Root fractures pass across the root and involve the
cementum, dentine and the pulp. They can present with
or without clinical signs of luxation of the coronal
fragment, and they are an indication for routine
radiographic examination of all traumatized teeth. The
clinical sign is commonly an extruded and lingually
displaced crown. The fracture can appear radio-graphically
as a single line or multiple lines across the
root.
The image of the fracture is dependent on the
angle of the fracture and the angle at which the film is
taken. It is usually clearly evident on radiographic
examination, although multiple radiographic views at
different vertical angles may be necessary to obtain a
clear image. Flores et al .
suggest occlusal and tube-shift radiographs,
in addition to a parallel periapical
radiograph, are useful to identify and investigate root-fractured teeth.
Radiographs taken immediately
following trauma may not show the fracture line clearly.
Many root fractures heal without intervention in one
of three modalities: hard tissue interposition, inter-position
of bone and periodontal ligament or
interposition of periodontal ligament alone.
A non-healing inflammatory process associated with pulp
necrosis and infection of the coronal fragment can also
occur. Factors that have an effect on healing include
age, stage of root development, mobility, fragment
dislocation and the separation between the fragments.
Pulp tissues are not essential to the healing of a root
fracture.
Healing is more favourable in incompletely-formed teeth and
where displacement of the coronal
fragment is minimal.
Pulp canal calcification is a
common feature that may develop in root-fractured
teeth, but this rarely poses a problem in the long term.
Canal calcification can only occur if the pulp tissues
remain vital.
Pulp survival rates are higher in root-fractured teeth
than in traumatized teeth without fracture. Pulp necrosis
has been reported to range from 20 per cent to 44 per
cent.
In most instances, if pulp necrosis develops, it
will do so within two to five months after the trauma.
Maintenance of pulp vitality is affected by the extent of
apical maturation, the location of the fracture site, the
extent of dislocation and the separation between the
fragments. If separation is greater than 1mm the
incidence of pulpal necrosis in the coronal fragment
increases substantially, suggesting that this is the limit
to which the pulp tissue can be stretched before first the
neural and then the vascular components are
compromised.
Should the fracture communicate with
the gingival tissues, pulp necrosis inevitably occurs and
the prognosis for the coronal fragment is extremely
poor.
Pulp sensibility testing immediately after trauma is
an unreliable means of predicting the final status of the
pulp.
Sensibility testing involving thermal and electrical
stimuli is nevertheless an important feature of the initial
examination of a root-fractured tooth.
A negative response is a common finding immediately and for
some time after the root is fractured and is an
indication that the pulp has suffered some trauma.
Teeth that initially give a negative response can respond
after periods ranging from one month to one year.
Responses to sensibility testing need to be followed up
over time before a diagnosis is made of pulp necrosis.
Endodontic treatment is only indicated for those teeth
in which pulp necrosis has occurred.
In a root-fractured tooth, this diagnosis is usually based on the
development of radiographic changes, often a widening
of the space between the two segments and of the
periodontal ligament space adjacent to the fracture site,
and the development of tooth discolouration or a sinus
tract. Localized root resorption may at times occur in
the area of the fracture. This should not be taken as a
sign of pulp necrosis without other corroborating
evidence.
As the blood supply to the apical fragment is usually
not disturbed, if pulp necrosis occurs, it is invariably
restricted to the coronal fragment only.
Thus, the endodontic management of root-fractured teeth can be
restricted to the coronal fragment. It has been clearly
established that the insertion of calcium hydroxide in
the root canal to the level of the coronal fracture leads
to the production of a barrier at the level of the fracture
site, permitting root filling to this level without over
extension.
More recently, the use of MTA has been
recommended in some cases.
Early and accurate repositioning of the coronal fragment has been shown
to reduce the likelihood of pulp necrosis.
Optimum repositioning should be verified radiographically.
Traditionally, long-term rigid splints have been used
in an attempt to promote hard tissue healing of root-fractured teeth.
A recent review,
however, found no real difference between teeth that were splinted in this
manner when compared to non-splinted teeth. Where
excessive mobility dictates the need for a splint, it
should be non-rigid, atraumatically placed and
removed after a maximum of four weeks, except in
teeth where the fracture occurs in the coronal third
where the tooth may need splinting for up to four
months.
As a general rule, the location of the
fracture has not been shown to influence the survival of
the pulp; except that in permanent teeth, pulp necrosis
is less likely in teeth fractured in the coronal one-third
of the root.
The long-term prognosis of these teeth is
poorer, however, principally due to an increased
susceptibility to new luxation injury or increased
mobility of the coronal fragment.
Root fractures are rare in immature teeth as these
teeth are more likely to be avulsed or luxated than to be
fractured. However, where root fractures occur, the
possibility of calcific repair is quite high.
Endodontic treatment is generally unnecessary in root-fractured
immature teeth.