Accuracy of Implant Position Reproduction According to Exposed Length of the Scan Body during Optical Scanning: An In Vitro Study

Effect of different surface locking patterns on the trueness of complete arch digital implant scans: An in vitro study

STATEMENT OF PROBLEM

The effect of different surface locking patterns on the trueness of a digital implant scan of a completely edentulous arch remains uncertain.

PURPOSE

The purpose of this in vitro study was to evaluate whether locking surfaces with different patterns affected the trueness of complete arch implant digital scans.

MATERIAL AND METHODS

An edentulous maxillary cast with 4 implants (2 anterior implants parallel and 2 posterior implants tilted at 17 degrees) was fabricated. Four implant-level scan bodies were fixed onto the implants, and the cast was scanned with a desktop scanner to create the reference file. Four groups (L0, L1, L2, and L3) were formed, each with a distinct locking surface configuration, and all scans were made using the same intraoral scanner. L0 kept all 4 implant-level scan bodies during scanning. L1 involved removing the right first premolar (RPM) scan body, scanning the other 3 implant scan bodies, then reattaching the RPM's scan body, and continuing scanning. In L2, the RPM and right lateral incisor (RIC) scan bodies were removed, followed by scanning the left implants to create a locking surface, and scanning the right implants. In L3, only the left posterior molar's (LPM) scan body was retained and scanned; then a locking surface was generated, and then the remaining implants were scanned. A metrology software program (Geomagic Control X) was used for comparison. Statistical analyses were performed using the Kruskal-Wallis, the 1-way ANOVA, the Welch ANOVA, the Friedman test, the repeated-measures ANOVA, the Bonferroni post hoc test, and the Games-Howell post hoc test (α=.05).

RESULTS

Significant 3D surface deviations were observed in the coronal bevel (CB) region and in the entire scan bodies when assessing trueness in the L0, L1, L2, and L3 groups (P<.001). L2 exhibited the highest discrepancies in 3D surface deviation for CB (0.030 ±0.002 mm) and implant scan bodies (0.357 ±0.052 mm) and distance deviation, while the highest mean angular deviation values were found in L0 (0.924 ±0.131 degrees).

CONCLUSIONS

Locking half of the arch showed the highest trueness discrepancies when performing digital scans for complete arch implant-supported prostheses.

Extraoral Scanning of Implant Prosthetic Components under Difficult Conditions Using a Transfer Device

Obtaining an extremely precise virtual model is decisive for the final success of prosthetic restorations on implants using CAD–CAM technology. Intraoral digital implant impression can be challenging under specific conditions (e.g., narrow spaces, lack of visibility, or subgingival margins) because sometimes the scan body does not reach an optimal supragingival level so that it can be scanned accurately. We propose an easy and quick solution, which uses an extraoral transfer device that requires minimum time and cost investment.