lit rev 04/22 Subject: Decoronation

Sigurdsson, Asgeir. Decoronation as an Approach to Treat Ankylosis in Growing Children. Pediatric Dentistry v 31/no 2 Mar/Apr 09.

The main problem with ankylosis is that the tooth will not erupt further nor will it allow the alveolar bone to grow and develop and follow the eruption of adjacent teeth. Extraction of an ankylosed tooth can cause osseous defects i.e. collapse of buccopalatal plate and lack of vertical bone height.

After a PDL injury, there are generally 4 possible SEQUELA of HEALING:

1) healing without any root resorption

2) surface root resorption

- histologically:

- mild transient changes to PDL

- some loss of dentin

- clinically:

- no relationship btwn root canal and formation of the resorption

- self-limiting – it will heal with cemental repair w/o any tx

- radiographically: difficult detecting resorption

3) inflammatory root resorption

- histo: resorption of cementum, dentin, and adjacent bone

- clinical:

- inflammatory tiss with continue to replace tooth substance until tx

- direct relationship between inflammatory root resorption and bacteria in the root canal system

4) replacement root resorption aka ankylosis

- histo:

- bone and dentin are as if there were fused together

- PDL and cementum are completely lost

- clinic:

- no way to arrest, it is continuous and progressive but slows when fully grown

- no cemental repair

- no correlation btwn this type of root resorption and the contents of the canal

- no endo will arrest replacement resorption

TREATMENT OPTIONS:

1) Early extraction, esthetic replacement

- difficult to deal with osseous defect from ext

2) Ext followed by ortho space closure

- only if they have crowding

- must be of a certain age because the ortho must be done immediately after ext

3) surgical ext and reimplantation

- only if ankylosis is minimal, detected early, and the patient is near the end of growth

- Emdogain only delays onset of root resorption not prevent it

- risk of fracture of tooth or bone when ext

- if apex if closed or if there is necrotic pulp with open apex, RCT must be done

- affordable and at least buys time until patient able to get an implant

4) surgical block movement (cortical plate, tooth, bone repositioned into more esthetic position)

- patient is fully grown and have minor infra-position of the tooth

- expensive, technique sensitive

5) ext followed by autotransplantation of another tooth

- optimal if : patient has crowding, possible donor tooth – ¾ root growth and prior to apical closure for revascularization of transplanted tooth

- must have good alveolar bone for the transplant therefore decision must be made early prior to severe infra-occlusion due to probability of osseous defect following ankylosed tooth ext

6) decoronation - root submersion and transplant or osseous implant at later time

- few inflammatory changes around the submerged roots whether the pulp vital or endo tx’d

- advantages:

- preserves alveolar process width and height likely negating need expensive alveolar ridge augmentation

- vertical bone apposition is possible after

CASE STUDY

- 10 yr 8 mos male suffered CNS injury and avulsed #9 in an accident

- due to more emergency needs, reimplantation delayed for 12 hours stored in milk

- calcium hydroxide therapy was completed 10 days after

- recalls every 3 mos

- after 1 yr showed replacement resorption, infra-occlusion

- patient beginning growth spurt and recommended decoronation

- mucoperiosteal flap reflected à crown cut off and root reduced below marginal bone à flap closed à crown used as temporary by attaching to #8 for esthetics à 6 mos recalls

- radiographs showed alveolar bone maintained with no significant collapse of faciopalatal width

- ready for implant in 2-3 yrs