Trueness and scanning time of complete-arch intraoral scans of edentulous arches with implants under different moisture conditions: Effects of splinting-aid, scan body height, and scanner.

Abstract

Purpose: This in vitro study evaluated the influence of the presence of saliva in varying levels on the trueness and scanning time of complete-arch intraoral scans for implant-supported prostheses, considering different scan body heights, splinting protocols, and scanners.

Materials and methods: A three-dimensionally (3D)-printed edentulous maxillary model with six implants and multi-unit abutments was digitized using a metrology-grade industrial scanner (Artec Micro), using polyetheretherketone scan bodies (ISBs) of two heights (short: 4.5 mm and tall: 8.0 mm). The model was also scanned with three intraoral scanners (IOSs) (TRIOS 5 [TR], NeoScan 1000 [NS], and Primescan [PS]) under two splinting wire aids (splinted and non-splinted) and dry or artificial saliva-moisturized (lightly or highly) conditions. A total of 192 scans (n = 8 per experimental condition) were analyzed. Scanning time was recorded with a stopwatch, and trueness was analyzed as root mean square (RMS) deviation when industrial and IOS scans were aligned using Geomagic Control X. Data were analyzed with Kruskal-Wallis, Mann-Whitney U, and Bonferroni-adjusted pairwise comparisons (α = 0.05).

Results: Saliva significantly affected trueness and scan time, with higher moisture levels resulting in greater deviations (p < 0.001) and longer acquisition times for all tested IOSs (p < 0.001). IOS type, ISB height, and scan-aid also had significant effects on scan trueness (p < 0.001). TR presented the lowest RMS values, followed by PS and NS. Under moisture conditions, short ISBs and non-splinted configurations produced more reliable scans (p < 0.001). Short ISBs consistently reduced total scanning time compared with tall ISBs (p < 0.001). PS demonstrated the shortest scanning times under dry and highly moisturized conditions, whereas NS combined with short ISBs showed the fastest acquisition under light moisture conditions.

Conclusion: The simulation of intraoral saliva presence compromised scan trueness, particularly when moisture level increased. Clinically, minimizing saliva presence during scans and selecting appropriate-height ISBs can enhance trueness for digital implant scans. Although scan-aid may reduce scanning time, its use should be limited to situations in which stabilization is critical, such as long edentulous arches or long interimplant distances, as these conditions may increase optical deviations in the presence of saliva. These findings support the refinement of clinical protocols for complete-arch implant scans, emphasizing saliva control and careful scan strategy selection to improve trueness of digital edentulous scans.