CAD/CAM Milled Versus Rapidly-prototyped Complete Dentures: An Evaluation of Trueness

Objectives: This in vitro study evaluated the trueness of the intaglio surfaces of complete removable dental prostheses (CRDPs) manufactured by rapid proto-typing (3D printing) and CAD/CAM milling techniques.
Methods: Twenty identical maxillary CRDPs were manufactured (Group#1: rapidly proto-typed: n=10; Group#2: CAD/CAM milled: n=10) using a scan of a reference cobalt-chrome master model. The intaglio surfaces of CRDPs were scanned at baseline (BL) using a laboratory scanner (IScan D103i, Imetric 3D SA, Courgenay, Switzerland). The CRDPs were then incubated in a Glandosane^®-like artificial saliva solution for 21 days, and a post-incubation (PIS) scan was done. To simulate the clinical scenario of wearing and removal of the CRDP by the patient, they were incubated in artificial saliva during the day and stored dry at night, for a further period of 21 days. A third scan was made after this wet-dry cycle (WDC). The scans were superimposed and the differences were analyzed using a 3D software (Oracheck version 2.10, Cyfex AG, Zurich, Switzerland). The analyses were carried out for the entire intaglio surface and separately for seven regions of interest: crest, palatal-vault, posterior palatal seal area (PPS), tuberosity, anterior-ridge, vestibular-flange and, mid-palatal raphae. Parametric tests (t-tests) were applied for statistical analyses (?=0.05).
Results: The trueness of the CRDPs in group#2 at BL, PIS and WDC were significantly better than those of group#1 with regards to the entire intaglio surface (p<0.001), crest (p<0.001), palatal-vault (p<0.001), PPS (p<0.001), tuberosity (p<0.001), anterior-ridge (BL: p<0.001; PIS: p=0.001; WDC: p=0.011), vestibular-flange (p<0.001), and mid-palatal raphae (p<0.001).
Conclusions: The trueness of the CRDPs manufactured by the CAD/CAM milling technique seems to be superior to those manufactured by rapid proto-typing. However, this superiority should be further confirmed for clinical parameters, patient/clinician satisfaction, hygiene, maintenance, allergic potentials and, costs.