Patients with moderate mandibular anterior crowding will be treated in this study. The efficacy of micro-osteoperforations technique by special drill in accelerating orthodontic tooth movement during clear aligners therapy will be assessed along with patient's pain and satisfaction.

There are two groups:

1. a group of patients in which participants will be received treatment with the traditional clear aligners technique in addition to a micro-osteoperforations technique.
2. a group of patients in which participants will be received treatment with the traditional clear aligners technique alone

Dental crowding is one of the most common orthodontic problems in adults as it was found that 80% of adults had crowding in the lower incisors area.

Although many adults need orthodontic treatment, they do not like and sometimes refuse to apply fixed orthodontic devices, so the emergence of Clear Aligners Technique (CAT) where the aesthetic aspect is one of the most important characteristics of this technique which can alleviate the response and anxiety of adult patients related to orthodontic treatment, its approach relies on the use of a series of clear aligners that slowly move each tooth into the desired position.

But the strict protocol that requires wearing each aligner 22 hours a day leads to poor patient compliance with it during the treatment period, so many clinical and laboratory attempts have been made to find different methods that achieve faster results and reduce the extent of orthodontic treatment, and among all the previous methods, the surgical approach is the most clinically used and the most tested with known expectations and stable results.

Although these surgical methods have proven effective, they are considered aggressive in nature as they require lifting of full-thickness buccal and lingual flaps with extensive removal of the buccal and lingual cortical bone, in addition to the fact that they may face rejection of the patient due to anxiety and fear of pain and undergo surgery, patients are usually not open toward ideas involving surgery unless it is the only option to obtain a good bite.

Hence, the interest has increased dramatically in recent years to develop conservative surgical techniques that provide similar clinical efficacy with minimal trauma and greater acceptance by patients. One of these techniques is the micro-osteoperforations technique, which is ideal for adult patients who have limited time and wish to finish their treatment as quickly as possible.

To date, no randomized controlled trial (RCT) has been conducted to study the effects of micro-osteoperforations Technique on the duration of orthodontic treatment along with patient's pain and satisfaction during clear aligner therapy (CAT) in moderate mandibular anterior crowding cases which are one of the most common types of malocclusions.

The current study will have two parallel arms as following:

Group 1 (the intervention group): patients in which participants will be received treatment with the traditional clear aligners technique in addition to a micro-osteoperforations technique.

Group 2 (the control group): patients in which participants will be received treatment with the traditional clear aligners technique alone.

In the intervention and control groups: patients will change aligners depending on the fit of the new aligner.

In the intervention group:

On the placing day of the initial clear aligner, special drill (1 mm in diameter and 10 mm in length) were used to perform the MOPs procedure in the intervention group. Buccal transmucosal MOPs were performed between mandibular canine and first mandibular premolar bilaterally and between mandibular canine and lateral incisor bilaterally and between mandibular lateral incisor and central incisor bilaterally and between central incisors in the midline on labial aspect of mandible.

Two MOPs at each site were performed, first perforation will be performed at a distance of 2mm from free gingival margin and second perforation will be performed 2mm from the first one in a vertical line (which will measure using customized length guides on special drill), making a total of fourteen MOPs.

The depth of perforation will be 1mm in buccal cortical bone (which will measure using customized depth guides on special drill).

Inclusion Criteria:

• Completion of permanent dentition (except third molars)
• Moderate crowding (4-6 mm according to Little's index)
• Absence of medications intake that interferes with pain perception for at least one week before the beginning of the treatment
• Number of aligners ≥ 8 aligners.

Exclusion Criteria:

• • Systematic diseases that could affect bone and tooth movement and no contraindication avoid oral surgery

  • Medical conditions that affect tooth movement (Corticosteroid, NSAIDs)
  • Patients had previous orthodontic treatments
  • Poor oral hygiene or concurrent periodontal disease