A single-operator, randomized controlled trial (RCT) will be conducted to evaluate the clinical effectiveness of moisture insensitive primers (MIPs) in bonding molar tubes under moisture contaminated conditions by comparing the clinical bond failure and survival rate of molar tubes using two MIPs which are Transbond ™ MIP (3M Unitek Dental Products, Monrovia, CA, USA) and Assure® Plus-All Surface Light Cure Bonding Primer (Reliance, Itasca, IL, USA).

A single-operator, a multi-centre, a split-mouth, cross-quadrant RCT, with 1:1 allocation ratio will be conducted for patients seeking for orthodontic treatment with fixed orthodontic appliance. The study will be conducted at postgraduate Orthodontic Clinic/ College of Dentistry/University of Baghdad in addition to private dental clinics in Baghdad, Iraq. Patients seeking for orthodontic treatment and their treatment will be planned with metal fixed orthodontic appliance (0.22" for both arches) will be recruited for this trial. Patients who will met the eligible criteria will be randomly assigned to either group of primer type. A single operator to avoid inter-operator variation will bond all molar tubes. A standardized protocol of tooth preparation and molar tubes bonding will be adopted for all the patients. All teeth will be isolated and cleansed with a mixture of water and pumice using a rubber-polishing cup on a low speed hand piece. The teeth will be rinsed and dried with an oil-free air syringe, and will be etched with the conventional acid etching technique (37% orthophosphoric acid applied for 30sec). They will be subsequently rinsed thoroughly with water for 10sec to ensure total removal of etchant according to the manufacturer's instructions.

Without drying, one coat of the patient own non-stimulated saliva will be applied to the etched and wet surface using bond brush; the excess will be blotted with a moist cotton pellet maintaining the surface moist.

A liberal coat of the MIP will be applied to the etched area of the teeth destined for a specific primer (split-mouth) using a nylon bond brush. Air will be gently blown on each tooth for 2sec, aiming the air stream perpendicular to the enamel surface then light cured for 20sec. After etching and priming, molar tubes will be bonded to the teeth with a light-cured adhesive according to the manufacturer's instructions.

Initial wires will be fitted 10-15mins after bonding completion in the context of the straight wire technique.

All patients will receive the same instructions and will be seen at 3-4-week intervals. They will be, however, requested to inform the operator immediately and attend as soon as possible once a bond failure was apparent. the molar tubes bond survival will be followed up for 6 months. They will be instructed to brush with a manual toothbrush using a fluoride-containing toothpaste.

Inclusion Criteria:

• Patients seeking for metal fixed orthodontic appliance with 0.22"*0.28";
• Complete set of permanent dentition with fully erupted molar teeth on both arches;
• Intact 1st molars and mainly their buccal surfaces are free from caries, fillings, or gingival hyperplasia;

Exclusion Criteria:

• Patients with systemic problem or genetic syndrome that affecting enamel surface like patients with generalized enamel hypoplasia.
• Patients exhibit parafunctional habits;
• Patients who their treatment plan need appliance that soldered on molar bands.
• No occlusal interferences that can affect the ideal position of molar tubes, especially in the lower arch.

No Plan to Share IPD because this trial is a prospective study and yet we can't promise for any sharing.

This trial will be triple-blinded in which neither the participants nor the trial team will know which one of the primers a patient has received, as well as the outcome assessor will be blinded. This can be achieved by placing the two primers in two similar masked bottles and giving them numerical coding i.e. number one and number two coding for either type of primer.