Evaluation of Push Out Bond Strength of Two Calcium Silicate Based Cements with Bone Cement in Retrograde Cavities Prepared by Ultrasonic Retro Tips

Introduction: Surgical endodontic treatment comprises ofthorough debridement of pathological periradicular tissue,root end resection followed by a Class I retrograde cavitypreparation and insertion of root end filling material into theprepared cavity. The aim of this study was to evaluate the pushout bond strength of Biodentine, Mineral Trioxide Aggregate(MTA) and Bone Cement used in the retro cavities, preparedwith ultrasonic retro tips.Material and methods: 60 human extracted single rootedteeth were selected and sectioned with a diamond disc (Horico,Germany) to standardize the root length of 15mm. The rootswere instrumented with rotary ProTaper Universal (DentsplyMaillefer) system till size F2. The root canals were obturatedusing gutta percha (Dentsply, Maillefer) and AH Plus sealer(Dentsply, Germany). 3mm of root end resection wasperformed with high speed hand piece under water coolant.3mm deep retro cavities were prepared with ultrasonic stainlesssteel retro tip (Woodpecker). All the specimens were dividedinto 3 groups (n=20) Group I: MTA (ProRoot, Tulsa Dental,USA), Group II Biodentine (Septodont, France), Group IIIBone Cement (Depuy, Johnsons and Johnsons). Each materialwas mixed according to the manufacturers instructions andfilled into the retro cavities. The specimens were sectionedperpendicularly to obtain 1mm thick slices from the apicalportion and subjected to push out bond strength testing underUniversal Testing Machine (Instron).Results: Biodentine showed more push out bond strength thanMTA and Bone Cement. There was no significant differencebetween MTA and Bone Cement groups.Conclusion: Bone Cement can be considered as one of thepotential retro filling material.

Evaluation of Root Dentin Cracks Caused by Three Single File Systems Versus Pro Taper System – An In Vitro Study

Introduction: Biomechanical preparation of root canals isone of the main steps in achieving endodontic success dueto enabling bacterial elimination, removal of debris, andfacilitating obturation. The aim of this study was to comparethe incidence of dentinal cracks observed in the canal wallafter canal instrumentation with 3 single-file systems and theProTaper system (Dentsply Maillefer, Switzerland).Material and Methods: Eighty mandibular premolars withsingle root canal were selected. Teeth were decoronated andmounted in resin blocks with simulated periodontal ligaments.They were divided into 4 experimental groups (n = 20); theninstrumented to the full working length with the ProTaper,OneShape (MicroMega, Besancon, France), Reciproc (VDW,Munich, Germany), and WaveOne Gold (Dentsply Malliefer)was performed. The roots were sectioned perpendicular to thelong axis at 3, 6, and 9 mm from the apex and were observedunder a stereomicroscope. The presence of cracks was noted.The chi-square test was performed to compare the appearanceof cracked roots between the experimental groups.Results: Cracks found after canal instrumentation with theProTaper, OneShape, and Reciproc and WaveOne Goldfiles, were 46.6%, 23.3%, 13.6%, 11.6% respectively. Thedifference between the experimental groups was statisticallysignificant (P < .001).Conclusion: Nickel-titanium instruments cause cracks in rootsurface or in the canal wall; Reciproc and WaveOne Gold filescaused less cracks than the ProTaper and OneShape files.