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While the dimensional accuracy of the intaglio surface of a removable complete denture is key to its adaptation, comfort, and clinical performance, information on the ability of milling and 3D-printing workflows to accurately reproduce this surface is lacking.The purpose of this clinical study was to compare the trueness of the intaglio surface of milled and 3D-printed removable complete digital dentures.Intraoral scans were obtained from 14 participants for a total of 20 edentulous arches. Ten maxillary and 10 mandibular denture bases were then designed and fabricated with a completely digital workflow, both with milling and 3D-printing. Fabricated dentures were digitized with the same intraoral scanner used to obtain intraoral digital scans of the edentulous arches. Standard tessellation language (STL) files of the printed and milled denture bases were used for 3D analysis and comparisons with the STL file of the corresponding designed denture base. Specifically, a reverse engineering software program was used to trim and extract intaglio surfaces, align them, and measure their global mean 3D distance. In order to evaluate the homogeneity of production accuracy of each manufacturing process, the intaglio surfaces were also divided into several regions of interest and the corresponding 3D distances measured. Within- and between-group differences and maxillary and mandibular dentures differences were assessed with parametric and nonparametric tests (α=.05).Milling showed a global better trueness of the entire intaglio surface (-0.002 mm) than 3D-printing (0.018 mm), both for the whole data set (P.001) and for maxillary (P=.032) or mandibular (P=.049) denture base subgroups. Within each fabrication technology, maxillary (P.11) and mandibular dentures (P=.2) showed no significant difference in trueness. Measured deviations were significantly different from zero for the 3D-printed dentures (P.001), but not for the milled dentures (P=.487). Additionally, for milled dentures, no significant difference in trueness was found among the 11 regions of interest identified for the maxillary dentures (P=.085) and the 13 regions of interest for the mandibular dentures (P=.211). Conversely, 3D-printing showed significant variations in trueness among the same zones of interest, both in maxillary (P.001) and mandibular (P=.004) dentures.Within the limits of the manufacturing methodologies used for complete dentures, milling can provide a slightly better trueness of the intaglio surface than 3D-printing, with less variation across several zones of interest. However, given the magnitude of such differences, they may be reasonably considered to be of limited, if any, clinical significance.

Stereolithography (SLA) additive manufacturing (AM) technologies have become popular for the fabrication of complete dentures; however, the trueness and precision of the dentures under different postpolymerization conditions remain unclear.The purpose of this in vitro study was to investigate the effect of different postpolymerization times and temperatures on the trueness and precision of SLA dentures.Specimens simulating maxillary complete dentures were fabricated by SLA 3D printing. They were polymerized for 15 minutes or 30 minutes at different temperatures (40 °C, 60 °C, and 80 °C). The intaglio surface trueness of the specimens was evaluated by superimposing the postpolymerization standard tessellation language (STL) file on the original STL file for each specimen via a best-fit method (n=10). The precision was measured across specimens by superimposing the postpolymerization STL file from each specimen group and using the combination formula (n=45). Subsequently, root-mean-square estimates (RMSEs) and color map data were obtained, and a normality test was conducted on the obtained data. The results indicated that the distributions were not normal; therefore, nonparametric Kruskal-Wallis and Mann-Whitney tests were used to analyze the data (α=.05).For trueness, the lowest RMSE corresponded to the postpolymerization time of 30 minutes and a temperature of 40 °C. This result was significantly different from specimens those of the 15-minute and 60 °C, 15-minute and 80 °C, and 30-minute and 80 °C specimens (P.001). For precision, the median of the lowest RMSE corresponded to the 30-minute and 40 °C specimens. This median value was significantly different from those of other specimens (P.001). The findings indicate that the postpolymerization condition of 30 minutes and 40 °C affords the highest trueness and precision and the most favorable intaglio surface adaptation of the denture.The postpolymerization conditions influenced the RMSE values of the trueness and precision of a clear photopolymer resin. The RMSE and color map data associated with the 30-minute and 40 °C condition corresponded to the greatest trueness and precision of all the SLA denture specimens considered.

Computer-aided design and computer-aided manufacturing (CAD-CAM) systems are increasingly used to fabricate removable complete dentures. However, comparisons and analyses of the trueness and adaptation of the socketed surface of denture bases produced by milling (MIL) and digital light processing (DLP) are lacking.The purpose of this in vitro study was to evaluate and compare the trueness and socketed surface adaptation of denture bases fabricated by using additive and subtractive manufacturing.Based on a denture base standard tessellation language (STL) file, a total of 15 denture bases were produced by using DLP (horizontal and vertical direction) and MIL. The intaglio and cameo surfaces of the fabricated denture bases were scanned with a dental scanner. The scanned intaglio and cameo surfaces were overlapped with the corresponding reference denture base STL file for trueness evaluation. In addition, the ridge lap STL file of the diagnostic tooth arrangement, in which reverse normal was performed, was superimposed on the socketed surface of the denture base of all groups to evaluate adaptation.The root mean square (RMS) values of trueness and adaptation showed statistically significant differences (P.05). For the trueness RMS value of the intaglio surface of the denture base, the MIL-denture base (MDB) group had the lowest value of 150 ±6 μm, whereas the vertical denture base (VDB) of the DLP group was the largest with 328 ±4 μm. For the trueness RMS value of the cameo surface, the MDB group was the lowest with 50 ±1 μm, whereas the VDB group was the largest with 334 ±24 μm. For the adaptation RMS value of the socketed surface of the denture base, the MDB group was the lowest with 44 μm, whereas the VDB group was the largest with 117 ±2 μm.Within the limits of this in vitro study, the MDB group showed better trueness and socketed surface adaptation than the DLP groups (HDB and VDB).

Purpose To conduct an in vitro comparison of the amount of three-dimensional (3D) deviation of 3D printed casts generated from digital implant impressions with an intraoral scanner (IOS) to stone casts made of conventional impressions. Material and methods A maxillary master cast with partially edentulous anterior area was fabricated with two internal connection implants (Regular CrossFit, Straumann). Stone casts (n = 10) that served as a control were fabricated with the splinted open-tray impression technique. Twenty digital impressions were made using a white light IOS (TRIOS, 3shape) and the Standard Tesselation Language (STL) files obtained were saved. Based on the STL files, a digital light processing (DLP) and a stereolithographic (SLA) 3D printer (Varseo S and Form 2) were used to print casts (n = 10 from each 3D printer). The master cast and all casts generated from each group were digitized using the same IOS. The STL files obtained were superimposed on the master cast STL file (reference) to evaluate the amount of 3D deviation with inspection software using the root mean square value (RMS). The independent-samples Kruskal-Wallis test and Dunn's test with Bonferroni correction (for post hoc comparisons) were used for statistical analyses. Results The Varseo S group had the lowest median RMS value [77.5 µm (IQR = 91.4-135.4)], followed closely by the Conventional group [77.7 µm (IQR = 61.5-93.4)]. The Form 2 had the highest mean value [98.8 µm (IQR = 57.6-87.9)]. The independent-samples Kruskal-Wallis test revealed a significant difference between the groups (p = 0.018). Post hoc testing revealed a significant difference between Varseo S and Form 2 (p = 0.009). Conclusion The casts generated from the Varseo S 3D printer had better 3D accuracy than did those from the Form 2 3D printer. Both the Varseo S group and the conventional stone casts groups had similar 3D accuracy.

Purpose: The objective of the research was to investigate dimensional accuracy concerning denture teeth deviation and vertical dimensional changes for three-dimensional printed, monolithic dentures relative to heat-cured, acrylic resin dentures. Materials and methods: A waxed-up reference maxillary denture was constructed on an educational master cast, and then duplicated to produce ten simulated waxed-up dentures. The planned virtual denture was designed by subtracting the scanned cast from the scanned waxed-up denture with the cast. This virtual denture was considered as a reference and saved alone in 3D- Standard Tessellation Language (STL) format. From this reference (CAD maxillary denture) ten DLP dentures were fabricated. Each fabricated heat-cured, and 3D-printed denture was scanned separately, and the scanned data was saved in an STL file. Each STL file of scanned maxillary dentures was superimposed on a reference virtual maxillary denture to evaluate the degree of denture teeth deviation. An electronic digital caliper was used to measure the occlusal vertical dimension (OVD) of the waxed-up denture and after denture fabrication for both groups to evaluate the change in OVD. Results: A paired t-test was used to compare the recorded data between both groups. It was reported that the higher mean values for either denture teeth deviation or vertical dimensional changes after dentures fabrication were noticed in heat-cured acrylic resin dentures. These values were highly statistically significant between the tested groups for both items of investigations at p ≤ 0.01.

Different digital tools have been used in clinical practice to assist in the planning and rehabilitation of patients. Some applications (apps) and software programs used in esthetic planning allow simulation of the smile design, improving communication between patients and professionals. Nonetheless, they are usually difficult to use, time-consuming, unattractive to present to the patient, and complicated to link with the 3D workflow. This article presents a new 3D digital smile design app for esthetic planning, smile simulation, chairside 3D virtual wax pattern, and trial restoration performed with portable devices. In this technique description, a facial frontal photograph, a facial scan standard tessellation language (STL) file, and a maxillary intraoral scan STL file were uploaded to the app. The files were calibrated to each other to allow a 3D facially driven smile design project. The definitive maxillary 3D digital waxing of facial templates was exported to a 3D printer as an STL file. The printed resin templates were directly placed in the mouth with flowable composite resin for an immediate trial restoration without the need for casts, silicone guides, or autopolymerizing resin. The workflow presented in this article linked the 3Dapp project to a printer and allowed straightforward chairside trial restorations.

Statement of problem Digital scans have increasingly become an alternative to conventional impressions. Although previous studies have analyzed the accuracy of the available intraoral scanners (IOSs), the effect of the light scanning conditions on the accuracy of those IOS systems remains unclear. Purpose The purpose of this in vitro study was to measure the impact of lighting conditions on the accuracy (trueness and precision) of different IOSs. Material and methods A typodont was digitized by using an extraoral scanner (L2i; Imetric) to obtain a reference standard tessellation language (STL) file. Three IOSs were evaluated—iTero Element, CEREC Omnicam, and TRIOS 3—with 4 lighting conditions—chair light 10 000 lux, room light 1003 lux, natural light 500 lux, and no light 0 lux. Ten digital scans per group were recorded. The STL file was used as a reference to measure the discrepancy between the digitized typodont and digital scans by using the MeshLab software program. The Kruskal-Wallis, 1-way ANOVA, and pairwise comparison were used to analyze the data. Results Significant differences for trueness and precision mean values were observed across different IOSs tested with the same lighting conditions and across different lighting conditions for a given IOS. In all groups, precision mean values were higher than their trueness values, indicating low relative precision. Conclusions Ambient lighting conditions influenced the accuracy (trueness and precision) of the IOSs tested. The recommended lighting conditions depend on the IOS selected. For iTero Element, chair and room light conditions resulted in better accuracy mean values. For CEREC Omnicam, zero light resulted in better accuracy, and for TRIOS 3, room light resulted in better accuracy.

The full digital workflow involves the combination of intraoral and cone beam computerized tomography scans. In the present case report, a second intraoral scan is performed after soft tissue management facilitated by the use of a 3-dimensional-printed interim implant restoration. The new STL file resulting from the second intraoral scan can be associated with the previous STL from the initial intraoral scan. The custom abutment was also digitally designed as an STL file, and no implant scan bodies were required for intraoral scanning.

Purpose To evaluate the accuracy of implant position using surgical guides fabricated by additive and subtractive techniques. Materials and methods A partially edentulous standardized mandibular implant model with different bone densities and soft tissue was duplicated and a diagnostic wax-up was performed for the #30 area. A reference radiographic guide was fabricated and cone beam computed tomography (CBCT) was made with the reference radiographic guide in place. A surgical guide was designed using BlueSky Plan 4 software and a reference implant was placed in the #30 region. The STL file of the surgical guide was exported and specimens (n = 15) were fabricated by two different techniques: additive (3D printing) and subtractive (milling). The standardized mandibular model was surface-scanned and duplicated with printed dental model resin (n = 30). Each surgical guide was used to place an implant in thirty duplicate printed models. Differences in implant position as compared to the reference were measured from digital scans with scan bodies in place. The angular deviations, differences in depth, coronal and apical deviations were measured using GeoMagic Control X software. Results were analyzed by Wilcoxon-Mann-Whitney test and PERMANOVA (Permutational Multivariate Analysis of Variance). Intraclass correlation was used to assess measurement reproducibility with Bonferroni adjustment for multiple testing as needed (α = 0.05). Results There were no significant differences in accuracy of implant placement using guides fabricated using additive vs subtractive techniques. The mean angular deviations between the reference and actual position of implant in mesio-distal cross-section were 0.780 ± 0.80° for printed group and 0.77 ± 0.72° for the milled group. The differences in bucco-lingual cross-section were 1.60 ± 1.22° in in printed group and 1.77 ± 0.76° in the milled group. The differences in depth (mm) were measured at the top of the scan body at four locations: mesial, distal, buccal and lingual. The mean differences in depth for the group that used printed surgical guides were (mesial) 0.37 ± 0.29 mm, (distal) 0.32 ± 0.23 mm, (buccal) 0.24 ± 0.23 mm, and (lingual) 0.25 ± 0.17 mm. The mean differences in depth for the group that used milled surgical guides were (mesial) 0.51 ± 0.33 mm, (distal) 0.40 ± 0.32 mm, (buccal) 0.22 ± 0.23 mm, and (lingual) 0.23 ± 0.12 mm in those four aspects, respectively. The mean coronal deviation showed 0.32 mm in the printed group and 0.27 mm in the milled group. For the apical deviation, the results of this study showed mean apical deviation 0.84 mm in the printed group and 0.80 mm in the milled group. Conclusions Results indicate that 3D-printed surgical guides are statistically as accurate as milled guides for guided-implant surgery with the benefits of high accuracy, ease of fabrication, less waste compared to subtractive techniques, and reduction of laboratory time thereby increasing cost-effectiveness.

PURPOSE To compare the accuracy of fit and trueness of maxillary poly(etheretherketone) (PEEK) removable partial denture (RPD) frameworks fabricated by direct and indirect computer-aided design/computer-aided manufacturing (CAD/CAM) techniques. MATERIALS AND METHODS A definitive maxillary class I master epoxy model was duplicated to create a stone cast. The cast was scanned, and an RPD was designed. Standard tessellation language (STL) data were used to fabricate 20 identical RPD frameworks using two CAD/CAM techniques: direct milling of PEEK and indirect additive manufacturing (resin printing combined with PEEK thermopressing using the lost-wax technique). All the frameworks for each technique (n = 10) and the reference cast were scanned. To assess the accuracy of fit, a color map was constructed using metrology software, and the misfit (distance between each framework and the reference cast) was measured at 25 standardized points. To assess the overall trueness, each framework STL file was superimposed over the original design's STL file, and the average deviation was recorded in microns. Data were statistically analyzed using t-test. RESULTS Color mapping showed distinct pressure areas in the anterior and posterior straps of the major connector in the indirect technique, while a more uniform distribution of the color map was observed in the direct technique. A significant difference was found between the two techniques regarding the overall accuracy of fit. Compared with the indirect technique, the milled frameworks showed significantly better overall trueness (p < 0.001). CONCLUSIONS Although a significant difference in the overall fit accuracy was noted between both techniques, the fit was an acceptable clinical fit. The fabrication method affects the fit in the anterior and posterior strap areas. The frameworks of the direct technique revealed better overall trueness values compared with the indirect technique.

With the advent of 3D printing technologies in dentistry, the optimization of printing conditions has been of great interest, so this study analyzed the accuracy of 3D-printed temporary restorations of different sizes produced by digital light processing (DLP) and liquid crystal display (LCD) printers. Temporary restorations of 2-unit, 3-unit, 5-unit, 6-unit, and full-arch cases were designed and printed from a DLP printer using NextDent C&amp, B or an LCD printer using Mazic D Temp (n = 10 each). The restorations were scanned, and each restoration standard tessellation language (STL) file was superimposed on the reference STL file, by the alignment functions, to evaluate the trueness through whole/point deviation. In the whole-deviation analysis, the root-mean-square (RMS) values were significantly higher in the 6-unit and full-arch cases for the DLP printer and in the 5-unit, 6-unit, and full-arch cases for the LCD printer. The significant difference between DLP and LCD printers was found in the 5-unit and full-arch cases, where the DLP printer exhibited lower RMS values. Color mapping demonstrated less shrinkage in the DLP printer. In the point deviation analysis, a significant difference in direction was exhibited in all the restorations from the DLP printer but only in some cases from the LCD printer. Within the limitations of this study, 3D printing was most accurate with less deviation and shrinkage when a DLP printer was used for short-unit restorations.

As comparative data on the precision of 3D-printed anatomical models are sparse, the aim of this study was to evaluate the accuracy of 3D-printed models of vascular anatomy generated by two commonly used printing technologies. Thirty-five 3D models of large (aortic, wall thickness of 2 mm, n = 30) and small (coronary, wall thickness of 1.25 mm, n = 5) vessels printed with fused deposition modeling (FDM) (rigid, n = 20) and PolyJet (flexible, n = 15) technology were subjected to high-resolution CT scans. From the resulting DICOM (Digital Imaging and Communications in Medicine) dataset, an STL file was generated and wall thickness as well as surface congruency were compared with the original STL file using dedicated 3D engineering software. The mean wall thickness for the large-scale aortic models was 2.11 µm (+5%), and 1.26 µm (+0.8%) for the coronary models, resulting in an overall mean wall thickness of +5% for all 35 3D models when compared to the original STL file. The mean surface deviation was found to be +120 µm for all models, with +100 µm for the aortic and +180 µm for the coronary 3D models, respectively. Both printing technologies were found to conform with the currently set standards of accuracy (&lt, 1 mm), demonstrating that accurate 3D models of large and small vessel anatomy can be generated by both FDM and PolyJet printing technology using rigid and flexible polymers.

The purpose of this study is to define the accuracy of four intraoral scanners (IOS) through the analysis of digital impressions of a complete dental arch model. Eight metal inserts were placed on the model as reference points and then it was scanned with a laboratory scanner in order to obtain the reference model. Subsequently, the reference model was scanned with four IOS (Carestream 3600, CEREC Omnicam, True Definition Scanner, Trios 3Shape). Linear measurements were traced on an STL file between the chosen reference points and divided into four categories: three-element mesiodistal, five-element mesiodistal, diagonal, and contralateral measurements. The digital reference values for the measurements were then compared with the values obtained from the scans to analyze the accuracy of the IOS using ANOVA. There were no statistically significant differences between the measurements of the digital scans obtained with the four IOS systems for any of the measurement groups tested.

To evaluate the influence of rinsing solvents, namely isopropyl alcohol (IPA) and tripropylene glycol monomethyl ether (TPM), and rinsing times (5-, 7-, 9-, and 11-minutes) for the postprocessing procedures on the manufacturing accuracy of an additively manufactured dental model resin material.The standard tessellation language (STL file) of the digital design of a bar (15 mm × 4 mm × 3 mm) was obtained. A resin dental material (E-Model Light; Envisiontec, Dearborn, MI) and a 3D printer (VIDA HD; Envisiontec) was selected to manufacture all the specimens using the STL file following the recommended printing parameters at a room temperature of 23 °C. Two groups were generated based on the rinsing solvent used on the postprocessing procedures, namely isopropyl alcohol (IPA-group) and tripropylene glycol monomethyl ether (TPM-group). Each group was further divided into 4 subgroups (IPA-1 to IPA-4 and TPM-1 to TPM-4) depending on the rinsing time performed (5-, 7-, 9-, and 11-minutes). Twenty specimens per subgroup were fabricated. The dimensions (length, width, and height) of all the specimens were measured using a low force digital caliper (Absolute Low Force Caliper Series 573; Mitutoyo, Takatsu-ku, Kawasaki, Kanagawa). Each measurement was performed 3 times and the mean value determined. The volume of each specimen was calculated using the formula V = l × w × h. Shapiro-Wilk test revealed that the data were not normally distributed. Data were analyzed using Kruskal-Wallis (α = 0.05), followed by pairwise Mann-Whitney U tests (α = 0.0018).The IPA groups obtained significantly lower trueness and precision values compared with TPM groups (p0.0018). Among the IPA groups, IPA-1 subgroup obtained the highest trueness and precision values compared to the rest of the IPA subgroups. The TPM-1 and TPM-2 subgroups obtained the highest trueness and prevision values among the TPM group and among all the groups tested. No significant difference was found between the TMP-1 and TPM-2 subgroups (p0.0018).None of the manufacturing workflows tested were able to manufacture a perfect match of the bar virtual design dimensions. TPM solvent group obtained higher trueness and precision values compared to the IPA solvent group. The IPA-1 subgroup that replicated the manufacturer´s recommendations obtained the highest manufacturing accuracy among the IPA subgroup. TPM solvent used in a rinsing ultrasonic bath between 3 and 4 minutes followed by a second ultrasonic clean bath between 2 and 3 minutes of the just printed vat polymerized dental model specimens obtained the highest manufacturing accuracy values.

Background DNA base identification is a proper and high specificity method. However, identification could be challenged in a situation where there is no database or the DNA sequence is almost identical, as in the case of monozygotic (MZ) twins. The aim of this study was to introduce a novel forensic method for distinguishing between almost identical MZ twins by means of an intraoral scanner using the 3D digital pattern of the human palate. Methods The palatal area of 64 MZ twins and 33 same-sex dizygotic (DZ) twins (DZSS) and seven opposite-sex dizygotic twins (DZOS) were scanned three times with an intraoral scanner. From the scanned data, an STL file was created and exported into the GOM Inspect® inspection software. All scans within a twin pair were superimposed on each other. The average deviation between scans of the same subject (intra-subject deviation, ISD) and between scans of the two siblings within a twin pair (intra-twin deviation, ITD) was measured. One-sided tolerance interval covering 99% of the population with 99% confidence was calculated for the ISD (upper limit) and the ITD (lower limit). Results The mean ISD of the palatal scan was 35.3 μm ± 0.78 μm. The calculated upper tolerance limit was 95 μm. The mean ITD of MZ twins (406 μm ± 15 μm) was significantly (p p p Conclusion The reproducibility of palatal intraoral scans proved to be excellent. The morphology of the palate shows differences between members of MZ twins despite their almost identical DNA, indicating that this method could be useful in forensic odontology.

This study evaluated the effects of the differences in the printing directions of stereolithography (SLA) three-dimensional (3D)-printed dentures on accuracy (trueness and precision). The maxillary denture was designed using computer-aided design (CAD) software with an STL file (master data) as the output. Three different printing directions (0&deg, 45&deg, and 90&deg, ) were used. Photopolymer resin was 3D-printed (n = 6/group). After scanning all dentures, the scanning data were saved/output as STL files (experimental data). For trueness, the experimental data were superimposed on the master data sets. For precision, the experimental data were selected from six dentures with three different printing directions and superimposed. The root mean square error (RMSE) and color map data were obtained using a deviation analysis. The averages of the RMSE values of trueness and precision at 0&deg, were statistically compared. The RMSE of trueness and precision were lowest at 45&deg, followed by 90&deg, the highest occurred at 0&deg, The RMSE of trueness and precision were significantly different among all printing directions (p &lt, 0.05). The highest trueness and precision and the most favorable surface adaptation occurred when the printing direction was 45&deg, therefore, this may be the most effective direction for manufacturing SLA 3D-printed dentures.

Background Extracting and three-dimensional (3D) printing an organ in a region of interest in DICOM images typically calls for segmentation as a first step in support of 3D printing. The DICOM images are not exported to STL data immediately, but segmentation masks are exported to STL models. After primary and secondary processing, including noise removal and hole correction, the STL data can be 3D printed. The quality of the 3D model is directly related to the quality of the STL data. This study focuses and reports on the DICOM to STL segmentation performance for nine software packages. Methods Multidetector row CT scanning was performed on a dry human mandible with two 10-mm-diameter bearing balls as a phantom. The DICOM image file was then segmented and exported to an STL file using nine different commercial/open-source software packages. Once the STL models were created, the data (file) properties and the size and volume of each file were measured, and differences across the software packages were noted. Additionally, to evaluate differences between the shapes of the STL models by software package, each pair of STL models was superimposed, with the observed differences between their shapes characterized as the shape error. Results: The data (file) size of the STL file and the number of triangles that constitute each STL model were different across all software packages, but no statistically significant differences were found across software packages. The created ball STL model expanded in the X-, Y-, and Z-axis directions, with the length in the Z-axis direction (body axis direction) being slightly longer than that in the other directions. The mean shape error between software packages of the mandibular STL model was 0.11 mm, but there was no statistically significant difference between them. Conclusions Our results revealed that there are some differences between the software packages that perform the segmentation and STL creation of the DICOM image data. In particular, the features of each software package appeared in the fine and thin areas of the osseous structures. When using these software packages, it is necessary to understand the characteristics of each.

PURPOSE To evaluate the effects of two postprocessing methods in terms of the overall, intaglio, and cameo surface dimensions of in-office stereolithographic fabricated implant surgical guides. MATERIALS AND METHODS Twenty identical implant surgical guides were fabricated using a stereolithographic printer. Ten guides were postprocessed using an automated method. The other ten guides were postprocessed using a series of hand washing in combination with ultrasonics. Each guide was then scanned using cone-beam computed tomography to produce a set of digital imaging and communications in medicine (DICOM) files which were converted into standard tessellation language (STL) files. The STL file was then superimposed onto the original STL design file using the best fit alignment. The average positive and negative surface discrepancy differences in terms of means and variances were analyzed using t-test (α = 0.05). RESULTS For the alternative group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 77.38 ± 10.68 µm and -67.74 ± 6.55 µm; 78.83 ± 8.65 µm and -68.16 ± 5.26 µm; and 70.5 ± 8.48 µm -64.84 ± 5.55 µm, respectively. For the automated group, the average positive and negative overall, intaglio, and cameo surface discrepancies were 51.88 ± 4.38 µm and -170.7 ± 11.49 µm; 64.3 ± 4.44 µm and -89.45 ± 6.25 µm; and 83.59 ± 4.81 µm and -144.26 ± 13.19 µm, respectively. There was a statistical difference between the means of the two methods for the overall, intaglio, and cameo positive and negative discrepancies (p < 0.001). CONCLUSIONS For a single implant tooth-supported implant guide, using hand washing with ultrasonics appeared to be consistently better than the automated method. The manual method presented with more positive discrepancies, while the automated method presented with more negative discrepancies.

Background Mock-up based approach allows the preview of the aesthetic rehabilitation, however, it is crucial that the mock-up does not differ from the expected aesthetic outcomes. With CAD-CAM technologies, it is possible to directly create mock-ups from virtual planned smile project, with greater accuracy and efficiency compared to the conventional moulded mock-ups. In this study, we investigated the trueness of mock-ups obtained with milling and 3D printing technology and a full digital work-flow system. Methods Ten adults subjects were included and digital smile design/digital wax-up were performed to enhance the aesthetic of maxillary anterior region. Ten milled mock-ups and 10 prototyped mock-ups were obtained from the original .stl file and a digital analysis of trueness was carried out by superimposing the scanned-milled mock-ups and the scanned-prototyped mock-ups to the digital wax-up, according to the surface-to-surface matching technique. Specific linear measurements were performed to investigate and compare the dimensional characteristics of the physical manufactures, the 3D project and the scanned mock-ups. All data were statistically analyzed. A clinical test was also performed to assess the fitting of the final manufacture. Results The prototyped mock-ups showed a significant increment of the transversal measurements (p p p Conclusion Both prototype and milled mock-ups showed a slight dimensional increment comparing to the original 3D project, with milled-mock-ups showing less fitting after clinical tests. Caution must be taken when assessing the trueness of scanned manufacture since an intrinsic error in the system can underestimate the dimensions of the real object.

Maxillary expansion is a common orthodontic treatment used for the correction of posterior crossbite resulting from reduced maxillary width. Transverse maxillomandibular discrepancies are a major cause of several malocclusions and may be corrected in different manners, in particular, the rapid maxillary expansion (RME) performed in the early mixed dentition has now become a routine procedure in orthodontic practice. The aim of this study is to propose a procedure that reduces the patient cooperation as well as the lab work required in preparing a customized Haas-inspired rapid maxillary expander (HIRME) that can be anchored to deciduous teeth and can be utilized in mixed dentition with tubes on the molars and hooks and brackets on the canines. This article thus presents an expander that is completely digitally developed, from the first moment of taking the impression with an optical scanner to the final solidification phase by the use of a 3D printer. This digital flow takes place in a CAD environment and it starts with the creation of the appliance on the optical impression, this design is then exported as an stl extension and is sent to the print service to obtain a solid model of the device through a laser sintering process. This &ldquo, rough&rdquo, device goes through a post-processing procedure, finally, a commercial expansion screw is laser-welded. This expander has all the advantages of a cast-metal Haas-type RME that rests on deciduous teeth, moreover, it has the characteristic of being developed with a completely digitized and individualized process, for the mouth of the young patient, as well as being made completely of cobalt-chrome, thus ensuring greater adaptability and stability in the patient&rsquo, s mouth.

Aim To compare soft tissue dimensional changes and relative differences in soft and hard tissue volumes 4 months after single-tooth extraction and three different treatment modalities: spontaneous healing (SH) and alveolar ridge preservation by means of a deproteinized bovine bone mineral and a collagen matrix, with (IMPL/DBBM/CM) or without (DBBM/CM) immediate implant placement. Materials and methods STL files from study casts obtained at baseline and after 4 months were matched to calculate buccal soft tissue linear and volumetric changes. DICOM files from CBCTs were superimposed to STL files allowing the evaluation of soft tissue thickness at baseline and 4 months. Results Mean horizontal reduction accounted for 1.46 ± 0.20 (SH), 0.85 ± 0.38 (DBBM-CM) and 0.84 ± 0.30 IMPL/DBBM-CM, with no statistical differences. Soft tissue thickness had a significant mean increase of 0.95 for SH group, compared to a non-significant mean decrease for DBBM-CM (0.20) and IMPL/DBBM-CM groups (0.07). Conclusion A preservation technique with DBBM-CM, with or without immediate implant placement, did not reduce the horizontal linear and volumetric changes at the buccal soft tissue profile significantly at 4 months after tooth extraction when compared to spontaneous healing. This is due to a significant increase in soft tissue thickness in spontaneously healing sites.

Biologically oriented preparation technique (BOPT) is a vertical preparation technique without a finish line to create a new anatomic crown with a prosthetic emergence profile. This case report describe the protocol realized digitally in a patient who required a new fixed partial denture (FPD) in the anterior esthetic zone. After time of temporary restoration, definitive conventional (CI) (double-cord retraction and vinyl polysiloxane material), and digital impression (DI) with three different intraoral scanner (IOS) (Trios®, True Definition® and iTero®) were taken. All digital impression were obtained through three different scans: temporary restoration in the mouth after healing period, prepared teeth, and temporary restoration out of the mouth. To establish which of the IOS was the most accurate, it was necessary to compare the STL files obtained from each of the IOS with the STL file of the conventional impression, which was digitized with a laboratory scanner (3Shape D800). All these STL were imported to a software (ExoCAD 2.4 Plovdiv®), and they were superimposed. To establish the difference in trueness with SC, 6 points were chosen, 3 points in teeth, and another 3 points in soft tissue. The mean measurement in terms of trueness in teeth were: STS (0,039 mm), SI (0,054 mm), STD (0,067 mm); and in soft tissue were: STS (0,051 mm), SI (0,09 mm), STD [0,236 mm]. The IOSs showed differences between them in terms of trueness, being the Trios the most accuracy IOS. Final restoration was fabricated and cemented. The patient was examined at 3, 6 and 12 months, without any type of biological or mechanical complications. Digital impression with an IOS seems to be a viable alternative to perform zirconia FPD in the BOPT tecbique. Key words:Intraoral scanners, accuracy, vertical preparation, precision, CAD-CAM, prosthodontics.

Aim. This study aims to evaluate the accuracy of scanned images of 4 clinically used intraoral scanners (CS3600, i500, Trios3, Omnicam) when scanning the surface of full arch models with various kinds of orthodontic brackets in the presence of artificial saliva. Materials and Methods. Four study models were prepared; bonded with ceramic, metal, and resin brackets, respectively, and without brackets. Reference images were taken by scanning the models with an industrial scanner. Study models were then applied with an artificial saliva and scanned 10 times, respectively, with the above 4 intraoral scanners. All images were converted to STL file format and analyzed with 3D analysis software. By superimposing with the reference images, mean maximum discrepancy values and mean discrepancy values were collected and compared. For statistical analysis, two-way ANOVA was used. Results. Omnicam (1.247 ± 0.255) showed higher mean maximum discrepancy values. CS3600 (0.758 ± 0.170), Trios3 (0.854 ± 0.166), and i500 (0.975 ± 0.172) performed relatively favourably. Resin (1.119 ± 0.255) and metal (1.086 ± 0.132) brackets showed higher mean maximum discrepancy values. Nonbracket (0.776 ± 0.250) and ceramic bracket (0.853 ± 0.269) models generally showed lower mean maximum discrepancy values in studied scanners. In mean discrepancy values, the difference between scanners was not statistically significant whereas among brackets, resin bracketed models (0.093 ± 0.142) showed the highest value. Conclusion. Intraoral scanners and brackets had significant influences on the scanned images with application of artificial saliva on the study models. It may be expected to have similar outcomes in an intraoral environment. Some data showed the discrepancy values up to about 1.5 mm that would require more caution in using intraoral scanners for production of detailed appliances and records.

PURPOSE The purpose of the present study was to compare scanning trueness and precision between an abutment impression and a stone model according to dental computer-aided design/computer-aided manufacturing (CAD/CAM) evaluation standards. MATERIALS AND METHODS To evaluate trueness, the abutment impression and stone model were scanned to obtain the first 3-dimensional (3-D) stereolithography (STL) file. Next, the abutment impression or stone model was removed from the scanner and re-fixed on the table; scanning was then repeated so that 11 files were obtained for each scan type. To evaluate precision, the abutment impression or stone model was scanned to obtain the first 3-D STL file. Without moving it, scanning was performed 10 more times, so that 11 files were obtained for each scan type. By superimposing the first scanned STL file onto the other STL files one by one, 10 color-difference maps and reports were obtained; i.e., 10 experimental scans per type. The independent t-test was used to compare root mean square (RMS) data between the groups (α=.05). RESULTS The RMS±SD values of scanning trueness of the abutment impression and stone model were 22.4±4.4 and 17.4±3.5 µm, respectively (P

Statement of the problem: researches studying the accuracy of the 3D printed dies were very rare.Aim: The aim of the current study was to assess the difference in accuracy and reproducibility of the three dimensionally printed dies versus the stone dies.Materials& Methods: A maxillary typodont (D13PP-TR.1; Nissan, Kyoto, Japan) model with missing upper 1st molar was prepared as master model. Two types of dies were obtained from the master model (n=6). Group 1 was the conventional stone dies using type IV stone (GC FujiRock EP; GC) while group 2 representing the 3D printed dies (Dent2 Mogassam LLC Co. Egypt, Cairo) using resin (industrial blended resin, Funtodo Co. Netherlands). All working models were scanned (Open Technologies 3D scanner, Brescia, Italy) and STL file was superimposed on the STL file of the master model with the best-fit alignment method to analyze the volumetric changes and color maps were provided using 3Shape 3D software software. The mean average distance between the master dies and the working dies in all groups was recorded. Data were fed to the computer and analyzed using IBM SPSS software package version 20.0. Quantitative data were explored for normality using Kolmogorov-Smirnov and Shapiro-Wilk tests. Results: There were no statistically significant differences in volumetric discrepancies between stone model (0.186±0.231) mm3 as a (mean±SD) and 3D printed model (0.176±0.211) mm3 as a mean±SD. Conclusion: Digital work flow can eventually replace the conventional techniques with minimal volumetric discrepancies in 3D printed dies.

Purpose Poland’s syndrome patients often seek medical interventions to improve their aesthetic appearances. Design and manufacturing technologies make it possible to produce custom-made implants for such medical conditions. The purpose of this study was to compare the 3D digital geometries that were designed using Magics and Geomagic® Freeform® for two anonymous case studies of Poland’s syndrome patients. Design/methodology/approach Computed tomography data were acquired and processed in Mimics® to isolate the pectoralis muscles in STL file format. STL files were imported into Magics and Geomagic® Freeform® to design 3D digital geometries. Thereafter, comparative analyses were performed of the respective 3D digital geometries. Findings The angle between the vertical and oblique planes for both sides of the thorax was 6.5° for the female and 14° for the male. The surface areas and volumes of the geometries for the female were smaller than the male. Deviation analyses between the healthy side and reconstructed side of a thorax showed that 73 per cent of the test points for Magics and 78 per cent for Geomagic® Freeform® fell in the nominated tolerance region of >−5 and ® Freeform®. Practical implications Geomagic® Freeform® provides a more versatile design environment; however, the STL editor Magics may be an option to design 3D geometries for less intricate and less contoured implants. Originality/value This was a first attempt to compare the 3D geometries for Poland’s syndrome designed with an STL editor to those designed with a computer-aided design program.

Introduction Optimal aesthetic results require suitable smile design that fulfils patient’s expectations. Psychological importance of teeth appearance is clear and often discussed in relation to the success of prosthetic treatment. The objective of this article was to present methodology for creating customized smile design using the Visagismile concept and evaluate aesthetic satisfaction with prosthetic treatment. Case report A 52-year-old female patient required complete esthetical dental mouth reconstruction. Digital planning software (Visagismile) provided dentists and technicians a 2D preview of the final design that relates facial perception and personality of the patient. The latest innovation of used software in addition to documents that dentists send for the Visagismile application is that they need to send an intraoral 3D scan of the patients mouth (with any scanner) and define the length and position of incisal edges of the central incisors. This information as a STL file is sent to new Visagismile/REBEL center that is actually a digital lab, that converts 2D designs created by the Visagismile concept into 3D and create a digital wax up immediately. Conclusions Visagismile concept supports both dentist and patient in deciding the aesthetics of the prosthetic restoration. The total coefficient of the assessment of patients for the final aesthetic result was highly satisfactory. Using the proposed methodology, a smile design corresponding to individual facial features, temperament and personal preferences of the patient can be reproduced.

PURPOSE To measure overall intaglio dimensional and tube deviations of implant guides printed at 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation using a stereolithographic (SLA) printer. MATERIALS AND METHODS A surgical implant guide design from a subject missing a maxillary right central incisor, used as the original standard tessellation language (STL) were stereolithographically fabricated at each thickness and angulation, 50 and 100 µm layer thickness at 0°, 45°, and 90° angulation (n = 10 each group). The guide was then scanned using cone beam computed tomography. The digital imaging and communications in medicine (DICOM) scanned files were then converted to an STL format. The overall dimensional deviations of the intaglio surface and the positioning of the implant guide tube were then superimposed onto the original designed STL file using best-fitting alignment. A t-test and an F-test as well as ANOVA followed by a post hoc t-test were used to determine statistical significant differences (α = 0.05) for the intaglio surface and guide tube deviation, respectively. RESULTS The overall intaglio surface discrepancies (µm) printed at 0°, 45°, and 90° were 55.07 ± 1.36, 52.39 ± 2.09, and 61.02 ± 15.96 for 50 µm layer; and 98.38 ± 10.55, 84.47 ± 10.61, and 90.26 ± 5 for 100 µm layer with statistically significant differences for both t-test and F-test, p < 0.001. The maximal guide tube linear deviations (µm) printed at 0°, 45°, and 90° were 10.78 ± 3.84, 8.16 ± 3.68, and 12.57 ± 5.39 for 50 µm layer (ANOVA, p = 0.096); and 10.95 ± 5.23, 16.79 ± 4.97, and 22.63 ± 2.81 for 100 µm layer (ANOVA, p < 0.001). The maximal guide tube angular deviations (°) printed at 0°, 45°, and 90° were 1.29 ± 0.30, 0.64 ± 0.13, and 0.56 ± 0.21 for 50 µm layer (ANOVA, p < 0.001); and 1.57 ± 0.29, 0.86 ± 0.14, and 1.02 ± 0.31 for 100 µm layer (ANOVA, p = 0.034). There was a statistical difference in the deviations between 50 and 100 µm layer printing in all printed angulations except at 0° (t-test, p = 0.05, p = 0.03, and p = 0.001 for 0°, 45°, and 90°) and linear deviations (t-test, p < 0.001, p = 0.009, and p = 0.001 for 0°, 45°, and 90°). CONCLUSION Printing at 50 µm layer reduces dimensional intaglio deviations in general and reduces tube angular deviations with different angulations of printing. However, the deviations were only ∼60 to 100 µm for the intaglio dimension deviations; and ∼0.04 to 0.26 mm and ∼0.25° to ∼2° for tube deviations.

PURPOSE To quantify the impact of ambient lighting conditions on the accuracy (trueness and precision) of an intraoral scanner (IOS) when maxillary complete-arch and maxillary right quadrant digital scans were performed in a patient. MATERIAL AND METHODS One complete dentate patient was selected. A complete maxillary arch vinyl polysiloxane impression was obtained and poured using Type IV dental stone. The working cast was digitized using a laboratory scanner (E4 Dental Scanner; 3Shape) and the reference standard tessellation language (STL file) was obtained. Two groups were created based on the extension of the maxillary digital scans performed namely complete-arch (CA group) and right quadrant (RQ) groups. The CA and RQ digital scans of the patient were performed using an IOS (TRIOS 3; 3Shape) with 4 lighting conditions chair light (CL), 10 000 lux, room light (RL), 1003 lux, natural light (NL), 500 lux, and no light (ZL), 0 lux. Ten digital scans per group at each ambient light settings (CL, RL, NL, and ZL) were consecutively obtained (n = 10). The STL$_{R}$ file was used to analyze the discrepancy between the digitized working cast and digital scans using MeshLab software. Kruskal-Wallis, one-way ANOVA, and pair-wise comparison were used to analyze the data. RESULTS Significant difference in the trueness and precision values were found across different lighting conditions where RL condition obtained the lowest absolute error compared with the other lighting conditions tested followed by CL, NL, and ZL. On the CA group, RL condition also obtained the best accuracy values, CL and NL conditions performed closely and under ZL condition the mean error presented the highest values. On the RQ group, CL condition presented the lowest absolute error when compared with the other lighting conditions evaluated. A pair-wise multicomparison showed no significant difference between NL and ZL conditions. In all groups, the standard deviation was higher than the mean errors from the control mesh, indicating that the relative precision was low. CONCLUSIONS Light conditions significantly influenced on the scanning accuracy of the IOS evaluated. RL condition obtained the lowest absolute error value of the digital scans performed. The extension of the digital scan was a scanning accuracy influencing factor. The higher the extension of the digital scan performed, the lower the accuracy values obtained. Furthermore, ambient light scanning conditions influenced differently depending on the extension of the digital scans made.

Background: The objective of this study was to digitally evaluate the effect of the cervical emergence of restorations in terms of gingival tissue volume. Materials and methods: In this study, 31 upper front teeth (from canine to canine) were selected and prepared using the biologically oriented preparation technique (BOPT). Each tooth had undergone a change in its provisional process with different emergence profile angles: 30&deg, and 60&deg, Each sample was digitalised (STL file) using an intraoral scanner. By using various pieces of manipulation software for STL files, a volumetric analysis protocol was carried out. Changes in gingival thickness and position were measured at the buccal and the lingual positions. Results: By increasing the angulation of the emergence profile to 60&deg, the gingival thickness increased by 0.255 &plusmn, 0.381 mm (p = 0.001, t-test) at buccal and by 0.038 &plusmn, 0.381 mm at lingual (p = 0.600, t-test). In relation to the gingival height, at buccal, there is an apical displacement of 0.262 &plusmn, 0.246 mm (p = 0.001, t-test), and at lingual, there is an apical displacement of 0.390 &plusmn, 0.279 mm (p = 0.001, t-test). It was shown that an increase in the provisional emergence profile angle significantly diminishes the gingival height while significantly increasing gingival thickness. The Pearson&rsquo, s correlation coefficient, r = 0.636, was moderately high and significant (p = 0.001, Pearson). Conclusions: The soft tissue surrounding the BOPT restored tooth evolved according to the prosthetic emergence angle of the provisional restoration, enabling us to plan for an apico-coronal and bucco-lingual displacement of the gingival tissue prior to the definitive restoration.

Background Effects of length and location of the edentulous area on the accuracy of prosthetic treatment plan incorporation into cone-beam computed tomography (CBCT) scans has not been investigated. Purpose To evaluate the effect of length and location of the edentulous area on the accuracy of prosthetic treatment plan incorporation into CBCT scans using different methods. Material and methods Direct digital scans of a completely dentate master model with removable radiopaque teeth were made using an intraoral scanner, and digital scans of stone duplicates of the master model were made using a laboratory scanner. Specific teeth were removed to simulate different clinical situations and their CBCT scans were made. Surface scans were registered onto the CBCT scans. Radiographic templates for each clinical situation were also fabricated and used during CBCT scans of the master models. Using metrology software, three-dimensional (3D) deviation was measured on standard tesselation language (STL) files created from the CBCT scans against an STL file of the master model created from a CBCT scan. Statistical analysis was done using the MIXED procedure in a statistical software and Tukey HSD test (α =.05). Results The interaction between location and method was significant (P = .009). Location had no significant effect on registration methods (P > .05), but on the radiographic templates (P = .011). Length of the edentulous area did not have any significant effect (P > .05). Conclusions Accuracy of digital image registration methods was similar and higher than that of radiographic templates in all clinical situations. Tooth-bound radiographic templates were significantly more accurate than the free-end templates. The results of this study suggest using image registration instead of radiographic templates when planning dental implants, particularly in free-end situations.

This article reports on techniques used in forensic facial identification with a 3D modeling software system to create a virtual sculpture. In this forensic case study, Free Form Modeling SensAble Technologies and a haptic feedback Phantom® Desktop™ were used to reconstruct the facial features of the deceased from her skull. It was previously C-T scanned and then imported as an STL file under which the work was done. The advantages of the haptic feedback device is that the forensic specialist is able to “feel” the surface of the skull, not only to provide a more accurate assessment of the individual -such as their ancestry, sex and age determination-but also to visualize the process of the Manchester method of forensic facial reconstruction step by step.

From last few years, the development in the area of design and techniques of surgical methods made the surgeons easy to handle the surgeries by reducing the risk of the patient. The main aim of this work is to develop a 3D CAD model of femur bone from CT scan images, which can later be used in 3D printing, the design of implants and replacement of bone. The femur model is developed from 3D Slicer and Blender software. The femur model obtained is saved in STL file format for further processes.

The primary goal of this study was to analyse the anatomic configuration of the acromio-clavicular joint in a healthy population to be able to develop a classification in a second step. On the basis of the primary findings a secondary goal was to find potential clinical indications in refer to AC-joint dislocation and lateral clavicle fractures. The upper thoracic aperture including both shoulder joints as well as both sterno-clavicular joints was retrospectively reformatted in a bone kernel in axial orientation with 0.6 mm slice thickness out of existing multiple trauma or post mortem computed tomography (CT) scans. The DICOM data was converted into the STL file format using a three dimensional (3D) reconstruction software (Smartbrush, Brainlab, Feldkirchen, Germany). The data analysis was performed using a 3D—Computer Aided Detection (CAD) Software (BioCAD, Technical University Munich, Germany). For the analysis, the angle between the cranial surface of the acromion and the tangent to its articular surface was evaluated. Accordingly, the angle between the cranial surface of the clavicle and the tangent to its articular surface was assessed. Overall CT-datasets of 80 healthy patients (40 males, 40 females, mean age 45 ± 8 years) were enrolled and evaluated regarding the configuration of the AC-joint. In this context, three statistically significant (p