ABSTRACT
PURPOSE: To update data on the transfer accuracy of digital implant impressions by using a coordinate-based analysis, latest intraoral scanners (IOSs) were investigated in an established clinical close model set-up. MATERIALS AND METHODS: An implant master model (IMM) of the maxilla with four implants in the posterior area (#14/#24 and #16/#26) and a reference cube was scanned with four different IOS (i700 (Medit), Primescan (Dentsply Sirona), Trios 4 and Trios 5 (3Shape) ten times each. Datasets were compared with a reference dataset of IMM that was generated with x-ray computed tomography in advance. 3D deviations for the implant-abutment-interface points (IAIPs) were calculated. Statistical analysis was performed by multifactorial ANOVA (p < .05). RESULTS: Overall deviations for trueness (mean) ± precision (SD) of the IAIPs ranged from 88±47 µm for the Primescan, followed by 112±57 µm for the i700, 121±42 µm for the Trios 4 and 124±43 µm for the Trios 5 with decreasing accuracy along the scan path. For trueness, one significant difference between the Primescan and the T4 was detected for one implant position. For precision, no significant differences were noticed. CONCLUSIONS: Although the latest IOS showed a significant improvement in transfer accuracy, the accumulating deviation along the scan path is not yet resolved. Considering the Trios system, the innovation seems to be limited as no improvement could be detected between Trios 4 and 5.
ABSTRACT
PURPOSE: A high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations persist between the intraoral implant position and the model obtained, even for the benchmark conventional custom implant impressions with polyether. Thus, new approaches using 3-D printed impression trays may increase the transfer accuracy of implant impressions. The ability to adjust parameters such as the thickness of the layers and the influence of the openings in the impression tray could potentially affect accuracy. METHODS: Four different types of impression trays (n = 10 for each group) for the conventional impression technique were investigated: conventional custom impression tray, customized foil tray, chairside 3-D printed impression tray with the SHERA system, and the Primeprint system using an implant master model with four implants in the posterior region and a reference cube. After plaster model casting, all models were measured using a coordinate measuring machine, and the deviation from the reference dataset was determined. A statistical ANOVA analysis was performed (p < 0.05). RESULTS: Chairside 3-D printed impression trays showed the best results, followed by conventional custom impression trays. Implant impressions obtained using a customized foil tray exhibited the lowest accuracy. Statistically significant differences were observed between 3-D printed impression trays and conventional custom impression and customized foil trays (p < 0.05). Whereas, the implant position did not have any significant influence on accuracy (p > 0.05). CONCLUSIONS: Chairside 3-D printed impression trays significantly increase the transfer accuracy for implant impression taking.
