The purpose of this study is to compare the human pulp response to partial pulpotomy using White ProRoot MTA or iRoot BP in the terms of dentinal bridge formation and inflammation.

This will be a randomized single blind clinical trial. Setting and conduct: Twenty caries free premolar teeth from fifteen patients assigned for orthodontic extraction will be included. Participants including major eligibility criteria: Their parents need to sign an informed form, Patients shouldn't have any systematic complication, The teeth should be free of any symptom, caries and decalcification and should reveal a normal response to pulp sensitivity tests, No mobility or swelling in the surrounding soft tissues, sensitivity on palpation or percussion should be present. Intervention: A class one cavity will be prepared and the depth will be increased until the pulp exposure occurs. One millimeter of the coronal pulp will be removed. Then the exposure site will be covered using two pulpotomy agents: White ProRoot MTA as control group and iRoot BP. After six weeks (42 days) the teeth will be extracted after radiographic and clinical examination to find any sign of swelling, abscess or sinus tract. Main outcome measures (variables): The teeth will be sectioned and examined to compare the presence of dentinal bridge, its thickness and feature in the terms of tunnel defect formation. The underlying pulp will be assessed and graded according to the degree of inflammation as follows: grade 0 no inflammation, grade 1 mild inflammation, grade 2 moderate inflammations, grade 3 severe inflammation, grade 4 abscess formation or necrosis. Our criteria are based on ISO 7405.

Inclusion Criteria:

• Patients who are assigned to extract two premolar teeth in one jaw for orthodontic treatment plan.
• Their parents need to read and sign a fully informed form.
• They shouldn't have any systematic complication or take any medicine during the period of study.
• The teeth need to be free of any symptom, caries and decalcification
• They should give a normal response to pulp sensitivity tests (cold test) compared to the control tooth on the same quadrant.
• The teeth need to be free of mobility or swelling in the surrounding soft tissues and any sensitivity on palpation or percussion.
• On radiographic examination no apical lucency or PDL widening should be detected.

Exclusion Criteria:

• tooth crack
• tooth filling
• any caries
• hypocalcification
• The teeth showing apical lucency
• PDL widening on radiography
• sensitivity to cold, heat or bite
• The responses beyond the normal limits to pulp vitality testing
• Any medicine consumption