Effect of Maxillary Third Molar Extraction vs Non-extraction on Distalization of First Molars in a Group of Adolescent Patients Using Infra-Zygomatic Gear Distalizer: A Randomized Clinical Trial
Phase: NA
Conditions: Class II Malocclusion
Sponsor: Future University in Egypt

 
Effect of maxillary third molars extraction and non-
extraction on distalization of first molars in a group 
of adolescent patients using infra-zygomatic gear 
distalizer 
A Randomized Clinical Trial  
 
Protocol submitted for the partial fulfilment of Master’s degree in 
Orthodontics and Dentofacial Orthopedics Department. 
Faculty of Oral and Dental Medicine, Future University in Egypt 
 
Submitted by 
Nadeen Hafez Mohammed 
B.D.S. Ain-shams University,2006 
Department of Orthodontics and Dentofacial Orthopedics. 
Faculty of oral and dental medicine, future university in Egypt 
 
 
Date: 1/7/2019 

 
 
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Funding: 
No sources of funding to be declared 
Roles and responsibilities: 
Principal investigator: 
 Nadeen hafez, BDS, will be responsible for applying the sample recruitment, 
clinical procedures of both interventions that will be carried out, follow up of 
patients, data management, results interpretation and writing the thesis as well 
as protocol registration.  
Main supervisor:  
Prof. Yehia Mostafa, BDS, MSc, PhD, FDS(RCSEd) – Chairman of the Department 
of Orthodontics and Dentofacial Orthopedics – Future University in Egypt. Helped 
in developing the idea of the research, will help in interpretation of results and 
drawing conclusions. 
Co-supervisor:  
Dr. Amr El-Dakroury (AD), BDS, MSC, PHD, (Co-supervisor): Helped with 
developing the idea of the research, will help in diagnosis of the sample, 
interpretation of results and drawing conclusion. 
 Dr. Mostafa Mohamed El-Dawlatly (ED), BDS, MOrth, (RCSEd) MSc, PhD, (Co-
supervisor): Initiated the idea of the project and helped in designing the mechanics 
of the new appliance. Also, will be responsible for interpreting the outcomes and 
aide in the writing phase. 
All authors contributed to refinement of the study protocol 

 
 
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Committees: 
• Orthodontics Department Council. 
• College Board Committee 
• Ethics Committee 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

 
 
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 Introduction 
Statement of the problem:   
Class II malocclusion is characterized by an incorrect relationship between 
the maxillary and mandibular arches due to skeletal or dental problems or a 
combination of both. The prevalence of this malocclusion was recently found to 
be 20.6% in the Egyptian population between 11 and 14 years 1,2 with 
mandibular retrusion as its most typical characteristic.   
        Non extraction Treatment of Class II malocclusions frequently requires 
distalization of maxillary molars into a Class I relationship by means of 
extraoral or intraoral forces. Several writers have studied the impact of the 
second molar eruption stage on the distalization of the first molar for many 
years3,4. However, there is a paucity of research on the effects of third molar 
existence when distalization of the first molars.  
 
In adults with erupted maxillary third molars, it is suggested to remove 
the third molars so that the extraction site may accommodate distalization and 
the regional acceleratory phenomena can aid in molar distalization. In contrast, 
adolescents often have unerupted third molars with partly developed roots the 
average age of third molar alveolar eruption is 20 years5. Kinzinger et al. 
suggested a germectomy of the third molars prior to distalization using a 
pendulum appliance in young children in order to accomplish physical 
distalization of the molars. However, surgical extraction of adolescents' 
unerupted third molars may be challenging and unpleasant. To our knowledge, 
no research has assessed the impact unerupted third maxillary molars on 
distalization. 

 
 
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Rationale for carrying out the trial:  
 
Non extraction Treatment of Class II malocclusions frequently requires 
distalization of maxillary molars into a Class I relationship using extraoral or 
intraoral forces. Several methods and devices can be used to distalize maxillary 
molars and to correct Class II malocclusions. The most conventional method for 
distalizing the maxillary molars was the headgear 6,7, which can be used for 
orthodontic or orthopedic corrections. It is easy to apply and may distalize the 
maxillary first molars and the first and second premolars via transeptal fibers.  
However, the success of the treatment depends heavily on patient cooperation, 
lack of patient cooperation results in anchorage loss and unsatisfactory 
treatment results. 
 
The disadvantages of the extraoral appliances have motivated many 
investigators to develop the mechanics of intraoral molar distalization. Several 
intraoral appliances have been used to distalize the maxillary molars in Class II 
patients without the patient’s cooperation 8–12. All these intraoral distalization 
appliances distalize the maxillary molars. However, anchorage loss was 
unavoidable, characterized by the protrusion of maxillary incisors, an increase 
in overjet, and a decrease in an overbite. 
 
Consequently, skeletal anchorage units were introduced and proven 
effective in molar distalization13–15 and other treatment protocols. The most 
common site for implant placement is in the maxillary body be-tween the roots 
of teeth16,17. Many working groups have recommended the zygomatic buttress 
as a site for mini-plate insertion, referred to as zygomatic anchorage systems18. 
With its thick cortical plate, the zygomatic process of the maxilla enables the 

 
 
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anchorage de-vice to be placed at a distance far from the developing teeth in a 
growing patient while maintaining better stability for anchor units under high 
forces19. Yet, the lengthy surgical inter-vention required to insert mini-plates 
with the techni-cal difficulties and high sensitivity in its insertion area have 
made this technique unpopular. 
 
In recent decades, certain researchers have proposed the infra-zygomatic 
crest (IZC) as an anchorage area for maxillary molar distalization using mini-
implants 20. The advantage of IZC is that it has a thick cortical bone that can 
withstand high strains. However, the treatment effects of maxillary dentition 
distalization with mini-screws implanted in the IZ crest have not yet been 
adequately evaluated in the literature. 
 
In addition, several scientists have studied the influence of the second 
molar eruption stage on the distalization of the first molar for many years. 
However, there is a lack of research on the effects of third molar existence when 
distalization of the first molars is necessary. Therefore, the purpose of this 
research was to compare the effect of maxillary third molar presence versus 
extraction on distalizing first maxillary molars utilising Infra -zygomatic gear 
distalizer. 
 
Literature Review: 
The review of literature is divided under the following headings: 
I. Techniques for maxillary molar distalization. 
1-Extra oral appliances. 
2- intra oral appliances. 
II. Anchorage and TADS. 

 
 
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III. Distalizers with skeletal anchorage. 
 IV. Accuracy and reliability of 3D digital model and CBCT. 
 V. Distalization efficacy with respect to the third molar presence 
 
I-Techniques for maxillary molar distalization. 
1-Extra oral appliances. 
Kingsley in (1880)6, introduced the headgear appliance as a source of 
extraoral forces and anchorage. This appliance was made from a cloth covering the 
back and top of the head with the use of elastics to transmit the pulling force, it was 
designed to distalize the maxillary teeth without extraction. 
 
Kloehn in (1947)7,  earned great popularity for the use of headgears, which 
have been used ever since. He reported great success in treatment of class II using 
an occipital headgear attached to hooks o the arch wire.  For controlled force, the 
arch wire had stops mesial to maxillary first molar. 
D. E. J. Bowden (1978)21 , provided a literature review to examine theories 
of mechanical principles of tooth movement and anchorage control achieved by 
headgear therapy. This study stated that the antero-posterior, vertical, and lateral 
positions of the outer face bow hooks in relation to the centre of resistance of upper 
first molars which approximates the trifurcation of the roots define the direction and 
moment system generated by the headgear. An intrusive effect was created when a 
line of force passed upwards from the occlusal plane, whereas an extrusive effect 
was created when a line of force passed downwards. When worn for 12 to 14 hours 
per day with 350 to 450 g (12 to 16 ozs) applied force to molar teeth, all types of 
headgear have been proven to generate acceptable tooth movement. 

 
 
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Doruk et al (2004)22, investigated headgear cooperation using an objective 
measurement tool, the Compliance Science System (CSS). The study comprised 46 
individuals, 32 girls and 14 boys between the ages of 10 and 15. (with a mean of 13 
years). The patients, who were not aware that they were being watched, were asked 
to wear the headgear for 16 hours each day, with an electronic module timer 
connected to the neck-strap. Only the uncooperative patients were told that they had 
been watched, and both groups were given a four-month therapy term. Patients who 
were unwilling to cooperate raised their daily headgear use to about 4.5 to 6 hours. 
During the four-month period, all cooperative patients also wore their headgear as 
advised. 
2-Intraoral appliances. 
Hilgers (1992)9, introduced a new intra-oral distalizer and called it 
"Pendulum appliance”. It was a hybrid that used a large Nance acrylic button in the 
palate for anchorage, along with 0.032" TMA springs that delivered a light 
continuous force to the upper first molars without affecting the palatal button. 
Pendulum appliance produced force of 200 to 250 grams in a swinging arc like 
pendulum from midline. He observed a tendency for the bite to open anteriorly as 
the Pendulum appliance drove the upper molars distally quite rapidly.  Hilgers found 
that the molars could be moved much more effectively when they were being 
actively expanded by opening the screw of the Hybrid. The average amount of 
molar distalization was 5 mm in three to four months. 
Carano and Testa (1996)11, used the distal jet appliance to distalize the 
molars bodily. The appliance consisted of bilateral tubes of 0.036" internal diameter 
attached to a Nance appliance soldered to the second premolars bands, a coil spring 
and a screw-clamp soldered over each tube. In this study they used either stainless 
steel or nickel titanium coil springs (150 gm for children, and 250 gm for adults). 
The wire extending from the acrylic through each tube ended in a bayonet bend that 

 
 
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inserted into a lingual sheath of the first molar band. The appliance was activated by 
sliding the clamp closer to the first molar once a month. They achieved 5 mm of 
bodily molar distalization in a 10-year-old child in 4 months. 
 
Fortini et al (1999)12, developed the First-Class appliance which consisted of 
a buccal component of a formative screw soldered to the first molar band and split 
rings welded to the second premolar or deciduous molar bands. From the palatal 
side there was a butterfly extended Nance button for more stability. NiTi coil 
springs were compressed between the premolar solder joints and molar tubes. The 
tubes prevented the distal tipping during distalization. This appliance showed rapid 
molar distalization even with fully erupted second molar and the distalization was 
bodily with no tipping or anchorage loss. 
Keles et al (2001)23, introduced the Keles Slider for the distalization of the 
maxillary first molar. Fifteen patients with mean age of 13.32 years were selected 
for unilateral molar distalization. The maxillary first molars and first premolars were 
banded. The anchorage unit was a Nance button with an anterior bite plane. From 
the palatal side, the point of distal force application was carried towards the level of 
center of resistance of the maxillary first molar. A Ni–Ti coil spring was used and 
activated every month, and 200 grams distal force was applied. The molars were 
distalized bodily on average 4.9 mm with no extrusion or tipping but showed 
distobuccal rotation. The first premolars showed bodily mesial movement of 1.3mm, 
incisor protrusion was 1.8 mm and incisor proclination was 3.2 degrees. The 
overbite was reduced by 3.1 mm and the overjet increased 2.1 mm. 
II. Anchorage and TADS. 
In 1999 Umemori et al17, defined skeletal anchorage as the mechanism 
where the patient's skeletal component is utilized using attachments as mini-

 
 
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implants and mini-plates to reinforce the anchorage during various orthodontic tooth 
movements. Intraoral skeletal anchorage provides absolute anchorage, eliminates the 
need for patient cooperation and anchorage preparation, and gets predictable 
treatment results more rapidly.  
 
Park et al (2006) 24, examined the success rate and factors affecting the 
clinical success of mini-implants used as orthodontic anchorage. Eighty-seven 
consecutive patients (35 males, 52 females; mean age, 15.5 years) with a total of 
227 screw implants were examined. The screw implants were placed at 30°to 40° 
angles to the long axes of the teeth in the maxillary arch and at 10° to 20° angles in 
the mandibular posterior area. The screw implants in the retromolar area and the 
distobuccal bone to the mandibular second molars were placed at 90° to the bone 
surface, the different angulation was to reduce root contact by the mini screws 
without reducing the length of the screw. Results showed that the overall success 
rate was 91.6%. The clinical variables of mini-implant factors (type, diameter, and 
length), local host factors (occluso-gingival positioning and management factors, 
angle of placement, onset and method of force application, ligature wire extension 
and exposure of screw head) did not show any statistical differences in success rates. 
General host factors (age, sex) had no statistical significance, while Mobility, jaw 
(maxilla or mandible), side of placement (right or left), and inflammation around the 
screws due to bad oral hygiene showed significant differences in success rate. This 
study concluded that, to minimize the failure of screw implants, inflammation 
around the implant must be controlled, especially for screws placed in the right side 
of the mandible. 
 
Poggioa et al (2006)25, provided a clinical indication for a safe application of 
the mini-screws as well as the ideal miniscrews features. The volumetric 
tomographic images of 25 maxillae and 25 mandibles taken with the New Tom 
System were examined. The results showed that in the maxilla, the greatest amount 
of mesiodistal bone was on the palatal side between the second premolar and the 

 
 
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first molar. The least amount of bone was in the tuberosity. The greatest thickness of 
bone in the buccopalatal dimension was between the first and second molars, 
whereas the least was found in the tuberosity. In the mandible, the greatest amount 
of mesiodistal dimension was between first and second premolar. The least amount 
of bone was between the first premolar and the canine. Buccolingually, the greatest 
thickness was between first and second molars. The least amount of bone was 
between first premolar and the canine. 
III. Distalizers with skeletal anchorage. 
Gelgor et al. (2004)26 investigated the effectiveness of intraosseous screws 
for anchorage in maxillary molar distalization. The study included twenty-five 
participants (18 girls and seven boys; 11.3 to 16.5 years of age). The screw was 
placed behind the incisive canal at a safe distance from the mid-palatal suture 
following the palatal anatomy. The amount of force used was 250 g per side The 
average distalization time to achieve an overcorrected Class I molar relationship was 
4.6 months. In the cephalograms, the upper first molars were tipped 8.88°and moved 
3.9 mm distally on average. The upper molars showed distopalatal rotation. Mild 
protrusion (mean 0.5 mm) of the upper central incisors was also recorded. However, 
there was no change in overjet, overbite, or mandibular plane angle measurements. 
They concluded that immediately loaded intraosseous screw–supported anchorage 
unit was successful in achieving sufficient molar distalization without major 
anchorage loss. 
Kinzinger et al. (2005)13, conducted a study where the standard pendulum 
appliance was modified by integrating a distal screw into its base and by special pre-
activation of the pendulum springs. The suitability of this Pendulum K for the 
translatory distalization of maxillary molars was investigated in children and 
adolescents. The study with its collective of 66 patients confirmed that the 
Pendulum K allows a virtually translatory molar distalization with slight tipping of 

 
 
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4.75° to the palatal plane and 4.25° to the anterior basal plane. Palatal movements of 
the first molars were avoided. The proportion of molar distalization in the total 
movement was 73.53%.  
Erverdi et al. (2006)27, presented the fabrication and application of a new 
generation of posterior intrusion appliances using zygomatic anchorage. The use of 
zygomatic anchorage enabled en masse impaction of the posterior segment without 
any side effects such as labial flaring. A 14-year-old, female Class II patient with an 
anterior open bite was treated with the new generation posterior intrusion appliance. 
At the end of treatment, a Class I canine and molar relationship and a correction of 
the anterior open bite were achieved. The molars were impacted 3.6 mm, and this 
impaction was maintained throughout the treatment. The mandibular plane showed a 
counter-clockwise autorotation of 48. This case report demonstrates that zygomatic 
anchorage could be used effectively for molar intrusion and anchorage maintenance. 
Sugawara et al (2006)19, examined the treatment effects when using the 
skeletal anchorage system (SAS) in order to distalize the maxillary molars in non- 
growing patients. The SAS consists of titanium anchor plates and monocortical 
screws that were temporarily placed. The sample size consisted of 25 non growing 
patients with average age at the beginning of treatment of 23 years 11 months. The 
average amount of distal movement of the maxillary first molars was 3.20 mm at the 
root level and 3.78 mm at the crown level in about 19 months. The authors also 
concluded that the maxillary first molar was distalized with no regard to the 
extraction of the third or second molars.         
 
Polat-Ozsoy et al (2008)15, performed a retrospective study to investigate the 
dentoalveolar and skeletal effects obtained from 2 types of pendulum appliance with 
different anchorage designs: bone-anchored pendulum appliance (BAPA) and 
conventional pendulum appliance (CPA). The BAPA group included 22 patients 
while the CPA group included 17 patients with mean age 13.61 ± 2.01 years. 

 
 
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Approximately 230 g of distalizing force was used. Lateral cephalograms before 
treatment and at the end of distalization were measured. For the BAPA group, the 
distalization was 4.8mm in 6.8 months and 9.1° distal tipping, while for the CPA 
group, the distalization was 2.7 mm in 5.1 months and 5.3° distal tipping. The 
BAPA group also showed distaliazation in upper 1st and 2nd premolars by 2.7 ± 1.6 
mm and 4.1 ± 2.1 mm respectively, with retraction of maxillary incisors by -0.1 
±1.7 mm, -1.7° ± 2.9°, while in the CPA there was significant loss of anchorage 
showed as mesialization in upper 1st and 2nd premolars by 4.0 ± 2.7 mm and 2.3 ± 
2.1 mm respectively, together with proclination of upper incisors by 1.2 ± 1.7 mm, 
0.9° ± 2.4°.  
Fudalej et al (2011)28, performed a systematic review without meta-analysis, 
to analyze studies that used temporary anchorage devices during distalization. 
Several databases including Pub Med, Embase and Cochrane Central Register of 
Controlled Trials were searched until August 2010. This systematic review included 
only nonrandomized prospective and retrospective studies. Twelve articles met the 
inclusion criteria out of which 4 were of medium quality and 8 of low quality. The 
results showed that maxillary molars were distalized by 3.3 to 6.4 mm with the 
mean distal movement of the maxillary molars was 0.7 mm (SD, 0.3 mm) per month 
(range, 0.2-1.2 mm). with distal tipping from .080° to 12.20°. The maxillary incisors 
remained in the same position during distal movement of the molar with only 2 
studies showed statistically significant retraction of the central incisors. 
Nur et al (2012)29, utilized the zygoma gear appliance to bilaterally distalize 
the maxillary molars and performed research to determine its dentoalveolar, skeletal, 
and soft tissue effects. The research group included fifteen patients (mean age, 15.87 
1.09 years; range, 14–18 years), and lateral cephalometric images were obtained 
before and after distalization. A distalization force of 300 g per side was applied to 
the maxillary molars via the closed coil springs which replaced the heavy elastics in 
the previous design. The findings of the study showed that the maxillary molars 

 
 
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were effectively distalized into a Class I relationship in all patients in a short time 
despite the presence of the maxillary second and third molars, the rate for the distal 
movement of the molars was 0.84 mm per month by total distalization of 4.37 ± 
2.15 mm without anchorage loss, while distal tipping measured only 3.30º,maxillary 
first molars showed a slight intrusion (0.50 mm) and there were insignificant 
changes in both skeletal and soft tissue measurements.  
Kilkis et al (2016)30, conducted a study to evaluate the dentoskeletal effects 
of the zygoma-gear appliance used for unilateral maxillary molar distalization, this 
study consisted of 21 patients with mean age 15.68 ± 2.18 years and concluded that 
it was effective with significant amount of distalization for the maxillary first molar 
(5.31 ± 2.46 mm) in (0.45 ± 0.12 years), a 0.98 mm distalization rate per month 
Aline Rode Santos et al (2017)31, conducted a tomographic study to evaluate 
the infra-zygomatic crest region thickness, in adult (male and female) patients. 
CBCT images from 40 patients were used to assess cross-sectional measurements of 
the infra-zygomatic crest region. Measurement 1 considered thickness 2 mm above 
the distobuccal root of the permanent maxillary first molar, while measurement 2 
was taken 2 mm above the first measurement. The mean thickness of the infra-
zygomatic crest in males was 3.55 mm for measurement 1 and 2.84 mm for 
measurement 2, while in females these were 2.37 mm and 2.24 mm, respectively. 
The authors concluded that the overall mean thickness of the infra-zygomatic crest 
was 2.49 mm with respect to measurement 1, and 2.29 mm for measurement 2, with 
no statistically significant differences between genders. 
IV. Accuracy and reliability of 3D digital model and CBCT. 
Mavropouls et al (2005)32  used three dimensional digitized models to 
evaluated the treatment changes that occurred after modifying the Jones Jig 
appliance with a Nance button for anchorage demand. Ten patients with bilateral 

 
 
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class II molar relationship, that requires distalization, and fully erupted upper second 
molars were involved in this study. Dental casts and lateral cephalometric 
radiographs were taken immediately before placement and after removal of the 
appliance. The 3D models were superimposed on the anterior part of the palate 
comprising the palatal rugae and a zone in the palate along the midline raphe. The 
study proven that noncompliance simultaneous distalization of the first and second 
maxillary molars can be an efficient option for the correction of Class II molar 
relationship. The cast assessment of 3D sagittal and vertical tooth movements was 
more reliable than the cephalometric record. 
Peck et al (2007)33 performed a study to compare between the accuracy of 
CBCT and panoramic x-ray in detection of mesiodistal root angulation. This study 
included five patients in which at first a plaster study model was prepared for each 
patient, then a radiographic stent containing radiopaque markers was fabricated for 
each of these models.  Panoramic and cone beam computed tomography (CBCT) 
scans were taken on each patient with the radiographic stent seated on the dentition. 
Root angulations for each of the radiographic scanned images were measured. This 
study showed that CBCT scans produced very accurate measurements of root 
angulation compared to plaster model measurements (the gold standard), while 
panoramic projections did not provide reliable data on root angulation. 
EL-Zanaty et al. (2010) conducted a study comparing the dental 
measurements obtained from CBCT scans and plaster dental models using 3-
dimentional-based dental measurements program. The measurements were done in 
3planes of space, they found out there is excellent agreement between 3D based 
dental measurement program and the conventional method which can substitute the 
conventional plaster model. 
 

 
 
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El-Beialy et al. (2011)34 conducted a study to find out the accuracy and 
reliability of measurements obtained from CBCT for various head orientations. 
Stainless steel wires were fixed to a dry skull at different places which was then 
scanned by using CBCT in a central position and 5 other positions. Six landmarks 
were placed by two operators and compared to the true length of the wires glued on 
the skull which is considered as the gold standard. The results showed that the 
CBCT measurements were very accurate producing a 1:1 ratio to the real size 
measurements and that the accuracy and reliability were not affected by changing 
the skull orientation. The authors therefore recommended that the upper-lip and chin 
rests are not needed during CBCT scan. 
Nalcacia et al. (2015)35 investigated the reliability of measurements obtained 
after the superimposition of three-dimensional (3D) digital models by comparing 
them with those obtained from lateral cephalometric radiographs and photocopies of 
plaster models for the evaluation of upper molar distalization, Data were collected 
from plaster models and lateral cephalometric radiographs of 20 Class II patients 
who’s maxillary first molars were distalized with an intraoral distalizer. The 
posterior movements of the maxillary first molars were evaluated using lateral 
cephalometric radiographs (group CP), photocopies of plaster models (group PH), 
and digitized 3D models (group TD). The pre- and post-treatment scans of the dental 
models were superimposed on three points in the incisive papilla area (the most 
anterior point, the most prominent point, and the most posterior point of the incisive 
papilla). frontal line perpendicular to the midsagittal plane and passing through the 
most prominent point of the incisive papilla was constructed on the superimposed 
3D models to determine the distalization amounts of the central incisors, canines, 
premolars, and molars. It was concluded that 3D digital models are reliable to assess 
the results of upper molar distalization and can be considered a valid alternative to 
conventional measurement methods. 
 

 
 
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V. Distalization efficacy with respect to the third molar presence 
Kinzinger et al (2004)4, evaluated the efficiency of a pendulum appliance for 
molar distalization related to second and third molar eruption stage. The studied 
sample included 36 adolescent patients in various stages of the molar dentition. The 
patients were divided into 3 groups (PG 1-3) according to the stage of eruption of 
their second and third molars. In PG 1 (18 patients), eruption of the second molars 
had either not yet taken place or was not complete. In PG 2 (15 patients), the second 
molars had already developed as far as the occlusal plane, with the third molars at 
the budding stage. In PG 3 (3 patients), germectomy of the wisdom teeth had been 
carried out, and the first and second molars on both sides had completely erupted. A 
modified pendulum appliance, including a distal screw and special preactivated 
pendulum springs was used for bilateral maxillary molar distalization. The study 
showed that the degree of tipping of maxillary second molar was greater when a 
third molar bud was in the direction of movement. Moreover, the study concluded 
that third molar bud could sometimes act as a fulcrum, affecting the efficiency of 
upper 1st molar distalization. After previously completed germectomy of the wisdom 
teeth, almost exclusively bodily distalization of both molars is possible. In the 
presence of both 2nd and 3rd molars the duration of distalization will be longer, 
greater forces will have to be applied, and more anchorage will be lost. This study 
recommended germectomy of wisdom teeth prior to ditalization.  
Flores-Mir et al (2013),3 conducted a systematic review to evaluate the 
efficiency of molar distalization associated with the second and third molar eruption 
stage. A systematic computerized database search was done using several databases 
and out of the thirteen initially identified articles, only four fulfilled their final 
selection criteria. The results showed that three of the four studies showed no 
statistical significance in the linear amount of maxillary first molar distalization 

 
 
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based on the eruptive stage of the second and/or third molars, while the last study 
showed that the amount of distal movement of the first molars was significantly 
greater in the group with unerupted second molars. The study also noted that tipping 
of the first molar was greater when a third molar bud was located in the direction of 
movement. As a result, they concluded that effect of maxillary second and third 
molar eruption stage on both linear and angular maxillary molar distalization 
appears to be minimal. But this conclusion was based only on low–level of evidence 
clinical trials.  
Jin Lee et al (2019)36 , evaluated changes in the position of maxillary third 
molars with cone-beam computed tomography images in adolescents after total arch 
distalization using a modified C-palatal plate (MCPP) and to compare them with the 
changes in a matched control group. Forty adolescent patients (mean age, 12.6 
years) were divided into MCPP and control groups. Cone-beam computed 
tomography images were taken before and after molar distalization (mean 
duration,14.4 months) in the MCPP group and in the control group (mean duration, 
12.9 months). The changes in the position, angulation, and rotation of the third 
molars were assessed, and the volumes of maxillary tuberosity were measured. The 
results showed that after distalization, the third molars moved backward (1.2 mm) 
and upward (0.5 mm) in the MCPP group with a significant difference (P<0.003), 
and they moved downward and forward in the control group. The changes in 
rotation and angulation were insignificant. The volumes of maxillary tuberosity 
increased in both groups. The study concluded that maxillary total arch distalization 
caused unerupted third molars to move backward and upward, with an insignificant 
difference in the posttreatment volume of maxillary tuberosity. Therefore, it may be 
possible to perform maxillary total arch distalization in adolescents with unerupted 
third molars without a germectomy, at least in the short term. 
 

 
 
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Database research: 
A search was performed on electronic databases (PubMed, Cochrane library). 
Aim of the study 
 A-PICO format: 
 
Population: 
Adolescent patients having Class II molar relation with full permenant dentition 
including unerupted third molar. And indicated fore maxillary molar 
Distalization. 
Intervention: 
Distalization of maxillary first molars using infra-zygomatic gear distalizer  
after extraction of maxillary third molars. 
Comparator: 
Distalization of maxillary first molars using infra-zygomatic mini-implants as 
anchorage unit without extraction of maxillary third molars. 
Outcome measure(s): 
 
Outcome name 
Measuring 
device 
Measuring 
unit 
 
Primary 
outcome 
 
The total 
anteroposterior distance 
moved by the maxillary 
first molars. 
 
Digital models using 
3- shape     scanner 
and program. 
 
 
mm 

 
 
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CBCT images using 
Anatomage software. 
 
 
 
mm 
 
 
 
 
Secondary 
outcomes 
 
1-Maxillary first 
molar distalization 
rate. 
Digital models 
using 3 shape            
scanner and 
program. 
 
mm/month 
 
2-Maxillary first molar 
rotation 
Digital models using 3 
shape scanner and 
program. 
 
Degree 
 
 
 
3- Intermolar width 
Digital models using 3 
shape scanner and 
program. 
mm 
 
4-Maxillary first 
molar tipping and 
torque 
 
CBCT images using 
Anatomage software. 
 
Degree 
 
5-Maxillary first molar 
vertical changes 
 
 
CBCT images using 
Anatomage software 
mm 

 
 
20 
 
 
6- Total 
anteroposterior 
distance moved by 
maxillary first and 
second premolars. 
 
 
Digital models using 
3 shape                         
scanner and program. 
 
mm 
 
7- Maxillary second 
molar tipping. 
CBCT images using 
Anatomage software 
Degree 
 
8-Maxillary third 
molar tipping 
 
CBCT images using 
Anatomage software 
Degree 
 
9-Maxillary third 
molar vertical changes 
 
CBCT images using 
Anatomage software 
mm 
 
10-Maxillary four 
incisors 
anteroposterior and 
vertical linear 
measurements. 
CBCT images using 
Anatomage software 
 
mm 
 
11- Maxillary four 
incisors torque. 
CBCT images using 
Anatomage software 
 
mm 
 
B-Research question: 
Does extraction of the upper third molars have a different impact than non-
extraction on distalizing maxillary first molars in Class II adolescents? 

 
 
21 
 
Objectives of the study research 
Research hypothesis: 
The null hypothesis was that the presence and extraction of unerupted 
maxillary third molars would have a similar effect on the distalization amount 
of maxillary first molars and the other dental changes. 
Primary objective (s): 
Amount of maxillary fitst molar Distalization.  
Secondary objective: 
Evaluate the other dental changes in the upper buccal segment 
accompanying the Distalization technique and dental changes in the incisors.  
Study design 
This research was a single-cantered, 2-arm parallel group randomized 
controlled clinical trial 1:1 allocation ratio, performed following the 
Consolidated Standards of Reporting Trials guidelines. 
Material and Methods  
I) 
Participants, Interventions, and Outcomes 
 
A) Study Setting:  
The study will be performed in the clinic of the Orthodontic Department 
at the Faculty of Oral and Dental Medicine, Future University in Egypt. The 
recruited sample would be from the Egyptian urban and rural population. 
      B)  Eligibility: for the participants include the following:  

 
 
22 
 
        (1) Adolescent patients aged 16-19 years. 
(2) skeletal Class I (0°<ANB< 4). 
(3) bilateral Class II molar relationship. defined by at least an end-to-end       
molar relationship. 
(4) normal vertical growth pattern. 
 (5) full permanent dentition with unerupted upper third molars.  
Exclusion criteria included: 
 (1) a skeletal Class II or Class III relationship.  
(2) past orthodontic treatment.  
(4) poor oral hygiene.  
(5) Increased vertical dimension. 
       C) Interventions:  
 Medical History Questionnaire:  
will be filled by the patient to exclude the presence of any systemic 
condition.  
 Clinical Examination:  
Proper examination of the oral structures including; 
• Teeth will be examined for caries, fracture or missing teeth. 
• Gingival 
tissues 
will 
be 
examined 
for 
gingivitis, 
periodontitis, attachment loss, gingival recession, oral 
lesions and the nature of the gingival biotype. 
• Thorough intraoral examination is needed to evaluate the 
need for referral for consultation or intervention before the 
initiation of treatment. 

 
 
23 
 
 Diagnosis  
  
The patient is checked to fulfil the previously mentioned 
inclusion criteria. Full set of records will be taken for every patient 
(study models, lateral cephalometric radiographs, and photos as 
part of the routine procedure for treatment of patients in the 
outpatient clinic of the Orthodontic Department, future University 
in Egypt. 
  Clinical Procedure:  
 
After taking pre-treatment records, every patient will 
receive: 
    
 
• The third molars will be extracted surgically in the 
third molar extraction group four weeks before 
intervention commenced. 
•    Proper disinfection will be performed with a local 
disinfectant, BETADINE povidone-iodine 10%, at the 
area of mini-implant insertion. 
• Two infra zygomatic mini-implants will be placed 
(Screw Tomas pin 10mm, dentaurum, Germany). 
• Bands will be cemented to the upper first molars. 
• The inner bow (1.2mm) is a modified version of the 
inner part of a conventional face bow. Two hooks were 
soldered onto the inner bow distal to the lateral incisor 
teeth regions. A U loop at the first premolar region and 
bends acting as a mesial stop will be bent in front of the 
maxillary first molars. 

 
 
24 
 
• The inner bow will be adjusted to the headgear tubes on 
the maxillary first molar bands, as the anterior 
component of the inner bow is 3 mm free from the 
labial surface of the anterior teeth. 
•  A distalization force of 300 gm/per side was applied to 
the maxillary molars via a closed coil spring (Tomas-
coil spring, Dentourum, Germany). According to the 
desired activation length, the distal end of the coil 
spring was set to the IZ mini-screw, while the mesial 
end was linked to the wire framework hook either 
directly or with a 0.01-inch stainless-steel ligature 
 
 Follow up period 
The patient will be asked to attend follow up visits every 4 
weeks  
1-to check the following: 
1. The stability of the mini-implants 
2. The activity of the appliance (force recalibration is required). 
3. The amount of correction achieved. 
4. Any inflammation related to the appliance or the mini-
implants 
2- Impressions will be taken (without the appliance in place) 
followed by digital scanning of produced models). 
 

 
 
25 
 
 
 
Criteria for discontinuing or modifying the allocated  
 
In cases of prolonged swelling or pain related to the mini-
screw, the patient will be given strict oral hygiene measures and 
may wait for three weeks before the beginning of retraction.  
-In cases of loose or broken mini-implant, the screw will be 
removed and replace the mini-implant after total resolution of 
the inflammation.  
-In case of non-compliant patients. 
o Criteria of ending the distalization phase. 
 
- Class I molar relation or at the end of pre-determined 
treatment duration (eight months). 
                D] Outcomes 
1) Primary outcome 
The primary outcome of the current study was to determine the 
total Anteroposterior position changes of upper first molars.  
2) Secondary outcomes: 
The secondary outcomes were the changes in upper first 
molars rotation, intermolar width, tipping, torque, and vertical 
position, the upper first molars distalization rate, the changes in 
the anteroposterior position of the upper first and second 
premolars, tipping of upper second molars, tipping and vertical 
position of the upper third molars, and anteroposterior, vertical, 
and torque changes of the upper incisors. 

 
 
26 
 
 
3) Methods of measuring of all outcomes:  
Linear and angular measurements will be made on the pre, post and 
follow-up digital models and on the pre-and post distalization CBCT 
to assess the dental changes in intervention group.  
Participant timeline: 
1. The principal investigator will screen the potential patients through 
careful clinical examination of patients at the orthodontic department, 
Faculty of Oral and Dental Medicine, Future University in Egypt.   
2. All recruited patients should fulfil the previously mentioned 
inclusion and exclusion criteria.   
3. Every participant will be asked to sign an informed consent before 
the beginning of the study.   
4. After patient's enrolment, each participant will be asked for pre-
intervention records to ensure proper diagnosis.   
5. The principal investigator will randomly allocate the patients to 
one of the intervention groups.  
6. After patient's enrolment, pre-intervention records will be taken for 
each participant to ensure proper diagnosis (T0).  
7. Every 4 weeks Each patient will have follow up visit, for appliance 
activation, uptake of impression for interim records and checking for 
mini-screws stability (T1-T7). 
8. Post- records for each participant will be taken after duration of 
eight months (T8) at the same visit of appliance removal. 

 
 
27 
 
9. The principal investigator will continue the normal orthodontic 
treatment and achieved proper finished occlusion for every patient 
after the end of the study.  
  
 
 
E] Sample size calculation:  
The sample size calculation is based on the findings of a pilot study, 
including three patients from each group, in which the upper first molar 
distalization amount was the primary outcome. The mean (standard deviation) 
values were 3.17(0.81) mm and 4.32 (0.79) mm in the TMP and TME groups, 
respectively. The effect size was 1. 437. With alpha level of 0.05 and a test 
power of 80%, the minimum estimated sample size was 18 patients (9 patients 
per group). Considering drop out a sample size of 11 per group is appropriate.  
 Sample size calculation is performed Using G*Power version 3.1.9.2. 

 
 
28 
 
 
 
F] Recruitment strategy:   
The principal investigator will recruit the patients from the clinic of 
Orthodontic department, Faculty of Oral and Dental Medicine- Future 
University in Egypt.  Screening of patients will continue until the total 
number of participants for the study is collected.  
II) 
Assignment of interventions 
A]  Sequence generation: 
   
The supervisor of the study will apply Computer generated 
random numbers to randomly assign patients to group A (En-masse) 
or B (two steps) using Microsoft Office Excel 2007 sheet. The patient 

 
 
29 
 
numbers will be written in the first column and the supervisor will 
select function RAND to generate the randomization number in the 
second column. These numbers will be sorted according to the 
randomization number so the first column numbers will be randomly 
distributed.  
B]  Allocation concealment mechanism:  
  
The Co-supervisor of the study (Dr.Mostafa El-Dawlatly) will 
write the randomization numbers of the patients on opaque white 
papers folded three times to form sealed envelopes and store it inside 
a box. The codes for randomization will be securely held at the 
secretary’s office.   
C] Implementation 
At the time of intervention, the main operator will send the patient 
to the secretary’s office. Then, the assigned employee will open the 
box and ask the patient to select one envelope. The main operator 
will contact the supervisor to know the order and then the main 
operator will allocate each patient to assign each participant for the 
corresponding intervention either (extraction or non-extraction) 
according to the list of codes of randomization.   
           D]Blinding:   
Because both the operator and the patient are aware of the clinical 
intervention, double-blinding is not feasible. However, the digital 
dental models and CBCT will be assessed blindly by a trained external 
assessor.  
 
III) Data collection, management and analysis:  
 
A] Data collection methods:   

 
 
30 
 
to assess the primary and secondary outcomes, the principal 
investigator will take study models for every participant monthly 
during the follow up visits. Then will digitize the models and identify 
the landmarks, reference lines and planes on the pre, interim and 
post-retraction digital dental models for measurements reading. Also, 
by identifying the landmarks, reference lines and planes using CBCT 
taken before and after the completion of retraction.  
 
B] Data management:   
A colleague outside the research team will enter the data and 
organize it in excel sheets in the computer of the orthodontic 
department. Data will include all photographs, models, radiographs 
and filled questionnaire.   
 
 C] Statistical Analysis:   
 
• 
The principal investigator will be responsible for the extraction 
of the required data from the CBCT taken before and after retraction 
as well as the study models taken at every follow up visit. The data 
will be sent to a specialized statistician.   
• 
The specialized statistician will be responsible for the 
statistical analysis of the study by:   
  
1. Presenting the data as mean, standard deviation (SD) and Standard 
error (SE) values.   
2. Using Paired t-test to compare between the friction and the 
frictionless group of retraction as well as to compare between the 
pre-and post -treatment data for each group.   

 
 
31 
 
3. Using Anova test to determine the rate of anterior segment 
retraction.   
4. Statistically evaluate the patient acceptance for both techniques.   
• 
For this study, the specialized statistician will use IBM11 
SPSS12 Statistics Version 20 for Windows to perform the required 
statistics.   
• 
The significance level will be P ≤ 0.05. Highly significant 
variables are detected when P value is less than 0.01.   
       Assessors Reliability:   
• 
To achieve high reliability for measurements, the supervisor 
will choose a well experienced inter-examiner during the study.  
• 
A training session will be provided for the examiners to ensure 
standard measurements techniques.   
• 
Each examiner will complete the measurements on a model 
and will repeat the procedure after one week to assess the intra- and 
inter-examiner reliability.   
• 
The supervisor will compare the measurements of the two 
assessors for disagreement with a difference of more than one 
millimetre.   
• 
The supervisor will evaluate the amount of variation in 
measurements among and between examiners to test the performance 
of each assessor.   
• 
The examiner with less reliability will receive additional 
training but will be replaced during the study.   
• 
The specialized statistician will calibrate the intra and inter-
examiner reliability for the measurements of the study by the Intra-

 
 
32 
 
class correlation coefficient (ICC). The closer the ICC to 1.0, the 
higher reliability between assessors. According to Fleiss:" ICC values 
between 0.7 and 0.9 represent good reliability." The kappa scores 
between study examiners will be calculated, a range of 0.60-0.80 will 
represent acceptable reliability.   
IV) 
Method Monitoring:  
  
A] Data 
Monitoring: 
An 
independent 
Data 
Monitoring 
Committee (DMC) will monitor the results of the study. The 
Committee will include the trial’s supervisors, who will 
periodically review the trial data and identify the need for any 
adjustments or modifications during the study.   
  
B] Interim Analysis: no interim analysis will be performed 
during the study.   
  
C]Harm: The main operator will document and report any harms 
or unwanted effects during the study intervention to the trial 
supervisors. Also, any unpleasant experience will be reported by 
the patient in the final questionnaire at the end of the retraction. 
The main operator will be responsible for the management of any 
adverse effects or unfavorable side effects resulting from the 
appliance.  
  
D]Auditing: The supervisor will follow up and review the 
different interventions and resulting data. And he will periodically 
follow up the trial progress including recruitment of patients, 
allocation of participants to study groups; adherence to 
interventions and reporting of harms. A meeting with the senior 

 
 
33 
 
supervisor will be set every 3 months to monitor the progress of 
the study and the need for any adjustments.  
 
IV) Ethics and dissemination:   
A] Research Ethics Approval:   
The Ethical committee in Future University, Egypt will review the 
protocol before they approve it. The research Ethics committee will 
evaluate the different interventions of the study to ensure its ethical 
validity and the potential benefits to the participants.  
B] Protocol amendments:   
The main investigator will be responsible to complete a formal 
amendment in case of any modifications or adjustments to protocol 
that may affect the conduct of the study, as changes in the study 
design or intervention procedures. The Orthodontics department, 
Faculty of Oral and Dental Medicine, Future University in Egypt and 
the Ethics Committee will approve such amendment before 
proceeding in the study.  
C] Consent:   
The main investigator will be in charge for detailed explanation and 
elaboration of the different steps of the study interventions for each 
patient. Then will ask every participant to sign a written consent 
before they begin treatment. The consent will be written in Arabic.   
D] Confidentiality:   
The main investigator will store any personal information about the 
participants collected during the study separately from study records 
in locked files in areas with only access to the supervisors responsible 
for auditing and analysis. Also, will keep the files in the Department 
Of Orthodontics, Faculty of Oral and Dental Medicine, Future 

 
 
34 
 
University and will identify all the reports, data and administrative 
forms by a coded ID number to maintain participant confidentiality. 
Participant information won't be used outside the study except with 
written permission of the participant.   
E] Declaration of interests:   
No financial interests are to be declared by the supervisors and the 
principal operator. This study is a part of a Masters’ degree in 
Orthodontics, Faculty of Oral and Dental Medicine, Future University 
and it is self-funded by the principal investigator.   
F] Access to data:   
The supervisors and the principal investigator will only have access to 
the data of the study. All the data will be secured by a password to 
maintain confidentiality.  
No other parties are allowed to assess the results until the study is 
terminated and the conclusions are revealed.   
  
G] Ancillary and post-trial care:   
Any complication associated with the intervention will be managed by 
the principal operator. Then the two group of patients will continue 
their regular orthodontic treatment according to the treatment plan 
described for each case.  
H] Dissemination Policy:   
The trial results will be available to the participants, health care 
professionals and the public by publication of the study in high 
quality national and international journals. The principal investigator 
will present a copy of the thesis at the Faculty of Oral and Dental 
Medicine, Future University library and will distribute additional 
copies among the main universities in Egypt.  

 
 
35 
 
  
 
 
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