ABSTRACT
Abstract The aim of this study was to evaluate the quality of curved root canal preparation, torsional fatigue, and cyclic fatigue of rotary systems manufactured with different NiTi alloys. Ninety single-rooted canals with curvatures of 15° to 30o were scanned and divided into three groups according to the rotary system used: BT-Race (BTR) - 10.06, 35.00, 35.04; SequenceRotaryFile (SRF) - 15.04, 25.06, 35.04; and ProDesignLogic (PDL) - 25.01, 25.06, 35.05. Each system was used on three specimens. The teeth were prepared, scanned, and analyzed to assess increase in volume, transportation, and centering ability of the root canal. Torsional fatigue of glide path instruments (BTR 10.06, SRF 15.04 and PDL 25.01) and cyclic fatigue of the finishing instrument (BTR 35.04, SRF 35.04 and PDL 35.05) were obtained by analyzing completely new instruments (n = 10) and instruments after they had been used three times (n = 10). After the torsional and cyclic fatigue tests, the fractured surface of the new and used instruments were examined by scanning electron microscopy. Increase in volume, canal transportation, and centering ability showed no significant differences among the groups (p > 0.05). The torsional test showed that SRF 15.04 produced the highest torque values for both new and used instruments, followed by PDL 25.01 and BTR 10.06 (p < 0.05). PDL 25.01, both new and used, exhibited higher values of angular deflection followed by SRF 15.04 and BTR 10.06 (p < 0.05). As regards cyclic fatigue, use of PDL 35.05, both new and used, required a longer time and larger number of cycles than did SRF 35.04 and BTR 35.04 (p < 0.05). Clinical use affected the torsional fatigue of BTR; however, cyclic fatigue was not significantly affected (p < 0.05). All rotary systems were able to prepare the curved canals satisfactorily and were used safely on the three specimens. Relative to torsional fatigue, SRF 15.04 exhibited a higher torque, and PDL 25.01, higher angular deflection. BTR 10.06 was the most affected by clinical use. PDL 35.05 showed greater resistance to cyclic fatigue.
ABSTRACT
Abstract Filling materials should be restricted to the root canal space. However, sometimes it is impossible to control the apical extrusion, in this case, the fate of the filling material and the result of the treatment will depend on its physicochemical properties and biocompatibility. Objective To evaluate the tissue response and bone repair capacity of endodontic sealers that were implanted in the calvaria of Wistar rats, forming the groups (n=16): AH Plus and Sealer Plus, compared to the clot group. Methodology On days 30 and 60, the animals were euthanized, the calvaria was removed and processed for hematoxylin-eosin, immunohistochemistry for collagen type I, Picrosirus red and microtomographic analysis. Data were subjected to ANOVA and Tuckey tests (p<0.05). Results At 30 days, all groups showed an intense inflammatory reaction (p>0.05). At 60 days, the AH Plus and Sealer Plus maintained an intense inflammatory infiltrate compared to the clot group (p<0.05). We observed immunopositive areas for type I collagen in all groups at 30 days and 60 days (p>0.05). We observed more red collagen fibers for the Sealer Plus compared to the clot group at 30 days (p<0.05). Considering the total fibers, the clot group at 30 days compared to 60 days after surgery showed an increase in the amount of matrix (p<0.05). There were no statistical differences between groups for green and yellow fibers (p>0.05). Regarding morphometric parameters, at 30 days, the newly formed bone volume and number of bone trabeculae were higher in the groups with sealers compared to the clot group (p<0.05). At 60 days, AH Plus and Sealer Plus showed greater bone neoformation compared to the clot group (p<0.05). Conclusions Despite AH Plus and Sealer Plus induced an intense inflammatory reaction, they can be considered biocompatible materials, since they allowed bone repair.