Tooth extraction, how long before teeth shift back?

It varies widely!: Sometimes we see shifting in a matter of weeks or months, while other times it takes years. Every circumstance is different and we can't always predict what will happen nor when. Generally speaking, the sooner teeth are replaced the better. Your own dentist can probably give you a more accurate guess.

Retention necessary: When a tooth is lost an immediate loss of space can be had, without a replacement such as implant, bridge, or partial this space could be lost forever (without orthodontic intervention) the teeth without help may never return to there pre-extraction position.