Tooth decay will not heal itself by brushing your teeth. Tooth decay, also known as dental caries, is caused by bacteria invading the hard tissues of the teeth and causing damage to the hard tissues. The main purpose of brushing is to remove plaque and food debris from the periodontium to keep the mouth clean and maintain oral health. In the case of dental caries, brushing can stop it from worsening but does not have any curative effect. According to the degree of dental caries, there are four methods of treatment: fillings, root canal treatment, restorations and extractions. For shallow caries, fillings and preventive fillings can be done. If the caries reaches the nerve of the tooth, root canal treatment should be done. If the caries area is large, inlay restoration or crown restoration should be considered. The irreparable bad teeth need to be extracted and wait for the alveolar bone and gums to recover before making restorations. To protect your teeth, you need to brush your teeth in the right way and go to the hospital for regular checkups.