The ambient lighting condition has been identified as an important factor influencing the accuracy of digital scans performed using intraoral scanners (IOSs) [1], [2], [3], [4], [5], [6], [7], [8], [9]. A decrease in scanning accuracy of between 37% and 44% has been reported among different ambient lighting conditions, including no light (0 lux), natural light (500 lux), examination room light (1000 lux), and illuminance with the dental chair light (10,000 lux) [2,3]. Furthermore, the optimal ambient lighting condition varied among the different IOSs tested [1], [2], [3]. However, information on how the illuminance of ambient lighting influences the accuracy of dentate digital scans obtained with a confocal based IOS (PrimeScan; Dentsply Sirona, Bensheim, Germany) system is limited.

The ambient lighting conditions tested in previous studies [2], [3], [4], [5], [6], [7], [8], [9] corresponds with the lighting recommendations for the dental practice of the European Standard for Illumination (EN 12,464), which recommended 500 lux for general illumination, 1000 lx in medical or examination rooms, and 10 000 lx for the operating cavity [10,11]. However, lux meters have yet to be systematically included in dental practice to standardize illuminance of the ambient lighting when performing a digital scan. Therefore, understanding how the scanning accuracy of an IOS is affected across different illuminance values will allow the development of scanning protocols to maximize scanning accuracy. This might popularize the implementation of those auxiliary instruments to standardize illuminance in the patient´s mouth.

Different factors have been identified that influence scanning accuracy, including the scanning technologies [12], [13], [14], [15], [16], [17], [18], [19], [20], [21], [22], [23], [24], resolution at which the tooth is digitized [25,26], different fitting and smoothing algorithms that might be used to postprocess the data [27], [28], [29], [30], [31], [32], [33], IOS calibration [34], handling and learning curve [[35], [36], [37]], scanning conditions [35,38], surface characteristics, [[39], [40], [41], [42]], and scanning protocol [43,44].

According to the International Organization for Standardization (ISO) 5725–1 [24], the accuracy of a scanner has been defined as the combination of trueness and precision [45]. Trueness relates to the ability of the scanner to reproduce a dental arch as close to its true form as possible without deformation or distortion, while precision indicates the difference among images acquired by repeated scanning under the same conditions [45].

The aim of the present in vitro study was to evaluate the influence of 12 different ambient lighting conditions, specifically the illuminance of the light (0-, 500-, 1000-, 2000-, 3000-, 4000-, 5000-, 6000-, 7000-, 8000-, 9000-, and 10 000 lux) on the scanning accuracy of a confocal based IOS (PrimeScan; Dentsply Sirona, Bensheim, Germany). The null hypothesis was that no significant difference would be found in the digital scan accuracy (trueness and precision) of the tested IOS system (PrimeScan; Dentsply Sirona, Bensheim, Germany) under the 12 different ambient lighting conditions evaluated.