DMLS DENTAL ALLOYS VS TRADITIONAL TECHNIQUE

Additive Layer Manufacture (ALM) of dental prostheses allows the direct fabrication of parts from CAD data, replacing a human-sensible process with a faster reliable automatic one. Direct Metal Laser Sintering (DMLS) of Cr-Co alloys produces parts to be directly finished with ceramic and employed. PURPOSE: This study evaluated (1) the application of DMLS process for obtaining final dental prostheses in Co-Cr alloy, to compare mechanical characteristics of cast parts and layer-manufactured ones produced with different alloys and processes; and (2) the effect of porcelain firing cycles on mechanical properties. METHODS: This study was conducted on three classes of tensile specimens in five groups of six specimens: class 1 – 12 specimens built by DMLS (PM100T – Phenix System, France) with Co-Cr powder NOBIL 4000S (NOBIL METAL - Italy) divided in two groups (6 specimens were processed with ceramic heat treatment); class 2 – 12 specimens built by traditional lost-wax casting from Co-Cr bars for fixed prostheses V-CERAM MAGI LINE (SHERA - Germany) divided in two groups (6 specimens were processed with ceramic heat treatment); class 3 – 6 tensile specimens built by traditional lost-wax casting from Cr-Co bars for partial removable prostheses REMANIUM 800+ (Dentaurum - Germany). RESULTS: UTS of all sintered specimens (1174±165 MPa) was higher than of cast ones (503±45 MPa, 499±62 MPa, 712±51 MPa, respectively, for as cast Co-Cr, heat treated Co-Cr, and Remanium) where many porosities were found. UTS decreases after heat-treatment both for cats and DMLS parts. Yield strength was also highest for the laser sintered group (1148±161 MPa).No significant idfference was found for the elastic modulus of compared groups (P=0.398). CONCLUSIONS: DMLS of Co-Cr alloys produces excellent strength and absence of defects compared to traditional casting. This result is due to the fine microstructure obtained by DMLS (high thermal rate, heterogeneous nucleation).