Odontogenic infection is an infection that originates within a tooth or in the closely surrounding tissues. The term is derived from Greek words “odonto” meaning “tooth” and “genic” meaning “birth”.

Odontogenic infection has plagued human kkind for as long as the human species has existed. Generally, in the orofacial region, most bacterial infections involve either a disturbance of normal flora or a displacement of the normal organisms to the site, where they are usually not seen.

Routes of odontogenic infection :

• By direct continuity through tissues
• By lymphatics to the regional nodes
• By bloodstream

Causes of odontogenic infection :

1. Dental caries : plaque on tooth surface above the gingival margin consists of acidogenic and aciduric bacteria which cause dental caries and may invade the pulp, infection eventually spreading to the alveolar process.
2. Deep fillings : if the seal between the tooth enamel and the filling breaks down, food particles and decay causing bacteria can work their way under the filling. Additional decay develops in the tooth. Decay that is left untreated can progress to infect the dental pulp and may cause an abscessed tooth.
3. Failed root canal treatment : if there is an extended delay between root canal procedure and crown placement, bacteria can re-enter the tooth. Additionally, a crown can suffer a crack or other damage long after the procedure is complete. This damage allows new bacteria to enter the tooth and create decay.
4. Pericoronitis and periodontal diseases

Odontogenic infections are usually polymicrobial involving both strict anaerobes and facultative bacteria within unique ecosystems of the dental plaque and gingival crevice.

The most prevalent anaerobic bacteria include gram positive cocci such as Peptostreptococcus sp., and gram negative rods such as Bacterioids sp., Fusobacterium sp. The most prevalent aerobes are facultative gram positive such as Streptococcus mutans and Streptococcus viridans. Facultative gram negative bacilli and Staphylococcus aureus are uncommon in immunocompetent hosts but may be more important in immunocompromised patients.

Major symptoms of odontogenic infections :

• Antecedent toothache
• Facial swelling and pain
• Fever and chill
• Halitosis
• Bleeding gums with minor trauma

Prominent physical findings include :

• Dental plaques, tooth decay, gingivitis or periodontal pockets
• Facial or neck swelling and tenderness
• Inability to open the jaw
• Difficulty in swallowing
• Dyspnea with inspiratory stridor (high pitched wheezing sound caused by disrupted airflow)

Imaging studies :

• Orthopantomogram or AP radiograph of teeth to assess periapical abscess or advanced periodontal disease
• CT of face and neck to assess source and extension of orofacial space infection

Complications :

• Deep facial space infections
• Osteomyelitis of the jaws
• Cavernous sinus thrombosis
• Hematogenous dissemination
• Association of poor health with cardiovascular diseases

Clinical manifestations of specific odontogenic orofacial space infections :

• If pus perforates through either the maxillary or mandibular buccal plate inside the attachment of the buccinator muscle, infection will be intraoral; if the perforation is outside this muscle attachment, infection will be extraoral
• When a mandibular infection perforates lingually, it presents in the sublingual space if the apices of the involved teeth lie above the attachment of the mylohyoid muscle.
• Other superficial odontogenic orofacial space infection include the buccal, submental, masticator, canine and infratemporal spaces.

Treatment :

In normal host :

• Penicillin G + metronidazole
• Ampicillin – sulbactam
• Clindamycin
• Doxycycline
• Moxifloxacin

In immunocompromised host :

• Cefotaxime or ceftrioxime or cefepime each + metronidazole

Source : ncbi.nlm.nih.gov