Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 16 6 2020 06 24 415 420 EN Behnoosh Jalalian Department of Restorative Dentistry, Faculty of Dentistry, Qom University of Medical Sciences, Qom, Iran Parisa Golkar Dental Materials Research Center, Department of Operative Dentistry, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran Alireza Paktinat Private Practice, Tehran, Iran Elham Ahmadi Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran Seyed Ali Panahande Department of Restorative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran Ladan Ranjbar Omrani Dental Research Center, Dentistry Research Institute, Tehran University of Medical Sciences, Tehran, Iran AND Department of Restorative Dentistry, School of Dentistry, Tehran University of Medical Sciences, Tehran, Iran 2018 07 04 2018 10 19 Objectives: Hydroxyapatite (HA) nanoparticles are used to improve the physical and mechanical properties of glass ionomers (GIs). This study aimed to assess the effect of addition of different weight percentages of nano-HA on degree of conversion (DC) of Fuji II LC GI cement using a spectrometer. Materials and Methods: In this in vitro experimental study, 30 samples were fabricated of Fuji II LC (improved) GI cement in six groups (n=5) containing 0%, 1%, 2%, 5%, 7% and 10wt% nano-HA. The obtained paste in each group was subjected to Fourier-transform infrared spectroscopy (FTIR) before curing to assess the monomer to polymer DC percentage. The paste was then light-cured and underwent FTIR again. One-way ANOVA was applied to compare the DC percentage of different groups. Pairwise comparisons were performed using the Tukey’s test. Results: The DC was 57.88±0.57% in 0%, 60.04±0.63% in 1%, 66.92±0.54% in 2%, 65.5±0.71% in 5%, 51.49±0.24% in 7% and 50.09±0.32% in 10% nano-HA group. The difference in DC among the groups was statistically significant (P<0.0001). The highest DC was noted in 2% nano-HA and the lowest DC was found in 10% nano-HA group. Pairwise comparisons revealed significant differences between the groups in DC (P<0.0001). Conclusion: Increasing the weight percentage of nano-HA to 2% increased the DC but increasing the nano-HA weight percentage over 5% decreased the DC of resin-modified glass ionomer cement (RMGIC). The highest DC was noted in 5w% and 2w% nano-HA groups. Thus, 5w% and 2w% nano-HA can be used to improve the DC of RMGIC. https://fid.tums.ac.ir/index.php/fid/article/view/2685 https://fid.tums.ac.ir/index.php/fid/article/download/2685/1784