Shaping ability of Quantec Series 2000 rotary nickel-titanium instruments in simulated root canals: Part 1

The aim of this study was to determine the shaping ability of Quantec Series 2000 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Quantec instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, change in canal length and three-dimensional canal form. The time necessary for canal preparation was on average 5.7 min and was significantly influenced ( P < 0.01) by canal shape. One instrument fractured and three size nine instruments deformed; however, canal shape did not influence significantly instrument failure. All of the canals remained patent, none became blocked with debris. The majority of the canals maintained working distance (26 out of 40), however the mean change in length differed significantly ( P < 0.05) between canal types. Overall, canals with 40° curves lost length whilst those with 20° curves gained in length. Examination of intracanal impressions revealed that preparation with Quantec Series 2000 instruments produced canals with definite apical stops, smooth canal walls and good flow and taper. However, the quality of apical smoothness and flow was influenced significantly ( P < 0.0001) by canal shape with specimens having 40° canals displaying less desirable qualities. Under the conditions of this study, Quantec Series 2000 rotary nickel-titanium instruments prepared simulated canals rapidly, safely and with good three-dimensional form.     

不同根管器械预备弯曲根管的实验研究

目的比较手用不锈钢K锉、手用ProTaper锉、机用ProTaper锉在预备中、重度弯曲根管时的成形能力及其对根尖孔形态特征的影响。方法将40个树脂根管模型分为A、B、C、D组，A、B、C组各12个树脂根管模型，其中每组20°根管和30°根管各6个；D组4个树脂根管模型，均为小于5°根管。分别以手用不锈钢K锉、手用ProTaper锉、机用ProTaper锉预备根管，数码相机摄片，运用专业图像分析软件Auto-CAD比较根管偏移及根尖孔形态。结果B组中轴偏移明显高于A组和C组（P<0.05），其中C组与A组在个别根管段有显著差异（P<0.05）。预备后根尖孔B组各项值均显著高于其他各组，B3组根管值显著高于B2组（P<0.05）。相同根管弯曲度下C组值高于A组；不同弯曲度下30°根管值高于20°根管值，但均无显著性差异（P>0.05）。结论两种镍钛器械均产生根管偏移，根管弯曲度是偏移产生的主要原因；与不锈钢器械相比，镍钛器械能较好地保持原根管走向及根尖孔形态。     

Shaping ability of ProFile.04 Taper Series 29 rotary nickel-titanium instruments in simulated root canals. Part 1

The aim of this study was to determine the shaping ability of ProFile.04 Taper Series 29 nickel-titanium instruments in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using a step-down approach. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was not influenced significantly by canal shape. No instrument fractures occurred but a total of 52 instruments deformed. Size 6 instruments deformed the most followed by sizes 5, 3 and 4. Canal shape did not influence significantly instrument deformation. None of the canals became blocked with debris and loss of working distance was on average 0.5 mm or less. Intracanal impressions of canal form demonstrated that most canals had definite apical stops, smooth canal walls and good flow and taper. Under the conditions of this study, ProFile.04 Taper Series 29rotary nickel-titanium instruments prepared simulated canals rapidly and created good three-dimensional form. A substantial number of instruments deformed but it was not possible to determine whether this phenomenon occurred because of the nature of the experimental model or through an inherent design weakness in the instruments.     

不同机用镍钛器械对重度弯曲根管成形能力的比较研究

目的 通过预备树脂模拟根管,比较5种不同机用镍钛器械预备重度弯曲根管的成形能力,为其临床应用提供依据。方法 将50个40°弯曲的树脂模拟根管随机分成5组,每组10个,分别使用ProTaper Universal(PTU组)、ProTaper Gold(PTG组)、Reciproc Blue(RB组)、One Curve(OC组)和Rotate(R组)进行预备,并记录预备时间。拍摄树脂根管预备前后的墨水染色图像,并通过计算机图像分析软件进行重叠,测量分析根管偏移量及中心定位能力等指标。结果 5组预备时间总的比较差异有统计学意义（F=2230.958,P <0.05）,其中PTU组预备时间最长,RB组的预备时间最短。在距离根尖孔1、2、3、8 mm处,PTU组的根管偏移量大于其他组,差异均有统计学意义（均P <0.05）;在距离根尖孔4、5 mm处,PTG组、OC组和R组的根管偏移量小于其他组,差异均有统计学意义（均P <0.05）;在距离根尖孔6、7 mm处,OC组、R组的根管偏移量小于其他组,差异均有统计学意义（均P <0.05）。结论 5种机用镍钛器械均可快速...     

Shaping ability of Profile rotary nickel-titanium instruments with ISO sized tips in simulated root canals: Part 1

The aim of this study was to determine the shaping ability of ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips in simulated canals. A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by ProFile instruments using the 'crown down' approach recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. The time necessary for canal preparation was on average 5.2 min and was not influenced significantly by canal shape. Three instrument fractures occurred and a further 3 instruments deformed; size 35 instruments failed the most (4) followed by size 30 (2), four of the failures occurred in canals with 40° curves. None of the canals became blocked with debris and change in working distance was minimal. Intra-canal impressions of canal form demonstrated that most canals had apical stops and smooth canal walls whereas all canals had good flow and taper. Under the conditions of this study, ProFile 0.04 taper rotary nickel-titanium instruments with ISO sized tips prepared simulated canals rapidly and created good three-dimensional form.     

Shaping ability of Hero 642 rotary nickel-titanium instruments in simulated root canals: Part 1

AIM: To determine the general efficacy and shaping ability of Hero 642 nickel-titanium rotary instruments during the preparation of simulated canals. Part 1 of this two-part report describes the efficacy of the instruments in terms of three-dimensional canal form. METHODOLOGY: A total of 40 simulated root canals made up of four different shapes in terms of angle and position of curvature were prepared by Hero 642 instruments using a crown-down preparation sequence. The efficacy of the instruments was assessed in terms of preparation time, instrument failure, canal blockages and loss of canal length. Intra-canal impressions were taken of the prepared canals in order to assess three-dimensional canal form. RESULTS: The mean time for canal preparation was 8.6 min and was influenced significantly (P < 0.05) by canal shape. Two instruments fractured and eight instruments deformed; significant differences were observed between canal shapes (P < 0.05). All of the canals remained patent. Fifteen canals (39.5%) maintained the correct working distance, 15 lost distance and eight canals gained length. Examination of intracanal impressions demonstrated that the majority of canals (79%) had apical stops; canal shape had a significant influence (P < 0.001) on the quality of apical stops. With one exception all canals had smooth canal walls and all of the canals showed good flow characteristics. Taper was poor in 30 canals (79%) and good in eight canals (21%). CONCLUSIONS: Hero 642 rotary nickel-titanium instruments prepared simulated canals rapidly but with a three-dimensional form that lacked adequate taper.     

两种镍钛机动器械根管预备的比较研究

目的:评价两种镍钛机动器械预备后牙弯曲根管的效果。方法:选择根管弯曲度10°~20°之间,及>25°的单根管前磨牙各24个,包埋于Branmante模型中。采用Hero642和Profile镍钛机动系统进行根管预备。测定根管预备前后根尖、根中、根冠段的牙本质切削面积、形态因子,并记录操作时间和器械折断情况。结果:Hero642对根尖段及重度弯曲根管根中段的牙本质切削大于Profile,在根管预备过程中体现出较短的操作时间和器械折断率;根管预备后的截面形态在两者间无显著差异。结论:Hero642和Profile镍钛机动系统具有良好的根管成形作用,较高的工作效率,可作为临床上弯曲根管的预备器械。     

���ֻ���������еԤ��������ĥ�����������ٴ�Ч������

??Objective    To evaluate the clinical effects of two nickel-titanium ??NiTi?? instruments ??M3-Pro and Twisted File??TF???? in preparation of molar curved root canals for the aged. Methods    A total of 240 first molars and second molars with curved root canals??25°-30°??that required root canal treatment were selected and randomly divided into two groups. The root canals were prepared with M3-Pro NiTi rotary instruments in the M3-Pro group and with TF NiTi rotary instruments in the TF group. For general analysis??all the cases are chosen from the newly diagnosed cases of patients about 60 - 70 years old in clinic from Jun. 2015 to Sep. 2017. Then the root canal preparation time??incidence of the pain after root canal preparation??effects of root canal obturation??and incidence of instrument separation were compared. Results    The average root canal preparation time in the M3-Pro group was??5.22 ± 1.12??min??whereas in the TF group it was??6.47 ± 0.93??min??t = -17.816??P < 0.05??. The incidence of endodontic inter-appointment emergences in the M3-Pro group was 3.3%??whereas in the TF group it was 2.5%??χ2 = 0.147??P > 0.05??. Adequate root canal filling in the M3-Pro group was 96.72%??whereas in the TF group it was 95.84%??χ2 = 0.463??P > 0.05??. Instrument separations were not found in both groups. There were 10 instruments damaged in the M3-Pro group and 21 instruments damaged in the TF group ??χ2 = 4.482??P < 0.05??. Conclusion    M3-Pro instruments can make the preparation efficiently and reduce the incidence of endodontic inter-appointment emergences??in addition??it maintains a satisfactory anatomical shape of the root canal while significantly decreasing instrument separation. M3-Pro is suitable for the treatment of curved root canal??and has good clinical effect.     

两种机用镍钛器械预备老年人磨牙弯曲根管临床效果评价

目的    评价两种机用镍钛器械M3-Pro和Twisted File（TF）在老年人磨牙弯曲根管预备中的临床应用效果。方法    选择2015年6月至2017年9月在青岛市口腔医院牙体牙髓科门诊就诊的60 ~ 70岁因牙髓病需要行根管治疗的初诊患者215例,按Schneider测量法选择弯曲根管（25° ~ 30°）磨牙240颗,随机均分为M3-Pro组和TF组,分别用M3-Pro和TF机用镍钛器械进行根管预备,比较两组在根管预备时间、根管预备后疼痛反应、根管充填效果、器械分离和损伤情况等方面的差异。结果    M3-Pro组的根管预备时间为（5.22 ± 1.12）min,TF组为（6.47 ± 0.93）min,组间差异有统计学意义（t = -17.816,P < 0.05）;M3-Pro组根管治疗期间急症发生率为3.3%,TF组为2.5%,组间差异无统计学意义（χ2 = 0.147,P > 0.05）;M3-Pro组根管恰填率为96.72%,TF组为95.84%,组间差异无统计学意义（χ2 = 0.463,P > 0.05）;两组各使用镍钛器械120支,均未发生器械分离,M3-Pro组发生10支器械损伤,TF组发生21支器械损伤,组间差异有统计学意义（χ2 = 4.482,P < 0.05）。结论    M3-Pro能够高效率地进行根管预备,可有效降低根管治疗期间急症的发生,也能更好地保持根管解剖的原始走行,明显减少器械分离的发生,尤其适合弯曲根管的治疗,临床疗效较好。     

Matching the Dimensions of Currently Available Instruments with the Apical Diameters of Mandibular Molar Mesial Root Canals Obtained by Micro–computed Tomography

IntroductionThis micro–computed tomographic study investigated the original anatomic diameters of the apical portion of mandibular molar mesial canals and matched them to the dimensions of instruments that are currently available and commonly used for apical preparation.MethodsOne hundred eight mandibular molar mesial roots with Vertucci type IV configuration were scanned by micro–computed tomographic imaging, and the largest anatomic diameter of both mesial canals at 1, 2, 3, and 4 mm short of the apical foramen was measured. Canal diameters were compared with the dimensions of 10 endodontic instruments for simulation of preparation 1 mm short of the apical foramen. Accordingly, the instruments with a diameter larger than the largest canal diameter were regarded as having the potential to prepare 100% of the canal walls at each specific point or over the 4-mm apical segment.ResultsAt 1 and 2 mm short of the apical foramen, a 45/.02 instrument had a larger diameter than the mesiobuccal canal diameter in 73% and 55% of the teeth, respectively. Corresponding figures for the mesiolingual canal were 65% and 55%. When the entire 4-mm apical segment was considered, a 40/.06 instrument had better results, being larger than the apical canal in about 20% of the specimens. Overall, 78% of the apical canals would not be completely prepared by any instrument. Based on the mean (median) anatomic diameters, the adequate instrument dimensions would be 40/.10 (40/.08) for mesiobuccal canals and 45/.08 (40/.09) for mesiolingual canals.ConclusionsThe dimensions of the available instruments are not compatible with complete apical preparation in the majority of cases. The ideal instrument size/taper to include all the canal walls in apical preparation is too large and may not be safe for clinical use.     

Shaping ability of NT Engine and McXim rotary nickel-titanium instruments in simulated root canals. Part 1

The aim of this study was to determine the shaping ability of NT Engine and McXim nickel-titanium rotary instruments in simulated root canals. In all, 40 canals consisting of four different shapes in terms of angle and position of curvature were prepared by a combination of NT Engine and McXim instruments using the technique recommended by the manufacturer. Part 1 of this two-part report describes the efficacy of the instruments in terms of preparation time, instrument failure, canal blockages, loss of canal length and three-dimensional canal form. Overall, the mean preparation time for all canals was 6.01 min, with canal shape having a significant effect ( P <0.01) on the speed of preparation. One instrument fractured and only four instruments deformed, with most of the failures occurring in canals with curves which began 12 mm from the orifice, that is, in short acute curves. None of the canals became blocked with debris. Following preparation, 20 canals retained their original working length but 19 lost length and one gained in length; there were significant differences ( P <0.05) between the canal shapes in terms of mean loss of distance and in the category of distance change. Apical stops as determined from intracanal impressions were present in 37 of the canals; 16 were judged to be of good quality and 21 of poor quality. The canals were found to be smooth in the apical half of the canal in 33 specimens and in the coronal half of 39 specimens. All canals had good taper characteristics and 35 had good flow characteristics. Under the conditions of this study, NT Engine and McXim instruments prepared canals rapidly, with few deformations, no canal blockages and with minimal change in working length. The three-dimensional form of the canals demonstrated good flow and taper characteristics.     

Shaping ability of progressive versus constant taper instruments in simulated root canals

AIM: To compare the shaping ability of progressive versus constant taper shaft designed instruments in simulated root canals. METHODOLOGY: Simulated L- and S-shaped resin canals were prepared by ProTaper (progressive taper) and high elasticity in rotation 642 (Hero 642) (constant taper) instruments (n = 10 canals in each case). The pre- and post-instrumentation images were recorded and assessment of the canal shape was completed with image pro plus 5.0. The width of resin removed was measured at 9 measuring points. Incidence of canal aberrations, instrument fracture, preparation time and change of working length were recorded. In addition, the change of curvature and centring ability were also assessed. The data were analysed statistically using Student's t-test or Fisher's exact-test. RESULTS: In both canal types, Hero 642 instruments prepared canals more rapidly (P < 0.01) and maintained working length significantly more accurately than ProTaper instruments (P < 0.05). In canals prepared with Hero 642 instruments, there was less change in curvature. Instrumentation with ProTaper results in transportation towards the outer aspect of the L-shaped curved canals in the apical part and the inner aspect of the S-shaped canals at the curve. Hero 642 instruments had a better centring ability in the apical part of the canal, but resulted in shapes with a poor taper. CONCLUSIONS: ProTaper and Hero 642 instruments prepared curved canals rapidly, maintained working length well and were relatively safe without creating perforations and danger zones. In both canal types, Hero 642 instruments maintained the original canal curvature better, and had a better centring ability in curved canals because of its constant taper design. The taper prepared by Hero 642 instruments in the coronal part of the canal was generally poor.     

手用ProTaper镍钛器械预备弯曲根管的临床研究

目的:观察手用ProTaper镍钛器械预备弯曲根管的临床效果。方法:117例患者分为两组,手用ProTaper镍钛(PT)组59例,采用手用ProTaper镍钛器械预备根管,不锈钢K型根管锉(SS)组58例,采用改良双敞法预备根管。记录操作时间、器械折断情况、根管偏移发生情况、术后疼痛的发生、根管充填效果。结果:根管预备时间PT组为(5.59±1.66)min,SS组为(11.88±2.36)min;断针率PT组为3.39%,SS组为0;根管偏移率PT组为3.39%,SS组为17.24%;根充术后疼痛率PT组为5.08%,SS组为20.69%。结论:用手用ProTaper预备弯曲根管成形效果好,操作时间短,能很好地维持根管的走向和弯曲度,极少发生根管偏移等并发症,与目前较常用的K锉/改良双敞法相比有着明显的优势,可作为临床上预备弯曲根管的有效方法。但要注意预防因器械疲劳造成的折断,在形态复杂的根管中须小心操作。     

Shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canals

AIM: To compare the shaping ability of ProFile and K3 rotary Ni-Ti instruments when used in a variable tip sequence in simulated curved root canals with different curvature and radius. METHODOLOGY: ProFile or K3.06 taper instruments were used to prepare simulated canals of 20 degrees curvature and 5 mm radius (n = 10) and 30 degrees curvature and 3 mm radius canals (n = 10) in resin blocks. All canals were prepared to an apical size 40 at 0.5 mm from the canal terminus using a variable tip crown-down sequence. Pre- and postinstrumentation digital images were recorded, and an assessment of the canal shape was determined using a computer image analysis program. The material removal from the inner and outer wall of the canal was measured at 28 measuring points, beginning 0.5 mm from the end-point of the canal and the data compared using the Mann-Whitney U-test. RESULTS: In 20 degrees and 30 degrees canals both instruments significantly removed more (P < 0.05) material on the outer wall than the inner wall in the apical half of the canal. For ProFile files there was no significant difference in the amount of material removed on the outer canal wall between the 20 degrees and 30 degrees canals. However, in the K3 groups significantly more (P < 0.05) outer canal wall was removed in the apical area in 20 degrees canals. When comparing both instruments the results showed that in 20 degrees canals K3 instruments removed more outer and inner canal wall than ProFile instruments (P < 0.05) but that there was no significant difference (P > 0.05) between the instruments in 30 degrees canals. CONCLUSION: Within the limitation of this study, both rotary nickel-titanium instruments prepared a well-shaped root canal with minimal canal transportation.     

4种机用镍钛器械预备模拟弯曲根管的效果评价

目的:比较4种机用镍钛器械预备模拟弯曲根管的成形效果。方法:40个单弯(弯曲度38.5°)树脂根管,随机编号分4组(Hero642、Protaper、K3及Mtwo)。按厂家推荐方法预备,记录预备时间,扫描仪获取图像,使用图像分析、测量软件将预备前、后的图像重叠,测量根管内、外侧壁树脂去除量、弯曲度及弯曲半径等的变化。采用SPSS13.0软件包对数据进行单因素方差分析。结果:K3预备速度最慢,Mtwo最快(P<0.05)。在根管弯曲起始点(BC)、根管口(O)和两者中点(HO)处内侧壁以及弯曲最凸点(AC)、HO和O处外侧壁的预备量4组间差异显著,Protaper预备后根管锥度变化最大,Hero642最小(P<0.05)。Protaper在根管弯曲段的中心定位能力最差;越接近根管下份偏移增大。K3与Protaper各1例断针,K3有2例台阶,安全性能、不良形态、根管弯曲角度及半径的改变方面,4种器械无显著差异,但预备后根管工作长度缩短,略有被拉直趋势。结论:Mtwo能快速预备根管;Protaper预备后根管锥度最明显;4种机用镍钛器械均具备良好的切屑力且维持原始根管走向。     

Comparative study on the shaping ability and cleaning efficiency of rotary Mtwo instruments. Part 1. Shaping ability in simulated curved canals

AIM: To compare the shaping ability of Mtwo instruments with K3 and RaCe instruments. Part 1 of this two-part report describes the efficacy of these nickel-titanium instruments in simulated curved root canals. METHODOLOGY: Simulated canals with 28 degree and 35 degree curves in resin blocks were prepared with Mtwo instruments using a single length technique and with K3 and RaCe instruments using a crowndown preparation technique (n = 20 canals in each case). Pre- and post-instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 20 measuring points, beginning 1 mm from the endpoint of preparation. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. The data were analysed statistically using ANOVA and Student-Newman-Keuls test. RESULTS: On an average, canals prepared with Mtwo instruments remained better centred compared with those enlarged with K3 or RaCe instruments. Six RaCe instruments, four K3 files and none of the Mtwo instruments fractured during preparation (P > 0.05). In both of the canal types, Mtwo was significantly faster (P < 0.001). It was possible with all types of instruments to control working length as well. CONCLUSIONS: Mtwo instruments prepared curved canals rapidly, respected original canal curvature well and were safe to use.     

Comparative investigation of two rotary nickel-titanium instruments: ProTaper versus RaCe. Part 1. Shaping ability in simulated curved canals

AIM: To compare the shaping ability of ProTaper with Reamer with Alternating Cutting Edges (RaCe) instruments. Part 1 of this two-part report describes the efficacy of these two nickel-titanium instruments in simulated curved root canals. METHODOLOGY: Simulated canals with 28 degrees and 35 degrees curves in resin blocks were prepared with ProTaper and RaCe instruments using a crown-down preparation technique (n = 24 canals in each case). Pre- and postinstrumentation images were recorded, and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 20 measuring points, beginning 1 mm from the apex. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. The data were analysed statistically using the Mann-Whitney U-test or the chi-square test. RESULTS: On average, canals prepared with RaCe instruments remained better centred compared with those enlarged with ProTaper files. Three RaCe instruments and two ProTaper files fractured during preparation (P > 0.05). Between both the canal types, RaCe was significantly faster (P < 0.001) than ProTaper and maintained working length significantly better (P < 0.05). CONCLUSION: Both instruments prepared curved canals rapidly and were relatively safe. RaCe respected original canal curvature better than ProTaper, which tended to transport towards the outer aspect of the curve.     

Effect of canal preparation with TRUShape and Vortex rotary instruments on three‐dimensional geometry of oval root canals

The purpose of this study was to assess the geometry of non‐round root canals after preparation with TRUShape (a novel instrument with s‐shaped longitudinal design) in comparison to conventional rotary instrumentation using micro‐computed tomography. Twenty distal root canals of mandibular molars were randomly distributed in two groups to be shaped with either TRUShape or Vortex rotaries. Percentages of unprepared surface and volume of dentin removal for the entire canal and for the apical 4 mm were calculated. Canal transportation and the structure model index (SMI) were assessed. Data were compared with Student t‐tests. Shaping with both techniques resulted in similar prepared surface and volume of dentin removed, as well as the extent of canal transportation. The SMI shape factor was significantly lower for TRUShape preparations (P = 0.04) suggesting less rounding during rotary preparation. Although both instruments were suitable for the preparation of oval canals, TRUShape appeared to better conform to the original ribbon‐shaped anatomy.     

Efficiency of rotary nickel-titanium K3 instruments compared with stainless steel hand K-Flexofile. Part 1. Shaping ability in simulated curved canals

AIM: To compare the shaping ability of K3 rotary nickel-titanium instruments with stainless steel K-Flexofiles manipulated by hand. Part 1 of this two-part report describes the efficiency of these two instruments in simulated curved root canals. METHODOLOGY: Simulated canals with 28 degrees and 35 degrees curves in resin blocks were prepared by K3 instruments with a rotational speed of 250 r.p.m. using a crown-down preparation technique, or by K-Flexofiles using a reaming motion -i = 24 canals in each case). All canals were prepared up to size 35 at the end-point of preparation. Pre- and postinstrumentation images were recorded, and assessment of canal shape was completed with a computer image analysis program. Material removal was measured at 20 measuring points, beginning 1 mm from the apex. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were also recorded. RESULTS: In comparison with stainless steel K-Flexofiles, rotary K3 instruments achieved better canal geometry and showed significantly less canal transportation (P < 0.05) Eleven K3 instruments and none of the K-Flexofiles fractured during preparation (P < 0.05). Between both the canal types, K3 was significantly faster (P < 0.001) than K-Flexofiles. Both instruments maintained a good working distance. CONCLUSIONS: K3 instruments prepared curved canals rapidly and with minimal transportation towards the outer aspect of the curve. Fractures occurred significantly more often with K3.     

不同镍钛旋转器械平解剖性根尖孔长度预备根管后根尖孔表面形态变化的研究

目的:研究不同镍钛旋转器械在平解剖性根尖孔长度时预备根管后根尖孔表面形态的变化。方法:选取因牙周病拔除的离体牙40颗,随机分为两组并在扫描电子显微镜下拍摄术前片,记录根尖孔表面形态;分别采用K3锉、TF锉在工作长度下(平解剖性根尖孔长度)预备根管,扫描电子显微镜下观察并记录预备后根尖孔表面形态的变化:记录根尖孔的偏移、根尖孔周围牙骨质缺损及根尖孔周围表面的裂纹。结果:K3组、TF组根管预备后均存在根尖孔的偏移、牙骨质的缺损及根尖孔周围表面的裂纹,其中根尖孔的偏移的样本数目、根尖孔周围牙骨质缺损样本数目两组之间存在统计学差异(P<0.05),根尖孔周围表面裂纹样本数两组之间无统计学差异。结论:K3、TF两种镍钛旋转器械在平解剖性根尖孔长度下预备根管时由于超根尖止点预备,均可导致根尖孔偏移,根尖孔周围的牙骨质缺损及根尖孔表面裂纹线产生,与K3锉相比,TF锉在减少根尖孔偏移及根尖孔周围牙骨质缺损方面更具优越性。