Managing a Lateral Periodontal Cyst With Bone Graft:A Computed Tomography Assessment 18 Months Postoperatively

The lateral periodontal cyst (LPC) is considered an independent pathologic entity with well-established clinical, radiographic, and histologic features.¹ It is a nonkeratinized and noninflammatory developmental cyst located adjacent or lateral to the root of a vital tooth. Its name reflects its position; it arises from the periodontium and extends into the interproximal bony septum, midway between the apex and crest of the alveolar bone. The first well-documented case of an LPC was reported by Standish and Shafer in 1958.²

The source of origin for LPCs remains controversial, with extensive debate in the literature. An LPC is now believed to originate at the rests of the dental lamina, while early reports identified the reduced enamel epithelium as its tissue of origin.³ It is relatively rare, and its prevalence ranges from 0.7%⁴ to < 1% of all cysts found in the jaws.⁵ LPCs are more common in adults during the fifth to seventh decades of life and seem to show no gender or race predilection,^6,7 although a slight male predilection has been reported by Altini and Shear.⁴ Most LPCs are located in the canine-premolar areas^6,8 of the mandible, followed by the anterior region of maxilla.⁶

LPCs are asymptomatic in the majority of reported cases and are most often discovered during routine radiographic examinations. Their sizes may vary from 1 mm to one involving the entire lateral side of the root. LPCs are benign with a slow growth rate of approximately 0.7 mm per year⁹ and may cause resorption of the surrounding bone, roots, and periodontal structures. In cases of larger cysts, expansion of the buccal or lingual alveolar plate has been reported. The covering mucosa is usually normal in color or slightly whitish or bluish. The adjacent teeth are always vital; this is an important characteristic element of these lesions that helps in their differential diagnosis from other inflammatory odontogenic cysts. Pain is not a common clinical feature of LPCs. There is no communication between the cystic cavity and the gingival sulcus on probing.⁶

An LPC appears as a well-defined, oval or teardrop radiolucency with a clear demarcation of less than 1 cm in diameter.⁴ It usually presents along the lateral surface of the root of two adjacent teeth and is located between the alveolar crest and the root apices. The radiographic appearance of an LPC is not diagnostic and can resemble an odontogenic keratocyst or a lateral radicular cyst. An LPC usually appears unilocular; however, it can present as a multilocular radiolucency. Due to the macro- and microscopic features that resemble a “bunch of grapes,” LPCs are called botryoid odontogenic cysts¹⁰ and were first described by Weathers and Waldron in 1973.¹¹

The cystic cavity of this lesion is lined by a thin, nonkeratinized epithelium, usually one to five layers in thickness. Areas of local epithelial thickening are often noted and composed of glycogen-containing clear cells. Epithelial remnants of cells originating from the dental lamina, known as rests of Serres, can be visualized close to the cyst wall. This histologic feature is pathognomonic of an LPC. It is the only feature used to confirm the clinical diagnosis and to distinguish it from odontogenic keratocyst, which may present with a similar radiographic appearance but has a higher propensity to reoccur and can be more destructive.

If the LPC is untreated, root resorption,¹² tooth displacement, expansion of the jaw, and pain¹³ can occur. Treatment of an LPC includes surgical removal of the lesion by conservative enucleation of the lesion and radiographic follow-up of the patient to monitor for possible recurrence. Reappearance of an LPC is usually rare and has been reported mainly in cases of multilocular botryoid odontogenic cysts.¹⁴ However, in cases of larger cysts in which destruction of the interradicular and cortical bone has occurred, enucleation alone may not heal the osseous defect. Reconstruction or regenerative procedures of the associated defect are important to consider for elimination of ridge deformity and improvement of esthetics, especially for lesions found in the maxillary anterior teeth.

The overall objective of this report is to present a treated case of an LPC-associated defect with a bone allograft and reevaluation of the outcome using a cone-bean computed tomography (CBCT) scan.

A 61-year-old African-American female patient in good general health was referred to the Department of Periodontology at the College of Dentistry, University of Tennessee Health Science Center in Memphis, Tennessee, due to a radiolucency between the roots of the left mandibular canine and first premolar (teeth Nos. 21 and 22). The patient reported a mild discomfort localized to the area of concern (teeth Nos. 21 and 22). Intraoral examination of the area was unremarkable with no apparent expansion of the buccal or lingual plates. Periodontal probing revealed shallow probing depths from 2 mm to 3 mm with a mild degree of marginal gingival inflammation. The teeth were vital and not mobile or sensitive to percussion (Figure 1). Radiographic examination findings revealed a large teardrop radiolucency of approximately 10.5 mm by 3.9 mm between the teeth extending from the bony crest to the root apices. The lesion was well circumscribed with a radiopaque lining (Figure 2). To eliminate the cause of pain by enucleation of the lesion, the dental team recommended periodontal surgery to the patient, which she accepted.

Under local anesthesia, intrasulcular incisions extending from the distal of the left second premolar to the distal of the lateral incisor were made and full-thickness mucoperiosteal buccal and lingual flaps were reflected (Figure 3). The buccal bone between the first premolar and canine was intact but thin and easy to penetrate (Figure 4). The buccal bone covering the cyst was removed carefully by using a curette that revealed the cyst underneath (Figure 5). The lesion was removed in multiple fragments that were placed immediately in 10% neutral formalin and sent for histopathologic examination. The bony walls were curetted from all soft-tissue remnants and irrigated with sterile saline revealing a narrow communication track between the cystic cavity and the crestal bone (Figure 6 and Figure 7). The root surfaces of the involved teeth were thoroughly scaled and root planed to completely remove any residual epithelial cells. The interradicular bone between the canine and first premolar was resorbed and extending from the crestal bone to the lower third of the root length. The entire bony septum was undermined and left with thin lingual and buccal walls. This type of bony defect has limited regenerative potential unless an allograft bone is used or other regenerative techniques. Persistence of this defect or collapse of the bony ridge could jeopardize the periodontal stability and negatively affect the long-term prognosis of the involved teeth. It could also cause an esthetic issue and complicate oral-hygiene measures. For these reasons, we utilized a freeze-dried bone allograft cortical/cancellous combination material (MinerOss Cortical and Cancellous chips, BioHorizons, biohorizons.com) and filled the osseous defect completely (Figure 8). Flaps were repositioned and sutured in place with Vicryl® 4.0 (Ethicon, ethicon.com) using simple interrupted sutures (Figure 9). The postoperative regimen included amoxicillin 500 mg taken three times daily for 1 week, hydrocodone/acetaminophen 5/500 mg for pain management, and 0.12% chlorhexidine gluconate mouthwash for plaque control.

The histopathologic examination showed an epithelium-lined cyst, with the epithelium almost completely stripped from the underlying connective tissue wall. The cystic lining was predominantly characterized by cuboidal to flattened squamous epithelium of one to three cell layers in thickness. Inflammation was not a significant feature. Focal thickenings of the cystic lining were readily identified at scattered intervals. These histologic features were consistent with a diagnosis of an LPC (Figure 10 and Figure 11).

The sutures were removed 2 weeks postoperatively. Healing was uneventful; however, a slight collapse of the soft tissue was noted without any long-term esthetic or functional consequences. The patient was followed clinically every few months to ensure complete soft-tissue and bone healing.

At her 15-month postoperative appointment, a complete periodontal examination was performed. Good gingival health was noted in the treated area with shallow probing depths but with partial loss of the interproximal papilla and minor gingival recession (Figure 12). A periapical radiograph of the area revealed good bony fill and increasing bone density with no evidence of recurrence or root resorption (Figure 13). The patient was extremely satisfied with the positive results and had no pain or discomfort.

At approximately 18 months postoperatively, a CBCT scan of the mandible was taken to assess the bony healing pattern of the surgical site. The scan revealed a complete bone regeneration of the defect and increased density of the area between the canine and first premolar. A three-dimensional reconstruction of the area revealed complete healing of the cystic site and regeneration of the interproximal and the buccal plate (Figure 14 and Figure 15).

The standard treatment of a lateral periodontal cyst is enucleation and monitoring. However, the literature has limited reports regarding the extent of bone regeneration following enucleation. Furthermore, there are conflicting reports for the need for bone grafts to reconstruct the associated lesions. Meltzer¹⁵ reported successful bone healing without the use of any grafting materials, which were clinically confirmed by a reentry procedure and a visual inspection of the site 1 year postoperatively. In contrast, Angelopoulou and Angelopoulos¹⁶ reported a limited radiographic bone fill 1 year postoperatively when bone graft was not used. Savord and Krill¹⁷ were the first to report the need to “support the flap” after the removal of an LPC and the creation of an osseous defect. In their report in 1895, they used durapatite ceramic particles to fill the osseous defect. Later, Lehrhaupt et al¹⁸ reported the use of demineralized freeze-dried bone allograft to treat a through-and-through defect created by an LPC. Since then, several case reports have been published using guided tissue regeneration combined with a variety of bone-grafting materials or enamel matrix proteins¹⁹ with successful outcomes as documented by reentry procedures²⁰ or radiographic scans²¹ (Table 1). These regenerative techniques are not unique to an LPC and have been reported to manage bony defects associated with maxillary adenomatoid odontogenic tumor,²² botryoid cysts,²³ and buccal bifurcation cysts.²⁴

Reports on proper management of an LPC are readily available. However, the literature is sparse regarding the long-term outcomes following surgery. A traditional radiographic technique does not provide an adequate image of the healing, while a reentry procedure may meet patient resistance. The current report is the first to utilize a CBCT scan to evaluate the positive healing potential of a freeze-dried bone allograft approximately 18 months postoperatively.

Rania Livada, DDS, MS

Private Practice, Periodontics and Dental Implants, Oxford, FL; Adjunct Associate Professor, Department of Periodontology, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN

Jacob Shiloah, DMD

Professor, Department of Periodontology, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN

K. Mark Anderson, DDS, MS

Associate Professor, Director, Division of Oral and Maxillofacial Pathology College of Dentistry, University of Tennessee Health Science Center, Memphis, TN

William R. Callahan III, DDS

Assistant Professor, Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN