical applications. Horizontally printed models were more cost-effective than vertically printed models.

Do intraoral scanning technologies affect the trueness of dental arches with crowding, diastema, and edentulous spaces? A clinical perspective

ObjectivesTo evaluate the trueness of dental arches digitised by two intraoral scanning (IOS) technologies from patients presenting crowding, diastema, and bilateral posterior edentulous space with tilted molar. MethodsConventional impressions and dental stone models were generated from three patients presenting the aforementioned dental arch conditions. These models were digitised on a desktop scanner, and the resulting mesh was used as reference. Subsequently, the patients were scanned using confocal based (CF; iTero Element 2) and blue laser-multiscan (BLM; Virtuo Vivo) imaging IOS technology, totalling thirty scans. The meshes from the scans were exported in Standard Tessellation Language format and analysed using Geomagic Control X software. Root mean square (RMS) indicated deviation magnitude. Differences in IOS technologies were evaluated with paired t-tests, and dental arch conditions compared using ANOVA and post-hoc Tukey tests (α=0.05). ResultsDigital dental arch from blue laser-multiscan technology showed lower trueness compared to confocal based technology for crowding (p = 0.0084) and edentulous spaces (p = 0.0025) conditions. When the types of oral condition were compared, discrepancies were significantly different for both IOS technologies, featuring the arch with diastema showing the lowest trueness, followed by edentulous spaces and crowding. ConclusionDental arches presenting crowding and edentulous spaces digitised by blue laser-multiscan technology exhibited greater discrepancies compared to confocal based imaging technology. Furthermore, trueness varied among the dental arch conditions. Clinical SignificanceThe IOS technology and patient's dental arch condition can influence the trueness of dental arch digitisation. Being aware of these effects allows clinicians to take them into account during scanning procedures, digital planning and manufacturing.

Effect of preparation design and scan pattern on the accuracy of intraoral scans for complete arch laminate veneers under simulated intraoral variables.

The purpose of the study was to investigate the influence of different preparation designs and scan patterns on the accuracy of intraoral scans for complete-arch maxillary laminate veneers. Three maxillary typodonts were used to obtain reference models with three different laminate veneer preparation designs: windows (W), beveled (B), and incisal overlap (IO). Reference scans were obtained with a desktop scanner. A total of 90 complete arch intraoral scans were made with an intraoral scanner (Medit i700) following three different scan patterns: straight motion (SM), zigzag motion (ZM), and combined motion (CM). Ten scans were made in each subgroup and exported as standard tessellation language (STL) files. Assessment of accuracy was conducted with a 3D software analysis program (Geomagic Control X). Each STL file was individually aligned with the reference scan using the best fit algorithm tool, and 3D differences were calculated using the root mean square (RMS) value. Two-way analysis of variance (ANOVA) followed by post hoc comparison tests were applied to analyze precision and trueness data (α = 0.05). Two-way ANOVA and post hoc comparison tests revealed significant differences among different preparation designs and scan patterns (p < 0.05). Regarding trueness, the IO when scanned with SM presented higher mean RMS than the other preparation designs (W and B) scanned with the same scanning pattern (p < 0.05). Regarding precision, the groups of W and IO presented significantly higher mean RMS than the group of B when scanned with ZM (p < 0.05). Accuracy of intraoral scans for complete-arch laminate veneers was affected by different laminate veneer preparation designs and scan patterns. Modifying scan pattern according to preparation design helps to improve scan accuracy for complete-arch laminate veneers.

Impact of the superimposition methods on accuracy analyses in complete-arch digital implant investigation

ObjectivesTo measure the impact of the superimposition methods on accuracy analyses in digital implant research using an ISO-recommended 3-dimensional (3D) metrology-grade inspection software. Materials and methodsA six-implant edentulous maxillary model was scanned using a desktop scanner (7Series; DentalWings; Montreal, Canada) and an intraoral scanner (TRIOS 4; 3Shape; Copenhagen, Denmark) to generate a reference and an experimental mesh, respectively. Thirty experimental standard tesselletion language (STL) files were superimposed onto the reference model's STL using the core features of six superimposition methods, creating the following groups: initial automated pre-alignment (GI), landmark-based alignment (G1), partial area-based alignment (G2), entire area-based alignment (G3), and double alignment combining landmark-based alignment with entire model area-based alignment (G4 ) or the scan bodies' surface (G5). The groups underwent various alignment variations, resulting in sixteen subgroups (n = 30). The alignment accuracy between experimental and reference meshes was quantified by using the root mean square (RMS) error as trueness and its fluctuation as precision. The Kruskal-Wallis test with a subsequent adjusted post-hoc Dunn's pairwise comparison test was used to analyze the data (α = 0.05). The reliability of the measurements was assessed using the intraclass correlation coefficient (ICC). ResultsA total of 480 superimpositions were performed. No significant differences were found in trueness and precision among the groups (p > 0.05), except for partial area-based alignment (p < 0.001). Subgroup analysis showed significant differences for partial area-based alignment considering only one scan body (p < 0.001). Initial automated alignment was as accurate as landmark-based, partial, or entire area-based alignments (p > 0.05). Double alignments did not improve alignment accuracy (p > 0.05). The entire area-based alignment of the scan bodies’ surface had the least effect on accuracy analyses. ConclusionsDigital oral implant investigation remains unaffected by the superimposition method when ISO-recommended 3D metrology-grade inspection software is used. At least two scan bodies are needed when considering partial area-based alignments. Clinical significanceThe superimposition method choice within the tested ISO-recommended 3D inspection software did not impact accuracy analyses in digital implant investigation.

Comparison of Intraoral Scanning Modes in Three Distinct Full- Arch Digital Implant Impression Scenarios: An In Vitro Study.

The purpose of this study was to analyze the effect of scanning modes on the accuracy of the Trios for full-arch digital implant impressions. The trueness and precision of the intraoral scanning mode (IOSM) and the intraoral edentulous scanning mode (IOEM) of the Trios were evaluated in three edentulous models, each featuring 4, 6, and 8 implant analogues. Reference scanning data were obtained by scanning each model with a desktop scanner. Each model was scanned 10 times using the IOSM and IOEM modes of the Trios to establish the test groups. The scan bodies in the test and reference scans were isolated and exported in the reverse engineering program. The scan bodies in each group were superimposed with the corresponding reference scan (trueness) or with each other (precision). The overall 3D deviation between the aligned scan bodies was computed by the root-meansquare (RMS) values. As a result of the trueness and precision evaluation, no significant difference was found between scanning modes in any of the models. When comparing models, the 8-implant model showed significantly lower trueness than the 4-implant model. However, it also exhibited significantly higher precision when compared to both the 4-implant and 6-implant models. There were no significant differences in other pairwise comparisons between the models. Trueness and precision values were similar between the IOSM and IOEM groups across all the models. An increase in the number of implants in complete edentulous arches may have a negative impact on digital impression accuracy.

Calibrated intraoral scan protocol (CISP) for full-arch implant impressions: An in vitro comparison to conventional impression, intraoral scan, and intraoral scan with scan-aid.

To assess a newly developed intraoral scan protocol in enhancing the accuracy of complete-arch implant impressions. Four impression approaches were applied to the same maxillary edentulous model with 6 implants: (1) intraoral scan (IOS), (2) intraoral scan with scan aid (IOS-SA), (3) calibrated intraoral scan protocol (CISP), and (4) conventional splinted open-tray impression (CONV). Each approach was repeated 10 times, and a direct scan of the model with a desktop scanner was used as a reference model. The alignment of scans and the reference model was conducted by two methods: (a) aligning all scan bodies to evaluate the overall fit, and (b) aligning the first and second scan bodies to simulate the Sheffield fit test for passive fitting of multiple implant-supported prostheses. Linear deviations from the reference model (trueness) and within each group (precision) were analyzed using Python scripts. When aligned by all scan bodies, the CISP group exhibited comparable mean trueness (38.33 μm) and precision (45.97 μm) to the CONV group (44.30 and 47.92 μm respectively), both of which significantly outperformed the IOS group (86.82 and 83.17 μm, respectively). Furthermore, in the virtual Sheffield fit test, the CISP group achieved the highest levels of mean trueness at the end span (121.7 μm), making a linear deviation reduction of 36.7%, 60%, and 41.4% when compared to the CONV, the IOS, and the IOS-SA groups, respectively. Moreover, the CISP group (104.3 μm) displayed a remarkable 65, 182, and 86 μm advantage in precision over the CONV, IOS, and IOS-SA groups, respectively. CISP demonstrated comparable accuracy to the gold standard, the conventional splinted open-tray impression. Furthermore, it excelledin the virtual passive fitting test.

Evaluating free segmentation tools for CBCT-derived models: Cost-effective solutions.

This study evaluated the segmentation accuracy and reliability of free software packages and compared them with commercial alternatives. A total of 36 stone models were scanned using a desktop scanner and then imaged by cone beam computed tomography (CBCT). The CBCT volumes were segmented using 2 free software packages (3D Slicer and Blue Sky Plan) and 2 commercial software packages (Mimics and OnDemand3D). Stereolithography (STL) files generated by the desktop scanner were used as the control group (reference models). The accuracy of segmentation was evaluated by (1) comparing 6 linear measurements taken from each STL model generated by the 4 software packages with that obtained by the scanner, and (2) deviation analysis of each STL model generated by the 4 software packages with that obtained by the scanner. Absolute error and percentage error, repeated measures anova and Friedman test followed by post hoc analysis, intraclass correlation coefficient (ICC), and Pearson's r were used to evaluate the accuracy of the tested software packages. There was no statistically significant difference in all intra-arch measurements obtained using the four software packages. Measurements obtained using the free software packages and the scanner showed excellent positive correlation, ranging from 0.825 to 0.988, confirming equivalence with commercial software packages. Within the settings of the current study, accurate and time-saving segmentations with high positive correlation could be performed using the tested free segmentation software packages (3D Slicer and Blue Sky Plan). Nevertheless, further evaluation is necessary to gage their accuracy using different CBCT modalities.

Evaluation of the accuracy of full-arch impressions between three different intraoral scanners and conventional impressions: A prospective in vivo study.

This in-vivo study evaluated the accuracy of full-arch digital impressions obtained through different intraoral scanning technologies regarding trueness and efficiency against the standard alginate impressions. Alginate impressions were taken from 50 subjects, and the resulting stone casts were scanned using the Trios 3Shape desktop scanner. In-vivo scans were conducted on each participant using three intraoral scanners: Medit, CEREC Primescan, and 3Shape Trios. The scanned files were superimposed onto two software platforms: the 3Shape Orthoanalyser and Geomagic software. This superimposition was performed against the reference model to calculate 3D and 2D deviations, enabling efficiency comparisons between digital and traditional workflows based on work time in minutes. Measurements and comparisons were made in three planes: transverse, sagittal, and vertical dimensions for all the models and stone casts. Statistical analysis employed SPSS 23, with the significance level set at P<0.05. Significant deviations were observed between the three intraoral scanners and the alginate impression, with molar and premolar areas showing greater imprecision across dental arches. Compared to the alginate technique, Medit i500 tended to reduce the transverse dimension in the areas mentioned above, while CEREC exhibited higher precision. Molar and premolar areas emerged as the regions with the greatest discrepancies, both in excess and deficiency, compared to the alginate impression. This difference in dimensions was, however, statistically insignificant overall. 3Shape Trios exhibited the shortest scan times, indicating higher efficiency. Among the intraoral scanners, Medit recorded the longest scanning duration. Accepting the null hypothesis, the scans obtained using all three scanners were comparable with statistically insignificant differences in the measurements. The three scanners differed in the total scan time taken, with the Medit scanner requiring the longest scan time and the 3Shape TRIOS 3 scanner demonstrating the shortest scan duration.

Intraoral optical impression versus conventional impression for fully edentulous maxilla: an in vivo comparative study.

The aim of the present in vivo study was to compare the clinical trueness of primary mucostatic impressions obtained either by a classical alginate or an optical intraoral scanner technique in patients with a fully edentulous maxilla. A total of 30 patients with a fully edentulous maxilla were included in the study and underwent both conventional impressions and intraoral optical impressions (Trios 3). The conventional impressions were casted and the resulting plaster casts were digitized using a desktop scanner (Imetric D104i). These digitized impressions were superimposed over the optical impressions to compare the differences between the two data sets. Statistical analyses were performed to identify relevant deviations. For the 30 intraoral impressions, 80.88% of the surface areas were below the tolerance threshold of 25 µm and were thus considered similar to the areas scanned with the desktop scanner from the reference plaster cast. Interestingly, the differences (19.12% of the surface areas) were localized in depressible areas such as the vestibule, soft palate, incisive papilla, and flabby ridges. These locations were consistent with the mean of positive differences of +22.8 µm, indicating deformation or less compression with the use of the intraoral scanner. The digital primary impression of the fully edentulous maxilla can be considered similar to the conventional alginate impression except in the depressible areas. Considering the mucostatic objective of such a primary impression, one may consider the optical impression to be more accurate than the conventional one.

Influence of crown shade, translucency, and scan powder application on the trueness of intraoral scanners

ObjectivesNatural teeth and dental restorations present with various shades and levels of translucency. This study aimed to determine whether these variations in ceramic crowns and scan powder application affect the trueness of intraoral scanners. MethodsEight identical premade resin typodonts, each prepared for a crown on the maxillary right second molar, were used. Eight lithium disilicate crowns, distinguished by two levels of translucency (high and low) and four shades (BL1, A2, A3, and A4), were fabricated to an identical design and cemented onto each typodont, providing eight distinct experimental groups (2 levels of translucency × 4 shades). Reference scans were acquired using a desktop scanner. Test scans were performed ten times for each experimental group using two different intraoral scanners (Medit i700 and CEREC Primescan AC), with and without the application of scan powder (n = 10). Three-dimensional metrology software was used to assess the trueness of the intraoral scan datasets. Statistical analysis involved the Kruskal–Wallis H test, Mann–Whitney U test, and independent t-test (α=0.05). ResultsFor powder-free intraoral scan datasets, the crown shade did not significantly affect trueness within each translucency group (P = 1.000). For both intraoral scanners, compared with low translucency groups, higher marked deviations were exhibited by high translucency groups (P<.001). Scan powder use largely mitigated these differences (P>.05) and enhanced the trueness of the intraoral scan (P<.01). ConclusionsShade did not significantly influence the trueness of intraoral scans. High-translucency crowns were scanned with less accuracy than were low-translucency crowns. Clinical SignificanceUnlike tooth shade, translucency significantly affected the accuracy of intraoral scans. Therefore, considering the use of scan powder when scanning objects with high translucency may be beneficial.