Abstract : A retrospective study of
96 cases of temporomandibular joint dislocation
was undertaken. Patients' ages ranged from 9 to
85 years (mean+/-SD, 35.3+/-17.4 years) and peak
incidence was at 20-29 years. Mean duration was
7.9 weeks (range, 1h to 3 years). Acute, chronic
and recurrent dislocations were seen in 46
(47.9%), 29 (30.2%) and 21 (21.9%) patients,
respectively. Males dominated in all three
categories but this was not statistically
significant (P = 0.8). Excessive mouth opening
while yawning (44 cases) was the
commonest cause of dislocation, followed by road
traffic accidents (13 cases). Ten patients
(10.4%) had an underlying systemic disease, the
commonest being epilepsy (four cases); those
with acute dislocation recorded the highest
incidence of underlying illness. Bilateral
anterior (86 cases) dislocations were the most
frequent. Of the 96 patients, 89 (92.7%) were
available for treatment. Manual reduction with
or without anaesthesia proved effective for
38/45 acute, 5/24 chronic and 14/20 recurrent
cases. Chronic dislocations were treated mainly
by surgical osteotomy (13/24). Vertical
subsigmoid and oblique ramus osteotomies were
the commonest surgical techniques recorded.
Treatment was satisfactory for all patients
surgically handled except for one case of
anterior open bite postoperatively. This study
has shown that excessive mouth opening while
yawning is the commonest cause of
temporomandibular joint dislocation in
Nigerians, and conservative approaches to
management remain quite effective irrespective
of the duration and clinical subtype. The best
choice of surgical technique should be
determined by proper clinical evaluation and the
need to avoid or minimize postoperative
morbidity
Dislocation of the temporomandibular joint
(TMJ) is not an uncommon condition that occurs
when there is a complete separation of the joint
with fixation of the condyle in an abnormal
position. Subsequently, the facial profile
changes while the ligaments around the joint
often stretch with intra-articular effusion,
causing severe discomfort and difficulty with
speech and mastication from muscle spasms and
joint pain. While subluxation or habitual
luxation refers to excessive abnormal excursion
of the condyle secondary to flaccidity and
laxity of the joint capsule, recurrent
dislocation is characterized by a condyle that
slides over the articular eminence, catches
briefly beyond the eminence and then returns to
the fossa. The latter type occurs repeatedly and
is often associated with neurogenic dislocation
where there is increased i tone of the
masticatory muscles.
One or both mandibular condyles may be
affected, and various classifications of TMJ
dislocation have been reported based on the
direction of displacement and location of the
condylar head; most cases of TMJ dislocation are
anterior. However, the most popular
classification appears to be acute, chronic
(prolonged) and recurrent as described by
Adekeye et al. and Rowe & Killey.
Although there is no known overall i gender
predilection, there are conflicting reports
about the pattern of chronic recur- I rent
dislocation. While a higher prevalence in males
has been observed"5.'0, the reverse is the case
in other studies .
Previous reports have highlighted the
predisposing and etiological factors for
condylar dislocation. These include congenital
joint weakness; extreme mouth opening during
yawning; dental and
otorhinolaryngological (ORL) treatment; trauma;
drugs, especially the anti-emetics
(metoclopramide) and phenothiazines (compazine),
which produce extra pyramidal effects;
hypermobility, associated with systemic
diseases; and schogenic and neurological
disorders.
There is no standard evaluation and
treatment method for acute TMJ dislocation, but
the most effective course is immediate
reduction. In chronic and recurrent
dislocations, non-surgical and surgical
treatment modalities have been developed.
The present study evaluated all cases of TMJ
dislocation seen in three Nigerian Tertiary
Referral Centers, and documents the aetiology,
demographics, risk factors, treatment
approaches, and difficulties encountered in the
course of management. The findings of this study
will serve as baseline data on TMJ dislocation
in Nigerians.
Discussion
In contrast with other reports where
excessive mouth opening during dental or ORL
treatment was observed as the commonest cause of
TMJ dislocation, our results show that the
majority of cases irrespective of the clinical
subtype were due to yawning. Asymptomatic
TMJ disorders in apparently young healthy
Nigerians have previously been well documented.
These may act as a predisposing factor and
partly explain how yawning could trigger
off joint dislocation. Furthermore, it is not
unlikely that dislocations which occurred during
ORL or dental treatment go unrecorded because
the attending clinician subsequently reduced
such cases.
Research has shown that the presence of
underlying illness, such as connective tissue
disorders, Ehlers-Danlors syndrome, psychogenic
and neurological disorders, and use of drugs
containing amphetamine-like substances,
contributes substantially to the
aetiopathogenesis of condylar dislocation.
Although few cases of such predisposing
conditions were recorded in our study, they were
seen mostly in acute cases, unlike in previous
reports where they are often associated with
recurrent dislocations.
Similar to previous findings , most of the
TMJ dislocations observed are anterior, but this
is partly cause-related since the majority were
due to yawning.
This study has shown that excessive mouth
opening while yawning is the commonest
cause of TMJ dislocation in Nigerians and
conservative approaches to management remain
quite effective irrespective of the duration and
clinical subtype. The best choice of surgical
technique should be determined by proper
clinical evaluation and the need to avoid or
minimize postoperative morbidity.
