OBJECTIVEThis study aims to evaluate the shaping capability of Reciproc, WaveOne, Mtwo, and ProTaper instruments in simulated root canals.

METHODSA total of 40 simulated resin blocks were divided randomly into four groups. Each group was prepared with Reciproc (Group 1), WaveOne (Group 2), Mtwo (Group 3), and ProTaper (Group 4). The preparation time and reduction in working length after preparation were measured. Pre- and post-operative images were obtained with a scanner and superimposed through Photoshop. The changes in canal curvature and material removal from the inner and outer canal walls at 10 points beginning at 1 mm from the end point of the canal were measured with Image J. Centering capability was determined accordingly. Data were analyzed through one-way ANOVA, SNK, and Kruskal-Wallis at a significance level of P < 0.05.

RESULTSThe preparation time of Group 2 was (53.7 ± 6.7) s, whereas those of Groups 1, 3, and 4 were (86.9 ± 8.1) s, (112.2 ± 8.2) s, and (177.9 ± 11.2) s, respectively; the difference was found to be significant (P < 0.05). The reductions in working length among the four groups after preparation were not significantly different (P > 0.05). The canal curvature for Groups 1 to 4 were 2.671° ± 0.637°, 2.667° ± 0.450°, 3.664° ± 0.870°, and 3.797° ± 0.601°, respectively. The changes for Groups 1 and 2 were significantly smaller than those for Groups 3 and 4. At the 3 mm point, the transportation of Group 1 was (-0.016 ± 0.094) mm, which was significantly less than that of the other instruments (P<0.05). At the 4 mm and 5 mm points, the trans- portation values of Group 2 were (-0.080 ± 0.104) mm and (-0.312 ± 0.088) mm, which were significantly less than that of Group 1 [(-0.243 ± 0.099) mm, (-0.404 ± 0.064) mm, P < 0.05].

CONCLUSIONReciproc and WaveOne can complete preparation faster and can maintain the original canal curvature better than Mtwo and ProTaper. Reciproc exhibits superior centering capability in the apical part of the canal, whereas WaveOne exhibits superior centering capability in the middle part of the canal.

Dental Pulp Cavity ; Humans ; In Vitro Techniques ; Nickel ; Root Canal Preparation ; Titanium

Objective To evaluate the shaping ability of Reciproc ,WaveOne,Mtwo and ProTaper instruments in simulated S-shaped root canals.Methods A total of 40 simulated S-shaped resin blocks were divided randomly into four groups,each group was prepared with Reciproc (group A),WaveOne(group B), Mtwo(group C) and ProTaper(group D),respectively.The preparation time and reduction of working length after preparation were measured.Pre-and postoperative images were obtained by a scanner and superimposed using Photoshop.Changes of coronal curve and apical curve curvature ,as well as material removal from the inner and outer canal wall at 10 points beginning 1 mm from the end point of the canal ,were measured using ImageJ.Centering ability was determined ,accordingly.The data were analyzed using the one-way ANOVA and Student-Newman-Keuls.Results The preparation time of group A and group B were ( 42.1 ±2.7 ) and (41.5 ±3.2) s respectively,significantly less than that of group C and group D [(62.7 ±2.8),(62.8 ± 5.2) s](P<0.05).Reductions of working length after preparation were not significantly different among the four groups(P>0.05).Coronal curve curvature changes of group A ,group B and group D were (4.69 ± 0.63)°,(4.15 ±0.89)°and (4.13 ±0.59)°respectively,significantly less than that of group C [(5.26 ± 0.70)°],P<0.05.Apical curve curvature changes were not significantly different among the four groups (P>0.05).At the 2 mm point,the centering ability of group A [( -0.242 ±0.042) mm],group B [(-0.191 ±0.077) mm],and group D[(-0.272 ±0.046) mm] was better than group C [( -0.343 ± 0.057 mm] significantly(P<0.05).At the 3 mm and 4 mm point,the centering ability of group A and group B was better than group C and group D significantly ( P <0.05 ).Whilst at the 5 mm point , the centering ability of group D was better than group A and group B ( P<0.05 ).Conclusions Reciproc and WaveOne could complete preparation faster and could maintain the original S -shaped canal curvature better than Mtwo and ProTaper ,especially in the apical part.

Objective ??This?study?aims?to?evaluate?the?shaping?capability?of?Reciproc,?WaveOne,?Mtwo,?and?ProTaper?instruments?in?simulated?root?canals. Methods ??A?total?of?40?simulated?resin?blocks?were?divided?randomly?into?four?groups.?Each?group?was?prepared?with?Reciproc?(Group?1),?WaveOne?(Group?2),?Mtwo?(Group?3),?and?ProTaper?(Group?4).?The?pre-paration?time?and?reduction?in?working?length?after?preparation?were?measured.?Pre-?and?post-operative?images?were?obtained?with?a?scanner?and?superimposed?through?Photoshop.?The?changes?in?canal?curvature?and?material?removal?from?the?inner?and?outer?canal?walls?at?10?points?beginning?at?1?mm?from?the?end?point?of?the?canal?were?measured?with?Image?J.?Centering?capability?was?determined?accordingly.?Data?were?analyzed?through?one-way?ANOVA,?SNK,?and?Kruskal–Wallis?at?a?signi-ficance?level?of?P<0.05.?Results ??The?preparation?time?of?Group?2?was?(53.7±6.7)?s,?whereas?those?of?Groups?1,?3,?and?4?were?(86.9±8.1)?s,?(112.2±8.2)?s,?and?(177.9±11.2)?s,?respectively;?the?difference?was?found?to?be?significant?(P<0.05).?The?reduc-tions?in?working?length?among?the?four?groups?after?preparation?were?not?significantly?different?(P>0.05).?The?canal?curvature?for?Groups?1?to?4?were?2.671°±0.637°,?2.667°±0.450°,?3.664°±0.870°,?and?3.797°±0.601°,?respectively.?The?changes?for?Groups 1?and?2?were?significantly?smaller?than?those?for?Groups?3?and?4.?At?the?3?mm?point,?the?transportation?of?Group?1?was?(-0.016± 0.094)?mm,?which?was?significantly?less?than?that?of?the?other?instruments?(P<0.05).?At?the?4?mm?and?5?mm?points,?the?trans-portation?values?of?Group?2?were?(-0.080±0.104)?mm?and?(-0.312±0.088)?mm,?which?were?significantly?less?than?that?of?Group?1?[(-0.243±0.099)?mm,?(-0.404±0.064)?mm,?P<0.05].?Conclusion ??Reciproc?and?WaveOne?can?complete?prepa-ration?faster?and?can?maintain?the?original?canal?curvature?better?than?Mtwo?and?ProTaper.?Reciproc?exhibits?superior?centering?capability?in?the?apical?part?of?the?canal,?whereas?WaveOne?exhibits?superior?centering?capability?in?the?middle?part?of?the?canal.

OBJECTIVETo evaluate the shaping ability of Reciproc, WaveOne,Mtwo and ProTaper instruments in simulated S-shaped root canals.

METHODSA total of 40 simulated S-shaped resin blocks were divided randomly into four groups, each group was prepared with Reciproc (group A), WaveOne (group B), Mtwo (group C) and ProTaper (group D), respectively. The preparation time and reduction of working length after preparation were measured. Pre- and postoperative images were obtained by a scanner and superimposed using Photoshop. Changes of coronal curve and apical curve curvature, as well as material removal from the inner and outer canal wall at 10 points beginning 1 mm from the end point of the canal, were measured using ImageJ. Centering ability was determined, accordingly. The data were analyzed using the one-way ANOVA and Student-Newman-Keuls.

RESULTSThe preparation time of group A and group B were (42.1 ± 2.7) and (41.5 ± 3.2) s respectively, significantly less than that of group C and group D [(62.7 ± 2.8), (62.8 ± 5.2) s] (P < 0.05).Reductions of working length after preparation were not significantly different among the four groups (P > 0.05). Coronal curve curvature changes of group A, group B and group D were (4.69 ± 0.63)°, (4.15 ± 0.89)° and (4.13 ± 0.59)° respectively, significantly less than that of group C[(5.26 ± 0.70)°], P < 0.05. Apical curve curvature changes were not significantly different among the four groups (P > 0.05). At the 2 mm point, the centering ability of group A[ (-0.242 ± 0.042) mm], group B[(-0.191 ± 0.077) mm], and group D[(-0.272 ± 0.046) mm] was better than group C[(-0.343 ± 0.057 mm] significantly (P < 0.05). At the 3 mm and 4 mm point, the centering ability of group A and group B was better than group C and group D significantly (P < 0.05). Whilst at the 5 mm point, the centering ability of group D was better than group A and group B (P < 0.05).

CONCLUSIONSReciproc and WaveOne could complete preparation faster and could maintain the original S-shaped canal curvature better than Mtwo and ProTaper, especially in the apical part.

Analysis of Variance ; Dental Alloys ; Dental Instruments ; Dental Pulp Cavity ; Equipment Failure ; Humans ; Nickel ; Root Canal Preparation ; Titanium

Objective:To analyze the influence of operator′s experience on the quality and success rate of root canal treatment with new nickel-titanium instruments, providing support for improving the success rate of root canal treatment with new nickel-titanium instruments in clinic.Methods:Cases of root canal treatment and non-surgical root canal retreatment with 6-12 months recall performed by residents (resident group) with experience of 1-3 years and endodontic specialists (specialist group) with experience of 5-7 years were collected from the electronic medical system of the Department of Endodontics, School of Stomatology, Capital Medical University, from September 2020 to August 2021. All cases were prepared by engine-driven glide path files and controlled memory nickel-titanium finishing files. Chi-square test and logistic regression were used to analyze the differences and influencing factors of complications, filling quality and success rate of root canal treatment between the two groups.Results:A total of 277 cases performed by 24 residents and 3 specialists were included, 169 in the resident group and 108 in the specialist group. The clinical incidence of flare-ups was significantly higher in the resident group [3.6% (6/169)] than in the specialist group [0(0/108)] ( P=0.048). There were no significant differences in ledges, root canal transportations, perforations, or instrument separations between the two groups ( P>0.05). The prevalence of satisfactory fillings was 62.7% (106/169) in the resident group, which was significantly lower than that in the specialist group [86.1% (93/108)] ( P<0.05). The success rate of root canal treatment was 91.7% (155/169) and 94.4% (102/108) in the resident group and the specialist group, respectively, with no significant differences (χ 2=0.73, P=0.392). Multivariate analysis showed that the success rate of root canal treatment was related to complications and quality of root fillings ( P<0.05). Conclusions:Higher success rate of root canal treatment could be achieved by residents and endodontic specialists with engine-driven glide path files and controlled memory nickel-titanium files.