Rationale: Class II Division 1 malocclusion is characterized by upper anterior teeth protrusion resulting in upper lip protrusion and convex facial profile, which are considered esthetically unfavorable. Treatment of class II malocclusion due to maxillary protrusion can be done with bilateral maxillary first premolar extraction followed by en-masse retraction of upper anterior teeth using mini-implants placed at infrazygomatic or interradicular sites.

Aims and Objectives: To evaluate the treatment changes achieved in class II division 1 malocclusion during en- masse retraction of upper anterior teeth using mini-implants placed at infrazygomatic crest versus interradicular sites.

To compare patients' and orthodontist's perceptions of treatment being done in both the groups.

Method of study: Treatment will be initiated by bilateral maxillary 1st premolar extraction followed by bonding 0.022" slot MBT preadjusted edgewise appliance. Maxillary arch will be stabilized with the help of 0.019"×0.025" stainless steel wire and then randomized allocation of the patients into 2 groups-G1 and G2 will be done. G1 will receive infrazygomatic crest mini-implants bilaterally and G2 will receive bilateral interradicular mini-implants. Hooks will be soldered on archwire used for stabilizing dentition. Ni-Ti closed coil spring will be used to apply force.

The present study is a randomized clinical trial , non-pharmacological, double blind, to evaluate the treatment changes achieved in class II division 1 malocclusion during en-masse retraction of upper anterior teeth using mini-implants placed at infrazygomatic crest versus interradicular sites. The present study will be conducted in the Department of Orthodontics and Dentofacial Orthopaedics, in conjunction with the Department of Oral and Maxillofacial Surgery, P.G.I.D.S., Pt. B.D.Sharma University of Health Sciences, Rohtak. The study will be carried out after the institutional approval obtained from the ethical committee.

Inclusion criteria:- Non growing patients with bilateral Class II molar relationship at pre-treatment, all permanent teeth upto the second molars should be present, no or minor crowding in the maxillary arch, horizontal to average growth pattern.

Exclusion Criteria:- Subjects with a history of fixed orthodontic treatment, crossbite, vertical growth pattern, any systemic disease affecting bone and general growth, poor oral hygiene, cleft patients, patients who fail to follow up or undergo complete treatment.

INFORMED CONSENT OF THE PATIENT AND AGREEMENT TO BE RANDOMIZED A valid, written informed consent of the patient or parent/ guardian and an agreement to be randomized will be obtained from the patient before registering the patient in this clinical study. Patient will be informed about all the theoretical risks and benefits of the intervention under test . The patient will be given 72 hours to discuss the study with his/her family and take the decision regarding participation in the study.

RANDOMIZATION & ALLOCATION CONCEALMENT Randomization will be done by a person not involved in the trial using computer generated randomization list. The study subjects will be blinded regarding intervention group.

INTERVENTION AND DESIGN OF STUDY The main intervention in this prospective clinical study is the bilateral extraction of maxillary first premolars before initial leveling and alignment followed by retraction of anterior teeth using mini-implants placed at infrazygomatic crest in group 1 (G1) and mini-implants placed at interradicular sites in group 2 (G2). The study consists of 2 groups with equal allocation of subjects in each group:- Group 1 (G1):- This group will undergo bilateral extraction of maxillary first premolars before initial leveling and alignment followed by retraction of anterior teeth using mini implants placed at infrazygomatic crest.

Group 2 (G2):- This group will undergo bilateral extraction of maxillary first premolars before initial leveling and alignment followed by retraction of anterior teeth using mini implants placed at interradicular sites.

DATA COLLECTION The investigator will record the patient's name, address and contact number will be taken. Cephalometric radiographs will be recorded before placement of mini-implants and after 6 months of application of NiTi closed coil springs. These cephalometric radiographs will be analyzed and the relevant values will be entered in a predesigned format.

Patients will be asked to fill a questionnaire in which they will be asked about problems they might have while eating, talking ,laughing, yawning swallowing ,drinking ,brushing and also the pain experienced in tooth ,jaws, muscles, headache, swelling ,soft tissue ulceration ,restricted mouth opening ,and level of satisfaction .These questionnaires will be completed on the evening after force application and at 7 days ,14 days ,1 month and 6 months. .

In addition orthodontist's perceptions will be assessed during handling complexity of mini implant in both the positions on same day,1 month, 3 months and 6 months following orthodontic force application.

STATISTICAL ANALYSIS The data entered will be processed by standard statistical analysis. Results will be presented in the form of tables and graphs.

The data will be subjected to descriptive analysis for mean, standard deviation for quantitative and proportion for qualitative variables. Shapiro Wilk test will be used to check the normality of distribution.

Independent T test (normal distribution) and Mann Whitney U test (Non-normal distribution ) will be used to compare means between two groups at pre-retraction stage. Dependent T test (normal distribution) or Wilcoxon Signed Ranks(Non-normal distribution) test will be used to compare changes within groups. Independent T test and Mann Whitney U tests will be used to compare change between two groups i.e. Group 1 (Infrazygomatic mini-implant) and Group 2 (Interradicular mini-implant). In all the analysis, the level of significance will be set a 5 percent.

Patient pain perception and orthodontist perception regarding treatment has been evaluated using chi square test.

Inclusion Criteria:

1. Non growing patients
2. Bilateral Class II molar relationship at pre-treatment.
3. All permanent teeth upto the second molars should be present.
4. No or minor crowding in the maxillary arch.
5. Horizontal to average growth pattern.

Exclusion Criteria:

1. Subjects with a history of fixed orthodontic treatment.
2. Crossbite
3. Vertical growth pattern
4. Any systemic disease affecting bone and general growth
5. Poor oral hygiene
6. Cleft patients
7. Patients who fail to follow up or undergo complete treatment