Comparative Study On Curved Root Canals Preparation With Profile Niti Rotary Instruments Protaper Niti Hand Instruments And Stainless Steel K-Files

Objectives: To compare the root canal straightening, the apical transportation, the density of root canal fillings by using the three types of instruments to prepare curved root canals and offer experimental evidences for the ProFile and ProTaper's clinic implement.Methods:Thirty extracted mandibular first premolars with only one root canal and root-canal curvatures between 13° and 38.5° were divided into three groups.Group SS were prepared with stainless steel K-files by the method of which using step-back technique.Group PT were prepared with ProTaper NiTi hand instruments.Group PF were prepared by ProFile NiTi rotary instruments by the method of which using crow-down technique. After accessing cavities pulp extirpation were done,ISO 0.02/15# stainless steel K-files were inserted into the root canal and the working-length were measured.All samples were embedded in plastics vessls with selfcuring acrylic resin,and digital radiography were taken.The curvature of the canal was measured by Schneider's method.After preparations the pre-and postoperative radiographs were overlaped (using photoshop Version7.0),then use AutoCAD2000 to measure the apical transportation.At last,all canals were obturated with zinc-oxide-eugenol paste plus gutta percha points by the method of which using lateral condensation technique,then the post-obturation digital radiography were taken.The following parameters were evaluated: straightening of curved root canals and the density of root canal fillings.Statistical analysis were performed using software SPSS (vertionll.O). Results: The straightening of curved root canals(mean±SD) were -7.49 + 2.44°(group SS),-3.95 + 1.80°(group PT)and -2.34 ± 1.29°(group PF) respectively.The straightening degree of root canals in group SS was more than that of the other two groups.The difference was statistically significant(P=O.00**).There were no significant differences between the Group PT and GroupPF(P=0.069).The apical transportation in Group SS(mean + SD) was 263.02 + 67.81 u m,163.66±37.52 u m(GroupPT) and 134.47 + 26.90 u m(GroupPF).A statistically significant difference in apical transportation was found between the GroupSS and the other two groups(P=0.000**).There were no significant differences between the Group PT and Group PF(P=0.179). The Group SS showed lower density in apical(distance to apical 3mm) and middle sections(distance to apical 6mm) comparing to those of the PT and PF Groups (/><0.05).The density of coronal section(distance to apical 9mm) of the canals among the three groups were no statistical significance(P>0.05) Conclusions:1 .The apical transportation in Group PT and Group PF were less than that of the Group SS.2.The straightening degree of root canals in Group PT and Group PF were less than that of the Group SS.3.The Group SS showed lower density in apical and middle sections comparing to those of the PT and PF Groups .The density of coronal section of the canals among the three Groups were no statistical significance. 4. The abilities of shaping curved root canals of ProFile NiTi rotary instruments and Pro Taper NiTi hand instruments are more acceptive compared to stainless steel files and more suitable to the root canal obturation.