CEREC Omnicam Research Articles

In vitro evaluation of the accuracy and precision of intraoral and extraoral complete-arch scans

Statement of problemThe accuracy of intraoral and extraoral scanners for different models of edentulousness is unclear. PurposeThe purpose of this in vitro evaluation was to determine the accuracy (trueness and precision) of complete-arch scans made by 3 intraoral and 1 extraoral scanners compared with an industrial 3D scanner. Material and methodsDigital scans were made of a reference cast with 3 intraoral scanners (CEREC Omnicam; Dentsply Sirona, TRIOS 3; 3shape A/S; Carestream CS 3600; Carestream Dental) and an extraoral scanner (Deluxe scanner; Open Technologies). A dental maxilla model was used for tooth preparation for ceramic restorations with a shoulder finishing line. Maxillary right central and lateral incisors and third molar and maxillary left second premolar and first and third molar teeth were removed. One operator scanned the reference cast 10 times with each scanner. All the recorded standard tessellation language (STL) files were imported into an inspection software program and individually overlaid on the STL file for the reference model made by the 3D scanner. The measured distance between the distal point of the maxillary left second molar tooth and the mesial point of the maxillary left first premolar was defined as distance 1; distance 2 was defined as the distance between the mesial point of the maxillary second molar tooth and the distal point of the maxillary right first premolar tooth. The Levene test for homoscedasticity of variances was used to evaluate precision, and a 2-way repeated-measures ANOVA and Bonferroni-corrected Student t tests were used to evaluate trueness (α=.05). ResultsA statistically significant difference was found between the Carestream scanner and the other scanners when scanning both mucosa and teeth. The Carestream scanner had the lowest accuracy and highest magnitude mean deviation of all the scanners. ConclusionsObtaining an accurate partial-arch impression is still challenging for some intraoral scanners. The Carestream scanner’s trueness was outside the acceptable range. However, other scanners tested here appeared to be suitable alternatives to conventional impression techniques.

Three-Dimensional Accuracy of Conventional Versus Digital Complete Arch Implant Impressions.

The accuracy of digital impressions is still controversial for complete arch implant cases. The aim of this study is to compare the accuracy of different intraoral scanners with the conventional technique in terms of trueness and precision in a complete arch implant model. Eight implants were inserted asymmetrically in a polyurethane edentulous mandibular model with different angulations. A 3-dimensional (3D) reference model was obtained by scanning this polyurethane model with an optical scanner. First, digital impressions were made by using 3 different intraoral scanners: Carestream 3500 (DC), Cerec Omnicam (DO) and 3Shape Trios 3 (DT). Subsequently, a nonsplinted open tray impression technique was used for conventional impression group (C) and then the master casts were digitalized with a lab scanner. Each 10 STL files belonging to 4 different impression groups were imported to a reverse engineering program, to measure distance and angle deviations from the reference model. All statistical analyses were performed after taking absolute values of the data. After comparing the impression groups with one-way ANOVA, the trueness and precision values were analyzed by Tukey post hoc test and 0.05 was used as the level of significance. The mean trueness of distance was 123.06 ± 89.83 µm for DC, 229.72 ± 121.34 µm for DO, 209.75± 47.07 µm for DT, and 345.32 ± 75.12 µm for C group (p < 0.0001). While DC showed significantly lower deviation compared to DO and C, no significant difference was found between DC and DT. C showed the highest distance deviation significantly in all groups; and no significant difference was found between DO and DT groups. In angle measurements; the trueness was 0.26° ± 0.07° for DC, 0.53° ± 0.42° for DO, 0.33° ± 0.30° for DT, and 0.74° ± 0.65° for C group. There was no significant difference between the groups in terms of angular trueness (p = 0.074). In terms of the precision for distance, the results of DC 80.43 ± 29.69µm, DO 94.06 ± 69.96 µm, DT 35.55 ± 28.46 µm and C 66.97 ± 36.69 µm were determined (p = 0.036). The significant difference was found only between DT and DO among all groups. Finally, angular precision was determined to be 0.19° ± 0.11° for DC, 0.30° ± 0.28° for DO, 0.22° ± 0.19° for DT, and 0.50° ± 0.38° for Group C. No significant difference was found between the groups, in terms of angular precision (p = 0.053). All digital impression groups yielded superior data compared to conventional technique in terms of trueness. DC formed the impression group with the highest trueness in both distance and angular measurements. The results of this in vitro study suggest the use of intraoral scanners compared to the conventional impression techniques in complete arch implant cases with high angulations.

Accuracy of complete-arch intraoral scans based on confocal microscopy versus optical triangulation: A comparative in vitro study

Statement of problemFully digital dentistry is contingent on an accurate digital scan of the complete arch; however, the dimensional accuracy of different scanners for digitizing a complete arch is unclear. PurposeThe purpose of this in vitro study was to compare the accuracy of 2 intraoral scanners, TRIOS 3 (TR) and CEREC Omnicam (OC). Accuracy was assessed from changes to reference distances defined along the complete arch of a reference cast including 3 precision balls and 3 prepared teeth. The local accuracy (trueness and precision) of the scanned surface of each prepared tooth was also assessed. Material and methodsEach intraoral scanner was used to scan a metal mandibular reference cast 20 times in a randomized sequence. The complete dental arch of a mandible in which the second left premolar was missing contained 2 prepared teeth, the first left premolar (LP) and the first left molar (LM) to accommodate a fixed partial denture (FPD) with complete crowns. The arch also contained an inlay preparation on the right second premolar (RP). Stainless-steel precision balls (ball centers P1, P2, and P3), which were welded onto the left second molar (P1), the incisal contact point of the central incisors (P3), and the right first molar (P2), were used to determine dimensional changes over the complete arch. Powder (CEREC Optispray) was applied to the reference cast to reduce reflections. Deviations between the reference cast (digitized with high precision before the tests) and the intraoral scans were calculated using Matlab R2015a and Geomagic Design X. To evaluate dimensional changes, the centers of the balls were determined, and their absolute changes in distance (ΔP1P2, ΔP1P3, and ΔP2P3) were calculated. To calculate accuracy (trueness and precision) in relation to the prepared teeth, the mesh deviation between the intraoral scans and the superimposed reference teeth was determined. The data were statistically analyzed by using a nonparametric rank-based 2-way repeated-measures ANOVA, and differences in least square means for pairwise comparisons were calculated (α=.05). ResultsThe following mean absolute changes in distance were determined: ΔP1P2, TR: 74.4 μm, OC: 119.6 μm; ΔP1P3, TR: 24.7 μm, OC: 17.2 μm; ΔP2P3, TR: 68.6 μm, OC: 41.2 μm. The scanner did not have a statistically significant effect (P=.118) for distance, and the different distances differed significantly from each other (P<.001). Both scanners provided results acceptable for the fabrication of inlays and short-span FPDs. A complete-crown scan was more accurate than an inlay scan (P<.001). Accuracy and precision were better for TR than for OC (P<.001). ConclusionsWith maximum discrepancies of 192.5 to 294.6 μm across the dental arch, complete-arch scans cannot yet be recommended for the fabrication of long-span FPDs.

Influence of trueness for local finish lines of a full crown preparation on that of complete finish line

Objective To investigate the factors affecting the trueness of finish lines of full crown preparations in digital impressions. Methods A full crown preparation of the right maxillary molar was prepared on the standard resin dentition model, the trueness of the finish lines, the full crown preparation in the whole dentition and the isolated full crown preparation were measured respectively. Detection of scanning trueness of the finish lines of the full crown preparation in the whole dentition: (1) Using Imetric scanner to scan the full crown preparation, obtaining STL (Stereo lithographic) format data as the reference true value; (2) Using CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner to scan the full crown preparation, obtaining all the STL format data, import Geomagic Studio 2013 software, extraction of images and data of the complete finish lines or local finish lines (mesial, distal, buccal, lingual) of the full crown preparation, then using the data to 3D Compare Analysis with the reference true value, outputting RMS (root mean square) values which could evaluate the scanning trueness, the lower RMS value was, the lower the trueness was. The detection of scanning trueness of the finish lines of the isolated full crown preparation: (1) the anterior and posterior adjacent teeth of the preparation were removed to establish the model of the isolated full crown preparation; (2) CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner were used to scan the isolated preparations, and each group was repeated 6 times. Data collection and analysis were the same as the first part, that is, detection of scanning trueness of finish lines of the full crown preparation in the whole dentition. Results In the whole dentition, (1) the RMS value [(44±7) μm] of CEREC Omnicam oral scanner scanning complete finish lines was greater than that of 3Shape TRIOS oral scanner [(35±6) μm](P 0.05). The RMS values of 3Shape TRIOS oral scanner scanning mesial and distal finish lines were significantly higher than those of the buccal and lingual side (P>0.05), in which:(45±8) μm in mesial, (50±10) μm in the distal, (33±8) μm in the buccal and (33±6) μm in the lingual side. The RMS value of CEREC Omnicam oral scanner scanning distal finish line was greater than that of 3Shape TRIOS oral scanner (P 0.05), among which, CEREC Omnicam oral scanner buccal (44±7) μm, lingual (43±3) μm, 3Shape TRIOS oral scanner buccal (29±5) μm, lingual (40±7) μm. The RMS values of CEREC Omnicam oral scanner and 3Shape TRIOS oral scanner were significantly reduced and there was no significant difference between them (P>0.05). CEREC Omnicam oral scanner (32±8) μm and 3Shape TRIOS oral scanner (32±6) μm. The RMS values of the distal finish lines of CEREC Omnicam oral scanner and 3 Shape TRIOS oral scanner also decreased significantly (P 0.05. Conclusion When adjacent teeth exist in the full crown preparation, the mesial and distal parts of the finish line will be blocked by adjacent teeth, which will affect the trueness of the local finish line, and ultimately reduce the trueness of the complete finish line.

Marginal adaptation of different hybrid ceramic inlays after thermal cycling

ABSTRACT The aim of the study was to evaluate the marginal adaptation of various hybrid ceramics inlays before and after thermal cycling. Twenty-four extracted human molars were received inlay preparation, and randomly divided into three groups (n = 8/group). Specimens were restored with Ceramage by experienced technician, Enamic or Lava Ultimate by CAD/CAM using CEREC Omnicam. After cementation, all restorations were subjected to thermal cycling. Marginal gaps were measured under a stereomicroscope. The overall mean marginal gaps of the three groups were significantly different (p < 0.05) before thermal cycling, which were all within the clinically acceptable range. The digital intraoral impression and CAD/CAM systems did not show superior accuracy compared to the traditional technique, during the hybrid ceramic inlays manufactured operation. Thermal cycling had no effect on marginal adaptation of the different hybrid ceramic inlays (p > 0.05). Gingival margin presented larger gaps compared to occlusal and axial margin in all hybrid ceramic inlays.

Does ambient light affect the accuracy and scanning time of intraoral scans?

Statement of problemIntraoral scanners (IOSs) are based on light-optical imaging methods. However, little is known about whether the ambient light in dental practices influences the accuracy and scanning time of the IOS. PurposeThe purpose of this in vitro study was to investigate the influence of different illuminations on the accuracy of 4-unit and complete-arch scans of 6 IOSs. In addition, the required scanning time was evaluated. Material and methodsA reference structure was attached to the first premolars (P) and second molars (M) in both quadrants (L/R) of a maxillary model. The resulting measured distances were M1-P1, M2-P2, P1-P2, and M1-M2. The investigation included 6 IOSs: TRIOS 3 (TRI), Cerec Omnicam (OC), iTero Element (ITE), CS 3600 (CS), Planmeca Emerald (EME), and GC Aadva (AAD). With each IOS, 17 scans at different illuminances (100, 500, 1000, and 5000 lux) were performed (N = 408). The precision and trueness for all distances were determined, and the scanning time was recorded. For statistical analyses, the Levene tests (precision) and 1-way analysis of variance with the post hoc Tukey honestly significant difference and Games-Howell tests (trueness) were calculated. ResultsIlluminance significantly influenced the trueness of 4-unit scans for OC, EME, and AAD. TRI, OC, ITE, and CS demonstrated comparable results. AAD (>96 ±22 μm; 1000 lux) and EME (>248 ±88 μm; 500 lux) revealed greater deviations. For complete-arch scans, illuminance did not influence TRI and AAD, but significant variations were detected for ITE, CS, EME, and AAD. The least deviations were achieved with TRI and OC. The scanning time was extended for all IOSs except ITE at more than 500 lux. The shortest scanning times with OC and EME were recorded at 100 lux; with TRI, CS, and AAD at 500 lux; and with ITE at both 100 and 5000 lux. At all illuminances, the fastest scans were obtained with TRI. ConclusionsAmbient light was found to influence the accuracy and scanning time of IOSs. This influence varies depending on the device. For 4-unit scans, the effect was not clinically relevant, but for complete-arch scans, accuracy and scanning time can be improved with appropriate lighting.

Influence of operator experience, scanner type, and scan size on 3D scans

Statement of problemIntraoral scanners (IOSs) have some inherent distortions caused by optical and/or software imperfections. However, how other factors such as operator experience, scan time, scanner type, and scan size influence scan accuracy is not clear. PurposeThe purpose of this in vitro study was to evaluate the trueness and precision of scans performed by 3 professionals with different levels of experience by using 2 IOSs. Material and methodsThree operators with low, medium, and high levels of experience scanned a master model 10 times by using 2 IOSs (CEREC Omnicam; Dentsply Sirona and TRIOS 3; 3Shape), resulting in 10 standard tessellation language files for each group (N=60). Each standard tessellation language file was divided into 2 areas (prepared teeth and complete arch). Precision was evaluated by comparing the 10 scans from each examiner for each system. Trueness was evaluated by comparing each scan file with a reference scan obtained from a laboratory scanner (D2000; 3Shape). A 3D analysis software program (Geomagic Control; 3D Systems) was used to perform all the comparisons and superimpositions. The 3-way ANOVA test followed by the Tukey HSD test were used to assess precision and trueness. The 2-way ANOVA followed by the Tukey HSD test was used to assess scan time. The Pearson correlation test was performed between scan time and trueness for both scanners. An additional correlation was performed between scan time and number of images, as well as between number of images and trueness for the TRIOS 3. ResultsStatistically significant influences of operator (P<.001), scanner (P<.001), scan size (P<.001), operator and scan size (P<.001), and scanner and scan size (P<.001) were observed. The TRIOS 3 group reported higher precision than the CEREC Omnicam group for complete-arch scans (P<.001), although no difference was observed for scans of the prepared tooth. Medium- (P=.002) and low-experience operators (P<.001) reported lower precision for complete-arch scans performed with CEREC Omnicam when compared with TRIOS 3. The low-experience operator reported significantly worse results for complete-arch scans in comparison with the medium- (P=.008 and P<.001) and high-experience operators (P<.001 and P=.001), by using TRIOS 3 and CEREC Omnicam, respectively. Medium- and high-experience operators reported similar results among themselves. The CEREC Omnicam scanner reported lower trueness for complete-arch scans when compared with the prepared tooth (P<.001); for TRIOS 3, a difference was only observed for the low-experience operator when compared with the high-experience operator (P<.001). The CEREC Omnicam reported lower trueness than the TRIOS 3, except for the medium-experience operator with the prepared tooth scan. Comparing the trueness between operators and considering the same scanner and scan size, all groups were similar. The low-experience operator had a longer scanning time than the medium- and high-experience operators. For TRIOS 3, the low-experience operator obtained the highest number of images during each scan. ConclusionsThe accuracy of intraoral scans was influenced by operator experience, type of IOSs, and scan size. More experienced operators and smaller scan sizes made for more accurate scans. In addition, more experienced operators made faster scans, and the TRIOS 3 was more accurate than the CEREC Omnicam for complete-arch scans.

In vitro comparison of the accuracy of four intraoral scanners and three conventional impression methods for two neighboring implants.

PurposeTo determine whether the accuracy of two-implant model impressions taken with optical scanners was inferior to that of those taken with elastomeric materials.Materials and MethodsImpressions of a resin reference model with two almost parallel implants were taken using three elastomeric impressions (closed tray technique, open tray nonsplinted technique and open tray splinted technique) and scanned with four optical scanners (CEREC Omnicam, 3M True Definition Scanner, 3Shape TRIOS3 and Carestream CS 3600). STL files of the different methods were superimposed and analyzed with control software (Geomagic Control X, 3D systems) to determine the mean deviation between scans.ResultsCompared to elastomeric impressions, optical impressions showed a significantly improved mean precision. TRIOS3 and CS3600 showed a significantly improved mean trueness compared to that of closed tray, CEREC Omnicam and TrueDefinition. All methods showed a certain degree of implant rotation over their axes, which was significantly higher in the closed tray and the open tray nonsplinted techniques.ConclusionsOptical impressions, taken under these in vitro conditions, showed improved accuracy compared with that of elastomeric impressions.

Do “cut out-rescan” procedures have an impact on the accuracy of intraoral digital scans?

Statement of problemThe software programs of digital intraoral scanners typically offers the option to cut out areas from 3D casts, to do rescans, and to merge them with the initial scan. However, evidence of whether this procedure has an impact on the accuracy of the scan is lacking. PurposeThe purpose of this study was to determine whether “cut out-rescan” procedures change the accuracy of a 3D cast. Material and methodsA maxillary master cast was digitized with an industrial structured light scanner to obtain a digital reference cast. This master cast was repeatedly scanned by 3 intraoral scanners: TRIOS 3 [TR], Cerec Primescan [PR], and Cerec Omnicam [OM]. The scan data were duplicated, and the posterior area from the right lateral incisor was cut out and rescanned to obtain complete-arch casts containing the rescanned data [TR_rs], [PR_rs], and [OM_rs]. The trueness and precision of the scans were evaluated by superimposing procedures of the relevant data sets. To evaluate statistical differences, either the Mann-Whitney U test or the t test was used (α=.05). ResultsThe median precision values of the complete-arch scan data was 19 μm for [OM] and [TR], whereas the median for [PR] was 14 μm. In the “cut out-rescanned” data group, the values were 25 μm for [OM_rs], 16 μm for [TR_rs], and 14 μm for [PR_rs]. Statistically significant differences were found among the scanners [OM]/[PR], [OM_rs]/[TR_rs], and [TR_rs]/[PR_rs]. The mean ± standard deviation values of trueness for the complete-arch scan data were 54 ±4 μm for [OM], 42 ±5 μm for [TR], and 30 ±2 μm for [PR]. In the group of the “cut out-rescanned” data, the mean trueness results were 55 ± 6 μm for [OM_rs], 38 ±5 μm for [TR_rs], and 31 ±5 μm for [PR_rs]. Significant differences were found among the complete-arch scan data and the “cut out-rescanned” data of the different scanners, but not between the complete-arch scan data and the “cut out-rescanned” data within one scanning system. ConclusionsSignificant differences were found among the scanners, but “cut out-rescan” procedures did not affect the accuracy within each scanning system.

An in vitro 3D evaluation of the accuracy of 4 intraoral optical scanners on a 6-implant model

Statement of problemAlthough numerous studies have been performed on the accuracy of intraoral scanners, determining the clinical significance of the results is problematic. PurposeThe purpose of this in vitro study was to evaluate the trueness and precision of 4 intraoral optical scanners (IOSs) on a 6-implant model and provide a method to help determine clinical significance. Material and methodsA polymer mandibular edentulous model with 6 hexagonal scan bodies (Ritter) was fabricated, and a control scan was made by using an industrial laser line probe (FARO Edge HD Arm). Four IOSs (True Definition, TRIOS, CEREC Omnicam, Emerald Scanner) were used to scan the same model 5 times: the 20 standard tessellation language (STL) files were individually imported to a 3D inspection software program (Geomagic Control X) and superimposed over the computer-aided design (CAD) control scan. The tolerance was set at a limit of ±0.01 mm. ResultsNone of the tested scanners were true even 10% of the time at the ±0.01-mm tolerance, and the Emerald scanner was true less than 5% of the time. Within scanners, results were precise, showing variations of no more than 2% over repeated scans. When a ±0.05-mm tolerance was selected, the percentage within tolerance increased dramatically. This made the performance of the scanners to appear better but obscured valuable information. The 3D color map was the best method for understanding the data. The color maps showed how much was within tolerance and, equally important, the amount and direction of out of tolerance, providing an easily understandable qualitative and quantitative image. ConclusionsNo statistical or clinical differences were found among the scanners tested. The 3D map was the best method for observing the data.

Assessment of Bioactive Resin-Modified Glass Ionomer Restorative as a New CAD/CAM Material. Part I: Marginal Fitness Study

The objective of this in vitro study was to evaluate and compare the marginal fitness of monolithic crowns fabricated from a newly developed bioactive CAD/CAM resin block and reinforced resin CAD/CAM block pre-and post-cementation with adhesive and self-adhesive resin cements. Bioactive CAD/CAM block were fabricated from ACTIVA BioACTIVE-RESTORATIVE (Pulpdent Corporation, USA) using a clear rectangular Teflon mold. Thirty-two human maxillary first premolar teeth were prepared to receive full crowns then divided into two main groups of 16 teeth each according to the type of block used to fabricate the crowns: Group A: crowns fabricated from the bioactive resin block, Group B: crowns fabricated from reinforced composite block (BRILLIANT Crios, Coltene). Each group was then subdivided into two subgroups according to the type of resin cement used for cementation, Subgroups (A1, B1): RelyX Ultimate cement, Subgroups (A2, B2): ACTIVA BioACTIVE-cement. The prepared teeth were scanned using CEREC Omnicam digital intra-oral and the crowns were then designed using CEREC Premium software (version 4.4.4) and milled using CEREC MC XL milling unit. The marginal gap of each crown was measured before cementation at four points on each tooth surface using a digital microscope at a magnification of 230x. Each crown was then cemented on its respective tooth according to the manufacturers’ instructions of each cement, and the marginal gap was measured again at the same aforementioned points. The results of this study showed that the marginal gap of all groups are below the clinically acceptable limit. Meanwhile, the marginal gap of the crowns fabricated from both block types increased significantly after cementation with both types of cement. Pre-cementation, student’s t-test revealed that there is no statistically significant difference in the marginal gap of crowns fabricated from both block types (p&gt; 0.05). Post-cementation, a statistically highly significant difference was seen between both block types with both types of cement (p&lt;0.01). From the results of this study, the newly developed bioactive resin block seems a promising material for CAD/CAM applications in terms of marginal fitness.

Evaluation of the Precision of Different Intraoral Scanner-Computer Aided Design (CAD) Software Combinations in Digital Dentistry.

BackgroundThe aim of this study was to evaluate the precision of correlation between intraoral scanners and computer aided design (CAD) software programs used during scanning and designing phases of digital dentistry. In the present study, CAD software programs that accept data in Standard Tessellation Language (STL) and proprietary format have been evaluated and data loss has been examined in the scanned data.Material/MethodsA single unit crown preparation was conducted for maxillary right first molar on a fully dentulous model. The prepared tooth was scanned with a high precision industrial scanner (ATOS Core 80) and the reference digital model was obtained. The dental model was further scanned 10 times using 3 different intraoral scanners (CEREC Omnicam AC, TRIOS 3 Color Pod, and Aadva IOS 100). The data obtained from the reference scanner and intraoral scanners were transferred to different CAD programs (CEREC inLab, TRIOS Design Studio, Exocad) and digital crowns were designed for each scanned data-CAD combination. After that, the data losses that occurred between these transfers were evaluated by superimposition technique in a special software (VR Mesh v7.5) (α=0.05).ResultsAmong the all combinations of scanner and software, Omnicam AC-InLab was determined to be the most precise combination through the full digital workflow since the Omnicam AC-Exocad combination showed the highest deviations.ConclusionsWithin the limitations of this in vitro study, it was determined that the combinations of scanners and associated CAD programs yielded more accurate results, and data loss was revealed when the scanned data converted from the proprietary format to the STL format.

Comparison of three-dimensional digital technique with two-dimensional replica method for measuring marginal and internal fit of full coverage restorations.

PURPOSEThis study compared digital (reference point matching) and replica methods for measuring marginal and internal fit of full coverage restorations.MATERIALS AND METHODSA maxillary left first molar typodent was fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model was scanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricated from lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit of each restoration was measured by two examiners using replica and a new digital three-dimensional technique. Reliability between the two methods and two examiners was assessed by correlation and Cronbach's Alpha coefficient (P<.05). A Bland-Altman assessment for agreement was used to compare the two methods.RESULTSBland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap was respectively −1.04 µm, −41.9 µm, and −29.53 µm with limit of agreement (LOA) between −37.26 to 35.18 µm for marginal, −105.85 to 22.05 µm for absolute marginal and −80.52 to 22.02 µm for axial gap. Positive correlation for repeatability (P<.05) in determining marginal and internal gaps by the two examiners in both techniques was revealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α < 0.9).CONCLUSIONBoth measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations, while reference point matching provided higher values in axial and absolute marginal gap assessment.

Evaluation of the Accuracy of Digital Models Obtained Using Intraoral and Extraoral Scanners versus Gold Standard Plaster Model (Diagnostic Accuracy Study)

Introduction: Digital models showed promising results for orthodontic diagnosis and treatment planning. Digital models can be obtained from alginate impressions as well as direct intra-oral scanners. Studies assessing the accuracy of digital models have shown digital models to be valid, clinically acceptable, and more quickly obtainable. With the advent of new scanners with better scanning technology researches are necessary to evaluate their accuracy and reliability. Aim of Study: To evaluate the diagnostic accuracy of 3D digital models obtained through intraoral and extraoral scanning modalities to the reference gold standard plaster model. Material & Methods: Twenty-four adult male and female subjects were randomly selected for this study. The intraoral scanners evaluated in this study were Sirona (CEREC Omnicam) and 3 shape (TRIOS 3), while the laboratory scanners used were Sirona (inEos X5), and 3 shape (D850). Intra-oral scanning of the subjects and extra-oral scanning of their alginate impressions, plaster models of the alginate impression, rubber base impression, and plaster model of their rubber base impression were done. Linear dental measurements included intermolar width, interpremolar width, intercanine width, mesiodistal width of the 1st permanent molar, 1st premolar, canine and central incisor and arch width. All data were collected, tabulated and subjected to statistical analysis. Results: Small differences between the plaster and digital models were observed. Intra-observer reliability analysis for 14 out of the 16 measurements showed that all variables exhibited good to excellent reliability. Conclusions: There was no difference between the digitization using the intraoral scanner or the laboratory scanner. The most accurate digitization technique was the 3 Shape laboratory scanner of the cast of the alginate impression. The inEos X5 showed the highest error of digitization of the alginate and rubber base impressions.

Comparing the accuracy of six intraoral scanners on prepared teeth and effect of scanning sequence.

PURPOSEThe aim of this study was to evaluate the accuracy of six recently introduced intraoral scanners (IOSs) for single crown preparations isolated from the complete arch, and to determine the effect of scanning sequence on accuracy.MATERIALS AND METHODSA complete arch with right and left canine preparations for single crowns was used as a study model. The reference dataset was obtained by scanning the complete arch using a highly accurate industrial scanner (ATOS Core 80, GOM GmbH). Six different IOSs (Trios, iTero, Planmeca Emerald, Cerec Omnicam, Primescan, and Virtuo Vivo) were used to scan the model ten times each. The scans performed with each IOS were divided into two groups, based on whether the scanning sequence started from the right or left quadrant (n=5). The accuracy of digital impression was evaluated using three-dimensional analyzing software (Geomagic Studio 12, 3D Systems). The Kruskal Wallis and Mann-Whitney U statistical tests for trueness analysis and the One-way ANOVA test for precision analysis were performed (α=.05).RESULTSThe trueness and precision values were the lowest with the Primescan (25 and 10 µm), followed by Trios (40.5 and 11 µm), Omnicam (41.5 µm and 18 µm), Virtuo Vivo (52 and 37 µm), iTero (70 and 12 µm) and Emerald (73.5 and 60 µm). Regarding trueness, iTero showed more deviation when scanning started from the right (P=.009).CONCLUSIONThe accuracy of digital impressions varied depending on the IOS and scanning sequence used. Primescan had the highest accuracy, while Emerald showed the most deviation in accuracy for single crown preparations.

Confocal 3D Optical Intraoral Scanners and Comparison of Image Capturing Accuracy

Several capture techniques are used in intraoral optical scanners in the dental market, such as Triangulation (Cerec Omnicam, Dentsply Sirona), Activewave front sampling (3M ESPE) and confocal technology (iTero, Align). The accuracy of intraoral scanners is the most significant focal point for developers to research. This in-vitro study studied the accuracy of confocal scanners launched from 2015-2020 (Trios 3, Trios 4, iTero Element; 3Shape Trios A/S, Copenhagen, Denmark, and iTero Element2, and iTero Element5D; Align Technologies, San Jose, CA, USA). A 3D printing model modified from the American National Standard No. 132 was scanned five times each scanner. Both Trios3 and Trios4 were scanned using regular scan mode (N) and high-resolution mode (HR). All scanning methods followed the recommendations from the manufacturers. Then the digital models were exported and saved as STL files. Various measurements were determined in the digital model from each scan using Rhinoceros 3D Software (Rhino, Robert McNeel & Associates for Windows, Washington DC, USA). Measurements from the 3D printed model were used as control. All data were recorded in Microsoft Excel and then transferred to SPSS. Descriptive statistics were recorded. Multiple comparisons of various measurements were made among the different scanners and with the control using One-way ANOVA and post hoc using Sheffe (p < 0.01). The surface area in the X and Y axis ranged from 2–60 mm, while the depth (Z-axis) ranged from 2–8 mm. The Trios and iTero families showed similar accuracy. However, for the diagonal, the Trios series showed better results compared with the iTero series. Within the same brand, different versions showed no significant change regarding accuracy.

Comparison of Digital and Conventional Impression Methods by Preclinical Students: Efficiency and Future Expectations.

ABSTRACTAims and Objectives:The purpose of this study is to compare digital and conventional impression methods by preclinical students in terms of time and ease and to evaluate their preferences and future expectations.Materials and Methods:Twenty volunteered, 2nd year preclinical students (11 females and 9 males) participated in this study. Students took digital and conventional impressions of the left lower first molar which was made full ceramic crown preparation and opposite full arch from a typodont model (Frasaco, Frasaco GmbH, Tettnang, Germany). They used intraoral scanner (CEREC Omnicam, Sirona Dental GmbH, Bensheim, Germany) for digital impression and also used additional type (Express XT Penta H, 3M ESPE, Seefeld, Germany) and condensation type (Zetaplus, Zhermack SpA, Badia Polesine, Italy) silicones for conventional impression. Their taking impression time was measured. Before taking impression and after taking impression, two kinds of questionnaires were conducted to students about their preference, ease of impression methods, and their future expectations. Statistical analysis was performed by IBM SPSS 23 and Excel 2010 version. Differences between conventional and digital impression in terms of time were analyzed by student’s-t paired test and effect of gender was analyzed by students’s-t independent test.Results:There were statistically significant differences between digital and conventional impression methods in terms of taking impression and total impression time (P < 0.001). But there wasn’t any statistically significant difference between two methods in terms of preparation time. About 85% of students preferred the digital impression method and also 85% of students found that the digital impression method was easy. 95% of students expected to find intraoral scanner in the clinic where working first time.Conclusions:As a result of this study, it has been seen that the students preferred the digital impression method to the conventional impression method and found that the digital impression method was easier.

How adjustment could affect internal and marginal adaptation of CAD/CAM crowns made with different materials.

PURPOSERecently introduced hybrid and reinforced glass ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) materials have been used for full-coverage restorations. However; the effect of adjustment and type of materials on internal and marginal adaptation are unknown. This study aimed to evaluate and compare the marginal and internal adaptations of crowns made of three different CAD/CAM materials before and after adjustment.MATERIALS AND METHODSOne acrylic resin maxillary first molar was prepared and served as the master die. Thirty-six restorations were fabricated using CAD/CAM system (CEREC Omnicam, MCXL) with three materials including lithium disilicate (IPS e.max CAD), zirconia-reinforced lithium silicate (Suprinity), and hybrid ceramic (Enamic). Internal and marginal adaptations were evaluated with the reference point matching technique before and after adjustment. The data were analyzed using mixed ANOVA considering α=.05 as the significance level.RESULTSThe effect of adjustment and its interaction with the restoration material were significant for marginal, absolute marginal, and occlusal discrepancies (P<.05). Before adjustment, Suprinity had lower marginal discrepancies than IPS e.max CAD (P=.18) and Enamic (P=.021); though no significant differences existed after adjustment.CONCLUSIONWithin the limitations of this study, crowns fabricated from IPS e.max CAD and Suprinity resulted in slightly better adaptation compared with Enamic crowns before adjustment. However, marginal, axial, and occlusal discrepancies were similar among all materials after the adjustment.

Local accuracy of actual intraoral scanning systems for single-tooth preparations in vitro

BackgroundThe authors evaluated the local accuracy of intraoral scanning (IOS) systems for single-tooth preparation impressions with an in vitro setup. MethodsThe authors digitized a mandibular complete-arch model with 2 full-contour crowns and 2 multisurface inlay preparations with a highly accurate reference scanner. Teeth were made from zirconia-reinforced glass ceramic material to simulate toothlike optical behavior. Impressions were obtained either conventionally (PRESIDENT, Coltène) or digitally using the IOS systems TRIOS 3 and TRIOS 3 using insane scan speed mode (3Shape), Medit i500, Version 1.2.1 (Medit), iTero Element 2, Version 1.7 (Align Technology), CS 3600, Version 3.1.0 (Carestream Dental), CEREC Omnicam, Version 4.6.1, CEREC Omnicam, Version 5.0.0, and Primescan (Dentsply Sirona). Impressions were repeated 10 times per test group. Conventional (CO) impressions were poured with type IV gypsum and digitized with a laboratory scanner. The authors evaluated trueness and precision for preparation margin (MA) and preparation surface (SU) using 3-dimensional superimposition and 3-dimensional difference analysis method using (95% – 5%) / 2 percentile values. Statistical analysis was performed using Kruskal-Wallis test. Results were presented as median (interquartile range) values in micrometers. ResultsThe authors found statistically significant differences for MA and SU among different test groups for both trueness and precision (P < .05). Median (interquartile range) trueness values ranged from 11.8 (2.0) μm (CO) up to 40.5 (10.9) μm (CEREC Omnicam, Version 5.0.0) for SU parameter and from 17.7 (2.6) μm (CO) up to 55.9 (15.5) μm (CEREC Omnicam, Version 5.0.0) for MA parameter. ConclusionsIOS systems differ in terms of local accuracy. Preparation MA had higher deviations compared with preparation SU for all test groups. Practical implicationsTrueness and precision values for both MA and SU of single-unit preparations are equal or close to CO impression for several IOS systems.

Intraoral digital scans: Part 2—influence of ambient scanning light conditions on the mesh quality of different intraoral scanners

Statement of problemDigital scans should be able to accurately reproduce the different complex geometries of the patient's mouth. Mesh quality of the digitized mouth is an important factor that influences the capabilities of the geometry reproduction of an intraoral scanner (IOS). However, the mesh quality capabilities of IOSs and the relationship with different ambient light scanning conditions are unclear. PurposeThe purpose of this in vitro study was to measure the impact of various light conditions on the mesh quality of different IOSs. Material and methodsThree 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 made of a mandibular typodont. The mesh quality of digital scans was analyzed by using the iso2mesh MATLAB package. Two-way ANOVA and Kruskal-Wallis 1-way ANOVA statistical tests were used to analyze the data (á=.05). ResultsSignificant differences in mesh quality values were found among the different IOSs under the same lighting conditions and among the different lighting conditions using the same IOS. TRIOS 3 showed the highest consistency and mesh quality mean values across all scanning lighting conditions tested. CEREC Omnicam had the lowest mean mesh quality values across all scanning lighting conditions. iTero Element displayed some consistency in the mesh quality values depending on the scanning lighting conditions: chair light and room light conditions presented good consistency in mesh quality, indicating better mesh quality, and natural light and no light conditions displayed differing consistency in mesh quality values. Nevertheless, no light condition led to the minimal mean mesh quality across all IOS groups. ConclusionsDifferences in the mesh quality between different IOSs should be expected. The photographic scanning techniques evaluated presented higher mesh quality mean values than the video-based scanning technology tested. Moreover, changes in lighting condition significantly affect mesh quality. TRIOS 3 showed the highest consistency in terms of the mean mesh quality, indicating better photographic system in comparison with iTero Element.