IMPLANT THERAPY DECISION-MAKING FOR ENDODONTICALLY INVOLVED DENTITION
24, 25) have demonstrated that as long as all the
above factors are carefully addressed, endodontic
treated teeth will display high survival rates. On the
contrary, if these factors are not respected such as
crowns placed on compromised teeth, the survival
rate will be negatively impacted (26).
From a restorative perspective, the decisionmaking process to restore or to extract a tooth is
straightforward; if the tooth can be successfully
restored then the endodontic treatment is
recommended. If the tooth cannot be successfully
restored then the extraction with implant placement
is suggested. However, numerous factors must be
evaluated to determine the restorability of the
tooth. Within them, the residual tooth structure
is of paramount importance in determining the
treatment approach (27). Zitzmann considered
a tooth with a predictable prosthetic prognosis
when it has 4mm of remnant height with an
appropriate occlusal convergence angle (15-20°)
and a circumferential ferrule of at least 1.5mm
(28). On the other hand, a residual wall height
of less than 3mm with or without a convergence
angle of 25° represents a tooth with questionable
prognosis. Furthermore, a hopeless prosthetic
prognosis is characterized by an insufficient tooth
structure for a circular ferrule (<1.5mm) without the
possibility of a crown lengthening or orthodontic
extrusion (28). In addition, the morphology of
the root canal has also to be considered when a
post is required for the retention of a crown. If the
post cannot be placed then the extraction is often
recommended. On the other side, cracked tooth
refers to an incomplete fracture line extending
from the occlusal surface apically without the
separation into two segments (29, 30). Hence, the
prognosis of such tooth depends on the severity
and extension of the fracture line. While visible
fracture involves only the enamel, fractured cusp
is often associated with large restorations and is
limited to the crown but it can involve both dentin
and enamel. A split tooth and a vertical root
fracture are the two forms of real separate tooth
segments, the first extending in a mesio-distal
orientation while the latest has an apico-coronal
orientation. The extension and location of the
fractures could aid in selecting the most proper
treatment modality. Generally, asymptomatic
cracked tooth does not need any treatment except
occlusion assessment and adjustment if needed.
When fracture is limited to the crown of the tooth
with no periodontal involvement; restorations
combined with root canal therapy are oftentimes
preferred. On the other hand, vertical tooth
fractures are recommended for extraction due to
a poorer prognosis.
- Previous endodontic treatment
As aforementioned, restorability of a non-vital tooth
must be established prior to the start of treatment.
STOMA.EDUJ (2015) 2 (1)
If the tooth is non-restorable, it should be extracted
and replaced with a dental implant. Endodontic retreatment of previously treated teeth has a poorer
prognosis compared to non-vital teeth with no
history of endodontic treatment (31), especially
if a periapical lesion is present (32). However,
in contemporary Endodontics, same survival
rates might be obtained (33-35). Orthograde
endodontic re-treatment is recommended for a
restorable previously treated tooth with active signs
and symptoms. However, considerations must be
given prior to commencement of the endodontic
re-treatment. Oftentimes, these teeth would
have been restored with a post core restoration.
Removal of the post is technically challenging and
when done improperly could lead to root fracture
and the eventual loss of the tooth. Therefore, in
cases with large post, misaligned post, excessive
cleaning and shaping resulting in thin dentinal
walls, iatrogenic complications e.g. presence of
broken endodontic files within the root canal
system, orthograde endodontic retreatment may
not be the best option. Retrograde endodontic
treatment is preferred in attempt to minimize the
risk of root fracture, (33-35). Based upon Ng et
al. (2008) findings, we propose that if the apical
radiolucency is present and is < 5 mm then the
endodontic treatment might be preferred (36). If,
on the contrary, the lesion size extends ≥ 5 mm,
location should be considered before making the
decision. For instance, if the surgical site is close
to vital structures such as the inferior alveolar
nerve, mental nerve, maxillary sinus, retrograde
endodontic treatment may not be possible.
Therefor