Effect of lacebacks in maxillary canine retraction /certified fixed orthodontic courses by Indian dental academy

Effectiveness of LacebackEffectiveness of Laceback
Ligatures on MaxillaryLigatures on Maxillary
Canine RetractionCanine Retraction
Melih Y. Sueri . Tamer TurkMelih Y. Sueri . Tamer Turk
www.indiandentalacademy.com
INDIAN DENTAL ACADEMY
Leader in continuing dental education

AIMAIM
To evaluate the effects of lacebacks on canine
distalization during the leveling and aligning stage
and to compare the effectiveness of lacebacks with
a different distalization method (superelastic NiTi
closed coil springs).
www.indiandentalacademy.co
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MATERIALS AND METHODSMATERIALS AND METHODS
• SAMPLE- 15
• AGE- between 12 and 18 years.
• Angles Class I molar relationship.
• Fixed orthodontic treatment
• Extraction of first premolars to solve crowding in the
upper and lower arches.
• Stainless steel direct-bonding Roth brackets (0.022-
inch) (Leone SpA, Firenze, Italy) were used in all
patients
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• To evaluate the dental and skeletal changes,
predistalization lateral cephalometric and submento
vertical radiographs were obtained.
• To minimize measurement errors, reference bars
(0.019 times; 0.025-inch rectangular arch wire)
inserted into the canine bracket and molar tube,
were used.
• Longer reference bars on the right than on the left
side were inserted to identify left and right teeth.www.indiandentalacademy.co
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• Leveling of the teeth was started with a 0.012-inch
NiTi arch wire (Leone SpA).
• For canine distalization, superelastic NiTi closed-coil
springs (GAC International Inc, Central Islip, NY)
generating 150 g of force were used on one side (coil
group).
• Superelastic NiTi closed coil springs, placed from the
first molar to the canine, were activated at three
times their original length.
• Lacebacks made from 0.010-inch ligature wire
(Leone SpA) were applied on the contralateral side
(laceback group) .
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The closed coil springs were controlled and
reactivated, and lacebacks were reapplied at each
appointment.
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• All subjects were controlled once a month.
• Leveling and aligning was carried out with 0.014-
inch and 0.016-inch NiTi arch wires.
• Canine distalization was stopped when anterior
crowding was solved on one segment.
• Subsequently, lateral cephalometric and submento
vertical radiographs were obtained.
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• Local superimpositions were carried out with
reference to the palatal cortex of the maxilla.
• A coordinate system was set up on the preretraction
lateral cephalometric films.
• Linear and angular parameters measured on the
predistalization and postdistalization lateral
cephalometric films.
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The line through pterygomaxillary point (Ptm)
perpendicular to the ANS-PNS plane
represented the y-axis, and the ANS-PNS
plane represented the x-axis.
1) x/U1 indicates angle between the long axis
of the upper central incisor and x-axis (°)
(2) y-U1, distance between the incisal edge of
the upper central incisor and y-axis (mm)
(3) x/U3, angle between the long axis of the
upper canine reference bar and x-axis (°)
(4) x-U3, distance between the upper canine
and x-axis (mm)
(5) y-U3, distance between the upper canine
and y-axis (mm)
(6) x/U6, angle between the long axis of the
upper first molar reference bar and x-axis (°)
(7) x-U6, distance between the upper first
molar and x-axis (mm)
(8) y-U6, distance between the upper first
molar and y-axis (mm)
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For evaluation of the submento vertical radiographs,
a midsagittal line through the ANS and PNS points
served as a reference line.
Angular parameters measured on the predistalization and
postdistalization submento vertical films.
(1) ANS-PNS/U3 indicates angle between the horizontal axis of the
upper canine reference bar and ANS-PNS plane (°)
(2) ANS-PNS/U6, angle between the horizontal axis of the upper first
molar reference bar and ANS-PNS plane (°)
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A Wilcoxon test was applied to determine the
significance of the differences of predistalization
and postdistalization values and to determine the
significance of the mean differences of the two
groups.
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RESULTSRESULTS
• Skeletal changes were not found to be statistically
significant (P > .05). However, x/U1 angle and y-U1
distance showed statistically significant decreases at
the levels of .05 and .001, respectively.
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Descriptive statistical values of predistalization and
postdistalization dental (canine and molar)
measurements are given
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The significance of the differences betweenThe significance of the differences between
predistalization and postdistalization (predistalization and postdistalization (PP1,1, PP2) and2) and
the significance of the differences (the significance of the differences (PP3) between the3) between the
changes occurring during the distalization periodchanges occurring during the distalization period
(2.53 months)(2.53 months)
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CHANGES IN THE LACEBACK GROUP
• Distal movement (y-U3, 1.67 mm) and distal tipping
(x/U3, 4.50°) of the canines were significant (P1 < .
01 and P1 < .001, respectively).
• Mesial tipping (x/U6, 3.90°) and mesial movement
(y-U6, 0.70 mm) of the first molar teeth were found
statistically significant (P1 < .05).
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CHANGES IN THE COIL GROUP
• Distal movement (y-U3, 4.07 mm) and distal tipping
(x/U3, 11.63°) of the canines were statistically
significant (P2 < .001).
• Mesial movement (y-U6, 1.93 mm) (P2 < .001),
mesial tipping (x/U6, 3.10°), and extrusion (x-U6,
0.77 mm) of the first molar were significant (P2 < .
05).
• Furthermore, distopalatal rotation (ANS-PNS/U3,
7.75°) of the canines was significant (P2 < .05).
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COMPARISON OF THE CHANGES
BETWEEN LACEBACK AND COIL
SPRING GROUPS
• A statistically significant difference was found
between the canine distal tipping in the laceback
group (4.50°) and in the coil group (11.63°; P3 < .
01).
• A significant difference was observed between
canine extrusion in the laceback group (0.67 mm)
and in the coil group (0.47 mm; P3 < .05).
• A statistically significant difference was found
between canine distal movement in the laceback
group (1.67 mm) and in the coil group (4.07 mm;
P3 < .001).
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• The amount of first molar mesial movement was
bigger in the coil group (1.93 mm) than in the
laceback group (0.70 mm); this difference was
significant between groups (P < .01).
• Distobuccal canine rotation showed a significant
difference between the laceback group (2.68°
distobuccal) and the coil group (7.75°, distopalatal;
P3 < .01).
• The rate of canine movement showed a statistically
significant difference between the laceback and the
coil groups (P3 < .001).
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DISCUSSIONDISCUSSION
• The inclination of the upper incisors decreased
(2.37°) and posterior movement of the upper incisor
crowns was observed (1.27 mm).
• Robinson,in a study investigating the effects of
lacebacks, showed that lower incisors moved
posteriorly.
• Usmani et al observed the retroinclination of upper
incisors with canine lacebacks.
• Irvine et al found that canine laceback ligatures
convey no differences in the anteroposterior position
of the lower labial segment.
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In this study, two different force systems were used
along the same arch wire
• In the laceback group the canine moved and tipped
distally (1.76 mm, 4.50°).
• However, in the coil group, the canine movement
and tipping (4.07 mm, 11.63°) were significantly
different from the laceback group.
• In the coil group, the rate of canine movement (1.61
mm/mo) was bigger than in the laceback group
(0.66 mm/mo).
• The posterior teeth moved anteriorly in both groups.
• The anchorage loss for the coil group (1.93 mm) was
significantly different from the laceback group (0.70www.indiandentalacademy.co
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• These results clearly demonstrate that faster
movement and more displacement are achieved by
continuous forces.
• Other studies comparing continuous and interrupted
forces showed the same results.
• Daskalogiannakis and McLachlan compared the
effects of continuous and impulsive forces on tooth
movement. Twice the amount of tooth movement
was obtained with continuous force application after
3 months.
• Owmann-Moll et al stated that continuous force was
more efficient than interrupted force.
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• Huffman and Way investigated canine distalization
with the Pletcher spring.
• This biweekly activated spring produced a force of
200 g along different arch wire sizes with the 0.022-
inch slot appliance.
• Canine movement was 3.37 mm and canine tipping
was 5.30° along the 0.016-inch arch wire during a
distalization period of 10 weeks. The canine
movement rate was 1.4 mm/ mo.
• For the 0.020-inch arch wire the canine movement
and tipping was 2.99 mm and 1.70°, respectively.
The canine movement rate was 1.2 mm/mo.
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• Canine distalization with nickel-titanium coil springs
producing a force of 150–200 g along a 0.016-inch
arch wire was investigated by Rajcich and Sadowsky.
During a period of 7.1 months, right and left canine
distalization was 5.6 mm and 5.8 mm, respectively.
• Average canine distalization was 3.9 mm, with latex
elastics producing a force of 75–100 g during a period
of 4–8 months was investigated by Paulson RC,
Speidel TM, Isaacson RJ.
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• Ziegler P, Ingervall B found that canine
distalization with chain elastics producing a force
of 380 g along a 0.018-inch arch wire showed a
rate of movement of 1.4 mm/mo. The amount of
distalization was 6 mm and the amount of
tipping.
The main differences between this
study and the other studies can be
summarized in two points:
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First, in the coil group, the amount of distal tipping
was greater than in the other studies.
• This can be explained by the size and material of the
arch wire. Small (0.012, 0.014, and 0.016 inch) NiTi
arch wires were used in our study.
• In the other studies, the canine distalization was
performed on larger stainless steel arch wires.
• The strength and stiffness of NiTi arch wires are
quite different from those of stainless steel arch
wires.
According to Proffit Niti arch wires are 60% as strong
as steel, and the stiffness of NiTi arch wires is one
third that of steel.
It is difficult to control canine movement and to make
the canine root upright with NiTi arch wires because
of their low strength and stiffness.www.indiandentalacademy.co
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Second, in the laceback group, the amount and the
rate of canine movement were smaller than
measurements found in the other studies.
• This can be explained by the force characteristics of
laceback ligatures.
• Laceback ligatures, when tied to the canine, cause a
slight tipping of the canines with compression of the
periodontal ligament.
• Then, the cuspid roots have enough “rebound time”
to move upright into the correct position as the
main arch wire takes effect.
• The movement of the canine crown is limited by the
width of the periodontal ligament and the elastic
capacity of the alveolar crest.
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• Rotation of canines showed a statistically significant
difference between the two groups.
• In the laceback group, the canine rotated
distobuccally (2.68°)
• In the coil group, the canine rotated distopalatally
(7.75°).
• Ziegler and Ingervall and Rajcich and Sadowsky
observed distopalatal rotation of the canine (24° and
15.3°, respectively) during retraction.
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• Distopalatal rotation of the canines should be
observed because of the relationship between the
force application point and the center of resistance
of the canine.
• In both groups the line of action of force passed
buccally to the center of resistance. However,
distobuccal rotation was observed in the laceback
group.
• This distobuccal rotation may be explained by force
duration and by arch wire control.
As mentioned above, after the movement of the
canine with laceback ligatures (interrupted force),
the cuspid is given enough “rebound time” to rotate
distobuccally into the correct position as the main
arch wire takes effect.
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CONCLUSIONSCONCLUSIONS
• Laceback ligatures proved to be effective for
canine distalization.
• When compared to superelastic NiTi closed coil
springs, the amount and rate of canine
movement were less. However, a more controlled
canine movement was obtained for the sagittal,
vertical, and transverse planes.
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Effect of lacebacks in maxillary canine retraction /certified fixed orthodontic courses by Indian dental academy

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