JKACD Journal of Korean Academy of Conservative Dentistry J Korean Acad Conserv Dent 1225-0864 2093-8179 The Korean Academy of Conservative Dentistry 10.5395/JKACD.2004.29.1.44 jkacd-29-44 Original Article SHAPING ABILITY OF NICKEL-TITANIUMROTARY FILES ParkWan-Ky LeeHee-Joo HurBock Department of Conservative Dentistry, College of Dentisry, Pusan National University Corresponding author: Wan-Ky Park, Department of Conservative Dentistry, College of Dentisry, Pusan National University 1-10, Ami-dong, Seo-gu, Pusan, 602-739, Korea, Tel : 051)240-7454, E-mail: beatl@freechal.com 012004 14012004 29 1 44 50 Copyright © 2004 The Korean Academy of Conservative Dentistry 2004 This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ABSTRACT

This study compared the shaping ability of nickel-titanium rotary files with different rake angle and radial land.

The nickel-titanium files used in this study were Profile(Dentsply, Maillefer, Ballaigues, Switzerland), Hero 642(Micromega, Besancon, France), and K3(SybronEndo, Glendora, Ca, USA) file. Resin blocks substituted for root canals. 36 resin blocks were divided into 3 groups with 12 canals each. The time for canal preparation was recorded. The images of pre- and postoperative resin canal were scanned and those were superimposed. Amounts of canal deviation, total canal widths, inner canal widths, and outer canal widths were measured at apical 1, 2, 3, 4, 5, 6, and 7mm levels.

The amount of canal deviation was the smallest in Profile group, and the time for canal preparation was the shortest in Hero 642 group. K3 group resulted in competent characteristics in both measurements. Positive rake angle seemed to result in fast shaping of root canal and radial land guide the instrument in center of the canals and around curvatures. Radial land also tended to reduce the sense of screwing into the root canal.

The proper selection of the nickel-titanium file based on the knowledge about file design is needed for the safer, simpler and faster root canal therapy.

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Superimposing images of pre- and postoperative blocks

Classification of groups

Group Numbers of resin block File system
P 12 Profile(Dentsply, Maillefer, Ballaigues Switzerland)
H 12 Hero 642(Micromega, Besancon, France)
K 12 K3(SybronEndo, Glendora, Ca., USA)

Design of each files

File system Rake angle Radial land
Profile(Dentsply, Maillefer, Ballaigues, Switzerland) slight negative Yes
Hero 642(Micromega, Besancon, France) slight positive No
K3(SybronEndo, Glendora, Ca, USA) slight positive Yes

Preparation sequence

Sequence File Working length(mm)
1 #30-.06T 12mm
2 #25-.06T 14mm
3 #20-.06T 16mm
4 #20-.04T Working length
5 #20-.06T Working length
6 #25-.06T Working length

Time for canal preparation(second)

Sample No. Profile Hero 642 K3
1 162 120 136
2 165 116 129
3 160 118 133
4 145 115 138
5 160 124 134
6 148 115 130
7 140 105 134
8 162 120 129
9 170 106 119
10 167 110 135
11 163 114 119
12
 150
 125
 124
Mean(SD) 157.7(±9.1) 115.7(±6.3) 130.0(±6.4)

Mean values(standard deviation) of total canal width, outer canal width, inner canal width, and amount of deviation of each groups(mm)

Distance from apex 1mm 2mm 3mm 4mm 5mm 6mm 7mm
Total canal width Group P 0.237 0.312 0.378 0.402 0.465 0.506 0.573
(±0.030) (±0.026) (±0.032) (±0.034) (±0.015) (±0.059) (±0.020)
Group H 0.272 0.419 0.518 0.518 0.532 0.597 0.652
(±0.046) (±0.075) (±0.056) (±0.037) (±0.027) (±0.029) (±0.029)
Group K 0.266 0.375 0.476 0.476 0.537 0.591 0.636
(±0.058) (±0.016) (±0.020) (±0.023) (±0.028) (±0.038) (±0.038)
Outer canal width Group P 0.146 0.215 0.265 0.263 0.253 0.230 0.259
(±0.026) (±0.034) (±0.045) (±0.035) (±0.016) (±0.040) (±0.036)
Group H 0.159 0.294 0.372 0.326 0.270 0.251 0.283
(±0.038) (±0.066) (±0.052) (±0.053) (±0.025) (±0.027) (±0.030)
Group K 0.153 0.252 0.303 0.298 0.268 0.246 0.280
(±0.044) (±0.032) (±0.032) (±0.024) (±0.023) (±0.026) (±0.041)
Inner canal width Group P 0.091 0.097 0.113 0.139 0.212 0.277 0.314
(±0.005) (±0.015) (±0.021) (±0.027) (±0.022) (±0.034) (±0.035)
Group H 0.114 0.125 0.146 0.192 0.262 0.346 0.370
(±0.014) (±0.020) (±0.032) (±0.036) (±0.044) (±0.042) (±0.046)
Group K 0.113 0.123 0.113 0.178 0.269 0.346 0.357
(±0.021) (±0.022) (±0.029) (±0.017) (±0.027) (±0.040) (±0.051)
Amount of deviation Group P -0.025 -0.118 -0.152 -0.124 -0.041 0.047 0.055
(±0.023) (±0.046) (±0.062) (±0.052) (±0.035) (±0.046) (±0.068)
Group H -0.045 -0.170 -0.227 -0.135 -0.008 0.095 0.087
(±0.033) (±0.063) (±0.065) (±0.083) (±0.066) (±0.065) (±0.071)
Group K -0.040 -0.128 -0.171 -0.120 0.001 0.100 0.077
(±0.037) (±0.053) (±0.058) (±0.035) (±0.041) (±0.057) (±0.084)

Overview of file design

Profile Hero 642 K3
Rake angle Negative Positive Positive
Radial land Yes No Yes
Tip Non-cutting Non-cutting Non-cutting
Helical flute angle Consistent Variable Variable
Pitch Consistent Variable Variable
Shank Metal 15mm Plastic 14mm Metal 11.5mm