Analysis of Different Illuminance of the Room Lighting Condition on the Accuracy (Trueness and Precision) of An Intraoral Scanner.
Level 5 - mechanism / opinion, no new human data
In vitro bench study on a typodont mannequin model without human participants.
PubMed 33094878 · doi:10.1111/jopr.13276
What was done
A typodont digitized with an extraoral scanner served as the reference standard tessellation language (STL) mesh. Ten ambient lighting conditions were evaluated, ranging from 1,000 lux (room light only) to 10,000 lux (chair light added) in increments of 1,000 lux by adjusting the distance between the chair light and the mannequin. Ten digital scans per group were acquired (10 groups, 100 scans total) using an intraoral scanner (Trios 3; 3Shape). Accuracy (trueness and precision) was evaluated against the reference typodont mesh using 3D mesh processing software and analyzed with Kruskal-Wallis and pairwise comparison tests (α = 0.05).
What was found
Lighting conditions caused statistically significant differences in trueness and precision (p < 0.001). The 1,000-lux group yielded the lowest discrepancy values, with a median of 26.33 µm and an interquartile range (IQR) of 40.04 µm (11.97–52.00 µm; p < 0.001). The 5,000-lux group showed the highest discrepancy, with a median of 46.38 µm and an IQR of 99.94 µm (19.05–118.98 µm; p < 0.001). Pairwise comparison showed no significant difference between the 8,000-lux and 4,000-lux groups (p = 0.287). The scanning accuracy response was non-monotonic across the illuminance range, and relative precision was low across all groups as IQR exceeded mean errors from the control mesh.
Why it matters
Ambient operatory lighting directly affects intraoral scan accuracy, indicating that turning off direct dental chair lighting during digital impressions improves optical fidelity.
Limits
In vitro bench design on a dry typodont model that does not replicate in vivo factors such as saliva, soft tissue movement, tongue/cheek retraction, or intraoral humidity. Only one intraoral scanner model (Trios 3) was tested, limiting generalizability to other scanning technologies. The sample size was limited to 10 scans per lighting condition.
Cited by
- supports Indoor light is typically around 500 lux and rarely exceeds 1,000 lux, whereas bright direct outdoor sunlight can reach 200,000 lux and overcast daylight reaches at least 10,000 lux.