Effect of Maxillary Third Molar Extraction vs. Non-extraction on Distalization of First Molars in a Group of Adolescent Patients

Study Overview
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Brief Summary
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There is a scarcity in literature regarding the influence of maxillary third molar on distalization . This study aimed to compare the influence of unerupted maxillary third molars and their extraction on the bilateral distalization of upper first molars using the infra-zygomatic gear distalizer

Detailed Description
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Maxillary molar distalization is one of the non-extraction modalities for treating class II malocclusion. When distalizing maxillary molars In adults, it is not a problem to extract fully erupted third molars, and it may even be suggested that the extraction site may accommodate distalization. On the contrary, adolescents usually have unerupted third molars with partially formed roots, rendering the surgical extraction more difficult and traumatic. The necessity of surgically extracting upper third molar buds before distalization remains questionable. Therefore, this study was conducted to three-dimensionally assess the impact of maxillary third molar presence on distalizing maxillary molars in adolescent patients having Class II malocclusion.

Official Title
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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

Conditions
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Class II Malocclusion

Intervention / Treatment
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* Procedure: Distalization combined with upper third molars extraction
* Procedure: Distalization without upper third molars extraction


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adolescent patients aged 16-19 years skeletal Class I bilateral Class II molar relationship. defined by at least an end-to-end molar relationship. normal vertical growth pattern. full permanent dentition with unerupted upper third molars. Exclusion Criteria: skeletal Class II or Class III relationship. past orthodontic treatment. poor oral hygiene. Increased vertical dimension.

Ages Eligible for Study
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Minimum Age: 16 Years
Maximum Age: 19 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Third molar extraction group<br>After surgical extraction of unerupted upper third molars, the maxillary first molars were distalized using the infra-zygomatic gear distalizer, which is anchored to infra-zygomatic mini-implants inserted in the infra-zygomatic crest. | Procedure: Distalization combined with upper third molars extraction<br>* After surgical extraction of unerupted upper third molars, the maxillary first molars were distalized using a labial bow with two soldered crimpable hooks distal to the upper lateral incisors. The labial bow fitted in the flying tube of the upper first molar bands. It was anchored bilaterally to the infra-zygomatic mini-implant by closed coil spring that applied a force of 300gm on each side<br>|
| Experimental: Third molar presence group<br>Without extraction of unerupted upper third molars, the maxillary first molars were distalized using the infra-zygomatic gear distalizer, which is anchored to infra-zygomatic mini-implants inserted in the infra-zygomatic crest. | Procedure: Distalization without upper third molars extraction<br>* The maxillary first molars were distalized , without extracting upper third molars, using a labial bow with two soldered crimpable hooks distal to the upper lateral incisors. The labial bow fitted in the flying tube of the upper first molar bands. It was anchored bilaterally to the infra-zygomatic mini-implant by closed coil spring that applied a force of 300gm on each side<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| distalization amount of maxillary firs molars at the crown and root levels | Anteroposterior changes in the position of maxillary first molars assessed on digitized models and cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes(measured in mm) | From pre to post distalization (an average of 8 months) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Rate of maxillary first molar Distalization | Incremental changes in the antero-posterior position of maxillary first molars assessed on digitized models taken for each patient before and after distalization and in each follow up visit. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| Tipping of maxillary first molar | Angular changes of maxillary first molar assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes(measurement of the angles in degrees). | From pre- to post-distalization (an average of 8 months) | 
| Vertical position of maxillary first molar | vertical positional changes of maxillary first molar assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| Inter molar width | Changes in the transvers distance between the right and left upper first molars assessed on digitized models taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| Molar rotation | Study models that are taken pre and post retraction (then digitalized) will be used to assess the rotation of the maxillary first molars in relation to a reference line (measurement of the angles in degrees) | From pre- to post-distalization (an average of 8 months) | 
| Tipping of maxillary second molar | Angular changes of maxillary second molar assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes. (measured in of in degrees) | From pre- to post-distalization (an average of 8 months) | 
| Tipping of maxillary third molar | Angular changes of maxillary third molar assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measurement of the angles in degrees) | From pre- to post-distalization (an average of 8 months) | 
| Vertical position of maxillary third molar | Vertical positional changes of maxillary third molar assessed on cone beam computed (measured in mm)tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks , reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| Vertical position of upper incisors | Vertical positional changes of upper incisors assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| Anteroposterior position of upper incisors | Antero-posterior change in the anteroposterior position of upper incisors assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 
| upper incisors torque | Angular changes of upper incisors assessed on cone beam computed tomography (CBCT) taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measurement of the angles in degrees) | From pre- to post-distalization (an average of 8 months) | 
| Anteroposterior changes of upper first and second premolars | Antero-posterior change in the position of maxillary first and second premolars assessed on digitized models taken for each patient before and after distalization. Measurements were done by identifying landmarks, reference lines, and planes (measured in mm) | From pre- to post-distalization (an average of 8 months) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Infra-zygomatic mini-implant, Distalization, Infra-zygomatic crest, Digital models, molar tipping