Obstruction
and trauma (Table 42.4)
Papillary
obstruction
Occasionally a rough upper molar tooth or an overextended denture flange
will irritate the parotid papilla. If this is sufficient to cause ulceration
with consequent inflammation and oedema this may obstruct salivary flow,
particularly at meal times when the flow rate is increased. In this situation
the patient has classical rapid onset pain and swelling at meal times.
If
the trauma to the parotid papilla continues there will be progressive scarring
and fibrosis in the soft tissues and permanent stenosis of the papilla can
occur. A papillotomy
Stone
formation (sialolithiasis)
Eighty per cent of all salivary stones occur in the submandibular
gland, 10 per cent occur in the parotid, 7 per
The
classical presentation is of acute pain and swelling at meal times. Onset is
rapid — within a minute of starting the meal — and the swelling resolves
over a period of about 1 hour after the meal is completed.
However,
this classical picture only occurs when the stone causes almost complete
obstruction often when it is impacted at the opening of Wharton’s duct. More
often the stone causes only partial obstruction and is lying either within the
hilum of the gland or within the duct in the floor of the mouth. In this
situation the patient may complain of occasional swelling often with minimal
discomfort or of a chronically enlarged mass in the submandibular triangle with
episodes of dull aching pain. This results from chronic bacterial infection
If
the stone is lying in the submandibular duct in the floor of the mouth anterior
to the point at which the duct crosses the lingual nerve (second molar region)
the stone can be released by opening the duct longitudinally (Fig.
42.8). It is
important to pass a large suture around the duct proximal to the stone so that
during the operative procedure the stone cannot be displaced backwards in the
duct. Once the stone has been released the wall of the duct should be sutured to
the mucosa of the floor of the mouth to maintain an opening for the free
drainage of saliva. No attempt should be made to repair the duct wall as this
will lead to stricture formation. A parotid stone located at the confluence of
the collecting ducts can be released surgically by raising a preauricular flap,
exposing the parotid duct and again incising it longitudinally to release the
stone.
Obstruction
in and around the duct wall
Scarring and fibrosis in the duct wall stricture formation will also
result in obstruction to salivary flow. It often results as a complication of
long-standing sialolithiasis hut it may occur as a result of trauma particularly
to the floor of the mouth. Subsequent healing and scarring can result in a
stenosis of the duct. In patients with masseteric hypertrophy the parotid duct
may be stretched around the anterior border of the muscle and this may cause
obstruction of salivary flow at meal times.
Mucoceles
Mucus retention cysts and mucus extravasation cysts arise in the minor
salivary glands as a result of mechanical damage to the gland or its duct. The
common sites are on the mucosal aspect of the lower lip particularly in
patients with a deep overbite and in the buccal mucosa posteriorly where an
upper wisdom tooth is erupting buccally. Typically the patient presents with a
history of recurrent swellings that develop over days or weeks, rupture and then
recur after a few weeks. The cysts rarely exceed 1 cm in diameter and are tense
bluish sessile swellings. The treatment is not to the cyst itself but to the
underlying minor gland which should be excised under local anaesthesia.
A
ranula is no more than a large mucocele arising from the sublingual gland.
Classically the ranula presents as a large tense bluish swelling in the floor of
the mouth anteriorly often displacing the tongue (Fig.
42.9). However, the
ranula may push its way though the midline mylohyoid dehiscence in the floor of
the mouth and enter the submental space presenting as a midline swelling in the
upper neck. This is the ‘plunging ranula’. The treatment of a ranula is
excision of the sublingual gland.