Evaluation of the accuracy of digital and 3D-printed casts compared with conventional stone casts

Digital scans present an efficient substitute for traditional dental impressions, although physical casts are still needed for some procedures, leading to the use of 3D printing in fixed prosthodontics. However, studies comparing the accuracy of 3D-printed dental casts with digital and conventional casts are sparse.

The purpose of this in vitro study was to compare the accuracy of casts produced from 2 different intraoral scans using a stereolithographic (SLA) 3D- printing technique, their digital versions, and conventional stone casts with a reference cast and with each other.

A reference cast was scanned by using 2 intraoral scanners, the TRIOS 3Shape and the Dental Wings, producing 2 digital scans. SLA was used to print dental casts from the digital scans, and polyether impressions were poured in dental stone to produce conventional stone casts. Measurements of the 4 types of casts (TRIOS 3Shape digital, Dental Wings digital, TRIOS 3Shape printed, and Dental Wings-printed casts) were compared with the reference casts. Measurements of maxillary and mandibular canines, second premolars, and second molars included incisocervical or occlusocervical (crown height) and mesiodistal (crown width). Arch measurements included intercanine and intermolar widths. The Geomagic imaging software program was used to measure the digital casts. ANOVA was used to assess differences among groups in errors relative to the reference cast (α=.05).

In occlusocervical and mesiodistal, the errors of digital Dental Wings were significantly greater than the errors of the other 4 groups. For intercanine and intermolar widths, digital TRIOS 3Shape and digital Dental Wings had significantly greater errors (mean=0.11 and 0.15 mm in intercanine width and 0.14 and 0.18 mm in intermolar width) than their printed counterparts and the conventional casts (means=0.02, 0.06, and 0.01 mm in intercanine width and 0.02, 0.04, and 0.01 mm in intermolar width). The digital Dental Wings cast had significantly greater errors than those of the other groups in all measurements. All errors were within the clinically acceptable level (<0.5 mm).

3D-printed casts had the lowest error rate relative to the reference cast and were similar to those of conventional stone casts. Digital casts had the greatest errors.