Impacted Canines

Question 1

What are the 2 main theories for impacted canines?

Answer 1

1. Guidance theory

2. Genetic theory

Question 2

What are the clinical signs of impacted canines?

Answer 2

• unable to palate the canine in the buccal sulcus by age 10
• retained deciduous canine with no mobility
• absence of buccal bulge or presence of palatal bulge
• severe crowding - not enough space for canine to erupt
• mobility or loss of vitality of centrals and/or lateral incisors
• distal tipping or migration of lateral incisors
• missing or small lateral
• contralateral canine erupted for more than 6 months

Question 3

What are the risks of impacted canines?

Answer 3

• root resorption of adjacent teeth
• transposition of teeth
• ankylosis
• cyst formation

Question 4

What are the causes of impacted canines?

Answer 4

• displacement of crypt
• long path of eruption - ‘eye teeth’
• short rooted or absent lateral incisors
• crowing
• retained deciduous teeth
• genetics

Question 5

What is the difference between open and closed exposures?

Answer 5

Open exposure - tooth exposed, overlying vine and tissue removed and packing placed on the area. Patient has to go to practice for attachment to be placed ASAP

Closed exposure - tooth exposed and bracket/chain is attached to teeth, the gingival flap is placed back

Question 6

How do you investigate a potentially impacted canine?

Answer 6

1. Observe - check for bulge, inclination of laterals, colour of adjacent teeth
2. Palpate - canine crown, mobility of teeth
3. X-rays to establish - presence, position, pathology

Question 7

What is the incidence on impacted maxillary canines?

Answer 7

2-3 %

Question 8

What percentage of ectopic canines are palatally placed?

Answer 8

85%

Question 9

What percentage of ectopic canines are bucally placed?

Answer 9

15%

Question 10

What is transposition?

Answer 10

When two adjacent teeth switch position

Question 11

What is complete transposition?

Answer 11

When both the crown and root are transposed

Question 12

What is pseudo transposition?

Answer 12

Also known as incomplete transposition. When the crowns of adjacent teeth have changed position but the roots remain in normal order

Question 13

What interceptive treatment can be carried out for an ectopic canine?

Answer 13

Extraction of the deciduous canine - age 10-13 years

Question 14

What does the success of an expose and bond depend on?

Answer 14

1. Height of canine
2. Angulation of canine
3. Proximity to midline

Question 15

What is the Guidance theory in relation to ectopic canines?

Answer 15

Canine pathway of eruption is guided by the distal aspect of the lateral incisor. If the incisor is absent or diminutive, the canine has a higher chance of being ectopic

Question 16

What treatment options are there with ectopic canines?

Answer 16

• leave in place and monitor
• expose and bond
• surgical extraction
• fixed appliance to create space
• extraction of C’s

Question 17

What age are upper canines palpable?

Answer 17

10 years

Question 18

What age to upper canines erupt?

Answer 18

11-12

Question 19

In what time frame should a contra lateral canine erupt?

Answer 19

Within 6 months

Question 20

What 3D form of imaging is now more widely use in the localisation of canines that are closely positioned to incisors?

Answer 20

CBCT cone beam CT

Question 21

What is the definition of impacted canine?

Answer 21

A canine that is prevented from erupting due to an obstruction which could be bone, tooth or fibrous tissue

Question 22

What is the definition of ectopic?

Answer 22

Abnormal tooth eruption

Question 23

Radiographs show what percentage of upper lateral show root resorption due to impacted canines?

Answer 23

12%

Question 24

CT studies show that what percentage of upper laterals have root resorption due to impacted canines?

Answer 24

48%

Question 25

What are commonly transposed teeth?

Answer 25

U3s and 4s

L2s and 3s