الفهرس 
IntroductionOnly 14 pages are availabe for public view
 |  | from | 212 |  |  |
| | | from | 212 | | |
Abstract
Summary and conclusion
451 The aim of this study was to compare between two new rotary
systems GTX and TF through their Shaping properties regarding
the Preservation of canal shape before and after preparation, the
Amount of extruded debris from the apex and Instrument cyclic
fatigue; and their obturating properties regarding their Sealing
ability of the obturation Systems of the rotary systems, the Ease of
obturator removal for retreatment, the Postoperative pain and The
obturators radiodensity.
I. Shaping properties:
1.Preservation of path
Twenty extracted human mandibular first molar were selected with
mesial root curvature above twenty degrees of curvature.
Teeth were scanned using Scanora3D machine. Image reconstruction was performed using Ondemand3D software version 1.0.9. The dentine thickness was measured at the mesial and distal
sides of the mesiobuccal root canal in each tooth at the levels of 3,
5, and 8 mm from the root apex and the measures were saved for
comparison with the postoperative scans. The selected twenty
extracted teeth were randomly classified into two equal groups
according to the NiTi rotary systems used. In group (1): 10 teeth
were prepared using GTX rotary system while in group (2) 10 teeth
were prepared using TF rotary system.
Summary and conclusion 455
A post instrumentation CT scan were performed to all the teeth
under examination and measurement of the mesial and distal
aspects of the mesiobuccal root canal were done. The preinstrumentation
and post-instrumentation measurements are recorded, tabulated and statically analyzed. Three sections were
selected for each tooth at 3, 5 & 8 mm from the root apex.
Three way-ANOVA has been used to the effect of Rotary file
system, Wall type and level on mean percentage of change in canal
path. Tukey’s post-hoc test was used for pair-wise comparison
between the means when ANOVA test is significant. One Way-
ANOVA was used to study the effect of different level tested and
the interactions between all groups on mean percentage of change
in canal path within each group. Independent t-test has been used to
study the difference between different rotary system and tested wall
on mean percentage of change in canal path. The results came as
follows: Concerning the effect of the type of the file on preservation of root
canal path in the coronal level; TF file system showed significantly
higher mean percentage change than GTX on the mesial wall.
While an insignificant difference resulted between GTX and TF file
system on mean percentage of change in canal path at the distal
wall. In the middle level an insignificant difference resulted
between GTX and TF file system on mean percentage of change in
Summary and conclusion
451
canal path at both the mesial and distal wall. In the apical level, an
insignificant difference resulted between GTX and TF file system
on mean percentage of change in canal path at both the mesial and
distal wall. Concerning the effect of the region (root level) (GTX) System
showed an insignificant difference resulted between coronal level
middle level and apical level on mean percentage of change in canal
path at both the mesial and distal wall. While (TF) System showed
an insignificant difference resulted between Coronal Level, Middle
level and Apical level on mean percentage of change in canal path
at both the mesial and distal wall.
2. Evaluation of the amount of extruded debris from the apical
foramen
Twenty human freshly extracted single rooted mandibular
premolars. The teeth were randomly divided into two groups, group
1 and group 2, according to the type of rotary file used. In group 1:
the canals were instrumented with GTX NiTi rotary system, while
in group 2: the canals were instrumented by Twisted File NiTi
rotary system.. Teeth under investigation were put in the sealing cap
of glass test tubes so that the apical 3 mm of the root end were
piercing it. The empty test tubes were weighted individually on a
0.01 accuracy electronic scale. The sealing cap with the tooth in it
Summary and conclusion
451
was applied to the test tube and prepared according to its group as
mentioned previously in the evaluation of preservation of path.
The debris was collected, the sealing cap with the tooth inside was
removed and the tubes were weighted again. The difference
between each tube’s weight pre-operative and post-operative will
represent the weight of the debris extruded from the canal.
The results showed an insignificant difference between GTX file
system and TF File system.
3. Evaluation of the cyclic fatigue resistance
Ten new and ten used rotary NiTi files size #30 and 6% tapers were
selected from each system for use in this study. Samples were
classified into two main groups according to the type of alloy used
to manufacture rotary NiTi files.Group1: a total of ten rotary NiTi
files (GTX) of identical size (#30) and taper (0.06) which was
subdivided into subgroup 1a: representing new files and subgroup
1b: representing old files.Group2: a total of ten rotary NiTi files
(TF) of identical size (#30) and taper (0.06) which was subdivided
into subgroup 2a: representing new files and subgroup 2b:
representing old files.
Instruments from each system were tested from cyclic fatigue
resistance in a 45 degrees replicated curvature in the apparatus.
The handpiece of an endodontic motor was mounted on the
apparatus; each instrument was tested in the canal having its same
Summary and conclusion
451
dimensions and precisely positioned to the same point in the block
to ensure that it will not be displaced, instruments were rotated till
fracture.
Instruments fracture was visually and audibly detected, and the time
to fracture in seconds was recorded by using a digital stopwatch
manually operated, started at the moment the motor was turned on,
and stopped at fracture detection. All fatigue tests were performed
by the same operator. The number of rotations to fracture was then
calculated using the simple formula.
No. of rotations=
x time taken to fracture (in sec.)
The fractured fragments were collected and random samples were
chosen to be tested under scanning electron microscope.
Data was collected, tabulated and statistically analyzed using
independent t-test. Results cames as follows:
Concerning the effect of file condition, a significant difference
resulted between new files and used files on mean cyclic fatigue for
GT series X (GTX) system. Also for the twisted files (TF) system,
the new files produced the highest significant values for cyclic
fatigue compared to used files.
Summary and conclusion
451
Concerning the effect of rotary file used a significant difference
resulted between new GT Series X (GTX) and new Twisted Files
(TF) system on mean cyclic fatigue. Also Used GT Series X (GTX)
Files for produced the highest significant values for cyclic fatigue
compared to Used Twisted Files (TF) system.
Scanning Electron Microscope:
Examining the fractured segments of both rotary systems with the
SEM under different scales revealed many observations about the
behavior of instruments in their failure.
New and used GTX rotary files showed crack propagation at the
peripheries of the fractured surface and micro-cracks following the
grinding marks and some plastic deformation near the fractured
surface. Cross sectional studies showed areas of elevations and
depressions with rolling of the peripheries suggesting a ductile
pattern of fracture. Small black holes in some dimples were noted,
those were Nickel Titanium Oxide particles.
While regarding TF rotary files, the path of crack propagation
showed a tortuous, nonlinear path that was not related to the surface
texture of the TF instruments.
Summary and conclusion
411
II. Obturation properties of systems under investigation
1. Evaluation of the sealing ability of the obturation systems
Teeth investigated in extruded debris were used in this study.
Twenty root samples were divided into two equal groups (n=10)
according to the system used for preparation. In group (I) the teeth
were cleaned and shaped using GTX rotary NiTi instruments, while
in group (II) 10 teeth were cleaned and shaped using TF rotary NiTi
instruments. This was in addition to four teeth; two teeth were used
as negative controls and other two teeth were used as positive
control samples for the study.
The canals were dried using paper points size #30; roots were
obturated using cold lateral condensation technique.
Group (I): A standardized size #30, 0.4 taper GTX gutta-percha
cone was dipped in and out of the canal to introduce the sealer
along the whole length of the canal. Group (II): A standardized size
30, 0.4 taper resilone cone was dipped in and out of the canal to
introduce the sealer along the whole length of the canal.
Two way-ANOVA have been used to evaluate the effect of the
rotary file system and time on mean microleakage. Tukey’s posthoc
test was used for pair-wise comparison between the means
when ANOVA test is significant. One Way-ANOVA was used to
study the effect of time on mean microleakage. Independent t-test
has been used to study the difference between different rotary
systems on mean microleakage. Results showed the following:
Summary and conclusion
414
Concerning the effect of different rotary system used on mean
sealing ability regardless of time variable Twisted files showed
significantly higher mean microleakage than GTX.
Concerning Effect of time on mean sealing ability regardless of
different rotary system used variable non-statistically significant
decrease in microleakage was observed after one week. Three
weeks period showed statistically significantly lower mean
microleakage than 24 hours period. One week period didn’t show
significant difference from 24 hours or 3 weeks period.
Concerning Effect of rotary file system used on mean sealing ability
for each time. One week produced an insignificant difference after
storage followed by an insignificant decrease after 3 months of
storage on mean microleakage for (GTX) file system. Also On
week produced an insignificant difference After storage followed
by an insignificant decrease after 3 months of storage on mean
Microleakage for Twisted Files (TF) file system.
While the effect of rotary file used an insignificant difference
resulted between GTX and TF file system on mean Microleakage at
24 hours. Also an insignificant difference resulted between GTX
and TF file system on mean microleakage at one week. On the same
way, an insignificant difference resulted between GTX and TF file
system on mean microleakage at 3 weeks.
Summary and conclusion
411
2. Evaluation of the ease of obturator removal
The twenty extracted teeth used in the sealing ability study were
radiographed in a bucco-lingual direction. Roots were standardized
using a diamond disc operated at low speed to be 16 mm in length.
Filling material removal was judged complete when the working
length was obtained, and no more gutta-percha or resilon could be
removed with the instruments. The preparation time in seconds to
complete the retreatment procedures was recorded, not including
time for change of instruments and irrigation. The roots were then
grooved longitudinally, and then split by using a chisel.
Ten halves of each group were gold plated and examined under
Scanning Electron Microscope. The other parts were examined
under stereoscope to calculate the remaining debris.
Independent t-test has been used to study the different between
rotary file used on mean extruded debris and time of treatment in
Ease of treatment. Two way-ANOVA have been used to the effect
of Rotary file system and tested level on mean percentage of
remaining debris. Tukey’s post-hoc test was used for pair-wise
comparison between the means when ANOVA test is significant.
One Way-ANOVA was used to study the effect of level tested on
mean percentage of remaining debris. Independent t-test have been
used to study the difference between different rotary system on
mean percentage of remaining debris.
Summary and conclusion
411
Concerning the Effect of rotary File system used on mean time an
insignificant difference resulted between GTX file system and TF
File system.
While the effect of rotary file system and tested level on mean
remaining debris.
Two way-ANOVA shows that Rotary file system and tested level
produced an insignificant effect on mean Remaining debris (%).
Concerning effect of different rotary system used on mean
remaining debris (%) regardless of time variable an insignificant
difference resulted between GTX and TF file system on mean
Remaining debris (%).
Concerning Effect of tested level on mean Remaining debris (%)
regardless of different rotary system used variable:
An insignificant difference resulted between coronal level, middle
level and apical level.
Concerning the effect of rotary file system used on mean remaining
debris (%) for each level tested: An insignificant difference resulted
between coronal level Middle level and apical level for GT Series
X® (GTX) file system. Also an insignificant difference resulted
between coronal level, Middle level and apical level for Twisted
Files (TF) file system.
Summary and conclusion
411
While regarding the effect of rotary file used an insignificant
difference resulted between GTX and TF file system on mean
Remaining debris (%) for coronal level. An insignificant difference
resulted between GTX and TF file system on mean Remaining
debris (%) for Middle level. An insignificant difference resulted
between GTX and TF file system on mean Remaining debris (%)
for Apical level.
3. Postoperative pain
Twenty patients with age varying from 18 to 42 years old suffering
from mandibular first molar teeth acute pulpitis without apical
periodontitis and sound periradicular bone radiographically. They
were divided randomly into two groups; Group A, the canals were
obturated with gutta-percha cones and AH plus sealer using the
lateral condensation technique. Group B, the canals were obturated
by resilone points and AH plus sealer.
No systemic medication was prescribed; a chart was given to each
patient to record the postoperative pain after 6, 12, 24 and 48 hours.
A non-parametric one-way ANOVA (Kruskal–Wallis) test followed
by paired group comparisons using Mann–Whitney U tests at a 5%
significance level were used to analyses pain intensity scores
statistically for the effect of time. Mann-Whitney U test have been
used to test the statistical difference of the rotary systems used on
pain intensity scores. GTX group was a statistically significant
Summary and conclusion
415
lower in pain scores through all periods. While for TF group, there
was non-statistically significant decrease in pain scores from 6
hours to 12 hours. Then a statistically significant decrease was
observed from 12 hours to 24 hours as well as from 24 hours to 48
hours.
Concerning the rotary file system There was no statistically
significant difference between the two systems through all periods.
4. Radiodensity
After finishing the root canal treatment a periapical radiograph was
taken and comparison the radiodensity by mean of Gray Scale
Value.
Independent t-test has been used to study the different between
rotary file used on mean radiodensity.
Data were presented as mean and standard deviation (SD) values.
Data were explored for normality using Kolmogorov-Smirnov and
Shapiro-Wilk tests. Percentage change in canal path as well as pain
scores showed non-parametric distribution while all other variables
showed normal (parametric) distribution.
For parametric data; Student’s t-test was used to compare between
the two systems as well as to compare between cyclic fatigue of
new and used files. Two-way Analysis of Variance (ANOVA) was
used to study the effect of file system and storage time on sealing
ability. Tukey’s post-hoc test was used for pair-wise comparisons
when ANOVA test is significant.
Summary and conclusion
411
For non-parametric data, Mann-Whitney U test was used to
compare between the two systems. This test is the non-parametric
alternative to Student’s t-test. Friedman’s test was used to compare
between root levels or different time periods within the same group.
Wilcoxon signed-rank test was used for pair-wise comparisons
when Friedman’s test is significant. An insignificant difference
resulted between GTX file system and TF File system on mean
Radiodensity (Gray Scale Value).
Under the experimental condition of this study, the following
conclusions could be obtained:
Instruments produced by M-wire and R-phase proved to have
an almost equal performance regarding shaping ability.
Instruments manufactured using M-wire technology proved
to have a superior cyclic fatigue resistance than instruments
manufactured using R-phase technology.
Gutta percha is still the gold standard for evaluating new root
canal core filling materials.
Whatever is the instruments used in canal shaping or the
obturation material used, removal of the canal obturation
needs further interference.
Postoperative pain in both systems was similar.
Regarding the radiopacity, resilone was found to be more radiopaque than gutta percha, but both still meet the ADA requirements for ideal obturating materials.