RESUMEN
Aims: The aim of this in vitro study was to compare the cyclic fatigue resistance of three different endodontic nickel-titanium rotary instruments using a dynamic testing device. Materials and Methods: Ten files each of ProTaper Gold (PG), Hyflex Electro-discharge Machining (HEDM), and TruNatomy (TN) were tested in a custom-fabricated dynamic cyclic fatigue testing device at 60° curvature having a radius of curvature of 5 mm. The number of cycles to the fracture (NCF) of each instrument was calculated and three continuous groups were compared by the Kruskal-Wallis test and Dunn post hoc test was used for pairwise comparison. Results: Cyclic fatigue resistance of HEDM was the highest, followed by TN. PG had the lowest among the three. Conclusion: Within the limitations of the present in vitro results, it can be concluded that HEDM files appeared to be suitable for shaping complex canals with the greater number of cycles before it fractures.
RESUMEN
After endodontic therapy, restoring severely broken or damaged crown structure is a difficult task in conservative dentistry. Regular post and core followed by crown repair cannot restore a crown with steep incisal guidance, very little overjet, and highly damaged crown structure. Richmond crown is better recommended in these situations since Richmond crown is a crown having post. It is prepared as a single piece having a ceramic facing. We frequently encounter teeth having very less or no clinical crown portion that are structurally damaged. Support and retention of the restoration are challenging to achieve in such situations. The rehabilitation of anterior teeth that has been endodontically treated and structurally impaired is reviewed in two cases.