unerupted maxillary incisors

Question 1

summary of tx options (3)

Answer 1

1. accept malocclusion
2. bringing central incisor into line of the arch
3. remove unerupted central incisor

Question 2

option of accepting malocclusion

Answer 2

not advisable
1. large anterior space will have impact on self esteem & social interaction
2. if left untreated, drift of adjacent teeth can make future ortho / restorative tx more complicated
3. if left in situ risk of movement towards adjacent teeth and subsequent root resorption
4. risk of cyst formation (rare)

Question 3

option of bringing central incisor into line of arch

Answer 3

1. make sufficient space for tooth via URA / fixed appliances
2. in some cases at age of 9 if position of unerupted tooth is favourable you may decide to wait once space has been created to see if you get any spontaneous eruption
3. surgically expose tooth (most often closed exposure with gold chain attached to palatal surface of upper central incisor at time of surgery)
4. apply traction to tooth by attaching the gold chain to an orthodontic appliance; traction can begin 2 weeks after surgical exposure

Question 4

risks associated with bringing central incisor into line of arch (4)

Answer 4

1. tooth fails to erupt and / or move
2. ankylosis of central incisor
3. external root resorption of central incisor
4. poor resulting gingival aesthetics

Question 5

option of removing unerupted central incisor

Answer 5

1. pt not keen on complicated & prolonged ortho tx with minor OS
2. in u/e tooth fails to respond to ortho traction i.e. ankylosed
3. severe dilaceration so not possible to align tooth within bone

Question 6

risks associated with removing u/e central incisor (3)

Answer 6

1. damage to adjacent tooth roots
2. loss of space within arch for a future prosthetic tooth if not correctly managed
3. loss of alveolar bone in area may complicate future prosthesis especially with implants

Question 7

options to replace maxillary central incisor if surgically removed

Answer 7

1. ortho fixed appliance tx to move UR2 adjacent to UL1 & restore this tooth to look like central
2. ortho fixed appliance tx to open space for implant, fixed pros, RBB, removeable prosthesis
3. do nothing & allow further mesial drift of UR2 / UL1 if pt <9 yrs you may get quite a bit of space closure. space may be reopened at a later date with ortho appliance tx
4. autotransplantation if poor prognosis for upper central & premolars required to be xla to address other aspects of the malocclusion

Question 8

aetiology of u/e central incisor (6)

Answer 8

for maxillary incisors it is almost always a LOCAL cause if just the central incisor is affected
- unerupted supernumerary (MOST COMMON REASON for delayed upper central incisor)
- retained primary
- early loss of primary
- trauma to deciduous tooth leading to dilaceration of unerupted tooth
- crowding
- ectopic position of tooth germ
note - congenital absence is very rare

Question 9

generalised causes / syndromes associated with delayed eruption (6)

Answer 9

down syndrome
cleidocranial dysostosis
cleft lip & palate
hereditary gingival fibromatosis
turner syndrome
rickets

Question 10

primary failure of eruption

Answer 10

failure of eruption with no identifiable local or systemic cause
teeth can PE then stop
there is no ankylosis, it is the eruptive mechanism that is disturbed but application of a force to these teeth may precipitate ankylosis
true diagnosis may only be made retrospectively after attempts at ortho extrusion has failed
associated with mutation in parathyroid hormone 1 receptor (PTH1R)

Question 11

features of primary failure of eruption

Answer 11

uni / bilateral
lateral open bites
posterior teeth most frequently affected

Question 12

delayed eruption considered when (3)

Answer 12

1. eruption of permanent maxillary incisor occurred >6mths prior
2. maxillary incisors remain unerupted >1 yr after eruption of mandibular incisors
3. significant deviation from normal eruption sequence e.g. lateral incisors erupting prior to central incisor

Question 13

most common reason for delayed eruption of upper central incisor

Answer 13

supernumerary

Question 14

how position of impacted incisor affects tx

Answer 14

the higher the vertical position of an unerupted maxillary incisor the less likely it is to spontaneously erupt after obstructing supernumerary removed

Question 15

what is dilaceration

Answer 15

acute deviation of the long axis of the tooth located to the crown / root portion & originating from a traumatic non axial displacement of already formed hard tissue in relation to developing soft tissue

Question 16

tx options of ankylosed maxillary central (5)

Answer 16

1. periodical follow up with possible composite build up for minor infra occlusion
2. repositioning of ankylosed incisor inc surgical dislodgement & repositioning
3. xla followed by orthodontic space closure
4. decoronation of incisor if growth still active to preserve width & vertical height of alveolar bone
5. xla of ankylosed incisor followed by replacement with conventional / implant prosthesis if pt growth nearing completion

Question 17

when to consider spontaneous eruption / surgical exposure

Answer 17

if pt <9yrs with immature permanent maxillary incisor may be reasonable to allow up to 9-12mths for spontaneous eruption of incisor following removal of obstruction

if pt >9yrs with mature permanent maxillary incisor it is reasonable to consider open / closed surgical exposure