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ORIGINAL ARTICLE
Vincy Antony Margaret et al
A Clinical Evaluation of Three Force Delivery
Systems in Stage II of the Begg Technique
1
Vincy Antony Margaret, 2Prathapan Parayaruthottam, 3K Jyothindra Kumar
ABSTRACT
Introduction: Orthodontic treatment is presently dominated by two techniques, the Begg light wire differential force technique and the
preadjusted edgewise technique. Orthodontic appliances at present commonly utilize sliding mechanics for extraction space closure with
different types of force delivery systems.
Materials and methods: The present study was designed to compare the rates of retraction and anchorage loss between elastics, elastomeric
chains and nickel-titanium (NiTi) closed coil springs, using a continuous archwire system with the Begg light wire differential force technique.
Results: The rate of canine retraction was faster by 0.6 mm per month with the NiTi closed coil spring compared to elastics and elastomeric
chains. The NiTi closed coil springs produced more rapid rate of canine retraction but they also produced the greatest amount of anchorage
loss.
Keywords: Anchorage loss, Nickel-titanium closed coil springs, Elastics, Elastomeric chains.
How to cite this article: Margaret VA, Parayaruthottam P, Kumar KJ. A Clinical Evaluation of Three Force Delivery Systems in Stage II of
the Begg Technique. J Indian Orthod Soc 2013;47(4):468-473.
INTRODUCTION
Therapeutic extraction of teeth to gain space for the retraction
of anteriors is an accepted procedure in orthodontic practice.
The creation of space in the dental arch through extraction
therapy requires effective mechanisms to close and consolidate
this space to achieve the desired treatment objectives.
The Begg light wire differential force technique is one of
the most versatile orthodontic treatment philosophies. The light
wire technique is based on the concept of ‘differential force’.
In this technique, tipping of the crown is effected first and then
tipping of the root to translate the tooth. This produces an
efficient and effective anchorage control system.
Traditionally, in pure Begg mechanics, the extraction space
is closed with the help of light intramaxillary elastics in each
quadrant.1-3 However, there are a variety of force delivery
systems currently available that can produce optimum force
levels to move teeth through the alveolar bone. These include
coil springs, latex elastics, elastomeric chains and threads,
sectional archwire auxiliaries and magnets.
1
Reader, 2Associate Professor, 3Joint Director of Medical Education
Department of Orthodontics, MES Dental College, Perinthalmanna
Kerala, India
2
Department of Orthodontics, Government Dental College, Kozhikode
Kerala, India
3
Directorate of Medical Education, Thiruvananthapuram, Kerala, India
1
Corresponding Author: Vincy Antony Margaret, Reader, Department
of Orthodontics, MES Dental College, Perinthalmanna, Kerala, India
e-mail: [email protected]
Received on: 23/3/13
Accepted after Revision: 25/4/13
468
The ideal force delivery system would meet the following
criteria:4
1. Provide optimal tooth moving forces that elicit the desired
effect.
2. Be comfortable and hygienic for the patient.
3. Require minimum operator manipulation and chairtime.
4. Require minimal patient cooperation.
5. Be economical.
Thus, an optimal space closure system should result in the
highest possible rate of desirable tooth movement without
irreversible damage to the periodontal ligament, the alveolar
bone or the dental tissues.
However, cephalometric studies have shown that the space
gained by extraction is not completely utilized for the retraction
of anteriors. There are a variety of anchorage situations met
with in clinical practice:2
1. The high anchorage situation–in which the majority of the
space is to be utilized for anterior retraction.
2. The medium anchorage situation–where anchorage
concerns demand a 50% utilization of space by molar
protraction and incisor retraction.
3. The low anchorage situation–in which only 25% of the
space need be used for anterior retraction and the remaining
space closed by molar protraction.
Knowledge of the amount of space that can be utilized is
important for proper treatment planning.5 But there are very
few studies correlating the rate and amount of retraction with
the different retraction modalities which will help us to
appropriately use the particular modality for a particular
anchorage situation.6 Therefore, there is a need to estimate the
amount of incisor retraction that can be achieved by orthodontic
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A Clinical Evaluation of Three Force Delivery Systems in Stage II of the Begg Technique
procedures in extraction cases. As bimaxillary protrusion
constitutes a major racial feature of Kerala population,
determination of the amount of incisor retraction possible and
the molar anchorage loss that occurs with different retraction
modalities in the Begg technique will reveal the appropriateness
and applicability to this population. It is in this context that the
study is undertaken to identify and assess the use of a particular
force delivery system for respective anchorage situations.
The aim of the present study is to evaluate cephalometrically
and clinically the extent of molar anchor loss that has occurred
in vivo following the extraction of first premolars, using three
different retraction modalities applied in the second stage of
Begg technique. The rate of retraction of anteriors was also
studied. It was also intended to cephalometrically appraise the
changes in axial inclinations of incisors and interincisal angle
that have occurred during the treatment period with the different
retraction modalities.
AIMS AND OBJECTIVES
1. To estimate the molar anchorage loss that occurs while
retracting the anteriors in Stage II of the Begg technique.
2. To assess the effect on anchorage of three different force
delivery systems:
a. Latex elastics
b. Elastomeric chains
c. Nickel-titanium (NiTi) closed coil springs.
3. To compare the rate of retraction in Stage II of Begg
technique using different anterior retraction mechanics.
4. To analyze the changes in axial inclination of incisors and
interincisal angle brought about during treatment as a
function of time and retraction modality.
5. To determine the nature of association, if there is any,
between retraction modality, incisor retraction and molar
protraction.
MATERIALS AND METHODS
The samples for this study included 21 postpubertal patients
who had Angle’s Class I malocclusion with bimaxillary
dentoalveolar protrusion, the treatment of which required the
extraction of all four first bicuspids. All the objectives of Stage I
was to be ensured before commencing Stage II of the Begg
technique. These included molars in Angle’s Class I relationship
and correction of all individual tooth malalignments.
The inclusion criteria for the selection of cases for this study
were as follows:
1. A minimum dental age of 16 years.
2. All teeth inclusive of the second molars were to be fully
erupted and in functional occlusion before commencement
of the study.
3. Canine retraction of a minimum of 3.5 mm would be
required to be effected in Stage II.
4. Cephalometrically, the patients were to have ANB angles
of 2 to 4° and a normal growth pattern.
The samples in the three groups were tested to note if they
were homogenous. The data revealed them to have no
statistically significant difference in the linear and angular
measurements tested. Thus, the samples were concluded to be
homogenous.
The study had a sample size of 21 patients with seven
patients in each group. Three different force delivery systems
were evaluated. They were:
1. Latex elastics-5/16" Green, HP Elastics, HP Industries,
Calicut, Kerala, India.
2. E-chains-short filament. Ortho Organizers Inc., San
Marcos, CA.
3. NiTi closed coil springs with eyelets—12 mm medium
force. Ormco, Sybron Dental Specialities Inc., Glendora,
CA.
Based on the three force delivery systems used (Fig. 1),
the samples were divided into three different groups:
• Group I—Elastics
• Group II—E-chain
• Group III—NiTi closed coil springs
The 21 patients were then allotted to each of the groups by
the lottery method with each group comprising seven patients.
In the group using elastics for space closure, Class I
intramaxillary elastics were placed for all four quadrants with
initial force levels ranging from 3½ to 4 ounces (100-120 gm).
Previous studies have shown that the initial force of the latex
elastics was reduced in vivo by approximately 25 gm.7-11
Therefore, effective force delivered was found to be in the
optimum range of 3 to 3½ ounces (80-100 gm). The patients
were instructed to wear the elastics at all times except during
brushing and to change them every alternate day.
The elastic chain used was the short spaced variety from
the Ortho Organizers Company. Studies have revealed a force
degradation of 50 to 75% in the first 24 hours.12-15 The force
for the chains was measured and applied by the same operator,
to be as close to the selected value and rechecking minimizing
operator error.
The closed coil NiTi springs were Ormco’s 12 mm ‘medium
force’ type with dimensions of 0.010" × 0.030", being the wire
size and internal coil diameter respectively. Studies have shown
only 10% force decay for the springs.16-19 The closed coil
springs were adjusted so as to deliver an equivalent amount of
force as elastics and E-chains.
At each visit, the elastic chains were replaced whereas the
springs were left in situ, and tightened as needed to maintain
the force level. The force applied at each visit was recorded
with a Dontrix gauge.
The amount of incisor retraction and molar protraction
brought about by the force delivery systems in Groups I to III
were evaluated from serial lateral cephalometric radiographs
taken at the beginning of Stage II (T1) and at the end of Stage
II (T2). All lateral cephalograms were traced by one
investigator. Angular measurements were made to the nearest
0.5° and linear measurements to 0.5 mm (Figs 2 and 3).
Superimposed tracings of each case were then made and studied
to permit a visual assessment of molar anchorage loss versus
The Journal of Indian Orthodontic Society, October-December 2013;47(4):468-473
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Vincy Antony Margaret et al
Fig. 1: Methods of retraction used in the three groups
Fig. 2: Linear measurements -APog, -NA, -NB
Fig. 3: Angular measurements -NA, -NB, - , -SN, -MP,
MP-SN, FMA
Fig. 4: Tooth movement in Group I (elastics)
Fig. 5: Tooth movement in Group II (E-chain)
anterior retraction at the completion of extraction space closure
(Figs 4 to 6).
The rate of retraction was defined as the distance travelled
in millimetres divided by the time required to complete space
closure. Anchorage loss was recorded as the amount of
movement in millimeters that occurred in the direction opposite
to the direction of the applied force.
independently for the difference of the rates and amount of
retraction and anchorage loss. Mean values between the groups
were compared using student ‘t’-test. A ‘p’-value of less than
0.05, was considered statistically significant.
STATISTICAL ANALYSIS
All the measurements were tabulated and mean rates of space
closure were calculated. Paired ‘t’-tests were performed
470
DISCUSSION
Bimaxillary dentoalveolar protrusion is the most prevalent
malocclusion seen in the Kerala population and is characterized
by the increased axial inclination of the incisors and a reduced
interincisal angle. Begg technique is considered superior in
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A Clinical Evaluation of Three Force Delivery Systems in Stage II of the Begg Technique
Fig. 6: Tooth movement in Group III (NiTi coil springs)
Graph 1: Bar diagram showing mean values for rate of closure in
Groups I to III (upper and lower)
Graph 2: Bar diagram showing mean values for anchorage loss in
Groups I to III (upper and lower)
treating bimaxillary dentoalveolar protrusion because of
minimal anchor loss and greater extraction space utilization
compared to other techniques.
Therapeutic extraction of teeth to correct malocclusion is
an accepted procedure in orthodontic practice. Traditionally
in pure Begg mechanics, the extraction space is closed with
the help of light intramaxillary elastics in each quadrant. But
patient cooperation is a very important factor. Scientific
advancements now enable us to choose from a variety of space
closure systems. Furthermore, in treatment where the primary
objective is to retract the anterior units into the extraction space
using molars as anchorage units, the relative movements of
these two units using the different modalities is important.
This investigation was done on 21 postpubertal patients
with the samples being 14 females and seven males. The
patients had undergone treatment for the correction of Class I
bimaxillary dentoalveolar protrusion with the extraction of first
premolars and using the Begg light wire appliance.
Notable weaknesses of other studies in this area included
use of multiple operators and small sample size. This was a
prospective study performed by a single operator thus
eliminating interobserver variability. A preliminary report from
a statistician indicated that a minimum of six patients per group
should be studied in order to eliminate -error at 0.05.
Furthermore, this was also determined to be adequate to detect
a difference of 0.25 mm/3 week interval in this study with 80%
probability of detecting a difference between the space closure
systems for the rate of retraction.
The study was done using cephalometric radiographs taken
at the beginning and at the end of Stage II. Selection of
cephalometric roentgenography as a means of investigation was
done because of its scientific value and ability to produce
accurate and reproducible results. In the present study,
superimposition of the maxilla and mandible were done
separately (Fig. 6 and Graphs 1 and 2). Maxillary superimposition was done along the palatal plane registered at the
pterygomaxillary fissure. Mandibular superimposition was
done by the Bjork’s method whereby the inner contour of the
cortical plates at the inferior border of the symphysis and the
inferior alveolar canal were used for superimposition. Further,
the tooth movements were measured with respect to their initial
position.
Rate of closure: The rate of tooth movement is defined as the
displacement of the tooth per unit time. The mean rates of space
closure were 1.00 mm, 1.25 mm and 1.44 mm/3 weeks in the
upper arch and 0.68 mm, 1.06 mm and 1.27 mm/3 weeks in
the lower arch for Groups I, II and III respectively (Table 1).
Thus, the NiTi closed coil springs were found to have a
significantly greater rate of closure of premolar extraction
spaces compared to elastics and elastomeric chain in both
maxilla and mandible (Graph 1). The paired t-test was done
between the groups to test the difference noted in rate of space
closure (Table 2). In this study, the NiTi closed coil springs
produced nearly twice as rapid a rate of tooth movement as
conventional elastics rated at about the same force level. This
discrepancy is probably due to two factors: the ability of the
springs to maintain a relatively constant force level compared
to the elastics, and the elimination of the need for patient
cooperation. Similar results were reported by Sonis (1994) and
Samuels (1993, 1998) with the rate of space closure found to
be twice that of elastomers.
Molar anchorage loss: The present study attempted to compare
the effect of the three different force delivery systems on the
The Journal of Indian Orthodontic Society, October-December 2013;47(4):468-473
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Vincy Antony Margaret et al
Table 1: Mean data of rate of movement and anchorage loss in the
three groups within each arch
Group I- Upper
Group I- Lower
Group II- Upper
Group II- Lower
Group III- Upper
Group III- Lower
Mean rate of movement
(mm/3 weeks)
Mean of total
molar movement
1.004
0.68
1.251
1.064
1.44
1.071
0.916
0.900
1.76
1.63
1.683
1.77
Table 2: Paired t-test for the rate of space closure between the
three groups
Arch
Test
Groups I and II
Groups I and III Groups II and III
Upper
Lower
t-test
t-test
2.77+
3.91*
2.69+
2.95+
0.76x
0.05x
Graph 3: Bar diagram showing mean values for -SN in
Groups I to III (upper and lower)
+
x
Significant at 5% level (t = 2.447); *Significant at 1% level (t = 3.707);
Not significant
amount of mesial movement of the upper and lower molars. It
was done so with the aim of applying the results to different
anchorage situations and thus we can manage the time and
space problem appropriately. In the present study, the amount
of mesial movement was greatest for NiTi springs (Graph 2)
with a mean of 1.77 and 1.68 mm in the upper and lower arch
respectively (Table 1). The paired t-test was done between the
groups to test the difference noted in anchor loss (Table 4). It
was found that there was a statistically significant change
between the anchor loss noted in the groups with elastics and
NiTi springs with the t-value significant at the 0.05 level. This
may be explained due to the light constant force acting on both
the anterior retraction unit as well as the reactionary unit as
reported by Bennett and McLaughlin and Samuels (1998). The
paired t-test done between the groups with elastomeric chains
and elastics too showed a statistically significant difference at
the 0.1 level. But there was no statistically significant difference
in anchor loss between elastomeric chains and NiTi closed coil
springs.
Parameters involving the changes in the axial inclination
of incisors following retraction showed a significant change
with respect to IMPA and interincisal angle (Table 3) after
retraction with E chain and NiTi closed coil springs
(Graphs 3 to 5).
In the final analysis of the data, it may be stated that the
group which used elastics was found to have the least anchorage
loss. But on the other hand, it was also found to have the least
rate of retraction of anteriors. The behavior of Group II was
such that both the anchorage loss as well as the rate of retraction
was much greater than Group I which used elastics. The NiTi
closed coil springs were found to have the greatest rate of space
closure but also showed the maximum loss of anchorage. The
above observation could be explained as follows: it could be
due to the sustained action of the NiTi coil springs which caused
increased reactionary movement of the anchor unit as the
472
Graph 4: Bar diagram showing mean values for IMPA in
Groups I to III (upper and lower)
Graph 5: Bar diagram showing mean values for - in Groups I to III
(upper and lower)
retractive force is basically reciprocal in nature. In contrast,
the intermittent force of the elastomers did not produce such a
taxation of the anchorage unit. Thus, in low anchorage
situations, NiTi coil springs would be ideal for extraction space
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A Clinical Evaluation of Three Force Delivery Systems in Stage II of the Begg Technique
Table 3: Mean and standard deviation of the difference in angular and linear parameters in Groups I to III at the beginning and end of Stage II
Group I
Group II
Group III
Mean
SD
Mean
SD
Mean
SD
-NA
(angle)
-NA
(mm)
-NB
(angle)
-NB
(mm)
-
-SN
IMPA
-APog
GoGn-SN
FMA
U/Molar L/Molar
7.79
7.65
18.86
4.62
15.21
8.15
4.41
2.38
6.04
1.65
5.46
2.03
11.93
5.83
14.28
4.85
13.07
6.54
3.87
1.25
4.99
2.09
5.24
1.97
19.36
11.01
0.31
8.18
27.36
12.71
9.43
8.04
19.29
5.83
11.57
14.08
12.36
4.85
11.71
4.71
13.71
6.85
4.99
2.07
5.46
2.18
4.17
1.59
0.64
0.38
0.14
0.24
0.71
0.64
0.5
0.41
0.21
0.39
0.57
0.73
0.8
0.68
0.19
0.95
0.057
1.28
closure with its increased rate of tooth movement and high
anchor loss. But in high anchorage situations, caution should
be exercised when using NiTi springs and anchorage may need
to be reinforced in the posterior segment either by including
the second molars or by using adjuncts such as transpalatal
arches or lingual arches to reinforce the anchorage. The
different rates of space closure provided by the three different
force delivery systems could be used to close different amounts
of space on either side of the same arch. They also could be
used to maintain or move the midline when used in the same
arch with different space closure requirements on either side.
CONCLUSION
The present study attempted to evaluate cephalometrically the
influence of three different retraction modalities-elastics,
elastomeric chain and NiTi coil springs in Stage II of the Begg
technique. The study had a sample size of 21 patients with
seven patients in each group. The anchorage loss, rate of
retraction and other skeletal and dental parameters were
comparatively assessed. This was to identify and assess the
use of a particular force delivery system for appropriate
anchorage situations.
The following conclusions were obtained from the study:
1. Elastics were found to produce the least amount of
anchorage loss but it also had the least rate of retraction of
anteriors.
2. Elastomeric chains were found to produce greater
anchorage loss and the rate of closure was also increased.
3. NiTi closed coil springs were found to have the maximum
amount of retraction but they also produced the greatest
amount of anchorage loss.
Hence, NiTi springs are found to be a valuable adjunct to
the clinician, though its use has to be judicious and cautious.
Future studies can be done by increasing the sample size and
doing a similar study comparing the efficacy of retraction in
the same appliance and the preadjusted edgewise appliance.
The different retraction modalities can be used on the
contralateral sides of the same patient in those studies.
Parameters like patient discomfort, chairside time, root
resorption for the different methods of retraction, rate of
retraction with self-ligating brackets, can also be studied.
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0.81
0.63
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1.15
0.114
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Table 4: Paired t-test for anchorage loss between the three groups
Arch
Test
Upper t-test
Lower t-test
Groups I and II
Groups I and III
Groups II and III
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