Decoronation as an Approach to Treat Ankylosis in Growing Children

Resident: Cho
Author(s): Sigurdson, A.
Journal: Pediatric Dentistry
Year. Volume (number). Page #’s: 2009. 31. 123-128.
Major topic: Ankylosis, Decoronation
Type of Article: Conference Paper

Main Purpose: To present the most commonly recommended treatment options for ankylosed immature permanent anterior tooth.

Key points/Summary:
After PDL injury due to trauma, there are four possible sequelae:
1. Complete healing
2. Surface root resorption
3. Inflammatory root resorption
4. Replacement root resorption (ankylosis or ossesous replacement resorption) – surrounding bone and dentin are fused together, progressive and continuous, recommend removal of tooth within 2-3 years of diagnosis in children who are 10 years old or younger or before children experience a growth spurt. If the tooth is allowed to remain, there is a very high risk of severe infra-position.

Two main difficulties in restoring a defect caused by an ankylosed anterior tooth in the fully grown patient:
1. There is significantly less vertical bone height in the area of the tooth.
2. The difficulty of removing the existing root structure is very damaging to the remaining bone.

The following treatment options for ankylosed teeth:
1. Early extraction and esthetic replacement of the missing tooth by loose appliance or attachment to adjacent teeth.
2. Extraction followed by orthodontic space closure.
3. Surgical extraction and reimplantation – risk of re-ankylosis and root resorption
4. Surgical block movement – cortical plate, tooth, and surrounding bone are moved as a block and surgically repositioned.
5. Extraction followed by autotransplantation of a tooth.
6. Root submersion and transplant or osseous implant at later time (decoronation) – the crown is removed and the root is submerged to preserve the alveolus until it has reached full growth. It preserves the alveolar process’ width and height, less likely need for surgical alveolar ridge augmentation, vertical bone apposition is possible after the crown is removed. Placement of implants in the alveolus once the individual is fully grown have been reported to be relatively easy – there seems to be no need to remove root remnant prior to placement of the implant.

Steps of decoronation:
1. Full thickness mucoperiosteal flap
2. Crown removed at the level of the crestal border. The root surface’s coronal part is further reduced to 2mm below the marginal bone.
3. Any root filling material is removed. The canal lumen is left to fill with blood.
4. Primary soft tissue closure over the retained root is attempted.
5. The tooth’s crown can be used as a termporary replacement tooth by attaching it to adjacent tooth.

Case Study
10 year old patient had dental trauma to #9 - #9 avulsed and reimplanted 12 hours later, CaOH therapy was initiated 10 days after the injury, one year later, #9 was ankylosed and infra-positioned. It was determined patient was just beginning growth spurt, therefore, decoronation procedure recommended and carried out. Radiographic observation showed continued root resorption, alveolar bone maintained, no significant collapse of faciopalatal width. The patient and the family moved to a different state therefore could not be followed for the planned 30 months post-treatment.

Assessment of Article:
Very interesting article! Provides a new approach for treating ankylosed teeth that I had not heard of.