| As an important step of root canal therapy (RCT), root canal preparation aims to clean and shape the root canal and to facilitate the filling. The narrow and curved root canal of posterior teeth leads to the prolonged preparing time and unsatisfied root canal treatment effect in posterior teeth. The nickel-titanium device is a newly-rising root canal preparing system. It is efficient and well-shaping. It can shorten operating time and reduce tiredness, it also can get satisfied shaping and cleaning result in curved canals. To evaluate the immediate effect and efficiency of Profile rotary device in root canal therapy? this study observed the preparing of root canal in posterior teeth using HERO 642 nickel-titanium rotary device by crown-down technique (CD) and filling, K file was used as control.53 patients(18-49years old) who needed root canal preparing from 2001.2 —2003. 1 in our department was devided into two groups randomly. It consisted 83 teeth, which had no fracture, absorption , severe periodontitis and systematic diseases. The experimental group used HERO 642 nickel-titanium rotary device for root canal preparing and then filled with gutta percha point by lateralcondensation technique, it included 3 maxillary first premolair, 5 maxillary second premolarN 8 maxillary first molar, 1 maxillary second molars 6 mandibular first premolars 7 mandibular second premolar, 9 mandibular first molars 3 mandibular second molar, 42 teeth and 87 root canal in total. The control group used K file for root canal preparing and then filled with gutta percha point by lateral condensation technique, it included 5 maxillary first premolars 3 maxillary second premolars 7 maxillary first molars 2 maxillary second molars 5 mandibular first premolar, 7 mandibular second premolars 10 mandibular first molars 2 mandibular second molar, 41 teeth and 92 root canal in total.HERO 642 rotary device was used in preparing of root canal with crown -down technique in experimental group. K file was used in preparing with step-back technique in control group. After preparing the root canal preparing time was recorded. And acute clinical reaction was observed after one week. After sterilization for 5 — 7 days, all the root canal were filled with gutta percha point by lateral condensation technique. Then the filling quality , preparing time and acute clinical reaction were analysed in radiographs according to the evaluation criterion of curative effect. There were different instruments and methods in two groups beside of the same drug, filling material, filling method and operator.The results of the study are as follows: two groups serving as to filling quality had significant difference (P<0.01), the filling quality of experimental group was better than the control group. The results showed that the HERO 642 rotary device had well-shaping ability HERO 642 rotary device could maintain the curvature and shape of the root canal. The preparing time of experimental group was 441 ±24 seconds and the control group was 664 ±113 seconds, and there was significant difference between two groups (P<0.01). The resultsshowed that the HERO 642 rotary device worked more efficiently. The immediate symptoms of two groups showed no significant difference. The symptoms were light and faded in 5 — 7 days after antiflammatory therapy. This might be due to the fact that HERO 642 rotary device had the same stimulation and damage to the apical tissue compare to K file during the preparation.Shown though above study, the nickel-titanium rotary device have many advantages compare to the traditional instruments, such as less preparing time, less effort and much better shaping ability. Certainly when using the nickel -titanium instruments, the operator should operate strictly and accumulate experience continuously so that he can prevent himself from accidents. So long as it is a good way to enhance the level of root canal treatment. |
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