This study compared the effects of stainless steel hand instruments and nickel-titanium rotary FlexMaster files on root canal curvature during root canal preparation. 194 root canals were prepared by 8 experienced dentists, with 110 canals prepared using FlexMaster files and 84 canals prepared using hand instruments. The results showed that the use of FlexMaster files resulted in significantly less straightening of the root canals and shorter preparation times, compared to the use of hand instruments. Master apical file sizes were also significantly larger when using FlexMaster files.

1. COMPARISON OF HAND STAINLESS
STEEL AND NICKEL-TITANIUM ROTARY
INSTRUMENTATIONS :A CLINICAL STUDY
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
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2. AUTHORS:
EDGAR SCHAFER,
UDO SCHULZ-BONGERT,
AND, GABRIEL TULUS.
JOURNAL OF ENDODONTICS.VOL.30,NO.6,JUNE 2004
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3. SOURCE :
LIBRARY
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Indian Dental academy
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• Leader continuing dental education
• Offer both online and offline dental
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5. AIM :
The aim of this clinical study was to
compare the effect of hand instruments
and rotary nickel titanium FlexMaster
files used by eight experienced dentists
in private practice on the extent of
straightening of curved root canals
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6. MATERIALS AND METHOD :
Eight experienced dentists
194 root canals of maxillary , mandibular
premolars and molars in patients
Each dentist was familiar with both the
hand and the rotary instrumentation.
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7. TOOTH INCLUSION CRITERIA:
 Teeth with at least one curved canal and
whose preoperative canal angulation was 10°
 Canals with more than one curve (s- shaped)
were eliminated from the study
 Canals that could not be distinguished from
each other because of superimposition of the
canals were eliminated from the study.
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8. ROOT CANAL PREPARATION :
 110 Root canals were prepared by FlexMaster
instruments using a crown-down technique.
 84 Canals were enlarged using hand
instruments and traditional techniques.
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9. ASSESSMENT OF ROOT CANAL CURVATURE
AND DEGREE OF STRAIGHTENING :
 Standardized working length radiographs were
taken before the instrumentation with the initial
instruments inserted into the canals
 Radiographs were taken with a bite block and
the EndoRay II film holding instrument.
 The degree and the radius of canal curvature
were determined using a computerized digital
image processing
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10. ASSESMENT OF CANAL PREPARATION AND
ANALYSIS OF DATA :
 In addition to the degree of straightening, the
time for canal preparation was also recorded.
 Preparation time and the degree of
straightening were statistically analyzed using
the Mann-Whitney U test .
 The level of significance was set at p<0.05
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11.  No. of fractured instruments and the size of
master apical file (MAF) were also recorded
 Chi-square test was used to determine the
differences, between the two instruments, in
instrument failure and MAF sizes.
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12. instrument Preoperative
degree of
canal
curvature
Preoperative
radius of
canal
curvature,
mm
Degree of
canal
straightening
Preparat
ion
time
Hand files
FlexMaster
p values
22.75 ± 7.17
23.31 ± 8.70
0.957
5.02 ± 1.62
5.50 ± 1.73
0.171
-3.36 ± 4.34
-1.12 ± 1.87
<0.0001
18.28 ±
7.15
13.01 ±
4.13
<0.0001
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13. 20 25 30 35 40 45 50 55 60
hand instrument
FlexMaster
MAF sizes
%Of teeth
Bar graph showing the percentage of MAF sizes for
hand instrumentation and preparation with rotary NiTi
FlexMaster files
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14. RESULT :
The use of FlexMaster instruments
resulted in significantly less straightening
and a shorter preparation time
(p<0.0001) compared with hand
instruments. Master apical file sizes
were significantly greater for FlexMaster
than for the hand instruments (p< 0.01)
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15. DISCUSSION
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16. CONCLUSION
The original curvature was significantly
better maintained with rotary FlexMaster
files than with hand instruments.
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