The aim of the present study was to evaluate the effect of two and four activations /day of periodontal distractor on pain intensity and pulp vitality of maxillary canine.

Orthodontic therapy is generally referred to as a lengthy process because a good orthodontic treatment normally takes 18 to 24 months to finish.

Long-term orthodontic treatment has a number of disadvantages, including as poor psychosocial effects on patients, white spots, long-term enamel damage, gingival recession, and root resorption.

The rate of tooth movement that can be achieved is a major determinant of orthodontic treatment time. Many studies have been conducted to determine the pace of orthodontic tooth movement. The majority of these studies demonstrate about 1mm of tooth movement per month.

As a result, finding treatment options that reduce treatment time without compromising results is a main focus of orthodontic research.

The approaches for hastening tooth movement rely on inducing a biological tissue reaction. These procedures are classified into two types based on their level of intrusion: conservative (biological, physical, and biomechanical measures) and surgical techniques Prostaglandins are the most often used biological agents , interleukins , leukotriene , vitamin D platelet rich plasma .Mechanical or physical approach include direct electrical current , pulsed electromagnetic field , low-energy laser , and Vibration Oral surgical procedures quicken orthodontic treatment by affecting the continuity of the alveolar bone resulting in a decrease in bone density and a corresponding reduction in the bone's resistance to orthodontic tooth movement . Surgical approach depends on Regional Acceleratory Phenomenon (RAP) which is a method to speed up orthodontic treatment by accelerating bone remodeling rates and bone density. The RAP is a series of tissue reactions that occur as a damaged bone heals . These surgical methods including corticotomy , bone perforation , Distraction osteogenesis is also one of surgical methods that allow rapid canine retraction .

The technique of distraction of the periodontal ligament (PDD) was introduced for rapid tooth movement then, dento alveolar distraction (DAD) was performed to achieve rapid tooth movement using the principles of distraction osteogenesis The canine was distracted by distractor twice daily for a total about 0.4 mm per day . It has been reported in literature that up to 2 mm is distracted per day (four activations of 0.5 mm each) . The distractor was activated till the distal surface of canine became in contact with the mesial surface of second premolar.

Previous Studies of periodontal distractor have been mainly focused on the assessment of the rate and angular changes on retracted canine. No clinical study has attempted to investigate pain intensity or pulp vitality for both activation protocols of periodontal distractor during rapid canine retraction. Therefore, the aim of the present study was to evaluate the effect of two and four activations/day of periodontal distractor on pain intensity and pulp vitality of maxillary canine.

Inclusion Criteria:

• Orthodontic Patients need extraction of first permanent premolar for orthodontic reasons (dentoalveolar maxillary protrusion, Class II div 1 malocclusion)
• No history of previous orthodontic treatment
• Absence of any systemic disease
• Good oral hygiene and healthy gums look, with no signs of redness, edema, or bleeding during brushing (periodontal inflammation)
• Highly motivation and cooperation

Exclusion Criteria:

• Medically compromised patients
• Use of medication that may affect tooth movement during the period of the study