Case Study On Curved Root Canals Of Molars And Instrument Separation Of Molars

Many studies have found that the root canals of human teeth were curved,especially in posterior teeth.It is an important step to understand and evaluate the root canals morphology before root canal therapy.At present,the curved shape of root canals was mainly described by the curved type and curved direction.The curvature of root canals was quantitatively analyzed by curved angle and curved radius.Preparation of curved root canals was considered to be the difficulty of curved root canals treatment.Improper selection of instruments or improper preparation of root canal would affect the effect of root canals treatment,and even cause complications such as root canals steps,root canals straightening,apical foramen destruction and instrument separation and so on.The main reason of root canals treatment failure caused by instrument separation was that the broken instruments obstructed the root canal,causing the bacteria and infection in the root canal could not be cleaned thoroughly.It is necessary for the instrument separation cases with apical inflammation or patients with psychological burden due to the separation instrument remaining in the teeth to remove the broken instruments successfully.What’s more,the removal of endodontic separation instruments was a difficult point in root canals retreatment.In this report,with the help of CBCT and other radiography technologies we could diagnose and evaluate molar curved root canals cases and molar instrument separation cases easily.And using dental operating microscopes,mechanical nickel-titanium instruments,ultrasonic root canals therapy equipment,separation instrument extraction kits and other tools to treat these cases.Cases 1 and 2 showed the treatment process of curved root canals,analyzed the morphology of curved root canals of molars and also discussed the choices of preparation instruments and the important points of treatment of curved root canals.Cases 3 to 5 showed the process of removing separated instruments by different methods under dental operating microscope.We summarized the reasons,treatment plan and prognosis evaluation of instrument separation and concluded the factors affecting the removal of separated instruments in order to apply them to clinical cases analysis and treatment.Through the successful treatment of these cases,we could further improve the theory and technical essentials of root canals therapy and retreatment,and accumulate clinical experience.