Your permanent teeth are designed to last a lifetime, but for numerous reasons, some may not. For instance, you might need to have a tooth extracted because it's too seriously broken to keep. Lifestyle choices, trauma, and decay can all lead to needing a tooth pulled.
Your dentist may recommend an extraction if you're dealing with one of the following situations:
Risk of infection from a failed root canal
Risk of infection during chemotherapy or an organ transplant
Advanced periodontal (gum) disease
Crowded or extra teeth
No room for wisdom teeth (third molars)