- The main indication for extracting premolars during orthodontic treatment is the reduction of dental crowding.
- Premolar extraction creates the necessary space within the dental arch to properly align teeth that are otherwise overcrowded.
- This space allows for the correction of malpositioned teeth, facilitating a more ideal occlusion and improving both aesthetics and function.

- Extracting premolars is particularly helpful when the dental arches are insufficiently sized to accommodate all the permanent teeth without overlap or misalignment.
- By removing premolars, orthodontists can retract anterior teeth and improve dental arch form, which is essential in cases of significant crowding.

Other options such as management of deep overbite and correction of skeletal malocclusion usually require different orthodontic or orthopedic interventions rather than premolar extraction. Improving tooth mobility is not an indication for extraction but rather a condition to be managed conservatively or via periodontal treatment.

In summary:
- Premolar extraction is primarily done to reduce dental crowding.
- It provides space for teeth alignment and occlusal correction.
- It is not the primary treatment for skeletal problems or bite correction, although it can aid in some cases.

Reference: Orthodontics: Current Principles and Techniques, 6th Edition, Chapter 4: Treatment Planning and Extraction Decisions