The purpose of this study was to evaluate which type of Ni-Ti files are able to maintain canal configuration better in the simulated canal with abrupt curvature near it's apex.

Ninety six simulated root canals were made in epoxy resin and #15 finger spreader was used as root canal templates. The simulated root canals were made with radius of curvature of 1.5 mm, 3.0 mm, 4.0 mm, 6.0 mm respectively and the angle of curvature of all simulated canals were adjusted to 90 degree. The simulated canals were instrumented by ProFile, ProTaper, Hero 642, and K³ at a 300 rpm using crown-down pressureless technique. Pre-instrumented and post-instrumented images were taken by digital camera and were superimposed with Adobe Photoshop 6.0 program. Images were compared by image analysis program.

The changes of canal width at the inner and outer side of the canal curvature, canal transportation were measured at 9 measuring point with 1 mm interval. Statistical analysis among the types of Ni-Ti files was performed using Kruskal-Wallis test and Mann-Whitney U-test.

The result was that ProFile maintain original canal configuration better than other engine driven Ni-Ti files in the canals above 3.0 mm radius of curvature, and in the 1.5 mm radius of curvature, most of Ni-Ti flies were deformed or separated during instrumentation.

Citations

Citations to this article as recorded by  

• A study on transportation of apical foramen after overinstrumentation by ProFile®, ProTaper™ and K3TMin simulated canals with different curvatures
  Hyun Yang, In-Seok Yang, Yun-Chann Hwang, In-Nam Hwang, Suk-Ja Yoon, Won-Jae Kim, Won-Mann Oh
  Journal of Korean Academy of Conservative Dentistry.2007; 32(2): 87.     CrossRef

The purpose of this study was to investigate the quantity of debris which was extruded apically after canal instrumentation using different types of enlarging instrument in endodontic resin models.

Five groups of 9 endodontic resin models were instrumented using each different technique: hand instrumentation without early coronal flaring, hand instrumentation after early coronal flaring, and three nickel-titanium engine-driven instrumentations (Hero 642, Protaper, K³). Debris extruded from apical foramen during instrumentation was collected on preweighed CBC bottle, desiccated and weighted using electronic balance. The results were analyzed using Kruskal-wallis test and Mann-Whitney U rank sum test at a significance level of 0.05.

The results were as follows:

All of instrumentation techniques produced apically extruded debris.

The early coronal flaring is very important to reduce the amount of debris extruded apically.

There are increasing usage of Nickel-Titanium rotary files in modern clinical endodontic treatment because it is effective and faster than hand filing due to reduced step.

This study was conducted to evaluate the effect of canal preparations using 3 different rotary Nickel-Titanium files that has different cross sectional shape and taper on the maintenance of canal curvature. Simulated resin block were instrumented with Profile(Dentsply, USA), GT rotary files(Dentsply, USA), Hero 642(Micro-Mega, France), and Pro-Taper(Dentsply, USA).

The image of Pre-instrumentation and Post-instrumentation were acquired using digital camera and overspreaded in the computer. Then the total differences of canal diameter, deviation at the outer portion of curvature, deviation at the inner portion of curvature, movement of center of the canal and the centering ratio at the pre-determined level from the apex were measured.

Results were statistically analyzed by means of ANOVA, followed by Scheffe test at a significance level of 0.05.

The results were as follows;

1. Deviation at the outer portion of curvature, deviation at the inner portion of curvature were showed largest in Pro-Taper, so also did in the total differences of canal diameter(p<0.05).

2. All the groups showed movements of center. Profile combined with GT rotary files and Hero 642 has no difference but Pro-Taper showed the most deviation(p<0.05).

3. At the 1, 2, 3mm level from the apex movements of center directed toward the outer portion of curvature, but in 4, 5 mm level directed toward the inner portion of curvature(p<0.05).

As a results of this study, it could be concluded that combined use of other Nickel-Titanium rotary files is strongly recommended when use Pro-Taper file because it could be remove too much canal structure and also made more deviation of canal curvature than others.

Citations

Citations to this article as recorded by  

• Stress distribution of three NiTi rotary files under bending and torsional conditions using a mathematic analysis
  T. O. Kim, G. S. P. Cheung, J. M. Lee, B. M. Kim, B. Hur, H. C. Kim
  International Endodontic Journal.2009; 42(1): 14.     CrossRef
• Comparison of shaping ability using various Nickel-Titanium rotary files and hybrid technique
  Jung-Won Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
  Journal of Korean Academy of Conservative Dentistry.2007; 32(6): 530.     CrossRef
• A study of insertion depth of buchanan plugger after shaping using NI-TI rotary files in simulated resin root canals
  Youn-Sik Park, Dong-Jun Kim, Yun-Chan Hwang, In-Nam Hwang, Won-Mann Oh
  Journal of Korean Academy of Conservative Dentistry.2006; 31(2): 125.     CrossRef
• Step by step analysis of root canal instrumentation with ProTaper®
  Mi-Hee Kim, Bock Huh, Hyeon-Cheol Kim, Jeong-Kil Park
  Journal of Korean Academy of Conservative Dentistry.2006; 31(1): 50.     CrossRef
• Effect of anticurvature filing method on preparation of the curved root canal using ProFile
  Hyun-Ji Song, Juhea Chang, Kyung-Mo Cho, Jin-Woo Kim
  Journal of Korean Academy of Conservative Dentistry.2005; 30(4): 327.     CrossRef
• A comparison of shaping ability of the three ProTaper® instrumentation techniques in simulated canals
  So-Youn Kim, Jeong-Kil Park, Bock Hur, Hyeon-Cheol Kim
  Journal of Korean Academy of Conservative Dentistry.2005; 30(1): 58.     CrossRef

The purpose of this in vitro study was to compare the effects of root canal debridement following rotary Ni-Ti instruments with positive versus negative rake angle. Seventy sound, extracted human anterior teeth & premolars were randomly divided into four groups. The used rotary instruments were Ni-Ti HERO 642(Micro-Mega in France, 20 specimen), Ni-Ti ProFile(Maillefer, Ballaigues, Switzerland, 20 specimen), stainless steel engine reamer(Mani, Matsutani Seisakusho Co.,Japan, 20 specimen) and negative control group(10 specimen) was only extirpated with barbed broach(Mani, Matsutani Seisakusho Co.,Japan)

Group 1 & 2 teeth were prepared to a #40 at the apex followed by 1 mm using crown-down technique. Group 3 teeth were instrumented from a #15 to a #40 in sequential order. After preparation and final irrigation, the roots split longitudinally into a bucco-lingual direction. Root halves were cross-sectioned in apical third portion again. all root specimens were prepared for SEM investigation & photographed. Separate evaluations were undertaken for smear layer on prepared walls with a five score-index for each using reference photograph in root halves. the penetration depth of smear layer into dentinal tubules was also estimated in the other halves. the following results were obtained :

1. Smear layer was observed on all the prepared walls with three experimental groups except negative control group

2. Smear layer characteristics

1) HERO 642 groups showed snowy & dusty appearance & were observed only few some dentinal tubuli open on the prepared walls, and the penetration depth of it into dentinal tubules may be 1-2 µm thick.

2) ProFile groups showed shiny & burnished appearance & complete root canal wall covered by a homogenous smear layer with no open dentinal tubuli and penetration depth of it into dentinal tubules may be 1-2 µm thick.

3) Engine reamer groups showed obviously file's passed tracks on the prepared walls & were observed complete root canal wall covered by a homogenous smear layer with no open dentinal tubuli.

The results revealed that a completely clean root canal could not be achieved regardless of positive & negative rake angle, which is in accordance with the majority of studies on root canal cleanliness.

In conclusion, throughout irrigation with antibacterial solutions or chelating agents is recommended to remove the smear layer on prepared canal walls.

Citations

Citations to this article as recorded by  

• Comparative evaluation of dentin volume removal and centralization of the root canal after shaping with the ProTaper Universal, ProTaper Gold, and One-Curve instruments using micro-CT
  Hatice Yalniz, Mehrdad Koohnavard, Aysenur Oncu, Berkan Celikten, Ayse Isil Orhan, Kaan Orhan
  Journal of Dental Research, Dental Clinics, Dental Prospects.2021; 15(1): 47.     CrossRef
• Microorganism penetration in dentinal tubules of instrumented and retreated root canal walls.In vitroSEM study
  Saad Al-Nazhan, Alaa Al-Sulaiman, Fellwa Al-Rasheed, Fatimah Alnajjar, Bander Al-Abdulwahab, Abdulhakeem Al-Badah
  Restorative Dentistry & Endodontics.2014; 39(4): 258.     CrossRef
• Shaping characteristics of two different motions nickel titanium file: a preliminary comparative study of surface profile and dentin chip
  So-Ra Park, Se-Hee Park, Kyung-Mo Cho, Jin-Woo Kim
  Journal of Dental Rehabilitation and Applied Science.2014; 30(2): 121.     CrossRef