Effect of three nickel-titanium rotary file techniques on infected root dentin reduction. Influence of the NiTi rotary system on the debridement quality of the root canal space. A retrospective study of endodontic treatment outcome between nickel-titanium rotary and stainless steel hand filing techniques. A comparison of Profile, Hero 642, and K3 instrumentation systems in teeth using digital imaging analysis.
OBJECTIVE This study compared the bacterial reduction of in vitro infected root canals after instrumentation by 3 nickel-titanium ( NiTi ) rotary files with different taper and diameter versus manual stainless steel files . STUDY DESIGN Sixty-four single-rooted human teeth were infected with a suspension of Streptococcus sanguis measured by optical density . Teeth were divided r and omly into 4 groups of 16 and prepared with Flexofiles , GT rotary files , HERO 642 , and ProFile . Bacterial samplings were performed before ( S1 ) , during ( S2-S3 ) , and after ( S4 ) instrumentation . RESULTS All techniques significantly reduced the number of bacterial cells in the root canals ( P < .05 ) . There was no significant difference between NiTi and manual instrumentation at S2 , S3 , or S4 . Concerning bacterial reduction , the results suggest that a manual stainless steel file preparation is as efficient as a NiTi rotary instrumentation . CONCLUSION Regardless of the root canal preparation technique , its taper , and diameter , the root dentin remained infected and was not bacteria-free at the end of the experiment OBJECTIVE The present study was design ed to test the null hypothesis that there is no significant difference in debridement quality promoted by 3 nickel-titanium ( NiTi ) rotary systems . STUDY DESIGN Sixty-seven vital m and ibular molars that were prospect ively collected in vivo were used . The teeth were extracted and then pulp tissue fixed by 10 % formalin . The use of different NiTi rotary systems result ed in 3 experimental groups with 20 specimens each : G1 : Hero 642 ; G2 : K3 ; and G3 : ProTaper Universal . Afterward , the specimens were histologically prepared and serial 0.5 microm cross-sections were obtained every 0.2 mm from the 1 - 3 mm apical levels . The remaining pulp tissue was assessed using a morphometric approach . The cross-sectional area of each root canal and remaining pulp tissue were measured ( mcirom(2 ) ) . Thus , the percentages of remaining pulp tissue area were calculated for each root canal . RESULTS Overall , the pooled data obtained from all levels revealed a variable amount of remaining pulp tissue for all experimental groups . Remaining pulp tissue existed in every specimen . However , the Kruskal-Wallis H test was unable to show significant differences among the experimental groups ( P > .05 ) for the pooled data from all levels . CONCLUSIONS The present study did not find a significant difference in the quality of canal debridement between different NiTi rotary systems , because an adequate tapered shape is obtained AIM The purpose of this study was to compare the periapical healing of molar root canal treatment using two instrumentation techniques . METHODS A total of 225 maxillary and m and ibular first and second permanent molars endodontically treated by undergraduate or postgraduate students were r and omly selected from a computerized hospital data base of which 110 molars had been prepared using a hybrid rotary technique with nickel-titanium instruments ( group NR ) and 115 with h and stainless steel files ( group HF ) . Patients were recalled and the teeth were examined both clinical ly and radiographically for signs of periapical inflammation . RESULTS Some 19 % and 39 % of teeth in the NR and HF group , respectively , were judged to have some form of procedural errors . A higher rate of periapical healing was noted for NR ( 77 % ) than the HF group ( 60 % ) ( p < 0.05 ) . Factors contributing favorably to treatment outcome included the use of rotary technique , maxillary molar , experienced operator , and absence of preoperative radiolucent lesion . CONCLUSION There was a higher incidence of procedural errors and a lower success rate for primary root canal treatment of teeth prepared with stainless steel files compared with the use of NiTi instruments in a continuous reaming action OBJECTIVE To evaluate the changes in cross-sectional area morphology of curved canals after instrumentation with Profile((R ) ) , Hero 642((R ) ) , and K3((R ) ) using digital imaging analysis . Study design Thirty mesial m and ibular curved canals were used ( 25 - 40 degrees ) . The molars were embedded in resin and the roots were sectioned transversely at three levels : apical , middle , and coronal . The canals were r and omly distributed into 3 groups for instrumentation using Profile.04 and .06 , Hero 642 , and K3 . The pre- and postinstrumentation sections were digitized and areas corresponding to the canals were measured with image-processing software . RESULTS Hero  eliminated significantly more dentine than K3 and Profile in all 3 sections ( P < .01 , ANOVA test ) , with no differences observed between the latter 2 systems ( P > .05 , Student-Newman-Keuls test ) . All 3 systems yielded a rounded canal morphology in the coronal , middle , and apical thirds . CONCLUSION Hero rotary instruments produced more changes in cross-sectional area of the root canal
Therefore , the rotary NiTi Hero 642 and K3 files demonstrated comparable shaping abilities and maintenance of working length
The aim of the present study was to compare the root canal preparation ability of rotary nickel-titanium ( NiTi ) Hero 642 and K3 files in curved m and ibular or maxillary molars .