unerupted maxillary incisors

Question 1

tx options

Answer 1

accept
bring central into line of arch
remove unerupted incisor

Question 2

tx options - accept

Answer 2

poor aesthetics
drift can make future tx more complicated
risk of movement towards adjacent tooth roots - RR
risk of cyst formation (rare)

Question 3

tx options - bring central into line of arch

Answer 3

make space for tooth (URA/fixed app)
in some cases at age 9 if position of UE tooth is favourable you may decide to wait once space has been created to see if you get any spontaneous eruption
surgically expose tooth (most often closed exposure with gold chain attached to palatal surface at time of surgery)
apply traction to tooth by attaching gold chain to an ortho appliance (traction can begin 2 weeks after the surgical exposure)

Question 4

tx options - removing the unerupted incisor indications

Answer 4

pt not keen on complicated and prolonged ortho tx together with MOS
if UE tooth fails to respond to ortho traction i.e. ankylosed
severe dilaceration so not possible to align tooth within bone

Question 5

tx options - removing the unerupted incisor replacement options

Answer 5

fixed app tx to move 2 adjacent to 1 and restore it as a central
fixed app tx to open space - RBB, implant, fixed prosthesis, RPD
do nothing and allow further mesial drift. if pt <9yrs you may get quite a bit more space closure. space could be reopened at a later date with ortho
autotransplantation - if poor prognosis for U1 and premolars require ext to address other aspects of malocclusion
segmental osteotomy to reposition central

Question 6

aetiology of unerupted U1s

Answer 6

nearly always a local cause if just U1 affected:
- UE supernumerary (most common)
- retained primary tooth
- early loss of primary tooth
- trauma to primary tooth leading to dilaceration of UE tooth
- crowding
- ectopic position of tooth germ
or a generalised cause/syndrome associated with delayed eruption
congenital absence of U1 vvvv rare

Question 7

generalised causes/syndromes associated with delayed eruption

Answer 7

Down syndrome
cleidocranial dysostosis
CLP
hereditary gingival fibromatosis
Turner syndrome
rickets

Question 8

what is primary failure of eruption?

Answer 8

failure of eruption with no identifiable local or systemic cause
sometimes teeth can partially erupt and then stop erupting
no ankylosis. it is the eruptive mechanism which is disturbed. - but application of ortho force to these teeth may ppt ankylosis

Question 9

features of primary failure of eruption

Answer 9

unilateral or bilateral
lateral open bites
posterior teeth most freq affected

Question 10

how can a true definitive diagnosis of primary failure of eruption be made?

Answer 10

only retrospectively after attempts at ortho extrusion have failed

Question 11

prevalence of primary failure of eruption

Answer 11

rare 0.06%

Question 12

what gene is primary failure of eruption associated with a mutation of?

Answer 12

PTH1R gene

Question 13

assessment and diagnosis - history

Answer 13

any FH of missing teeth?
underlying medical syndromes/conditions?
prev trauma?

Question 14

assessment and diagnosis - recognising early

Answer 14

asymmetrical eruption pattern (>6m since contralateral tooth erupted)
disturbance of normal sequence of eruption

Question 15

management principles

Answer 15

diagnose reason for lack of eruption (likely need radiographs)
remove any physical obstruction
preserve space within the arch or make space for the tooth
consider stage of development of UE tooth - <9yrs pt likely to have open apex and still potential for spontaneous eruption (80% will erupt spontaneously) so may be appropriate to await eruption
if tooth fails to erupt or root formation complete plan for surgical exposure, attach gold chain and traction

Question 16

what to warn pt in addition to the routine ortho risks

Answer 16

commitment required - lack of space maintainer wear can have significant consequences in relation to tx length and complexity
lengthy overall tx time
sometimes 2nd surgical approach becomes necessary
2nd phase of appliances once U1 is initially aligned if there is an underlying malocclusion
possible failure to achieve tx objectives
- tooth won’t respond to ortho force
- insufficient bone depth to keep dilacerated tooth within alveolar bone (dilacerated tooth may require elective root filling and apicectomy)