22. Understanding dental infection
Assoc. Prof. Dr. Ngeow Wei Cheong
BDS, FFDRCSI, FDSRCS, AM Department of Oral and Maxillofacial Surgery Faculty of Dentistry University of Malaya 50603 Kuala Lumpur Malaysia.
Dental infection is one of the most common infections in the world. The good news is that tooth decay, which in actual fact is an infection on the tooth structure is normally localise and restorable. Another common infection in the mouth are gingivitis and periodontitis. They are in fact gum disease, with gingivitis being milder and periodontitis being more severe. Occasionally dental infection from the tooth and gum spread to the surrounding and/or distant tissue. Dental infections can present as abscesses, sinus tracts or severe cellulitis involving the superficial spaces, masticator spaces, floor of the mouth spaces or deep neck spaces. This write-up reviews the local spread of dental infection namely, periapical abscess and sinus tract formations. The spread of infection to the maxillary sinus is briefly discussed.
The spread of caries in a tooth, if not arrested, will result in infection of the pulpal tissue and eventual pulpal necrosis i.e. the tooth dies off. This necrosed tissue may collect at the around the root of the tooth concerned. Inflammatory process will occur as the body responses to this collection. In essence the body tries to cure and protect oneself from the bad effect of this infection. However, in normal circumstances, the body usually is not able to wall-off the infection. Hence, there would be accumulation of acute inflammatory cells at the tip of a dead tooth. This is termed a periapical abscess by the dentist. Periapical abscess may arise as the initial periapical pathosis or from an acute exacerbation of a chronic periapical inflammatory lesion (phoenix abscess). It has to be reminded that the infection can happen in any part of the root i.e. not necessarily at the tip of the root.
Abscesses usually consists of a sea of polymorphonuclear leukocytes (aka white blood cells) often intermixed with inflammatory exudate, cellular debris, necrotic material, bacterial colonies or histiocytes. Periapical abscess has been classified into acute and chronic types, but it has been suggested that this is a misnomer since both types represent acute inflammatory reactions. Some dentists prefer to designate periapical abscesses as either symptomatic or asymptomatic based on their clinical presentations. Periapical abscesses become symptomatic when the purulent material accumulates within the alveolus. The initial stages produce tenderness of the affected tooth that is often relieved by direct application of pressure. With time, the pain becomes worse and the tooth will become very sensitive to percussion. Extrusion and swelling either around the tooth, at the labial sulcus or occasionally the lingual or palatal area may be noted.
The abscess may not be detected radiographically. If an radiograph (x-ray) is taken, dentists may only see a thickened peri-radicular periodontal ligament, an ill-defined radiolucency, or both depending on the time lapse between the onset of infection and time the radiograph is taken. Radiolucency (dark shadow in radiograph) is a sign that something may be wrong in the jawbones. It normally tell us that some bone has been lost, hence the dark shadow seen in radiograph. (Note: Bone and any hard tissue look opaque/white in radiograph). Radiolucency may not be appreciable in radiograph when there is not enough time for significant bone destruction. Phoenix abscess, however, will demonstrate the outline of the original chronic lesion with or without an associated ill-defined bone loss.
Most dental abscesses perforate bucally i.e. going away from the oral cavity toward the face because the bone is thinner on the buccal surface. Conversely, infections associated with maxillary lateral incisors, the palatal roots of maxillary molars and mandibular second and third molars typically drain through the lingual cortical plate.
With progression, the abscess may extend to the path of least resistance, away from the tooth. The purulence may extend through the medullary spaces away from the apical area, resulting in osteomyelitis, or it may perforate the cortex and channelised though the soft tissue or spread either diffusely through the overlying soft tissue as cellulitis, or to adjacent and/or distant potential tissue spaces. Fortunately, most dental abscess remained localised around the tooth concerned.
If the abscess finds its way through the oral mucosa, a sinus tract is formed. The pressure in the swelling may be relieved and if a chronic path of drainage is achieved, the abscess becomes asymptomatic. At the distal opening of an intraoral sinus tract, there is often a mass of subacutely inflamed granulation tissue known as a parulis (gum boil).
If it channelised through the skin, a cutaneous sinus tract may be formed. A cutaneous sinus that discharges on the skin of the face and neck is called scientifically a “cervicofacial sinus”. Among the commonly dental-caused cervicofacial sinus are those related to apical pathology around mandibular anterior teeth. This type of cervicofacial sinus has been described as “median mental sinus”. Other sites of extra-oral drainage of dental infection are the cheek, canine space, nasolabial fold, nose, upper lip and even the inner canthus of the eye.
Cervicofacial sinus can clinically simulate skin infection (carbuncle), sebaceous cysts, basal cell epithelioma, basal cell carcinoma (a type of skin cancer) or even squamous cell carcinoma (a type of skin cancer). Thus, many cases have been documented of patients receiving multiple biopsies and surgical excisions, multiple antibiotic regimens or radiotherapy without success because of misdiagnosis. The sinus tract continues to pour out discharges as the primary dental cause was never correctly diagnosed and treated. There was even a case that was correctly diagnosed only after 32 years.
Most patients are unaware of any associated dental problem, hence delaying the correct diagnosis of the cervicofacial lesion with its primary odontogenic origin. Only 50% of patients with cervicofacial odontogenic sinus tracts have a history of toothache. Otherwise, the involved area is usually asymptomatic and the patient generally healthy. Hence, anybody with an infection on the face that never heals may need dental check-up to rule out possible dental cause.
Spread of infection to the maxillary sinus
It is generally accepted that dental infections can cause sinusitis or more precisely maxillary sinusitis. Selden referred to such a manifestation as the endo-antral syndrome (EAS). This is a pathological condition resulting from the spread of infection from the root canal apices near the maxillary sinus into both the antral and periapical tissues. The degree of sinus involvement is related to the proximity of the involved apex to the sinus. Reported frequencies of sinusitis of dental origin vary considerably, between 4.6 and 47.0%.
Treatment for periapical abscesses consists of drainage and elimination of the source of infection. Normally incision and drainage can be performed under local anaesthesia by any dentists. The pus should be sent for culture and sensitivity. Open drainage of the tooth shall be done if there is intention to retain it, otherwise it may be extracted. If extraction is to be done, normally extraction is done a day or two after the patient is prescribed antibiotics and analgesics. Of course dentist must use their personal judgement, as, if the patient is in severe pain but the dentist is still able to numb the region involved, then extraction there and then would be the best treatment. Dentists may consider giving prophylactic antibiotics 1 hour prior to dental extraction with pus present. Persistent parulis may need to be excised surgically.
Treatment for sinus tracts involves confirming the source of infection. This can be done by the dentist by inserting a soft gutta percha point and appropriate radiographs taken. Once the source is found, it can either be treated by endodontic therapy or exodontia. Surgical apicectomy may be needed for recurrent persistant sinus that does not respond to endodontic therapy.
Treatment for maxillary sinusitis consists of elimination of the source of infection. Open drainage followed by root canal therapy of the tooth shall be done if there is intention to retain it, otherwise it may be extracted. If extraction is to be done, it is suggested that this is done a day or two after the patient is prescribed antibiotics and analgesics. Patients may need a course of antibiotics until the sinusitis has resolved.
Note: The information provided in this article is meant to be used as general guidelines. It is best to consult your dentist if you suspect that you have dental infection.
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