Impact of polymerization and storage on the degree of conversion and mechanical properties of veneering resin composites

Abstract

To investigate the degree of conversion (DC), Martens hardness (HM), elastic indentation modulus (Eit), and flexural strength (FS) of veneering resin composites (SR Nexco Paste (NP), Ceramage Incisal (CI), Gradia Plus (GP); n=60/group) cured with different polymerization devices (bre.Lux Power Unit, Labolight DUO, Otoflash G171, LC-3DPrint Box, PCU LED; n=12/subgroup) after storage. Otoflash G171 and Labolight DUO showed increased DC/HM/Eit. CI presented the lowest DC and highest HM/Eit. NP showed the highest DC and lowest HM/Eit. Within Otoflash G171, Laboligth DUO and PCU LED, highest FS was observed for CI. Storage did not affect DC/HM/Eit for specimens cured with Otoflash G171 or Labolight DUO. With storage not showing an influence on the tested parameters for polymerization devices that otherwise presented superior results, increased storage time cannot be recommended. For the tested resin composites, this study observed a high/low degree of conversion to coincide with respectively low/ high amounts of fillers/mechanical properties.