Can you explain how do orthodontist treat teeth crowding with braces; besides extracting teeth?

Force: Teeth move by responding to a light, constant force. This is because the bone remodels by losing itself to make space for the tooth to move into, and filling in more in the space where the tooth moved out of. Very small implants may be placed as an anchoring device to move teeth also. Any pushing or pulling creates force, and that is how teeth move to more ideal position.

Sure: Crowding of the teeth is a very common malocclusion treated by orthodontists. Your questions has to deal with the "amount of dental crowding". Without extraction of teeth, one of the ways to create space is to expand the dental arches. Dental expansion does have its limitation based on the boney support of the jaws.

Finite: It's a finite decision. If teeth are malposed but there is adequate bone support they can be realigned. If there isn't enough bone support, expansion can cause permanent bone/gum damage. There are limits to how much expansion is therapeutic, beyond which it's pathologic. Please see a qualified Orthodontic Specialist to evaluate your malocclusion.