An in-vitro study on factors influencing the accuracy of current intraoral scanners

Intraoral scanning devices are an essential part of many digital pathways in dentistry. The aim of this first factorial comparative in-vitro study was to evaluate the influence of different jaw model configurations (model types: upper jaw [upper], upper jaw with palate [upper-pal], lower jaw [lower]) and examiners on trueness and precision of digital full-arch impressions across seven intraoral scanners. Reference models were scanned with Emerald Green [EME]; iTero 5D [ITE]; Medit i900 [MED]; Primescan [PRI]; Primescan2 [PS2]; Aoralscan 3 [SHI]; Trios 5 [TR5]. Each model type was scanned ten times (n = 10) per device, divided between two examiners with different experience levels. Trueness and precision were calculated using the (90_10)/2-percentile. Data were analyzed using a linear mixed-effects model with model type and examiner as fixed effects and scanning device as a random effect. The trueness values ranged from PRI (29.0 ± 3.7 μm, [upper-pal]) to EME (94.9 ± 18.5 μm, [lower]). Examiner and model type had no significant effect on trueness. For precision, the model type [upper-pal] showed a significant positive effect (p < 0.001), factor examiner had a significant effect (p = 0.04). The model type and examiner experience can influence the accuracy of digital impressions; however, the values observed were within clinically acceptable thresholds (< 100 μm). Including the palate in upper jaw scans can improve accuracy for certain intraoral scanners. Optimizing scanning strategies, exercising and considering jaw anatomy-especially the inclusion of the palate-may enhance scanners' accuracy.