unerupted ectopic canines

Question 1

incidence & aetiology

Answer 1

incidence = 1-2% in caucasian population
aetiology = possible causative factors inc:
- long path of eruption
- genetic link; associated with other dental abnormalities i.e. class II/III malocclusion, missing or diminutive laterals, F>M
- crowding; canine often last tooth to erupt
- ectopic position of tooth germ

Question 2

risks of accepting malocclusion & leaving canine unerupted (5)

Answer 2

1. resorption of roots of adjacent teeth (40% risk of lateral root resorption)
2. resorption of canine crown (14%)
3. ankylosis of unerupted canine
4. eventual loss of primary canine & complex restorative solutions may be required in future
5. cystic change of canine (rare)

Question 3

when might the canine be surgically removed (5)

Answer 3

1. canine not deemed alignable
2. if no significant risk of damaging adjacent teeth during a surgical procedure
3. pt is happy with dental appearance and the retained primary canine has a good long term prognosis
4. no radiographic evidence of early root resorption of adjacent teeth
5. pt does not want to wear orthodontic appliances

Question 4

what deems ectopic canine unable to be aligned (3)

Answer 4

1. too high - above apical 1/3 of incisor roots
2. too close to dental midline
3. angle >55 degrees to midsagittal plane

Question 5

option of removable appliance

Answer 5

removeable appliance alone not going to comprehensively treat the malocclusion but could be used at start of tx to aid OB reduction

Question 6

use of growth modification

Answer 6

addresses underlying class II malocclusion:
1. functional appliance i.e. twin block
- converts class II div 2 incisors into class II div 1 relationship
- facilitates mandibular growth
- aids OB reduction
2. headgear to restrain maxillary growth
- could be combined with removeable and fixed but not well tolerated; mainly historical

Question 7

option of fixed appliances, surgical exposure & orthodontic alignment

Answer 7

1. make sufficient space for tooth, a deciduous canine if retained may require removal
2. surgically expose the canine; open or closed depending on site of canine
3. orthodontic traction; gold chain (closed exposure) or a traction hook for open exposure
4. upper & lower fixed appliances; highly anchorage demanding so may need palatal arch
5. fixed & removeable retainers

Question 8

tx option of autotransplantation (indications)

Answer 8

1. malposition of tooth is toot great for orthodontic alignment to be possible
2. no evidence of ankylosis of the canine
3. canine root development is ideally 2/3 to 3/4 length root
4. pt is looking for a quicker tx option
5. other possible active / interceptive treatment has failed or is considered to be inappropriate

Question 9

risks of autotransplantation (2)

Answer 9

1. pt may require RCT of transplanted tooth
2. pt needs to accept risk of ankylosis or external root resorption of the transplanted tooth

Question 10

in addition to routine orthodontic risks what are some case specific risks here

Answer 10

1. pt commitment required as twin block challenging appliance to wear, tx complex & tx time likely lengthy
2. sometimes a 2nd surgical approach becomes necessary
3. failure to achieve tx objective is possible
4. long term retention required as palatal canines & upper midline diastemas prone to relapse
5. roots were shorter than average pre tx so pt may be at greater than average risk of root resorption

Question 11

key points on tx options for unerupted ectopic canines

Answer 11

1. leave in situ
2. if c still present consider interceptive XLA of c
3. surgical removal
4. surgical exposure & orthodontic alignment
5. autotransplantation

Question 12

when to suspect canine is ectopic

Answer 12

if not palpable in buccal sulcus by age of 10-11yrs
if palpation indicates asymmetrical eruption pattern
if position of adjacent permanent teeth implies malposition of canine
abnormal mobility of adjacent permanent teeth should also be regarded as suspicious

Question 13

options for parallax to localise unerupted canine

Answer 13

1. HORIZONTAL
   - upper standard occlusal & PA
   - 2 PAs
2. VERTICAL
   - upper standard occlusal & panoramic
   - PA & panoramic
   horizontal more reliable than vertical in localising unerupted canines