(4) leave the impacted canine in situ.
Exposure and orthodontic alignment
This is the treatment of choice for a well-motivated patient, provided the impaction is
not too severe. The canine should lie within these limits:
(1) canine crown overlapping no more than half the width of the central incisor root;
(2) canine crown no higher than the apex of the adjacent incisor root;
(3) canine apex in the line of the arch.
The tooth can either be exposed into the mouth and the wound packed open, or a
bracket attached to a gold chain can be bonded to it and the wound closed. An
orthodontic appliance, usually fixed, then applies traction to bring the tooth into
alignment. This treatment can take up to 2 years, depending on the severity of the
canine's displacement. Exposure works well for palatally impacted canines, but
buccally impacted canines usually have a poor gingival contour following exposure,
even when an apically repositioned flap procedure has been used. For this reason
some operators prefer to attach a chain to buccally impacted canines and to close the
wound, so that the unerupted canine is brought down to erupt through attached, rather
than free, gingiva.
Transplantation
The attraction of transplantation is that orthodontic treatment is avoided and yet the
canine is brought into function. Two criteria must be met: the canine can be removed
intact with a minimum of root handling; and there must be adequate space for the
canine in the arch.
The major cause of failure is root resorption, but the incidence of this is reduced if the
surgical technique is atraumatic and the transplanted tooth is root- filled with calcium
hydroxide shortly after surgery. The success rate for canine transplantation is about
70% survival at 5 years, but many clinicians regard it as being appropriate in only a
few cases.
Extraction of the permanent canine
This is appropriate if the position of the canine puts it beyond orthodontic correction,
or if the patient does not want appliance treatment. If present, the primary canine can
be left in situ, and although the prognosis is unpredictable, a canine with a good root
may last for many years. When it is eventually lost a prosthesis will be needed, and
provision of this can be difficult if the overbite is deep⎯another factor to be taken
into account when considering treatment options.
Extraction of the permanent canine may also be considered where the lateral incisor
and premolar are in contact, giving a good appearance. In this case it is often
expedient to accept the erupted teeth and extract the canine.
Leaving the unerupted canine in situ