A dental student’s guide to…odontogenic infections

odontogenic infectionsIn this month’s dental student’s guide, Hannah Hook explores odontogenic infections and how to manage them.

The need for management of odontogenic infections is a daily occurrence in dentistry. Whilst most odontogenic infections may cause no more than pain and mild swelling, some may progress, leading to severe complications such as deep-neck space infections, tissue necrosis, endocarditis, Ludwig’s angina and sepsis (Igoumenakis et al, 2014).


In the development of an odontogenic infection, there are four key stages. These include (Jevon, Abdelrahman and Pigadas, 2020; Saravanakumar, Senthilnathan and Prabu, 2020):

  • Stage one – inoculation stage; one to three days; soft and mildly tender doughy swelling; streptococci
  • Stage two – cellulitis stage; three to five days; hard, red, and severely sore swelling; mixed flora
  • Stage three – abscess stage; five to seven days; liquefied abscess formation in the centre of the swelling; anaerobic organisms predominate
  • Stage four – resolution stage; drainage of the abscess via spontaneous or surgical means; healing.

Once odontogenic infection reaches stage three, and abscess formation has occurred, it is believed that the best management in order to achieve resolution is through surgical drainage (Osborn, Assael and Bell, 2008).

Medical history

To maintain an effective defence against infections, a healthy immune system is essential.

There are numerous medical conditions that can impact a patient’s immune status, predisposing them to exacerbation of odontogenic infections.

Undertaking a comprehensive medical history will enable the clinician to highlight any conditions that may compromise the patient’s immune system and help plan treatment accordingly. Listed below are several factors that can compromise a patient’s immune system (Jevon, Abdelrahman and Pigadas, 2020; Weise et al, 2019):

  • Alcoholism
  • Chemotherapy
  • Chronic renal disease malnutrition
  • Diabetes mellitus
  • Immunodeficiency
  • Immunosuppression
  • Malignancy
  • Obesity
  • Organ transplants
  • Radiotherapy.

Extraoral assessment

The initial steps in examination of a patient presenting with an odontogenic infection should include an assessment of the patient’s airway, breathing and circulation. This will help to identify any cases of severe infection that require referral to a hospital for immediate treatment.

Explicit signs and symptoms of severe infection are included below in the referral section.

Extraoral examination of the patient will allow assessment of the extent and location of any facial swelling. Things that clinicians should check include:

  • Asymmetries – looking at the patient from straight on, does there look to be any swelling of the head and neck causing asymmetry?
  • Swelling – assess the size and site of the swelling, does it extend below the lower border of the mandible or to the infraorbital region? Is it firm or fluctuant?
  • Lymph nodes – should be gently palpated to check for any tenderness or enlargement
  • Mouth opening – is there any restriction or pain? Is the mouth opening normal for the patient?
  • Spread of infection – is there any erythema tracking down the neck? Does the swelling cross the midline?
  • Speech – is the patient’s speech affected? Do they have a ‘hot-potato’ voice?
  • Breathing/swallowing – does the patient have any difficulty breathing or swallowing?

Intraoral assessment

Assessment of the intraoral tissues should then be undertaken. Check the soft tissues in a systematic approach and the teeth in an effort to identify the offending tooth. Things clinicians should note include (Vytla and Gebauer, 2017):

  • Swelling – any areas of swelling present. Is the swelling firm or fluctuant? Is there any pus draining from the swelling?
  • Floor of mouth – is the floor of mouth raised?
  • Teeth – are any teeth grossly carious? Are any tender to percussion/palpation/pressure? Any mobility? Is there any deep periodontal pocketing?

Following extra and intraoral assessment, take radiographs to aid identification of the causative tooth.


Regarding treatment of the infection, early intervention is essential in preventing spread of the infection into anatomical spaces of the head. A healthy person with an uncomplicated and localised dental abscess who is not demonstrating any signs or symptoms of a worsening immune response can be safely treated in practice.

If a patient is demonstrating signs of severe infection, as listed below, practices should promptly refer them to the Emergency Department at the nearest hospital with a written referral.2 Furthermore, make an effort to contact the hospital’s on-call maxillofacial doctor to brief them on the patient.

Symptoms that should prompt immediate referral:

  • Signs of airway compromise such as: difficulty breathing or speaking, severe trismus, drooling, inability to protrude tongue
  • Dehydration and difficulty in swallowing
  • High or low temperature
  • Significant submandibular, mandibular, or infraorbital swelling
  • Involvement of orbital contents
  • Spreading facial infection or orbital cellulitis
  • Neurological signs such as decreased level of consciousness.


Early surgical intervention can result in a dramatic improvement in the outcome of odontogenic infections. After assessing the patient and deeming that they are not at risk of severe/spreading infection and there is no sign of airway compromise, clinicians can safely drain the majority of odontogenic infections in general practice (Jevon, Abdelrahman and Pigadas, 2020).

  1. Anaesthesia – best achieved through regional nerve blocks. This avoids the risk of spreading the infection further by inserting a needle into infected tissue
  2. Local measures – once anaesthesia has been achieved then you can undertake local measures, such as root canal access, extraction or incision and drainage
  3. Root canal access – rubber dam placement and root canal access into the offending tooth. Once the clinician reaches the pulp chamber, irrigate the tooth with sodium hypochlorite. The canal can then be dressed with a non-setting antibacterial medicament, PTFE tape and a temporary filling material
  4. Extraction – removal of the offending tooth. Once removed, pus may drain from the socket. Irrigate the socket with saline
  5. Incision and drainage – if there is a fluctuant swelling intraorally incision and drainage can be undertaken. An incision into healthy mucosa is made, a closed haemostat (such as mosquito forceps) is inserted into the abscess cavity and opened at the depth of the cavity. Remove the instrument whilst still open. This enables the clinician to gently explore the abscess cavity whilst avoiding damaging surrounding vital structures. Following exploration of the cavity, undertake copious irrigation with saline or iodine. Leave the cavity open to drain
  6. Antibioticsonly prescribed if immediate drainage of the infection is not achievable with local measures, or if there are signs of systemic involvement (malaise, fever) or spreading infection (cellulitis, swelling, lymph node involvement).

Key points

  • Dental practices commonly encounter odontogenic infections
  • Carry out a thorough extra and intraoral assessment to aid identification of the offending tooth
  • Treat the majority of infections in practice with local measures such as extraction, root canal access or incision and drainage
  • Some patients may present with signs and symptoms of a severe or spreading infection. Refer these patients to a local hospital urgently.

Catch up with previous Student’s guides:

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Igoumenakis D, Gkinis G, Kostakis G, Mezitis M and Rallis G (2014) Severe odontogenic infections: Causes of spread and their management. Surg Infect (Larchmt) 15: 64-8

Jevon P, Abdelrahman A and Pigadas N (2020) Management of odontogenic infections and sepsis: an update. Br Dent J 229: 363-70

Osborn TM, Assael LA and Bell RB (2008) Deep Space Neck Infection: Principles of Surgical Management. Oral and Maxillofacial Surgery Clinics of North America 20: 353-65

Saravanakumar, Senthilnathan V and Prabu NP (2020) Management Of Odontogenic Infection : A Review. Eur J Mol Clin Med 07: 6374-81

Vytla S and Gebauer D (2017) Clinical guideline for the management of odontogenic infections in the tertiary setting. Aust Dent J 62: 464-70

Weise H, Naros A, Weise C, Reinfert S and Hoefert S (2019) Severe odontogenic infections with septic progress – A constant and increasing challenge: A retrospective analysis. BMC Oral Health 19: 1-6

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