- Microbiology of dental infections
Recent reports have confirmed that oral/dental infections are poly microbial, including
facultative anaerobes, such as viridans-group streptococci and the Streptococcus anginosus
group, with predominantly strict anaerobes, such as anaerobic cocci, Prevotella and Fusobacterium
species. The use of sophisticated non-culture methods has identified a wider range of
organisms, such as Treponema species and anaerobic Gram-positive rods such as Bulleidia
extructa, Cryptobacterium curtum, and Mogibacterium timidum
- Anatomical Spread of Infection
Bone, muscle, aponeurosis or fascia, neurovascular bundles, and skin can all act as barriers to
the spread of infection. However, no tissue barrier or boundary is so restrictive or confining
to universally prevent spread of infection into contiguous anatomical spaces[
- Upper lip
Infection at the base of the upper lip typically originates from the upper anterior teeth. It
spreads to the orbicularis muscle, from the labial sulcus between the levator labii superioris
muscle and the levator angularis oris muscle.
- Canine fossa
Spread of infection to the canine fossa usually originates from maxillary canine or upper
premolar teeth, often presenting above the buccinator muscle attachment. These swellings
obliterate the nasolabial fold. This space is in close proximity to the lower eyelids, and therefore
early management is essential to avoid circumorbital infection. There is a risk of spread
cranially, via the external angular vein, which may then become thrombosed.
- Buccal space
The attachment of the buccinator muscle to the base of the alveolar process can control the
spread of infection in the region of the mandibular and maxillary molars. An infection spreads
intraorally, superficial to the buccinator muscle, in front of the anterior border of the masseter
muscle. Thus, the clinical manifestations of infection in this space are characterized by swelling
confined to the cheek. However, infection may spread superiorly, towards the temporal space,
inferiorly, to the submandibular space, or posteriorly, into the masseteric space. In some cases,
infection may spread to the surface of the skin, leading to fistula formation
- Palate
The palate is usually involved in infections originating from the maxillary lateral incisor or the
palatal roots of the posterior teeth. The infection spreads from the apices of these teeth,
perforating the palatal alveolar bone, and pus accumulates below the palatal mucoperiosteum.
- Pterygomandibular space
Infection in this space is manifested by trismus, due to the involvement of the pterygoid
muscles. This space is bounded medially by the medial pterygoid muscle and laterally by the
medial surface of the mandible, anteriorly by the pterygomandibular raphe, and posteriorly
by the deep lobe of the parotid gland. The lateral pterygoid muscle forms the roof of this space.
- Submasseteric space
The most common source of infection in this space is from lower third molar pericoronitis.
This space is bound medially by the masseter muscle and laterally by the outer surface of the
ramus of the mandible. It is in direct communication with the lateral pharyngeal space
posteriorly. The temporalis muscle divides the superior part of this space into two portions,
the superficial temporal space, which is bounded by temporalis muscle medially, and the deep
temporal space, with the temporalis muscle laterally and the periosteum of the temporal bone
medially. Severe trismus due to spasm of the masseter muscle is a characteristic feature of
involvement of this facial space.
- Infratemporal space
Extension of infection from maxillary molars can pass into this space. Infection may also spread
from the pterygomandibular, parotid, or lateral pharyngeal region to the infratemporal space.
The patient then complains of pain, particularly with mouth opening, some dysphagia, and
difficulty with lateral mandibular movements. This space is located behind the zygomatic bone
posterior to the maxilla and medial to the insertion of the medial pterygoid muscle. The
infratemporal space is bounded superiorly by the greater wing of the sphenoid and is in close
proximity to the inferior orbital fissure, with a possible risk of spread of infection to the orbit.
- Parotid space
Involvement of this space may be an extension of infection in the middle ear or the mastoid
region. Infection in the masseteric or the lateral pharyngeal space may also spread to the
parotid region. Thus, the most characteristic feature of involvement of this space is swelling
of the parotid gland region, below the ear lobe. This space contains several important structures
that may be affected by infections. These include the 7th cranial nerve, the auriculotemporal
nerve, the facial vein, the parotid lymph node, and, more deeply, the external carotid with its
branches.
- Submandibular space
This space is located below the mylohyoid muscle, medial to the ramus and the body of the
mandible. It is bounded anteriorly by the attachments of the anterior belly of the digastric
muscle and posteriorly by the posterior belly of digastric muscle and the stylomandibular
50 A Textbook of Advanced Oral and Maxillofacial Surgery
ligament. Infection from the posterior mandibular teeth may pass lingually, below the
attachment of the mylohyoid muscle, into this space. Clinically, swelling of the submandibular
regions tends to obliterate the angle of the mandible, causing pain and redness of the skin
overlying this region. Dysphagia is also usually a marked symptom.
- Submental space
This space lies between the two anterior bellies of the digastric muscle. Anteriorly and laterally
this space is bounded by the body of the mandible. It is contained, superficially, by the
platysma muscle and, deeply and superiorly, by the mylohyoid muscle. Infection of this space
usually arises from mandibular anterior teeth, where the infection perforates the lingual cortex;
swelling of the submental region is a characteristic clinical feature. The skin over the swelling
is stretched and hardened, and the patient experiences considerable pain and difficulty with
swallowing. The infection may progress buccally, causing swelling in the labial sulcus and
over the chin.
- Sublingual space
Infection spreads into this space as the result of perforation of the lingual cortex, above the
attachment of the mylohyoid muscle. This space is bounded superiorly by the mucous
membranes and inferiorly by the mylohyoid muscle. The genioglossus and geniohyoid
muscles form the medial boundary. Laterally, this space is bounded by the lingual surface of
the mandible. Infection in this space will raise the floor of the mouth and displace the tongue,
medially and posteriorly. Such tongue displacement may compromise the airway and
immediate intervention may be required. Dysphagia and difficulty with speech are also
common.
- Pharyngeal space
This space is located on the lateral side of the neck, bounded medially by the superior
constrictor muscle of the pharynx and posterolaterally by the parotid space. Infection in this
space may originate from mandibular molars or third molar pericoronal suppuration. This
could also be a site of spread of infection from the parotid space or fascial space around the
body of the mandible. The lateral pharyngeal space contains the carotid sheath, glossopharyngeal
nerve, accessory nerve, and the hypoglossal nerve, as well as the sympathetic trunk.
Thus, spread of infection into this space carries a significant danger of spreading into a
descending neck infection and involvement of the mediastinum. Clinically, stiffness of the
neck, swelling of the lateral wall of the pharynx, medial displacement of the tonsils, dysphagia,
and trismus are among the characteristic clinical features of involvement of this space.
- Retropharyngeal space
This space is located between the posterior wall of the pharynx and the prevertebral fascia.
This space is in direct communication with the base of the skull, superiorly, and the media‐