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Pathway 1

Buccal (labial) spread intra-orally

This pathway will occur if the tooth apex is closer to the buccal bone cortex (i.e the anterior aspect of the teeth) and so the swelling will be visible buccally

The swelling will present intra-orally if the root length of the tooth is short in relation to the muscle attachment (i.e origin of the buccinator muscle).

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  • General steps of infection:

    1. Follows the same general notes of infection (i.e bacteria gets in and spreads down to the apex of the tooth and then eventually erodes it way through the mandibular bone cortex).

    2. Then, when the apex of the tooth is closer to the buccal bone cortex, the infection will exit buccally.

    3. But, if the roots of the tooth are short and lie above the origin of the buccinator muscle, then the exit point of the infection is usually above the origin of the buccinator muscle and results in vestibular space infection, producing a vestibular abscess.

Vestibular space

  • This is a potential space between the vestibular mucosa and the underling muscles of fascial expression

  • Borders

    1. Superior = buccinator muscle

    2. Inferior = buccinator muscle

    3. Anterior = Intrinsic lip musculature

    4. Posterior = buccinator muscle

    5. Lateral = vestibular mucosa

    6. Medial = mandible with overlying periosteum

    7. So, the labial/buccal vestibular space is located between the vestibular mucosa and the muscles of facial expression

  • Contents of the space

    1. Areolar connective tissue

    2. Parotid gland

    3. Long buccal nerve

    4. Mental nerves

  • Signs and symptoms of vestibular space infection:

    1. Vestibular fluctuance (a fluid-filled structure like an abscess that produces a wave-like motion when palpated) and swelling – the swelling will be intra-oral

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 a mandibular 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 bacterial infection insights an acute inflammatory reaction that causes vasodiltation that in turn causes an increase in hydrostatic pressure that in turns causes osteoclastic bone resorption

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, which causes a build-up of 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.

In teeth with short roots close to the buccal plate, which is relatively thin, the acute inflammatory response will incite bone resorption of the buccal plate and as the apex is above the buccinator muscle attachment this will allow spread through the buccal plate due to bone resorption and present as a swelling inside the mouth (intra-oral). Thus eventually pus can be seen discharging through gum. For the infection to be cleared, the pus has to be drained and the focus of the infection treated by either removing the dead tissue from the pulp chambre and root canals by starting an endodontic root treatment or alternatively extracting the tooth.

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3D Model

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