Methods: One control (CerX; CeramX, Dentsply Caulk, Germany) and three ACP based composite resins: without added fillers (0-ACP), with added 10wt% of barium-glass fillers (Ba-ACP) and with 10wt% of silica fillers (Si-ACP) were tested. The samples were polymerized for 30sec by LED curing unit (1150mW/cm2; Bluephase G2, Ivoclar Vivadent, Liechtenstein). Fourier transform infrared spectroscopy (FTIR) was used to determine the structure of ACP and the DC, 20min and 72h after polymerization. DC (n=10) was calculated from the molar ratios of aliphatic and aromatic peaks of cured and uncured composite samples. HV (n=10) was measured with the load of 5 or 10g. Micromorphology of composite samples was visualized by scanning electron microscope. The results were analyzed by Mann-Whitney-test, ANOVA and Tukey’s post hoc test (p<0.05).
Results: FTIR spectra revealed the amorphous structure of ACP. The addition of barium fillers did not reduce the DC (76.73%) and exhibited high post-cure increase of DC. Si-ACP (72.32%) had significantly lower DC than 0-ACP (75.28%). CerX had the lowest DC (56.76%), but the highest HV (20.73). Si-ACP had significantly higher HV (12.82) than 0-ACP (10.54) and Ba-ACP (10.75).
Conclusions: Lower DC of Si-ACP was attributed to the polymerization-induced phase separation of matrix. Despite the lower DC, Si-ACP demonstrated higher HV, probably due to more intimate contact of nano-filler particles and resin matrix in comparison to the barium micro-fillers. Careful selection of inert fillers to be added into ACP composite’s composition can improve its properties.
This study was supported by MZOS (065-0352851-0410, 035-0352851-2854, 098-0982904-2952), CSF, Forschungsgemeinschaft Dental and NIDCR (DE13169).