A 45-year-old male visited a dental office for a routine checkup. During the examination, a bony swelling was noted between the mandibular canine and lateral incisor. A radiograph of the region revealed an ovoid radiolucency.
The patient denied any history of pain associated with the mandibular canine-incisor area. The patient appeared to be in a general good state of health with no significant medical history. His dental history included sporadic checkups and routine restorative dental treatment.
The patient's vital signs were all found to be within normal limits. Extraoral examination of the head and neck region revealed no enlarged or palpable lymph nodes. Intraoral examination revealed a small, bony enlargement of the alveolar bone between the mandibular canine and incisor (see photo).
Based on this clinical finding, a periapical radiograph of the region was exposed. The film revealed a well-defined, ovoid radiolucency located between the roots of teeth #26 and #27 (see film). The teeth adjacent to the swelling were pulp-tested for vitality, and both tested vital. The patient was referred to an oral surgeon for biopsy and removal of the lesion. Microscopic examination revealed a cyst lined by stratified squamous epithelium with nodular thickenings and a thin, fibrous-connective tissue wall.
Based on the clinical, radiographic, and histologic information presented, which one of the following is the most likely diagnosis?
• radicular cyst (lateral location)
• lateral periodontal cyst
• odontogenic keratocyst
• primordial cyst
• residual cyst
• Lateral periodontal cyst
The lateral periodontal cyst (LPC) is a cyst of odontogenic origin that arises from remnants of the dental lamina. By definition, the LPC is developmental; it is not induced by inflammation, not associated with pulpal necrosis, and is not associated with periodontal disease.
The LPC is uncommon and is believed to account for less than 2 percent of all odontogenic cysts.
The LPC is found within bone and is located lateral to the root surface of a vital tooth. The teeth adjacent to the LPC are vital. In more than 75 percent of cases, the LPC is most often seen in the mandibular premolar-canine-incisor region. When seen in the maxilla, the lateral incisor area is most often affected. The LPC occurs most often in adults, most frequently in the fifth through seventh decades of life. Rarely is the lesion seen in persons under the age of 30. The lesion is seen more often in males than in females. The LPC is typically asymptomatic, and the patient is rarely aware of its presence. Bony expansion may or may not be present.
Most lateral periodontal cysts are discovered during routine radiographic examination. The typical LPC appears as a round to ovoid radiolucency with well defined and corticated borders. The size of the lesion tends to be small and measure less than one centimeter in diameter.
The location of the LPC can be described as inter-radicular, meaning between the roots of adjacent teeth. The adjacent teeth may exhibit root divergence.
Diagnosis and treatment
A diagnosis of a LPC cannot be made based on the radiographic appearance alone. Microscopic evaluation of the tissue is necessary in order to establish a diagnosis. Histologically, the LPC is a true cyst lined by stratified squamous epithelium with characteristic nodular thickenings. The wall of the LPC consists of thin, fibrous connective tissue and does not exhibit inflammation.
As with all odontogenic cysts, the LPC must be removed. The treatment of choice is conservative surgical enucleation.
Special care must be taken not to damage the adjacent tooth surfaces during the surgical procedure. Cysts that are not removed may continue to grow, destroy bone, and damage adjacent teeth. After surgical removal, it is unlikely that the LPC will recur.
Joen Iannucci Haring, DDS, MS, is a professor of clinical dentistry, Section of Primary Care, The Ohio State University College of Dentistry.