The purpose of this study was to compare the root canal shaping ability of 4 rotary NiTi instruments in simulated root canals.

For the preparation of thirty two curved root canals, Mtwo instruments using "single length"technique, and Profile, ProTaper Universal, and K3 using crown-down technique (N = 8) were used. All canal samples were prepared by reaching an apical canal size of #30. Pre- and post-instrumentation digital images were recorded and an assessment of canal shape was determined using a computer image analysis program SigmaScan Pro (Systat Software Inc., San Jose, CA, USA). The changes of the dimension of inner walls of canals, (2) the changes of the dimension of outer walls of canals, and (3) the centering ratio were measured at 7 measuring points, and then data were statistically analyzed using one-way ANOVA and Duncan's test. The results were as below;

The root canal shaping ability of Profile was significantly faster than that of other rotary NiTi instruments (p < 0.05).

Results suggest that in the coronal part of canal preparation, active cutting files such as ProTaper Universal may efficiently flare the canal orifice and form a better taper, and in the apical part of the canal, files which have a better centering ability such as Profile may maintain the original canal curvature and reduce the shaping time.

The purpose of this study was to evaluate the insertion depth of several brands of master gutta percha cones after shaping by various Ni-Ti rotary files in simulated canals.

Fifty resin simulated J-shape canals were instrumented with ProFile, ProTaper and HEROShaper. Simulated canals were prepared with ProFile .04 taper #25 (n = 10), .06 taper #25 (n = 10), ProTaper F2 (n = 10), HEROShaper .04 taper #25 (n = 10) and .06 taper #25 (n = 10). Size #25 gutta percha cones with a .04 & .06 taper from three different brands were used: DiaDent; META; Sure-endo. The gutta percha cones were selected and inserted into the prepared simulated canals. The distance from the apex of the prepared canal to the gutta percha cone tip was measured by image analysis program.

Within limited data of this study, the results were as follows

1. When the simulated root canals were prepared with HEROShaper, gutta-percha cones were closely adapted to the root canal.

2. All brands of gutta percha cones fail to go to the prepared length in canal which was instrumented with ProFile, the cones extend beyond the prepared length in canal which was prepared with ProTaper.

3. In canal which was instrumented with HEROShaper .04 taper #25, Sure-endo .04 taper master gutta percha cone was well fitted (p < 0.05).

4. In canal which was instrumented with HEROShaper .06 taper #25, META .06 taper master gutta percha cone was well fitted (p < 0.05).

As a result, we concluded that the insertion depth of all brands of master gutta percha cone do not match the rotary instrument, even though it was prepared by crown-down technique, as recommended by the manufacturer. Therefore, the master cone should be carefully selected to match the depth of the prepared canal for adequate obturation.

The purpose of this study was to compare the shaping ability of three Ni-Ti file systems used by dental students or the experts and consequently to aid in choosing a proper systems for educational courses of dental students and beginners.

Fifty students and ten dentists who have clinical experience over two years prepared 180 simulated root canals in resin blocks with three Ni-Ti systems; ProFile® (PF), HeroShaper® (HS), K3^TM (K3).

After preparation, the Ni-Ti files were evaluated for distortion and canal preparation time was recorded. The images of pre- and post-instrumented canals were scanned and superimposed. Amounts of increased canal widths, deviation, and centering ratio were calculated at apical 1, 3 and 5 mm levels and statistical analysis was performed.

The results were as follows:

HS showed the shortest preparation time and instrumented canal width in K3 was significantly larger than other groups (P < 0.05).

Based on the results, it is surmised that the ProFile® is the safest and most ideal instrument for students and beginners.

The purpose of this study was to compare the shaping ability of the two different Ni-Ti file systems and the two different engine systems in simulated canals.

A total of four groups of each 10 were tested. Each group was instrumented with HeroShaper®and Endo-Mate2® (Group HE), HeroShaper® and Tecnika® (Group HT), ProFile® and Endo-Mate2® (Group PE), and ProFile® and Tecnika® (Group PT).

Canal preparation time was recorded. The images of pre- and post-instrumented root canals were scanned and superimposed. The amounts of increased width and centering ratio were measured and calculated at apical 1, 3 and 5 mm levels.

These data were statistically analyzed with one-way ANOVA and Duncan's multiple range test

The results of this study were as follows;

1. Canal preparation time of HT group was the shortest (p < 0.05).

2. The amount of increased canal width in HE group was significantly larger than PT group at apical 1 mm level (p < 0.05). At apical 3 mm level, PT group was significantly smaller than other groups (p < 0.05). At apical 5 mm level, PE group was significantly larger than PT group (p < 0.05).

3. The amount of centering ratio in HE group was significantly larger than other groups (p < 0.05). At apical 5 mm level, HT group was significantly larger than PE group and PT group (p < 0.05).

Under the condition of this study, torque-controlled endodontic motor is safer than no torque controlled motor, especially when the active file is used.

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.

The purpose of this study was to evaluate the canal configuration after shaping by ProFile, ProTaper and K-Flexofile in simulated resin canals with different angles of curvature.

Three types of instruments were used : ProFile, ProTaper, K-Flexofile. Simulated root canals, which were made of epoxy resin, were prepared by ProFile, ProTaper with rotary instrument using a crown-down pressureless technique, and hand instrumentation was performed by K-Flexofile using a step-back technique. All simulated canals were prepared up to size 25 file at end-point of preparation. Pre and post instrumentation images were recorded with Scanner. Assessment of canal shape was completed with Image Analysis program. Measurements were made at 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 mm from the apex. At each level, outer canal width, inner canal width, total canal width, and amount of transportation from original axis were recorded. Instrument deformation and fracture were recorded. Data were analyzed by means of one-way ANOVA analysis of variance and the Sheffe's test.

The result was that ProFile and ProTaper maintain original canal shape regardless of the increase of angle of curvature than K-Flexofile. ProFile show significantly less canal transportation and maintained original canal shape better than ProTaper.

The purpose of this study was to compare and evaluate the shaping ability of the three different Ni-Ti file systems used by undergraduate students.

Fifty undergraduate students prepared 150 simulated curved root canals in resin blocks with three Ni-Ti file systems - ProFile® (PF), Manual ProTaper® (MPT), Rotary ProTape® (RPT). Every student prepared 3 simulated root canals with each system respectively. After root canal preparation, the Ni-Ti files were evaluated for distortion or breakage. Assessments were made according to the presence of various types of canal aberrations. The pre- and post-instrumented canal images were attained and superimposed. The instrumented root canal width were measured and calculated for the net transportation (deviation) and the centering ratio.

Under the condition of this study, both ProTaper® systems allowed significantly more removal of root canal wall than the ProFile® system. In the important other aspects such as the centering ratio, there was no significant differences between the systems. Novice dental students were able to prepare curved root canals with any kinds of Ni-Ti file systems with little aberration and great conservation of tooth structure. Students want to learn effective methods and at the same time simple rotary procedures. The rotary ProTaper® systems were one of the most compatible to these students from the point of view of cutting ability. The ProFile® system was also compatible in safe and gentle shaping.

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.