Tooth extraction is a process of removing a tooth which decayed, damaged beyond repair and the tooth where the tissues and bones are completely damaged.

Reasons for tooth extraction
·    A tooth extraction might be indicated if repairing a damaged tooth is not practical...
Extraction can be done under the following
1.      Teeth with extensive decay (dental caries) Or
2.      Teeth broken or cracked in such an extreme manner i.e. beyond repairable. 
3.      In some cases the obstacles  might be so formidable that a repair for the tooth is simply not possible. 
4.      In other cases the cost of dental treatment or else a dubious long-term outlook for the success of the treatment may be the reason why an extraction is chosen. 
·   Teeth that are unsuitable candidates for root
   canal treatment should be extracted... 
In some cases when the root canal treatment cannot be performed then the tooth extraction is carried out. There are some teeth that may require treatment of the nerve space that lies within them. While most teeth typically are candidates for root canal treatment there can be complicating factors that remove this option and the dentist has no options other than tooth extraction In order to make a tooth repair.
·     Malpositioned or nonfunctional teeth may need to be extracted... 
Sometimes tooth extraction can be done for the ones which are mal-positioned and create constant irritation to the patients. For example, wisdom tooth which is a constant source of irritation to the person's cheek can be remove during tooth extraction.

Impacted teeth are often extracted. These are teeth with jaw bone positioning that cannot erupt into normal alignment. So by definition, impacted teeth are mal-positioned, precisely why they are often non-functional. This combination of factors makes impacted teeth common candidates for extraction. 

·       Tooth extractions may be required in
    preparation for orthodontic treatment (braces)... 

In an orthodontic treatment the dentist is trying to perfect the alignment of the patient's teeth. But they can only do so within the confines the person's jaw size. Especially in cases where a large discrepancy exists between the size of the patient's jaws and the space needed--- for the improved teeth alignment---some strategically located teeth may need to be extracted. 

Procedure for tooth extraction:

Local anesthesia is used for numbing the area to be affected of the tooth. In cases where the tooth is exposed and appears to be easily removable in one piece. Most dentists or oral surgeons use an instrument called an elevator to luxate, or loosen, the tooth; widen the space in the underlying bone; and break the tiny elastic fibers that attach the tooth to the bone. Once the tooth is dislocated from the bone, it can be lifted and removed with forceps.

Procedure for impacted tooth extraction:

Extracting an impacted tooth or a tooth with curved roots typically requires cutting through gum tissue to expose the tooth. It may also require removing portions of bone to free the tooth. Some teeth must be cut and removed in sections. The extraction site may or may not require one or more stitches (sutures) to close the incision.