What Are the Features of a Lateral Periodontal Cyst?
Lateral periodontal cysts (LPC) may be defined as non-keratinized and non-inflammatory cysts of developmental origin located either adjacent or lateral to the root of a vital tooth. It is considered a developmental-origin odontogenic cyst and has the lowest incidence compared to other developmental cysts in the oral cavity. The most frequent location for LPC is the mandibular premolar area, followed by the anterior region of the maxilla. It is usually asymptomatic and may be a finding by the dentist on a routine radiographic examination.
The cysts exhibit round or ovoid radiolucent areas with sclerotic margins (less uniform borders as a reaction of the bone to the inflammatory lesion) and less than one centimeter in size. Lateral periodontal cysts are mostly associated with vital teeth, but in rare cases, they can occur around a nonvital tooth. According to research, these cysts contribute nearly 0.8 to 2 percent of all odontogenic cysts encountered clinically. LPC is more prevalent in age groups of adults, specifically between the 5th to 7th decades, with mean peak prevalence at 52 years of age and does not have any gender predilection.
How Can Lateral Periodontal Cysts Be Identified?
The World Health Organization (WHO) mainly classifies odontogenic cysts into two varieties based on their epithelial lining as;
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Cysts of inflammatory origin.
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Cysts of developmental origin.
In most cases, a lateral periodontal may be diagnosed by radiographs. It presents as a well-circumscribed or teardrop-shaped radiolucent area. Due to its location, LPC can be commonly mistaken to be an endodontic or infectious lesion. The final diagnosis can be confirmed by a histopathologic examination.
Histologically, lateral periodontal cysts are similar to most developmental cysts, with the presence of a thin, nonkeratinized epithelium. These epithelial layers are one to five cell layers thick and often resemble the reduced enamel epithelium. The epithelial lining may also exhibit focal thickening, showing the presence of glycogen in the epithelial cells. The connective tissue below or adjacent to this epithelium exhibits a specific hyalinization zone which is a marked feature for diagnosing LPC.
What Are the Types of Lateral Periodontal Cysts?
Based on the morphological characteristics, lateral periodontal cysts can be classified into two variants, the unicystic form and the multicystic form. A botyroid odontogenic cyst is not considered a true form of LPC, as it is a cystic lesion extending beyond the lateral area of the tooth root and has the potential for recurrence even after enucleation.
How Is a Lateral Periodontal Cyst Formed?
The exact pathogenesis of lateral periodontal cysts is not clearly defined, but according to research, one of these three hypotheses may explain its possible origin and development :
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According to histologic observations, the cyst is lined by nonkeratinized epithelium, indicating that the reduced enamel epithelium is retained. This cyst is of developmental origin, supported by the patterns observed through immunohistochemical methods.
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The cyst arises from the remnants of the dental lamina, which is attributed to the fact that LPC presents with specific glycogen-rich clear cells.
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The cyst originates from the remnants of epithelial cell rests of Malassez, which may be responsible for the adjacent location.
How Can Lateral Periodontal Cysts Be Diagnosed and Managed?
The diagnosis of a lateral periodontal cyst is considered when the cyst location is restricted to the periodontal segment of the tooth, anterior maxillary tooth roots, or around mandibular premolar roots. The radiographic findings play a major role in establishing a diagnosis. Differentiation between LPC from other cysts stemming from inflammatory origins or potential keratocystic odontogenic tumors is based on histopathological studies and analysis. After establishing a confirmatory diagnosis, treatment is carefully planned and executed to prevent the recurrence of the lesion.
The main treatment modality adopted for LPC is the surgical enucleation of the cyst. This procedure can be performed conservatively (without causing any injury to the adjacent teeth) by an oral and maxillofacial surgeon. The clinical and radiological outcome of the treatment is satisfactory, and the recurrence of the lateral periodontal cyst is usually uncommon.
Conclusion
Lateral periodontal cysts are non-keratinized and non-inflammatory cysts of developmental origin located lateral to the root of a vital tooth. It is usually asymptomatic and may be identified on a routine radiographic examination. The lateral periodontal cyst must be considered in the differential diagnosis for any radiolucent lesion around or adjacent to the roots of the teeth. Timely diagnosis, histopathological examination, and appropriate treatment can be useful in eliminating the lesion along with preventing the recurrence.
