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    Comparison of intraoral and laboratory scanners to an industrial-grade scanner while analyzing the fabrication trueness of polymer and titanium complete-arch implant-supported frameworks
    (Elsevier Sci Ltd, 2023) Yilmaz, Burak; Dede, Dogu Omur; Donmez, Mustafa Borga; Kucukekenci, Ahmet Serkan; Lu, Wei-En; Schumacher, Fernanda Lang; Cakmak, Gulce
    Objectives: To compare the scans of different intraoral scanners (IOSs) and laboratory scanners (LBSs) to those of an industrial-grade optical scanner by measuring deviations of complete-arch implant-supported frameworks from their virtual design file. Material and methods: Ten polyetheretherketone (PEEK) and 10 titanium (Ti) complete-arch implant-supported frameworks were milled from a master standard tessellation language (STL) file. An industrial-grade blue light scanner (AT), 2 LBSs (MT and E4), and 3 IOSs (PS, T3, and T4) were used to generate STL files of these frameworks. All STLs were imported into an analysis software (Geomagic Control X) and overall root mean square (RMS) values were calculated. Marginal surfaces of all STL files were then virtually isolated (Medit Link v 2.4.4) and marginal RMS values were calculated. Deviations in scans of tested scanners were compared with those in scans of AT by using a linear mixed effects model (alpha = 0.05). Results: When the scans of PEEK frameworks were considered, PS and T3 had similar overall RMS to those of AT (p >= .076). However, E4 and T4 had higher and MT had lower overall RMS than AT (p <= .002) with a maximum estimated mean difference of 13.41 mu m. When the scans of Ti frameworks were considered, AT had significantly lower overall RMS than tested scanners (p <= .010) with a maximum estimated mean difference of 31.35 mu m. Scans of tested scanners led to significantly higher marginal RMS than scans of AT (p <= .006) with a maximum estimated mean difference of 53.90 mu m for PEEK and 40.50 mu m for Ti frameworks. Conclusion: Only the PEEK framework scans of PS and T3 led to similar overall deviations to those of AT. However, scans of all tested scanners resulted in higher marginal deviations than those of AT scans. Clinical Significance: Scans performed by using PS and T3 may be alternatives to those of tested reference industrial scanner AT, for the overall fabrication trueness analysis of complete-arch implant-supported PEEK frameworks.
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    Comparison of measured deviations in digital implant scans depending on software and operator
    (Elsevier, 2022) Çakmak, Gülce; Marques, Vinicius Rizzo; Dönmez, Mustafa Borga; Lu, Wei-En; Abou-Ayash, Samir; Yılmaz, Burak
    Objectives: To investigate the effect of 3-dimensional (3D) analysis software and operator on the measured deviations in implant scans. Material and Methods: A combined healing abutment-scan body (CHA-SB) system was digitized with an industrial scanner (ATOS Core 80) to generate a master standard tessellation language file (MRM-STL) and an intraoral scanner (TRIOS 3) to generate 9 test-scan STL files, which were transferred into metrology-grade (Geomagic Control X, GX and GOM Inspect, GM) and nonmetrology-grade (Medit Link, ML) software for deviation analysis. Test-scan STLs were superimposed over MRM-STL and 2 planes passing through the center of the SB were generated. Distance deviations at 8 points on these planes were analyzed by two different operators with similar level of experience. Data were analyzed with analysis of variance and F tests (?=.05). Results: Only model 1 (P=.049) analyzed by operator 2 showed significant differences among tested software, and the highest deviations were measured with GM (P?.037). However, the difference in values measured with GX and ML was nonsignificant (P=.91). Operator correlation was high (ICC?.712, P?.011), except for models 1 (GM, ICC=-.335, P=.813), 2 (GM, ICC=.025, P=.468 and ML, ICC=-.013, P=.507), 6 (GM, ICC=-.085, P=.583), and 8 (GM, ICC=-.386, P=.85). Conclusion: The measured deviations in implant scans in all models, except for one, were similar among the tested software, regardless of the operator. The inter-rater reliability of operators while using tested 3D analysis software was overall high. When observed, low inter-rater reliability was mostly with only one of the metrology grade software. Clinical Significance: Nonmetrology-grade 3D analysis software may be a suitable alternative to metrology-grade software to measure the deviations in digital implant scan body scans. When GOM metrology-software is used, measured deviations in implant scan body scans may vary more across operators. © 2022
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    Effect of printing layer thickness on the trueness of 3-unit interim fixed partial dentures
    (Elsevier Science, 2022) Çakmak, Gülce; Cuellar, Alfonso Rodriguez; Dönmez, Mustafa Borga; Abou-Ayash, Samir; Lu, Wei-En; Schimmel, Martin; Yılmaz, Burak
    Statement of problem. Three-dimensional printing has facilitated the fabrication processes in dentistry. However, knowledge on the effect of layer thickness on the trueness of 3D-printed fixed partial dentures (FPDs) is lacking. Purpose. The purpose of this in vitro study was to compare the effect of printing layer thickness on the trueness of 3-unit interim FPDs fabricated by using additive manufacturing with that of those fabricated by subtractive manufacturing. Material and methods. The right first premolar and first molar teeth of a dentate mandibular model were prepared for a 3-unit restoration and then digitized by using an intraoral scanner. A 3-unit interim FPD was designed to fabricate 40 restorations by using either the additive (NextDent C&B MFH) with layer thicknesses of 20 mm (n=10), 50 mm (n=10), and 100 mm (n=10) or subtractive manufacturing technique (Upcera) (milled, n=10). After fabrication, the interim FPDs were digitized by using the same intraoral scanner and were superimposed over the design data by using a 3D analysis software program. Root mean square (RMS) was used to analyze the trueness of the restorations at 4 different surfaces (external, intaglio, marginal area, and intaglio occlusal) and as a complete unit (overall). Data were analyzed with the Kruskal-Wallis and Wilcoxon tests with Bonferroni correction (a=.05). Results. The 100-mm-layer thickness interim FPDs showed the greatest overall (P .015), external (P .021), and intaglio occlusal (P .021) deviations, whereas the milled interim FPDs showed the lowest (P=.001). No significant differences were found among the test groups for marginal RMS (P .108). The differences between the 50-mm-layer thickness and 100-mm-layer thickness interim FPDs for the intaglio surface deviations (P=.064) and between the 20-mm-layer thickness and 50- mm-layer thickness interim FPDs for each surface tested were not statistically significant (P .108). Conclusions. The printing layer thickness had a significant effect on the trueness of the additively manufactured interim FPDs. However, subtractively manufactured interim FPDs presented higher trueness than those additively manufactured, regardless of the printing layer thickness. (J Pros- thet Dent 2022;-:---)
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    Effect of scan powder and scanning technology on measured deviations of complete-arch implant supported frameworks digitized with industrial and intraoral scanners
    (Elsevier Sci Ltd, 2023) Donmez, Mustafa Borga; Cakmak, Gulce; Dede, Dogu Omur; Kucukekenci, Ahmet Serkan; Lu, Wei-En; Schumacher, Fernanda Lang; Revilla-Leon, Marta
    Objectives: To evaluate the suitability of intraoral scanners (IOSs) to analyze the fabrication trueness of titanium complete-arch implant-supported frameworks by comparing with an industrial-grade scanner and investigate how anti-reflective scan powder affects measured deviations.Methods: Ten titanium complete-arch implant-supported frameworks were milled from a reference standard tessellation language (STL) file. An industrial-grade blue light scanner (ATOS Core 80 (AT)) and three IOSs (Primescan (PS), TRIOS T3 (T3), and TRIOS T4 (T4)) with (PS-P, T3-P, and T4-P) or without (PS, T3, and T4) anti-reflective scan powder application were used to generate test STL (TSTL) files of the frameworks. Reference STL and TSTLs were imported into a metrology-grade analysis software (Geomagic Control X) and whole surface root mean square (RMS) values were calculated. Another software (Medit Link v 2.4.4) was used to virtually isolate marginal surfaces of all STL files and marginal RMS values were calculated by using the same metrologygrade analysis software. A linear mixed effects model was used to compare the transformed deviations of the scans performed by using each IOS (with or without powder) with the deviations of those performed by using the reference AT scanner within each surface, where a Box-Cox type transformation was used for variance stability. Bonferroni corrected post-hoc tests were used to compare conditions within each IOS (alpha=0.05).Results: All IOSs had significantly higher whole surface and marginal RMS values than AT, regardless of the condition (P <=.002). However, scan powder application did not affect the whole surface and marginal RMS values in scans of tested IOSs (P >=.054).Conclusion: Measured whole surface and marginal deviations in all IOS scans performed with or without the use of scan powder were higher than those in AT scans. The application of anti-reflective scan powder did not affect the deviations in scans of tested IOSs.Clinical Significance: Even though deviations measured in the scans of tested scanners were significantly different than those in the reference scanner, the maximum raw mean difference was 37.33 mu m and the maximum raw confidence interval value of estimated differences was 47.88 mu m, which can be considered clinically small taking into account the size of the frameworks tested. Therefore, tested intraoral scanners may be feasible to scan prostheses similar to or smaller than tested frameworks for fabrication trueness analysis, which may facilitate potential clinical adjustments.