There are many people who have badly grown teeth and want to straighten them, but are worried about breaking them, especially adult patients. So, are there any side effects of having orthodontic treatment? Everything is divided into two, especially in the medical field, there may be some side effects while treating diseases, such as side effects of medications, scars left by surgery, etc. In contrast, the side effects of orthodontic treatment are mild, while its therapeutic effect is remarkable. Orthodontic treatment will mainly produce some effects as follows. (1) Effects on the dental pulp. At the beginning of the treatment, a mild, temporary inflammatory reaction will occur in the pulp, manifested as pain or discomfort in the patient’s mouth during the first few days of force, but it will return to normal after a period of adaptation. (2) The effect on the roots of the teeth. When orthodontics, the root surface of the tooth is also undergoing resorption and proliferation of this modification activity. After treatment, the roots of the teeth return to normal with their own repair ability, but if too much force is applied during treatment, it will increase the risk of root resorption. (3) The effect on the height of alveolar bone. People who have undergone orthodontic treatment may experience a small decrease in the height of the alveolar bone. This is due to the fact that oral hygiene is not easy to maintain with orthodontic appliances and the patient does not cooperate well with the doctor to clean the oral cavity, which causes gingivitis and the resulting reduction in the height of the alveolar bone. After the treatment is completed, if the oral hygiene is well maintained, the alveolar bone will gradually return to normal. (4) Looseness of teeth. Under normal circumstances, each tooth has a certain amount of physiological movement in order to cushion the chewing pressure and prevent trauma to the teeth. This is a normal reaction to increased tooth looseness during orthodontic treatment. To move the teeth, the alveolar bone and periodontal membrane need to be modified, therefore, the teeth will become looser during the treatment. However, after the teeth are corrected to normal position and stop moving, the teeth can be reattached to the periodontium by their own repair ability and become stable, and no permanent damage will occur. However, it should be reminded that if too much tooth looseness is found clinically, the doctor should be asked to suspend the force and let it recover for a period of time before continuing to add force. In conclusion, orthodontic treatment should be done both to achieve the therapeutic effect and to make the movement of the teeth as close to the physiological state as possible, which is the reason for the long course of orthodontic treatment, and only scientific treatment will not cause damage to the oral tissues.