First off a tooth should never be extracted unless a dental provider has been consulted. With that being said there are specific reasons why it’s a better idea to extract the tooth. Most dental providers will not extract a tooth without discussing the pros and cons. Many will also recommend getting an implant in place of that tooth. An implant will help to keep healthy bone around the site where the original tooth was lost. When a tooth is extracted, bone around that area can be lost which can result in surrounding teeth becoming loose as well.
One very common reason to extract a tooth is that it has been too damaged from a trauma or decayed to have it repaired.
Another reason to extract the tooth is if your mouth is too crowded. If working with an orthodontist this is something that may have come up during discussion of a crowd of mouth. This procedure is done often to make room for the shifting of teeth during a treatment plan.
Another reason is infection, if tooth decay or damage has reached the pulp of the tooth this can cause severe infection. Typically, a root canal can be an effective procedure; however, it’s not always successful. An extraction may be the next step.