Unerupted Ectopic Canines/Incisors Flashcards
How can adult teeth be distinguished from deciduous?
Darker colour
Less wear
Mamellons
Longer length of root compared to deciduous on OPT (look in relation to other teeth)
When do upper canines tend to erupt?
Girls- 11-12
Boys- 12-13
Palpate and check for canines from age 9
What are the signs of abnormal dental development?
Lack of symmetry- contra-lateral does not erupt within 6 months
Sequence- are they coming through in correct order (4->5->3- usually, if crowded sometimes 5 comes in last)
What are the steps in the development path of Upper 3?
Starts up high in alveolus above root of lateral incisors
Moves slightly buccal and passes down lateral side of 2
Sometimes canine can erupt in path in line with arch right on top of deciduous tooth
-> Assess mobility of deciduous canines and palpate for canines in buccal sulcus
What are the signs of ectopic canines seen in lateral incisor?
Mobile lateral- due to root resorption
DP tipping
What is a peg lateral?
Lateral incisor that is narrower at incisal edge than at gingival margin
What is the incidence of ectopic canines?
1-2%
What type of imaging may be helpful for ectopic canines after taking plain radiographs?
CBCT
Root resorption cases- extra detail
Unsure about exact position in relation to other teeth
-> Consider if there a path of traction/scope to surgically remove
What are the causes of impacted canines?
Crowding (buccal impaction is commonly due to crowding- as canine is last tooth in 345 sequence- pushed out of line if short of space, not all though)
Genetics- familial but not direct, females
Associated with other dental anomalies- class II div II, hypodontia, missing laterals (lack of guidance)
Long path of eruption
-> palatal canines tend to get stuck
Ectopic position of tooth germ
What is the IOTN score for missing unerupted tooth?
5i
When may you have to accept the position of unerupted ectopic canine?
XLA Uc unlikely to make much difference U3
Positioned mesial to the midline of U2
Patient above age where interceptive treatment for ectopic canine is likely to work (window of opportunity 10-13)
Insufficient space for U3
What are the risks of doing nothing with ectopic canines?
Resorption of the roots of adjacent teeth (40% risk of lateral incisor root resorption)
Resorption of the canine crown (14%)
Ankylosis of the unerupted canine
Eventual loss of primary canine and complex restorative solutions being required in the future
Cystic change of canine (rare)
When may an ectopic canine be surgically removed?
If case deemed to be not alignable:
-> Too high above apical third of incisor roots
-> Too close to dental midline
-> Angle greater than 55 degrees to midsagittal plan
If there is no significant risk of damaging the adjacent teeth during a surgical procedure
Patient is happy with the dental appearance and the retained primary canine has a good long term prognosis
Radiographic evidence of early root resorption of the adjacent teeth
Patient does not want to wear orthodontic appliances
What are the steps in surgical exposure and fixed appliance treatment for ectopic canines?
Make sufficient space for the tooth
-> retained deciduous canine may require removal.
Surgically expose the canine
-> Open or closed exposure depending on site of canine
Orthodontic traction
-> gold chain (closed exposure)
-> Traction hook for an open exposure
Upper and Lower fixed appliances
-> may need palatal arch due to high anchorage demand
Fixed and removable retainers
When may autotransplantation be indicated for ectopic canines?
Malposition of the tooth is too great for orthodontic alignment to be possible
No evidence of ankylosis
Canine root development is ideally 2/3 to 3/4 length
Patient is looking for a quicker treatment option
What are the risks of autotransplantation in ectopic canines?
Difficult to remove atraumatically
Requires RCT
High risk of root resorption and ankylosis
Why should you refer patient with ectopic canines to see orthodontic specialist?
Patient has high treatment need- 5i
Significant risks to dental health if you do nothing
Fixed appliance treatment is likely to be required
What special investigations can be useful for patient with unerupted central incisors?
Anterior occlusal maxilla or periapicals
+/- Orthopantomogram *
Bitewings to assess for caries
-> CBCT subject to the findings on the plain films
What position are ectopic 1s usually in?
Buccal
What are the local causes of unerupted centrals?
Unerupted supernumerary – most common reason for a delayed upper central incisor
Retained primary tooth
Early loss of primary tooth
Trauma to the deciduous tooth leading to dilaceration of the unerupted tooth
Crowding
Ectopic position of the tooth germ
How does dilaceration of permenant successor occur?
Damage to deciduous tooth causing it to impinge on permanent tooth germ making root go different direction
Can also occur due to supernumeraries
What syndromes are associated of unerupted or delayed eruption in 1s?
Down Syndrome
Cleidocranial dysostosis
Cleft lip and palate
Hereditary gingival fibromatosis
Turner syndrome
Rickets
What are the treatment options for unerupted centrals?
Accept
Bring central into line of arch
Remove unerupted central
Why is accepting position of unerupted central not advisable?
Effect of a large anterior space on facial and dental aesthetics may harm the patient’s self-esteem and social interaction
Drift of adjacent teeth can make future orthodontic and restorative treatment more complicated
If an unerupted tooth is left in situ there is a risk of movement of the tooth towards adjacent tooth roots and subsequent root resorption of adjacent teeth
Risk of cyst formation (rare)
How is the unerupted central brought into the line of the arch?
Make sufficient space for the tooth (may require fixed appliance or URA)
-> if position of unerupted tooth is favourable and the patient is aged 9, wait a year to see if tooth erupts spontaneously
Surgically expose tooth- usually closed exposure (buccally) with gold chain attached to palatal surface of the tooth at time of surgery
Apply traction by adding gold chain to fixed appliance
-> traction can begin after two weeks
What are the risks of bringing an unerupted central into the line of the arch?
Tooth fails to erupt/move
Ankylosis of central incisor
External root resorption
Poor result in gingival aesthetics
What are the indications for removing an unerupted central incisor?
Patient not keen on complicated and prolonged orthodontic/minor oral surgery tx
If the unerupted tooth fails to respond to the orthodontic traction (i.e. ankylosed)
Severe dilaceration so not possible to align tooth within the bone
What are the risks of removing unerupted central incisor?
Damage to adjacent tooth roots
Loss of space in arch for prosthodontics in future if it is not managed
Loss of alveolar bone- issues with bridges and implants in future
What can be used to replace unerupted central if it removed?
Move 2 into position of 1 and restore to appear like a 1
Ortho treatment to open space for RBB, implant, denture
Autotransplantation- if poor prognosis of central and premolars require extraction to address other aspects of malocclusion
Segmental osteotomy
Do nothing more and allow further mesial drift of UR2, UL1
-> If patient <9 years you may get quite a bit more space closure
-> Space could be reopened at a later date with Orthodontic appliance treatment
What is primary failure of eruption?
Failure of eruption with no identifiable local or systemic cause (can occur in partially erupted teeth)
-> Eruption process has been disturbed
What is the issue with orthodontic force in teeth with primary failure of eruption?
It may precipitate ankylosis of the tooth
What are the features of primary failure of eruption?
Unilateral or bilateral
Lateral open bites
Posterior teeth most frequently affected
What is the prevalence of primary failure of eruption?
0.06%
What gene mutation is associated with primary failure of eruption?
Parathyroid hormone 1 receptor (PTH1R) gene
