Objective: This study aimed to compare the marginal gap values of prefabricated zirconia and resin crowns fabricated using different three-dimensional (3D) printing technologies for primary molars using a 3D digital analysis method. Materials and Methods: Forty crowns (n = 10/group) were evaluated, including prefabricated zirconia crowns (NuSmile) and three resin crown systems fabricated using different additive manufacturing technologies: Crowntec (Saremco, DLP), Permanent Crown Resin (Formlabs, SLA), and Graphy TC-80DP (MSLA). All restorations were cemented with self-adhesive resin cement. The specimens were scanned before and after cementation, and the obtained STL datasets were superimposed using the Geomagic Control X software. Marginal gap values were calculated using three-dimensional (3D) digital analysis. Data were analyzed using one-way ANOVA and Games–Howell post hoc tests (α = 0.05). Results: The mean marginal gap values differed among the groups. The lowest marginal gap value was observed in the Formlabs group (113.22 ± 1.94 µm), followed by that of the Saremco group (118.54 ± 1.58 µm). Higher marginal gap values were recorded in the Graphy group (134.23 ± 2.16 µm), whereas the highest value was observed in the prefabricated zirconia crown group (163.14 ± 3.95 µm). Statistically significant differences were observed among all groups (p < 0.001), with all 3D-printed resin crown systems exhibiting lower marginal gap values than the prefabricated zirconia crowns. Conclusions: Within the limitations of this in vitro study, 3D-printed resin crowns exhibited superior marginal adaptation compared to prefabricated zirconia crowns. Among the evaluated materials, the SLA-fabricated Formlabs crowns exhibited the lowest marginal gap values. All tested resin crown systems demonstrated marginal gap values within clinically acceptable limits.
Background Achieving a passive and accurate fit in full-arch implant-supported prostheses remains a significant challenge in digital dentistry. Intraoral scan bodies (ISBs) are essential components for transferring implant positions digitally. However, variations in ISB material, geometry, and height may influence the accuracy and precision of intraoral scans. This study aimed to evaluate how different ISB designs affect the trueness and precision of digital impressions in a completely edentulous maxillary arch with multiple implants. Methods An in vitro model with 8 implants was scanned using the Primescan intraoral scanner. Five ISB configurations were tested: four from different manufacturers (ELOS, GT Medical, ZIACOM, and 3Shape) and a fifth mixed group with alternating ISBs. A coordinate measuring machine (CMM) was used as the reference standard. Accuracy was assessed through linear (Euclidean distance) and angular (relative angulation) measurements. Statistical comparisons included ANOVA, pairwise analysis, and multivariate regression. Results Significant differences were found among ISBs in both trueness and precision. ZIACOM showed the best precision overall, particularly in repeated linear (21 ± 16 μm) and angular measurements (0.102± 0.081 degrees), while ELOS displayed the lowest deviation in linear distance (40 ± 33 μm). The mixed ISB group yielded the highest variability and the most extreme errors. Although mean values were within clinically acceptable limits, maximum deviations reached 223 µm and 1.2°, potentially compromising passive fit. Conclusions ISB selection significantly affects the accuracy and reproducibility of intraoral scans in full-arch implant scenarios. Using a consistent ISB system is recommended, as mixing components from different manufacturers may increase variability and compromise the reliability of digital impressions in complex rehabilitations.
OBJECTIVES To evaluate the effect of restoration span on scanner-related restoration fit obtained with six intraoral scanners and one dental laboratory scanner. METHODS A maxillary resin model with eight abutments was scanned with an ATOSQ reference scanner and subsequently with the Aoralscan Elite, Mediti900, Primescan2, R2i3, RunyesV6, and TRIOS6 intraoral scanners, and the AutoScan-DSEXPro(H) laboratory scanner (n=12 per test scanner). Complete-arch, four-unit bridge, and single-unit restorations were digitally designed. The designed restoration meshes were superimposed on the reference scan using a virtual-fit approach. Marginal gap (MG) and absolute marginal discrepancy (AMD) were calculated for each scanner in the metrology software. Statistical analysis was performed using generalized linear mixed models. RESULTS Mean MG ranged from 15-30 µm for single crowns, 16-44 µm for bridges, and 37-91 µm for complete-arch restorations. MG was significantly higher for bridges than for single crowns for all scanners except AutoScan-DSEXPro(H) and Aoralscan Elite. Complete-arch restorations showed significantly higher MG and AMD than bridges for all scanners, although mean MG remained below the clinically derived, model-based threshold of 100 µm. However, several R2i3 and TRIOS6 scans exceeded this MG threshold. Mean AMD exceeded the threshold for RunyesV6, R2i3, and TRIOS6 in complete-arch restorations. CONCLUSIONS Restoration span is a critical determinant of scanning accuracy, particularly when moving from four-unit bridges to complete-arch restorations, even for the laboratory scanner. The virtual-fit method enables robust, clinically interpretable comparison of scanner accuracy across restoration types. CLINICAL SIGNIFICANCE Intraoral scanner selection should consider the intended restoration span. While all evaluated scanners performed well for short-span restorations, only some maintained high accuracy for complete-arch tooth-borne restorations. Because these findings are based on an in vitro study, scanners with lower complete-arch accuracy should be used with caution in clinical practice.
Purpose: Digital impression techniques in dentistry have emerged as a precise alternative to conventional methods. The accuracy of this process depends on multiple factors, including the design and material of the scan body, the type of scanner used, and the implant conditions. Materials and Methods: Four types of scan bodies from Dentis, Dentium, Dio, and Novodent were evaluated across 40 samples (10 per group). A reference model was first obtained with an industrial scanner (T-SCAN Hawk 2), and the samples were then scanned with an itraoral scanner (Medit i700). The resualting STL files were aligned in 3-Matic, and geometric deviations from the reference model were measured using the Best-Fit Alignment algorithm. Data were analyzed in SPSS (version 27) using one-way ANOVA with Turkey’s post hoc test, with significance set at 0.05. Results: The mean and standard deviation of Root Mean Square Eror (RMSE) were calculated for four scan bodies: Dentis, Dentinum, Dio, and Novodent. The reference group, Dentis, had a mean RMSE of 0.21± 0.10. Dentium showed a similar RMSE (0.21±0.08), indicating comparable accuracy to Dentis (P˃0.05). In contrast, Dio and Novodent showed lower RMSE values (0.14±0.02 and 0.15±0.06, respectively), indicating higher accuracy, although the differences were not statistically were not statistically significant (P˃0.05). Conclusion: The type of scan body did not significantly affect the accuracy of digital impressions for bone-level implants (P˃0.05).