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The purpose of this in vitro study was to evaluate the effect of ambient light illuminance on the accuracy and scanning time of different intraoral scanners (IOSs) in complete-arch implant scans.Seven IOSs (TRIOS 3, Primescan, Element 5D, i700, i500, CS3700, and CS3600) at 5 ambient lighting illuminances (100, 500, 1000, 5000, and 10 000 lux) were evaluated. An edentulous cast with 4 implants was selected as the master model. An implant scan body was tightened on each implant. The cast was digitized by using a laboratory scanner to obtain a reference standard tessellation language (STL) file, and 50 scans (10 per ambient light condition) were recorded with each IOS. Scanning time was recorded by using a digital chronograph. Intraoral scan deviations were calculated by using a 3D metrology software program (Geomagic Control X). Kruskal-Wallis and pairwise comparison tests were used to analyze the data (α=0.05).The trueness and precision values obtained for each IOS tested were significantly different under the varying lighting conditions assessed. TRIOS 3 (34.0 ± 3.3 µm trueness; 24.5 ± 14.9 µm precision), Element 5D (34.5 ± 7.1 µm trueness; 25.9 ± 7.6 µm precision), and CS3700 (34.9. ±13.0 µm trueness; 34.6 ± 19.2 µm precision) performed better under 100 lux illumination, CS3600 (69.5 ± 24.0 µm trueness; 36.6 ± 20.1 µm precision) at 500 lux; i500 (36.2 ± 5.1 µm trueness; 21.4 ± 6.8 µm precision) at 1000 lux; i700 (34.8 ± 2.2 µm trueness; 15.4 ± 5.0 µm precision) at 5000 lux, and Primescan (37.4 ± 37.3 µm trueness; 26.2 ± 26.2 µm precision) at 10,000 lux. Additionally, the scanning time was different under different illuminance for each IOS. The fastest IOS in all light conditions was Primescan, with significant differences with all the groups (P.01), followed by TRIOS 3 in all groups except under 100 lux illumination, where i700 was the second fastest.Ambient light influenced the accuracy and scanning time of IOSs assessed; however, the effect was not the same for all devices. It is necessary to optimize ambient light illuminance for each IOS to maximize scanning accuracy.

This article describes a technique to assist with intraoral digital scans for fabricating tooth-supported prostheses by using a custom intraoral scan body when the extension of the scan or the clinical characteristics might compromise the reliability of the intraoral digital scan. A preliminary intraoral scan of the tooth preparations is used to design a custom intraoral scan body which is manufactured using polymethylmethacrylate and a 5-axis milling machine. A low-viscosity polyvinyl siloxane impression of the tooth preparations is obtained using the custom intraoral scan body. Subsequently, the custom intraoral scan body is digitized using an intraoral scanner. A design software program is used to align the digitized custom intraoral scan body with the preliminary intraoral scan to obtain the definitive virtual cast. This technique aims to reduce manual conventional laboratory procedures such as pouring dental impression or die trimming which might minimize inaccuracies on the virtual definitive cast.