Clinical Accuracy of Stereolithographic Casts Compared to Traditional Casts

Objectives: Poly(vinyl siloxane) [PVS] impressions are widely accepted for making definitive casts for restoration fabrication. The objective was to analyze differences in dimensions of casts produced from PVS impressions and by stereolithography / additive manufacturing (3-D printing).
Methods: Maxillary and mandibular arches of ten subjects (OUHSC IRB# 9504) of age 18-50 years with class I dentition were measured using a digital caliper to obtain three intra-oral measurements of the first molars (#s 3 and 30): mesiodistal crown length [A], cervical-occlusal crown height [B], buccolingual crown width [C], and two measurements of the arches: arch width [D] and arch perimeter [E]. Traditional casts were prepared from PVS impressions (Aquasil XLV Ultra Fast Set, medium and light body; Dentsply Caulk) using Silky-Rock Violet Low-Expansion Die Stone (Whip Mix), and digital impressions were sent to International Dental Arts, Inc. for printing using Vida (EnvisionTEC) and Form 2 (Formlabs) printers. Casts were measured, and differences in casts’ dimensions from intra-oral measurements were compared using General Linear Models and post-hoc Student-Newman-Keuls (SNK) tests (α=0.05; SAS software).
Results: Mean values of differences in A, B, D and E were not significantly different among cast types (p>0.05) and arches (maxillary vs. mandibular; p>0.05). Mean values of differences in C were significantly higher for mandibular casts than for maxillary casts (p<0.0001), but not among cast types (p>0.05).
Conclusions: Crown length, crown height, arch width and arch perimeter dimensions of casts produced from PVS impressions and by additive manufacturing differed similarly from the intra-oral measurements. Crown widths differed more from intra-oral measurements in mandibular casts of all types than in maxillary casts.