To compare the alignment efficiency of conventional NiTi arch wire to Thermal and Super elastic NiTi arch wires.

Method: All the participants will be recruited from Ziauddin University dental OPD, each will be provided with full information about study. An informed consent form will be signed from every patient or their guardian/parents. Patients who agree to be part of this study will be included.

Subjects will be treated by Orthodontic resident under faculty supervision. Pre-treatment mandibular crowding will be assessed on dental casts. Randomization of the three groups will be done by "Opaque envelope technique" Bonding will be done using 3M uniteck brackets. After initial bonding good quality mandibular impressions will be taken and poured to obtain dental casts. Impressions and casts will be obtained at every 4 weeks interval until the initial alignment phase is complete. At the time of bonding all lower anterior teeth will be fully engaged in the archwire. The principal researcher will tag every model with an identification code before calculating measurements.

The contact point displacements will be measured with vernier caliper using the Little's index of irregularity. All measurements will be then summed and aggregated value will represent the degree of anterior irregularities.

Inclusion Criteria:

• lower anterior crowding good oral hygeine all permanent lower incisors no previous orthodontic treatment

Exclusion Criteria:

• extracted or missing lower incisors poor oral hygeine relevant medical history previous orthodontic treatment