Teeth can become abscessed (infected) when dental decay is left untreated for a long time. Decay that starts on the hard enamel keeps continues until it enters the nerve or pulp of the tooth can result in an abscess.
Abscesses usually appear as a whit pimple in the gums adjacent to the tooth. Sometimes, the swelling can get so severe the cheeks or jawbone area get very swollen. Depending on the stage at which you get treatment, antibiotics may be required to get eliminate the swelling and treat the infection. A fever along with a severe pain may accompany the abscess.
Generally, abscessed baby teeth are extracted. However, permanent tooth are usually restored with a root canal.