Nonsyndromic bilateral maxillary dentigerous cysts: Review of literature and report of an unusual case

1. Introduction 

A dentigerous cyst is defined as an epithelial-lined developmental cavity arising from the enamel organ due to an alteration in the reduced enamel epithelium and enclosing the crown of an unerupted tooth at the cementoenamel junction [1], [2], [3]. Dentigerous cysts are the second most common odontogenic cysts after radicular cysts and account for approximately 24% of the jaw cysts [1], [2], [4], [7]. They usually present in the second or third decades of life and are rarely seen during childhood. These cysts are usually solitary [5] with multiple occurrences reported on occasion in association with syndromes such as cleidocranial dysplasia, mucopolysaccharidosis (type VI) and basal cell nevus syndrome [5], [6]. This case report presents the clinical and radiologic findings of bilateral maxillary dentigerous cysts in a nonsyndromic ten-year-old boy. A search of PubMed/Medline, using the key words, anterior, maxillary, dentigerous cyst, and bilateral was conducted and revealed only two instances of bilateral maxillary dentigerous cysts [7], [8].

2. Case report 

A ten-year-old boy presented with a painless swelling in the maxillary anterior region. There was a history of a fall from a height, 5 months back while flying a kite with the loss of an upper tooth. General physical examination was unremarkable and the patient's growth and development was consistent with age. Intraoral examination revealed a firm swelling in the premaxillary region, distinctly pronounced on both sides of the midline more so on the left. No bruit or pulsation was observed. Signs of acute and chronic infection were absent. Routine laboratory investigations were within normal limits. Radiographs-OPG (Fig. 1) and occlusal view (Fig. 2) revealed distinct unilocular radiolucencies surrounding the unerupted permanent maxillary central incisor on the right side and the canine on the left. A root stump of the possibly displaced and fractured maxillary lateral incisor was also seen on the right side. Computed tomography (CT) showed well-defined soft tissue masses displacing and obliterating both maxillary sinuses especially on the left maxillary sinus (Fig. 3). The bony walls were thinned and contained mural teeth structures. No clefts or cyst cavities were detected on a whole body skeletal survey. Aspiration of the cystic cavities with a no. 21 gauge needle yielded a straw colored fluid. Both the cysts were enucleated along with the involved teeth, under general anesthesia. The cavities were obliterated with iodoform gauze dressings that were changed at regular intervals. The patient had an uneventful recovery and one-year follow up radiographs reveal excellent bone formation (Fig. 4) and architecture (Fig. 5) at the surgical site.

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Fig. 1. Preoperative OPG showing well-defined (arrows) bilateral radiolucencies (A and B) in the anterior maxilla.

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Fig. 2. Occlusal radiograph showing well-defined radiolucencies with thinned out sclerotic margins (arrows-A) and involvement of the right maxillary central incisor (B).

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Fig. 3. Coronal CT image showing well-defined lesion with soft tissue attenuation containing impacted teeth (arrows).

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Fig. 4. Postoperative OPG at one year, showing bone regeneration at the surgical sites (arrows).

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Fig. 5. Occlusal radiograph at the end of one year showing excellent bony architecture (A and B).

The specimens consisting of cystic sacs measuring approximately 12mm×10mm×8mm for the left and 9mm×8mm×6mm for the right side were submitted for histopathological examination. The cystic lining was attached at the cementoenamel junction of the involved teeth. Microscopic sections of both specimens were similar, showing cyst walls composed of fibrous tissue and lined by stratified squamous, non-keratinized epithelium which was 2–4 cell layers in thickness. The superficial cystic capsule was delicate to dense at places and was infiltrated with chronic inflammatory cells. The deeper cystic capsule was made up of condensed collagen and exhibited few chronic inflammatory cells. Few small islands or cords of inactive appearing odontogenic islands were present in the fibrous wall (Fig. 6). The clinical, intraoperative and histopathological findings lead to a final diagnosis of dentigerous cysts.

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Fig. 6. Photomicrograph showing thin cystic wall with non-keratinizing squamous epithelium (arrow-A) overlying the non-inflamed fibrous stroma (arrow-B) H&E ×40.

3. Discussion 

Dentigerous cysts are benign odontogenic cysts that arise from the dental follicle of an unerupted or developing tooth [9]. These involve impacted, unerupted permanent teeth, supernumerary teeth, odontomas, and, rarely, deciduous teeth. In 75% of the cases, they are located in the mandible [1], [7], [10]. The most frequently involved teeth are the mandibular third molars and maxillary canines [2], [7]. Peak incidence is in the second and third decades. Dentigerous cysts are usually painless but may cause facial swelling and delayed tooth eruption. Although these cysts commonly present as solitary lesions, bilateral and multiple cysts have been reported in patients with systemic conditions like chicken pox [3] and syndromes such as, cleidocranial dysplasia [5], Maroteaux-Lawy [6] and basal cell nevus syndromes [7]. Prolonged concurrent use of cyclosporine A and amlodipine: a calcium channel blocker, in a patient with renal transplantation has also been reported to induce the development of bilateral dentigerous cysts [11]. Asymptomatic in majority of the cases, these cysts might become painful with infection, likewise reported in a case with Serratia infection [12] or produce signs of nerve compression, i.e. numbness and paresthesia [13]. Though the mandible has been the predominant (89%) site for the reported bilateral dentigerous cysts in nonsyndromic patients, Norris et al. [3] and Freitas et al. [4] reported multiple dentigerous cysts involving both the maxilla and the mandible. Henefer [8] reported a case of bilateral dentigerous cysts involving the maxillary third molar teeth.

As with our case, nearly one third (33%) of the patients were under twelve year and presented with painless facial swelling. To our knowledge, there has been a single report of nonsyndromic bilateral maxillary cysts, involving the canines till date [7]. However, in our case these cysts were associated with the right maxillary central incisor and the left maxillary canine. While the maxillary canine has been known to be frequently implicated with dentigerous cysts, the incidence of maxillary right central incisor involvement is unusual and is reported at 0.1–0.6% to 1.5% [14], [15].

On radiographic examination, dentigerous cysts appear as unilocular radiolucent cysts of varying sizes, with well-defined sclerotic borders, associated with the crown of an unerupted tooth [10], [16]. If a follicular space on the radiograph is more than 5mm, an odontogenic cyst can be suspected [2]. Other odontogenic cysts like radicular cysts, odontogenic keratocysts, and odontogenic tumors such as ameloblastoma, Pindborg tumor, odontoma, odontogenic fibroma, and cemetomas may share the same radiologic features as dentigerous cysts [10], [16].

Radicular cysts are odontogenic cysts that develop from a periapical granuloma in a carious tooth. Odontogenic keratocysts are often multilocular and most commonly located in the body or the ramus of the mandible. Ameloblastoma is the most common radiolucent, benign odontogenic tumor that may be unilocular or multilocular. It may cause expansion and destruction of the maxilla and mandible. Pindborg tumors are rare odontogenic tumors that are radiolucent with well-defined borders and associated calcified radiopaque foci. Odontomas and cementomas are lytic lesions most often accompanied by amorphous calcification. Odontogenic fibromyxoma usually has multiple radiolucent areas of varying size and bony septations, but unilocular lesions have also been described [7].

The role of CT (computerized tomography) imaging in evaluation of cystic lesions has been well-documented [17]. CT imaging helps to rule out solid and fibroosseous lesions, displays bony detail, and gives exact information about the size, origin, content, and relationships of the lesions. In the maxilla, dentigerous cysts may be destructive and may occupy the maxillary sinus; nasal cavities and even orbital encroachment may be observed.

The value of early diagnosis and removal of dentigerous cysts should be emphasized. One important reason for taking prompt action is to ensure elimination of the cystic lining, which might allow for the formation of aggressive lesions. Mourshed [18] showed that 33% of ameloblastomas arose from the epithelial lining of a dentigerous cyst. Also, the cystic lining may infrequently develop into squamous cell carcinoma or mucoepidermoid carcinoma [19]. The cysts may cause fractures and become secondarily infected. Dentigerous cysts have also occasionally caused pain, numbness, and paresthesia. Other studies have shown that impingement of the maxillary variant on the orbital floor can cause diplopia and possibly even blindness [20]. Associated aneurysmal bone cysts and hemangiomas have been reported in rare instances [16].

A dentigerous cyst associated with an anterior tooth will result in failure of eruption of the tooth and therefore lead to esthetic and orthodontic problems. Absence of the anterior teeth can have an impact on the psychology of the child [15]. A functional space maintainer later replaced by endosseous implants can lead to a successful functional and esthetic rehabilitation.

Surgical excision and pathologic analysis of the lesion is essential for the definitive diagnosis. Smaller lesions should be enucleated to prevent damage to the involved permanent teeth. Larger lesions may be decompressed and marsupialized to relieve the pressure within the cysts followed by enucleation when the size has decreased [1] also known as the Waldron's procedure. Following complete removal, dentigerous cysts are known to recur very rarely. This is related to the exhausted nature of the reduced enamel epithelium, which has differentiated and formed tooth crown enamel before becoming a cyst [9].