The Efficacy of Tow Mechanics for Total-maxillary-arch-distalization

Evaluation of the Efficacy of One-jaw Versus Tow-jaw Mechanics for Mini-implants Anchored Total-maxillary-arch-distalization in the Treatment of Class II Division 1 Malocclusion A Randomized Controlled Trial

Patients with class II division 1 malocclusion who have increased overjet will be treated in this study. The efficacy of one-jaw and tow-jaw mechanics for mini-implants anchored total-maxillary-arch-distalization in the treatment of class II division 1 malocclusion will be assessed. The skeletal, dental and soft tissues changes resulted by these tow interventions will be studied. As well as, the pain levels, oral-health related quality of life during all stages of the treatment and the smile components will be explored and compared with the traditional treatment results of this type of malocclusion (en-mass retraction with first premolars extraction).

There are three groups :

1. a group of patients in which participants will be undergo to the one-jaw mechanic for mini-implants anchored total-maxillary-arch-distalization (mini-implants in the maxillary arch).
2. a group of patients in which participants will be undergo to the tow-jaw mechanic for mini-implants anchored total-maxillary-arch-distalization (mini-implants in the mandibular arch with class II elastics).
3. a group of patients in which participants will be undergo to the en-mass retraction with first premolars extraction with mini-implants in the maxillary arch.

The number of adults seeking active orthodontic treatment has been increasing over the past several decades. Older patients tend to show a greater demand for esthetic considerations during and after active treatment. Also, the preservation of existing dentoalveolar structures becomes a more critical issue in their treatment, and this mandates vigilant monitoring of the periodontal and occlusal statuses throughout the course of tooth movement.

Nowadays, the tendency towards choosing nonextraction approaches has been increasing because of the availability of effective and minimally invasive treatment modalities. Several strategies have been introduced to address the arch length discrepancy by gaining space through enamel stripping, arch expansion, and distalization of dentition. Moreover, the introduction of temporary anchorage devices (TADs) has enhanced the efficiency of nonextraction therapies via improved anchorage management.

The total-maxillary-arch-distalization is a treatment modality respect the principle of structures preservation and the esthetic demands of patients.

Most of the published literature were case reports or retrospective studies so, there is a high need for a randomized controlled trial to assess some of these suggested approaches.

The current study will have three parallel arms as following:

1. Group 1: a group of patients in which participants will be undergo to the one-jaw mechanic for mini-implants anchored total-maxillary-arch-distalization (the mini-implants will be inserted in the maxillary arch between the roots of 2nd premolar and 1st molar and closer to the molar, then a force of 250 g will be applied from the TAD to a hook lateral to the laterals).
2. a group of patients in which participants will be undergo to the tow-jaw mechanic for mini-implants anchored total-maxillary-arch-distalization (the mini-implants will be inserted in the mandibular arch between the 2nd premolar and 1st molar, then, a class II elastics 3/16 and 6.5oz will be use from the TAD to the hook of canines brackets).
3. a group of patients in which participants will be undergo to the en-mass retraction with first premolars extraction with mini-implants in the maxillary arch inserted between the 2nd premolar and 1st molar, then a force of 250 g will be applied from the TAD to a hook lateral to the laterals .

Prior to enrollment of each subject into the study, they will be examined completely to determine the orthodontic treatment plan. The operator will inform them about the aim of the study and ask them to provide a written informed consent.

A fixed orthodontic appliance will be bonded ( MBT 0.022 inch prescription), the active distalization or retraction will start when the rectangular stainless steel archwires (0.019" × 0.025").

The end of the treatment will be determined clinically when a class I canine relationship achieved with a good incisor relationship obtained.

Dental casts will be used for the quantification of the anteroposterior movement of the anterior teeth and the first molars before the beginning of the treatment and when a class I canine relationship achieved with a good incisor relationship obtained.

Cephalograms will be taken 3 times: the first before the beginning treatment for diagnosis purpose, the second: after the completion of leveling and alignment stage, the third: when a class I canine relationship achieved with a good incisor relationship obtained.

Smile photographs will be taken in 2 times: the first before the beginning of the treatment, the second: after the treatment

Inclusion Criteria:

• Adult patients with permanent occlusion at age 18-30 years.
• Comprehensive medical and dental history ruling out any systemic disease
• Not under any systemic medication.
• No previous orthodontic treatment
• Patients with satisfactory periodontal health and Good oral hygiene
• Need to orthodontic treatment with fixed appliances
• No congenitally missing teeth except third molars in the maxillary arch
• Mild or no anterior crowding in maxillary arch.
• Patients with class Ⅱ division 1 (ANB angle ≤7 degrees) with severe overjet (5-9 mm)
• Maximum retraction of the anterior teeth was desired.

Exclusion Criteria:

• Patients with previous orthodontic treatment.
• Patients with severe skeletal dysplasia in all three dimensions.
• Patients suffer from systemic diseases or syndromes
• Patients on medication for systemic disorders, pregnancy or steroid therapy.
• Patients showing any signs of active periodontal disease
• Patients with severe crowding (≥ 3.5 mm) in maxillary arch
• Patients with missing or extracted teeth in maxillary arch except third molar.