Browsing by Author "Fehmer, Vincent"
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- Effect of splinting scan bodies on the trueness of complete-arch digital implant scans with 5 different intraoral scannersPublication . Azevedo, Luís; Marques, Tiago; Karasan, Duygu; Fehmer, Vincent; Sailer, Irena; Correia, André; Gómez-Polo, MiguelStatement of problem: The absence of fixed reference points can affect the trueness of complete-arch intraoral digital implant scans. The effect of splinting intraoral scan bodies (ISBs) or the inclusion of artificial landmarks (AL) on the trueness of complete-arch digital implant scans is still unclear. Purpose: The purpose of this study was to analyze the effect of splinting ISBs or the inclusion of AL on the trueness of complete-arch digital implant scans with 5 intraoral scanners (IOSs). Material and methods: Six tissue-level dental implants (Straumann Tissue Level) were placed in an edentulous patient, and the correspondent definitive cast was digitized with a desktop scanner (IScan4D LS3i) to obtain the reference digital cast. Digital scans (n=10) were performed with 5 IOSs: TRIOS 4, Virtuo Vivo, Medit i700, iTero Element 5D, and Cerec Primescan. Three different scanning techniques were evaluated: conventional (cIOSs), splinted (sIOSs), and AL (AL-IOSs). The scan data obtained were imported into a metrology software program and superimposed to the reference digital cast by using a best-fit algorithm. The overall deviations of the positions of the ISBs were evaluated by using the root-mean-square (RMS) error (α=.05). Results: The mean ±standard deviation trueness values for the cIOSs, sIOSs, and AL-IOSs groups were 48 ±8 µm, 53 ±7 µm, and 49 ±11 µm, respectively, with no statistically significant differences (P=.06). Significant differences were found for the IOSs used with each technique (P<.001). Primescan (27 ±4 µm cIOSs; 28 ±3 µm sIOSs; 31 ±3 µm AL-IOSs) showed significantly higher trueness than iTero 5D (47 ±5 µm cIOSs; 47 ±4 µm sIOSs; 50 ±6 µm AL-IOSs) (P=.002) and TRIOS 4 (93 ±18 µm cIOSs; 76 ±18 µm sIOSs; 107 ±13 µm AL-IOSs) (P=.001) for all techniques. In addition, no significant differences were found between the techniques by using iTero 5D or Primescan (P=.348 and P=.059, respectively). Conclusions: The cIOSs, sIOSs, and AL-IOSs techniques showed similar trueness. The IOS used influenced the trueness of complete-arch digital implant scans.
- Influence of horizontal intraoral scan bodies on the trueness of digital impressions for complete-arch prostheses on four implants: an in vitro evaluationPublication . Laureti, Andrea; Marques, Tiago; Pitta, João; Fehmer, Vincent; Sailer, Irena; Pozzi, Alessandro; Azevedo, LuísObjective: To assess the impact of horizontal intraoral scan bodies (H-ISBs) on the trueness of complete-arch digital impressions compared to vertical ISBs (V-ISBs). To evaluate trueness among four intraoral scanners (IOS) and inter-operator variability across different ISB × IOS combinations. Materials and Methods: Digital impressions were made from a dental cast with four multi-unit analogs using four H-ISBs: H-NB, H-NS, H-M6, H-SF, and a V-ISB (V-EA) as a comparison. Two operators performed 10 scans per ISB with four IOS devices (i5D, PS, T3, T4), generating 400 impressions. Reference scans were obtained with a desktop scanner, and trueness was analyzed using root-mean-square (RMS) error calculations (? = 0.05). Results: H-NS and H-SF exhibited the highest trueness across IOSs, whereas H-NB and H-M6 showed lower trueness. V-EA outperformed H-NB and H-M6 but not H-NS and H-SF. Significant IOS-ISB interaction effects (p < 0.01) indicated H-SF as the most accurate, especially with PS. T4 and i5D displayed greater variability, particularly with H-NB. V-ISBs exhibited higher inter-operator variability compared to H-ISBs. Conclusions: H-ISBs did not perform better than V-ISBs in all scenarios. The interactions among ISB design, IOS type, and operator significantly affect the digital impression trueness. The discrepancies measured among the systems remain well below the currently accepted threshold for clinically relevant misfit, supporting the suitability of the horizontal configuration for complete-arch impressions.
- Intra oral photogrammetry: trueness evaluation of novel technology for implant complete-arch digital impression in vitroPublication . Pozzi, Alessandro; Laureti, Andrea; Tawil, Isaac; Chow, James; Azevedo, Luis; Fehmer, Vincent; Sailer, IrenaObjectives: To investigate the trueness of intraoral photogrammetry (IPG) technology for complete-arch implant digital impression and evaluate the effect of implant number. Material and Methods: All data were fully anonymized in compliance with ethical standards, and a total of 30 complete-arch patient models with 4 (n = 13), 5 (n = 9), or 6 (n = 8) implants were selected from the archive. Digital impressions were taken with IPG and a desktop scanner. Test and reference standard tessellation language (STL) files were superimposed using a best-fit algorithm. For each implant position, mean linear (ΔX, ΔY, ΔZ axes) and angular deviations (ΔANGLE) and three-dimensional (3D) Euclidean distances (ΔEUC) were measured as primary outcomes with a dedicated software program (Hyper Cad S, Cam HyperMill, Open Mind Technologies) and reported as descriptive statistics. Secondary aim was to determine using linear mixed models whether implant number affected trueness. All statistical analyses were conducted using Stata 18 (Stata Corp, College Station) and significance was set at 0.05. Results: A total of 30 definitive casts with 4 (n = 13), 5 (n = 8), and 6 (n = 9) multi-unit abutment (MUA) analogs were analyzed (n = 146 implant positions). The mean deviations along the X-axis were −3.97 ± 32.8 μm, while along the Y-axis, they were −1.97 ± 25.03 μm. For the Z-axis, a greater deviation of −33 ± 34.77 μm was observed. The 3D Euclidean distance deviation measured 57.22 ± 27.41 μm, and the angular deviation was 0.26° ± 0.19°. Statistically significant deviations were experienced for ΔZ, ΔEUC, and ΔANGLE (p < 0.01). Additionally, the number of implants had a statistically significant effect only on the Z-axis deviation (p = 0.03). Conclusions: Within study limitations, IPG technology was feasible for complete-arch digital implant impression with mean linear, angular, and 3D deviations far below the acceptable range for a passive fit. Reported IPG trueness might avoid a rigid prototype try-in. The implant number had no influence on trueness except for Z-axis deviations. Integrating photogrammetry with intraoral optical scanning (IOS) improved practicality, optimizing the digital workflow. Further clinical trials are needed to confirm these findings.