Clinical Curative Effect Observation Of Removing Gutta-percha Point In Root Canal Through Protaper Universal Nickel-titanium Retreatment Instrument

Objective: To compare the curative effect of removing gutta-percha point in root canal through Protaper Universal nickel-titanium retreatment instrument and manual K file in terms of the reperfusion rate of root canal,retreatment time,the incidence of pain after retreatment and the root filling quality after retreatment through the form of case report and provide clinical basis for the use of Protaper Universal nickel-titanium retreatment system.Methods: 40 patients who needed retreatment were selected as the research subject according to the treatment order and needed a total of 40 root canals were randomly divided into experimental group and control group,with 20 cases in each group.All patients were healthy and older than 18 and could cooperate with the treatment.Besides,X-ray showed their root tip had fully developed;their previous gutta-percha point filling didn't need improving,but needed retreatment.The preoperative subjective symptoms and clinical examinations of the patients were recorded and the X-ray was taken so as to know about the original treatment of diseased teeth and root canal.The original fillings were removed to expose root canal orifice.Experimental group: gutta-percha point in the root canal was removed with the crown-down technique through Protaper Universal nickel-titanium retreatment instrument;control group: gutta-percha point in the root canal was removed with manual stainless steel K file.the instrument was replaced every time;the root canal was with alternately flushed with 2ml of chlorhexidine solution(2%)and 2ml of EDTA solution(17%).It can be considered the fillings are completely removed when the following conditions are met:(1)the instrument can reach the working length or cannot dredge;(2)the filling materials on instrument blade and flushing fluid are not visible to naked eyes.After completing dredging a root canal,the author cleaned the instrument and observed whether the thread changed or broke;if not,the author would continue using it;if yes,the author would stop using it.Eachinstrument couldn't use more than 10 root canals.In addition,the time required for each root canal treatment was recorded: the duration from the initial file into the root canal orifice to terminal file out of root canal orifice(including the time of replacing equipment and washing root canal).Lap was used to separate the wet and paper point was used to dry lumen;chlorhexidine calcium hydroxide cataplasm + zinc oxide were selected.The patients were suggested to timely see doctor in case of pain or swelling.Subsequent visit was conducted after a week,and the pain occurrence of diseased teeth after the retreatment was recorded.When the patients had no percussion pain and obvious exudation,the original temporary sealing was removed and alternately flushed with chlorhexidine solution(2%)and normall saline solution(0.9%);lap was used to separate the wet and paper point was used to dry lumen;the main point was inserted and the dental film was shot;after determining the main point reached the working length,the author filled the root canal from sides with zinc oxide iodoform paste and cold pressing glue and completed the shooting.Results: The differences between the experimental group and control group in the rate of root canal are not statistically significant(P>0.05);the experimental group has obviously shorter time in completing the root canal retreatment than the control group and the differences between them are statistically significant(P<0.05);in terms of the incidence of pain,the experimental group is significantly lower than the control group,and the differences between them are statistically significant(P<0.05);in terms of quality of root filling,postoperative X ray shows the successful filling rates of experimental group are 90% and 70% respectively,and they are statistically significantly different(P<0.05).Conclusions: Machine Protaper Universal nickel-titanium retreatment instrument can quickly remove the previous gutta-percha filling materials in the root canal,the has less pain incidence than the manual stainless steel K file group during the treatment,and in terms of quality of root filling is also better.