There are a number of problems with moving permanent canines from either a buccal or a palatal position. By and large, the older the patient the less chance there is of succeeding, and certainly moving canines in adults requires caution. If the canines have to be moved a considerable distance then ankylosis is a distinct possibility as well as loss of vascular supply and therefore pulp death. Treatment often takes in excess of 2 years and it is important to maintain a motivated and co-operative patient. It is necessary to create sufficient space for the canine to be aligned and this is usually around 9 mm.
The periodontal condition of canines that have been moved into the correct position in the arch can deteriorate, this is particularly true if care has not been taken to ensure that the canine either erupts or is positioned into keratinised mucosa. There may also be damage to adjacent teeth during surgery, or indeed the surgeons can damage the canine itself with burs or other instruments. Figure 19 shows the crown of a canine which has clearly been grooved by a bur which was used for bone removal when the canine was exposed. It is quite easy to induce root resorption of adjacent teeth (either the lateral incisor or the first premolar), particularly if care is not taken in the direction of traction applied to the impacted canine. Loss of blood supply of adjacent teeth can also occur. It is quite common at the end of treatment to see a slightly darker crown of the permanent canine, this probably results from either a change in vascularity and vitality of the canines, or potentially haemoglobin products can be produced and seep into the dentine thus changing the colour of the overlying enamel. The worst scenario of all is that the canine ankyloses and will not move. The protracted length of treatment also results in patients abandoning treatment.
Despite all of our improvements in treatment mechanics and diagnosis for impacted canines, the eruption path is often unpredictable. Canines which have a seemingly hopeless prog-
nosis can sometimes correct their position and erupt. Nevertheless, to sit and observe a patient where the canines are clearly in difficulty without referral to a specialist would be difficult to defend legally. Hopefully the days of patients arriving in orthodontic departments with retained deciduous teeth at the age of 16 will diminish as the profession takes on the challenge of life long learning.
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