Influencing factors on the accuracy of current intraoral scanners – an in-vitro study

OBJECTIVE The aim of this comparative in-vitro study was to evaluate the influence of different jaw model variants (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. MATERIALS AND METHODS Reference models were scanned with seven intraoral scanners (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. RESULTS 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 = 0.0047), factor examiner had a marginal significant effect (p = 0.0473). CONCLUSION The model type and examiner experience can influence the accuracy of digital impressions; however, the differences observed were within clinically acceptable thresholds. Including the palate in upper jaw scans can improve accuracy for certain intraoral scanners. CLINICAL RELEVANCE Despite measurable differences, current intraoral scanners provide clinically acceptable accuracy for full-arch impressions. Optimizing scanning strategies, exercising and considering jaw anatomy - especially the inclusion of the palate - may enhance scanners’ accuracy.