1. Oral Habits – Mouth breathing; thumb, finger, or lip sucking; tongue thrusting or posture; and other habits can prevent the teeth from moving to their correct position or cause relapse after braces are removed.
2. Facial Growth Patterns – Unusual skeletal patterns or unpredictable facial growth may compromise the occlusion (fit) of upper and lower teeth. Surgical assistance may be recommended in these situations.
3. Post Treatment Tooth Movement – Teeth may have a tendency to shift or settle after treatment, as well as after retention. Some changes are desirable, while others are not. Long-term use of retainers is advised.
4. Temporomandibular Joint (TMJ) Problems – TMJ problems may develop at any time: before, during, or after orthodontic treatment. Tooth position, occlusion, or pre-existing TMJ problems can be a factor in this condition. Often, an occlusal guard, or night guard, may be helpful.
5. Impacted Teeth – When moving impacted teeth (teeth unable to erupt normally), especially canines, various problems may be encountered, which may lead to periodontal problems, relapse, or loss of teeth.
6. Root Resorption – Shortening of root ends can occur when teeth are moved during orthodontic treatment. Under healthy conditions, the shortened roots usually pose no problem. Trauma, impaction, endocrine disorders, or idiopathic (unknown) reasons can also cause this problem. In rare cases, severe resorption may increase the possibility of premature tooth loss.
7. Non-vital or Dead Tooth – Injuries to a tooth, such as from a fall, can damage the pulp inside the tooth, causing the pulp to die. As a result, these teeth may discolor or flare up at any time, with or without orthodontic treatment. If this happens during orthodontics, tooth movement may be temporarily stopped so that the tooth may undergo endodontic root (canal) treatment.
8. Periodontal Problems (gum disease) – This condition can be present before orthodontic treatment or develop during treatment. It could deteriorate during treatment causing loss of bone around the teeth. Excellent oral hygiene and frequent cleanings by your dentist can help control this situation.
9. Unusual Occurrences -- Swallowing appliances, chipping teeth, and dislodging of restorations can occur.
10. Medications -- Some medications (e.g. bisphosphonates) may affect or prevent tooth movement.