Aim:The study was designed to investigate the sealing ability of two obturation systems (cold laterally compacted gutta percha and Obtura II) over different apically separated rotary nickel-titanium files (RACE and K3 system) using dye extraction method.Materials and Methods:Sixty-two mandibular premolars were divided into 2 groups of 30 teeth each, and 2 teeth served as negative controls. In Groups A and B, roots were prepared using RACE and K3 system, respectively, and were further subdivided into 4 subgroups. In subgroups A1, B1 and A2, B2 (n = 10 each), files were separated at 3 mm from the tip in apical 3rd of the canal. In subgroups A3, B3 and A4, B4 (n = 5), instruments were not separated. Subgroups A1, A3, B1, B3 and A2, A4, B2, B4 were obturated by lateral condensation method and Obtura II techniques, respectively. The sealing ability of the obturated specimens were tested using dye extraction method. The values for each group were recorded and analysis of variance (ANOVA), Student “t” test (two-tailed, independent), and Leven's test were performed.Results:Group A1 showed significantly less leakage than B1. No statistical significant difference between Groups A2 and B2 and Groups A3 and B3, respectively, were observed. Group A4 showed significantly less leakage than B4.Conclusion:Groups obturated with Obtura II showed less leakage than the lateral condensation technique irrespective of presence or absence of fractured NiTi rotary system.

To compare the efficacy of platelet-rich fibrin (PRF) and Hank's balanced salt solution (HBSS) in the preservation of the periodontal ligament (PDL) cells viability of avulsed teeth. Methods: A total of 30 non-carious third molars with healthy periodontium, indicated for extraction for orthodontic reasons or chronic pericoronitis, were selected for the study. Samples were divided into four groups: one standard group and one experimental group in addition to two control groups (positive and negative). The positive and negative control group corresponded to immediate and 2-hour dry time respectively. The experimental teeth were bench dried for 40 minutes and then immersed in one of the two storage media: HBSS (standard storage media) and PRF (experimental storage media) for 45 minutes. The teeth in each group were treated with dispase II and collagenase for 30 minutes and later centrifuged for 4 minutes at 1000 rpm. The supernatant was removed with sterile micropipette, the cells were labeled with 0.4% trypan blue, and the number of viable PDL cells was counted with a hemocytometer under a light microscope. One-way Kruskal-Wallis test and Mann-Whitney U test with Boneferroni correction were used for statistical analysis. Results: Results did not demonstrate any statistically significant differences in the viability of PDL cells between the groups with standard and experimental storage media. Group 1 showed a statistically significant difference of mean compared to Groups 2, 3 and 4. When Group 2 was compared with Groups 3 and 4, a P-value>0.05 suggested no statistical significance. Conclusion: Within the parameters of this study, HBSS and PRF demonstrated a similar number of viable PDL cells. Hence, PRF could be a used as a good substitute of HBSS as a storage media for avulsed teeth.