• Palpate for the permanent canine on the buccal and palatal aspect between the ages 8-10.
• Be cautious of false observations as the root of the deciduous canine may be mistaken for the crown of a permanent tooth.

Additional clinical features that may indicate the presence of an impacted canine:

• Deep bite
• Missing lateral incisors or peg shaped lateral incisors
• Proclined lateral incisors
• Retained primary canine following the age of 11-12

If an impacted canine is suspected radiographs should be taken for confirmation.

The following radiographs can be taken:

• DPT (panoramic)
• Periapical
• Upper anterior occlusal
• Cone beam computed tomography: Would give an accurate position of the impacted canine however comes with increased cost, time and radiation exposure.

Parallax

Parallax is defined as the apparent displacement of an object because of different positions of the observer.

Parallax radiographs are often taken to assess the presence/positioning of an impacted canine.

2 Types:

Horizontal Parallax:

• Upper standard occlusal (midline view) and periapical (centred on the canine region)
• 2 periapicals (one centred on the upper central incisor and the other centred on the canine region)

Vertical Parallax

• Upper standard occlusal (midline view with X-ray beam aimed downwards) and a panoramic radiograph (x-ray beam aimed upwards approximately 8 degrees to the horizontal)
• Periapical (bisected angle technique with X-ray beam aimed downwards) and a panoramic radiograph (x-ray beam aimed upwards approximately 8 degrees to the horizontal)

The SLOB Rule:

The SLOB rule (same lingual, opposite buccal) is used to assess if the canine is impacted palatal or buccal.

• This means if the tooth appears to move in the same direction as the movement of the x-ray tube when the two x-rays are taken- the tooth is positioned in the lingual/palatal direction.
• If the tooth moves in the opposite position the tooth is placed in the buccal position.

The radiographic report should include:

• The position of the canine’s crown and root relative to adjacent teeth and the arch
• Prognosis of adjacent teeth and the primary canine if present
• The presence of resorption, particularly of the adjacent central and/or lateral incisors

• Resorption of adjacent incisor roots
• Poor aesthetics
• Cyst formation
• Dilacerated roots

• At age 10 the canine should be palpable as bulges on the buccal aspect of the alveolus.
• If it isn’t palpable an abnormal path of eruption should be suspected especially if one canine is very delayed compared to the other.
• Un-erupted maxillary canines should be palpated routinely on all children from the age of 10 years until eruption.
• Delayed eruption, distal tipping or migration of the upper lateral incisor may indicate an impacted canine.

Early Removal Of C’s (Interceptive Treatment)
2. Surgical Exposure Of 3’s And Orthodontic Alignment
3. Retain 3 And Observe – Patient not keen on treatment and pathology or resorption of adjacent teeth not evident.
4. Surgical Removal Of Permanent Canine
5. Autotransplantation Of 3
6. Leave And Monitor

Early Removal of C’s (Interceptive Treatment)

Only appropriate under the following conditions:

• Early detection/mixed dentition between ages 8-9 years
• The canine crown cannot overlap more than half of the width of the adjacent incisor root
• Canine crown no higher than the apex of the adjacent tooth
• Angle of 300 or less between the canine’s long axis and the mid sagittal plane
• Reasonable space available in the arch- no more than moderate crowding

Unless the upper arch is spaced, the contralateral primary canine should be extracted to prevent centreline shift. If it fails to show reasonable improvement after a year seek specialist advice.
Note: If it’s too late for interceptive treatment then monitor radiographically the un-erupted 3 for cystic degeneration and/or root resorption of contralateral incisors. 

Surgical Exposure And Orthodontic Alignment

• Well-motivated patients
• Excellent oral hygiene
• Favourable canine position
• Space available (or can be created)

Whether the orthodontic alignment is feasible or not depends on the 3D position of the unerupted canine:

• Height– the higher the canine is positioned from the occlusal plane the poorer the prognosis. More restricted for access in surgical exposure. If the crown tip is above the apical third of the incisor root, orthodontic alignment will be very difficult
• Anteroposterior position– the nearer the canine crown is to the midline the more difficult alignment will be.
• Position of the apex– the further away the canine apex is from the normal the poorer the prognosis
• Inclination– the smaller the angle with the occlusal plane the greater need for traction.

 If factors are favourable: 


1. Make space available
2. Arrange exposure
3. Allow the tooth three months to erupt
4. Commence traction

Note: With deep canines, there is a risk that the gingivae may cover the tooth again so a gold chain is attached at the time of exposure or two days after the pack has been removed to be used during traction.

Surgical Removal Of Permanent Canine

• If retained deciduous canine is acceptable in appearance and patient is happy with aesthetics/reluctant to embark on complicated treatment.
  • Must explain that eventually the primary canine will fall out and a prosthetic replacement will be needed.
• Upper arch is very crowded and the 4 is adjacent to the 2
• Canine is severely displaced. Depending on the patient a prosthetic replacement can be provided or movement to close the gap with an orthodontic appliance.

Autotransplantation

Can only be attempted if there is space in the arch and the canine must be removed intact. Sometimes orthodontic treatment is done prior to the surgery to create space.
Long term survival rates are poor. The prognosis is improved if the root is 2/3 formed, minimal handling of canine root at surgery, and rigid splinting is avoided.
The main causes of failure are:

• Replacement resorption (or ankylosis)
  • Occurs when the root surface is damaged during surgery
  • Is prompted by rigid splinting of transplanted tooth which encourages bony healing rather than fibrous
  • Careful handling of the root surface and preventing desiccation during surgery with a method of splinting which allows movement during the immediate post- surgery phase is recommended
• Inflammatory resorption: Follows the death of the pulpal tissues

Walker L, Enciso R, Mah J.Three-dimensional localization of maxillary canines with cone-beam computed tomography. American Journal of Orthodontics and Dentofacial Orthopedics 2005;128: 418–423.
Ericson S, Kurol J. Longitudinal study and analysis of clinical supervision of maxillary canine eruption. Community Dentistry Oral Epidemiology 1986;14:172–76.
Hurme VO. Ranges of normalcy in the eruption of permanent teeth.Journal of Dentistry for Children 1949;16:11–15.
Husain J, Burden D, McSherry P. Management of the palatally ectopic maxillary canine. Royal College of Surgeons. 2010