Effect of posterior span length on the trueness and precision of 3 intraoral digital scanners: A comparative 3-dimensional in vitro study

PURPOSE: This in vitro study measured and compared 3 intraoral scanners' accuracy (trueness and precision) with different span lengths. MATERIALS AND METHODS: Three master casts were prepared to simulate 3 different span lengths (fixed partial dentures with 3, 4, and 5 units). Each master cast was scanned once with an E3 lab scanner and 10 times with each of the 3 intraoral scanners (Trios 3, Planmeca Emerald, and Primescan AC). Data were stored as Standard Tessellation Language (STL) files. The differences between measurements were compared 3-dimensionally using metrology software. Data were analyzed using 1-way analysis of variance with post hoc analysis by the Tukey honest significant difference test for trueness and precision. Statistical significance was set at P<0.05. RESULTS: A statistically significant difference was found between the 3 intraoral scanners in trueness and precision (P<0.05). Primescan AC showed the lowest trueness and precision values (36.8 µm and 42.0 µm; (39.4 µm and 51.2 µm; and 54.9 µm and 52.7 µm) followed by Trios 3 (38.9 µm and 53.5 µm; 49.9 µm and 59.1 µm; and 58.1 µm and 64.5 µm) and Planmeca Emerald (60.4 µm and 63.6 µm; 61.3 µm and 69.0 µm; and 70.8 µm and 74.3 µm) for the 3-unit, 4-unit, and 5-unit fixed partial dentures, respectively. CONCLUSION: Primescan AC had the best trueness and precision, followed by Trios 3 and Planmeca Emerald. Increasing span length reduced the trueness and precession of the 3 scanners; however, their values were within the accepted successful ranges.