advantageous in the internal resorption case where the antimicrobial and mild tissue
solvent actions of calcium hydroxide may be exploited further to clean the resorbed
area.
Obturation may then be undertaken with gutta percha and sealer, usually employing a
thermoplastic technique to allow satisfactory condensation and adaptation in the
resorbed area (758HFig. 12.46). Where internal reinforcement is indicated, dual curing
composite resin and fibre posts may offer some advantages over full canal filling with
gutta percha and sealer.
REPLACEMENT RESORPTION
Replacement resorption is a distinct form of root resorption which follows serious
luxation or avulsion injury that has caused damage to the investing periodontal
ligament. A classic scenario is the avulsed tooth, which has been stored dry, or p.l.
removed before replantation, with resultant death of periodontal fibroblasts on much
of the root surface. If more than 20% of the periodontal ligament is damaged or lost
and the tooth is subsequently reimplanted, bone cells are able to grow into contact
with the root surface more quickly than the remaining periodontal fibroblasts are able
to recolonize the root surface and intervene between tooth and bone. The consequence
is that the root now becomes involved in the normal remodelling process of the bone
in which it is implanted, and is gradually replaced by bone over the course of the
following years. In young children where the rate of bone remodelling is high, the
root may be entirely lost within 3-4 years. In adolescents, it may be 10 years or more
before the tooth is lost.
- Diagnosis. The absence of a ligamentous joint between the tooth and its supporting
bone (ankylosis) means that even when root resorption is advanced, the tooth will
appear rock solid. A bright, metallic tone will also be noted if the tooth is percussed.
Radiographically, the root will appear ragged in outline, with no obvious periodontal
ligament space separating it from the surrounding bone (759HFig. 12.47). - Treatment. There is no effective treatment for ankylosis but the rate of progression
is relatively slow and the tooth can be maintained for 10 years or more. However,
such teeth can be a problem in the growing child as they may cease to 'move' or 'grow'
with the rest of the jaws and cannot be moved orthodontically. There is no effective
treatment for established replacement resorption and parents and carers should be
advised of the inevitable course of events.
From an endodontic point of view, it is important to reiterate that if pulp extirpation is
undertaken within 2 weeks of reimplantation then the initial root canal dressing
should be an antibiotic/steroid (Ledermix, Lederle) preparation which should be
replaced subsequently with non-setting calcium hydroxide, no sooner than 2 weeks
after tooth reimplantation. The antibiotic/steroid paste may help to reduce subsequent
resorption.
If endodontic treatment was not undertaken soon after reimplantation and the tooth
subsequently loses vitality, conventional root canal therapy may be undertaken in
order to address any painful periapical pathosis and to avoid the additional insult of
inflammatory resorption which would lead to more rapid loss of root substance. A
resorbable root filling material such as root canal sealer alone or reinforced zinc oxide