Allaa Mohammed Kamel, Magdi Mohamed Ali And Essam Fawzy Mahmoud,

ABSTRACT


Aim: Evaluation Of The Ability Of Bypassing Separated Rotary NiTi Instruments According To Their Different Cross Sections And The Sealing Ability Of Different Sealing Materials Over The Separated Instrument.

Materials and Methods: This Study Was Conducted On 75 Mandibular Mesio Buccal Canals Of Mandibular Molar. Specimens Were Randomly Divided To Two Groups, Group 1 Assessing The Bypass Ability Of Apically Separated Instruments With Different Cross Sections, Group 2 Assessing The Effect Of Different Obturation Materials Over Apically Separated Instruments With Different Cross Sections. Group 1 Divided To 3 Subgroups PTN, PTU And Endostar (n=25). Group 2(n=45) Divided To 9 Groups According To Both The Separated Filetype (PTN, PTU Or Endostar) And The Obturation Material (Biodentine, MTA Or Gutta Percha) (n=5). Specimens Of Each Group Were Instrumented By Its Filesystem And Filesof Size #25 Were Notched To A Depth Of Half The Instrument Thickness With A Disc At A Point 3 Mm From The Tip Of The Instrument And Then Driven Into The Canals Until The Instrument Is Separated. Then Bypassing Trials Were Done And To Evaluate The Success Of The Procedure A Parallel Radiograph Was Done While The Apical Microleakage Was Assessed By Dye Penetration Method. Data Was Statistically Analyzed Using One-way ANOVA Followed By Tukey?s Post Hoc Test. The Significance Level Was Set At P?0.05 Within All Tests

Results: The Results Of Group 1 Showed That There Was No Significantdifference Between The Three Groups. Group 2 Showed That There Was No Significantdifference For The Microleakage According To The Type Of The Separated Filewhile There Was A Significantdifference Between The Three Obturation Materials As The Biodentine Showed The Least Amount Of Leakage Followed By MTA And The Gutta Percha Showed The Greatest Amount Of Leakage.

Conclusions: Within The Limitation Of This Study, The Cross Section Of Separated Fragment May Not Have A Great Effect On The Ability Of Being Bypassed. The Type Of Obturation May Have More Effective Role Than The Type Of Instrument Retained.