Pathway 3
Sublingual space infection
This pathway will occur if the tooth apex is close to the lingual bone cortex (i.e. the posterior aspect of the teeth).
It is called lingual spread through the cortex above the mylohyoid muscle to the sublingual space, elevating the tongue.
Therefore, the swelling will be visible on the lingual aspect.
General Notes of the Infection
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Once the bacteria enters, it spreads down to the apex of the tooth and eventually erodes its way through the mandibular bone cortex.
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When the apex of the tooth is closer to the lingual bone cortex, the infection will exit lingually.
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If the roots of the tooth are short and lie above the origin of the mylohyoid muscle, the exit point is usually superior to the origin of the mylohyoid muscle
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This results in a sublingual space infection.
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Sublingual Space
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Borders:
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Superior = mucosa of the floor of the mouth/oral cavity
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Inferior = mylohyoid muscle
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Lateral = body of the mandible
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Medial = base of the tongue/muscles of the base of the tongue
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Anterior = lingual aspect of mandible
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Posterior = body of the hyoid bone
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The sublingual space is a V-shaped space lying lateral to the muscles of the tongue in the lingual aspect of the body of the mandible
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Anteriorly, it communicates with the submental space and posteriorly, it communicated with the submandibular space at the edge of the mylohyoid muscle
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Contents of the sublingual space = lingual neve and hypoglossal nerve. Also contains deep part of submandibular gland and duct
Sublingual Space - Clinical Considerations
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Elevation and protrusion of the tongue due to oedema
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Breathless may occur if there is laryngeal oedema
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Speech may be affected
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Enlarged and tender submandibular nodes
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Pain and discomfort during deglutition (i.e. swallowing)
Signs and Symptoms of Lingual Infection Spread
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Floor of the mouth and tongue elevation
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Dyspahgia (difficulty in swallowing)
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Sialorrhea (also known as hypersalvation/excessive drooling)​
Stages of Infection
In a healthy tooth crown is made up of the dense mineralised outside layer of enamel, supported by the sensate less well mineralised layer that is dentine which contains dental tubules which connect to the pulp chamber in the middle of the tooth. The vital part of the tooth which is not mineralised is call the pulp chamber contains the blood vessels and nerves which supply the tooth and this vital material extends into the roots of the tooth as the root canal. The nerves and vessel exit the tooth via the apex of the tooth and join the structures within the periodontal ligament that surrounds the tooth and anchors it to the alveolar bone of the socket.
During the initial stages of the tooth infection, the healthy tooth gets invaded by bacteria contained in plaque, which thrive off the carbohydrates in the mouth and produce acid, which slowly destroys the enamel layer.
When the bacteria gain access to the dentine, they invade the dentinal tubules and in this way gain access to the pulp chamber in the middle of the tooth. Within the pulp chamber, the bacteria incite an acute inflammatory reaction which causes an increase in the hydrostatic pressure within the tooth and leads to hypoxia and this leads to destruction of the contents of the pulp and roots canal system, effectively killing the tooth.
It is here, within the pulp chamber, that most of the bacteria will reside, and having destroyed any access for white blood cells normally carried in the blood vessels, makes eradicating the bacteria difficult without either extracting the tooth itself or at least removing the dead contents of the pulp and root canal system and sterilising this area to kill the bacteria. The presence of bacteria means that their by-products/ toxins can leak out of the apex of the tooth, where the nerve would normally exit, and these insight an inflammatory response in the body that causes vasodiltation that in turn causes an increase in hydrostatic pressure within the apical tissues of the periodontal ligament, instigating bone resorption and so a widening the periodontal ligament. This causes the formation of pus (consisting of dead and dying white blood cell and bacteria) which is an abscess.
Because the apex of the tooth is positioned towards lingual aspect of the mandible, the bacterial infection insights an acute inflammatory reaction that causes vasodiltation which in turn causes an increase in hydrostatic pressure that leads to osteoclastic bone resorption, eroding through bone and invades the gums on the lingual side forming a sublingual abscess.
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If the roots of the tooth are short and lie above the origin of the mylohyoid muscle, then the exit point of the infection is usually above the origin of the mylohyoid muscle and results in sublingual space abscess. If the infection spreads to the sublingual space, the increased swelling of these areas leads to the tongue being elevated.