Effect of bilateral distalization of upper first molars in a group of patients after extraction of maxillary second molars using infra zygomatic mini implants : prospective clinical trial / By Hosam Abdullah Mohamed, B.D.S. Future University (2017)

Supervisors, Dr. Nagwa El- Mangoury, Professor of Department of Orthodontics, Faculty of Oral and Dental Medicine, Future University in Egypt,
Dr. Amr El-Dakroury, Professor, Department of Orthodontics, Faculty of Dentistry, Cairo University, Dr. Mostafa Mohamed El-Dawlatly, Associate Professor, Department of Orthodontics, Faculty of Dentistry, Cairo University.

Thesis (M.Sc.)-Future University in Egypt, Faculty of Oral and Dental Medicine, Department of Orthodontics, 2022.

Includes bibliographical references.

Before the introduction of sekeletal anchorage, maxillary 1st molar distalization was considered a complex treatment modiality with unreliable results & numerous drawbacks. However, thanks to the introduction of skeletal anchorage devices such limitations & drawbacks were eliminated enabling a new gate for more solutions and treatment modialities for maxillary 1st molar distalization with successful clinical result & without relying on extra-oral anchorage devices that put us through the challenge of patient compliance. As a result, it became an integral part of the treatment options for Angle’s Class II malocclusion.
During the present study, the infrazygomatic crest region was selected as the optimal site for infra-zygomatic mini-implants insertion, where an efficient anchorage for the maxillary first molar distalization could be obtained.
The aim of the current prospective clinical trial was to investigate the efficiency of the proposed infra-zygomatic gear appliance in distalizing the maxillary first molars bilaterally after extraction of the maxillary 2nd molars with the presence of third molars, using digital models and Cone Beam Computed Tomography imaging of the maxillary arch.
11 adult female patients requiring maxillary 1st molar distalization and ranging from the age of (17 to 25) years old were selected following sample size calculation. The sample was recruited from the outpatient clinic of the Orthodontic Department, Faculty of Dentistry, Future University.
Banding of the first maxillary 1st molars followed by impression for appliance fabrication, then mini-implants were inserted and maxillary 2nd molars were extracted, followed by cementation of the appliance cementation. Treatment duration was set until reaching Angle’s Class I relation & Data was collected from monthly upper impressions, which were poured into stone models and scanned to

obtain sequential digital models (T0-T7), in addition to pre- and post-distalization maxillary CBCT images.
The main outcome of the trial which was the amount of maxillary first molar distalization was assessed on both digital models and CBCT, whereas the secondary out comes such as rate of distalization of the maxillary first molar as well as changes in the maxillary premolars were evaluated by the assessment of digital models. Moreover, other three-dimensional changes of the maxillary molars, and anterior segment were evaluated by analyzing pre- and post-distalization CBCT and digital models. Statistical analysis was performed on the gathered data and results were withdrawn.
From the results of the clinical and statistical analysis, the following conclusions could be withdrawn:
1. After extraction of the maxillary 2nd molars, the maxillary 1st molars were distalized efficiently, with a highly significant amount and rate of distalization.
2. The average duration of treatment was about 6.4 months until all patients reached class I molar relation
3. The maxillary 1st molars were distalization was accompanied by distal crown tipping as a result of extraction of the maxillary 2nd molar eliminating the resistance at the crown level.
4. The maxillary 1st molar showed significant intrusion, which indicates the possibility of using the appliance in vertical gorwing patients
5. The Infra-zygomatic gear appliance was able to induce significant distal drifting of the maxillary 1st & 2nd premolars due to the trans-septal fibers.
6. Due to the rigidity of the wire framework no changes occurred on to the inter-molar width as well as molar rotation during the trial period.
7. No changes on the 3 dimentional position of the maxillary anterior segment had occurred denoting no anchorage loss through out the distalization period

Text in English, abstracts in English and Arabic.