At the time of tooth eruption, the root
development is only 60-80% complete. If the pulp undergoes necrosis due to trauma or carious exposure, dentin formation ceases and root growth is arrested.
The resultant immature root will have an apical opening that is very large.
This is called an open apex, also referred to previously as a blunderbuss
canal.
The walls of the canal with an
immature root are thinner and more fragile (because of less mineralization)
compared to a mature root. These walls may diverge, be parallel or converge
slightly depending on the stage of root development. Open apex may also occur
in mature teeth due to external resorption resulting from orthodontic treatment
or periapical inflammation.
Problems
with an open apex:
1. larger apical diameter vs. smaller coronal canal diameter
makes debridement difficult.
2.
lack
of an apical stop makes obturation difficult.
3. thin root canal walls are prone to fracture. Indeed, the most common cause
of treatment failure is cervical fracture.
Solution?
For many years, open apices have
treated by periapical surgery with a retrograde fill. But surgery has its
drawbacks:
1.
Relative
to the already shortened root, further root reduction (apicoectomy) could
result in an inadequate crown:root ratio.
2.
Surgery
could be both physically and psychologically traumatic to the patient.
3.
Young
patients, in whom open apices are commonly seen, are not very cooperative.
4.
The
apical walls are thin and could shatter when touched by a rotating bur.
5.
The
thin walls would make condensation of a retrograde filling difficult.
6.
The
periapical tissue may not adapt to the wide and irregular surface of amalgam.
7.
Surgery
would remove the root sheath and prevent any possibility of further root
development. (Morse et al)
8.
Concerns
that such treatment would generate a negative image of dentistry.
Hence, it is best to treat immature
teeth with a non-surgical approach.
Treatment is based on the vitality of
the pulp. If the immature tooth has vital pulp, exhibiting reversible pulpitis,
then physiological root end development or apexogenesis
is attempted. On the other hand, if irreversible pulpitis is present or pulp is
necrotic, then root-end closure or apexification
is induced.
Case:
A 24-year-old patient reported to the OPD with a history of trauma 10years ago, which lead to tooth fracture and the tooth was left untreated. The radiograph revealed maxillary lateral with Ellis class III fracture with open apex and apical radiolucency and apexification procedure was planned.
preoperative radiograph
Unlike a regular tooth RCT open apex poses a special challenge while determining the working length. the accuracy of apex locator is less in such cases and a 2D radiograph is not very reliable. A K-file is bent at the tip and manually the apical stop is located and confirmed with a radiograph. This is called Elayouti's technique which improves the accuracy.
Tactile sensation
Shaping and cleaning was done followed by calcium hydroxide dressing for 2 weeks. Later Biodentine was packed in the apical third of the root canal with pluggers and after 12 minutes the Biodentine hardens.
Biodentine placed
later obturation was completed in the rest of the root canal with Guttapercha.
Post operative radiograph
Apexification allows us to improve the longevity of the tooth with a minimally invasive predictable manner.
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