|Year : 2008 | Volume
| Issue : 4 | Page : 141-145
Dentigerous cyst associated with a maxillary permanent lateral incisor: Case report and literature review
BK Ramnarayan, M Manjunath
Department of Oral Medicine and Radiology, V. S. Dental College and Hospital, K. R. Road, V. V. Puram, Bangalore, Karnataka, India
|Date of Web Publication||18-Jun-2009|
B K Ramnarayan
Department of Oral Medicine and Radiology, Dayananda Sagar college of dental sciences, Kumarswamy Layout, Bangalore-560078
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Trauma to deciduous teeth can have severe consequences. Dentigerous cysts are common developmental odontogenic cysts of the jaws. They are associated with the crown of an unerupted/impacted or developing tooth. Reported cases most commonly involve mandibular third molars and maxillary canines. They rarely involve the incisors. The condition occurs predominantly in the second and third decades of life. We report a case of dentigerous cyst involving the permanent maxillary lateral incisor, which developed as a consequence to trauma to the deciduous predecessor. The pathogenesis and clinical and radiologic features are discussed.
Keywords: Cyst, dentigerous cyst, impacted teeth, lateral incisor, unerupted teeth
|How to cite this article:|
Ramnarayan B K, Manjunath M. Dentigerous cyst associated with a maxillary permanent lateral incisor: Case report and literature review. J Indian Acad Oral Med Radiol 2008;20:141-5
|How to cite this URL:|
Ramnarayan B K, Manjunath M. Dentigerous cyst associated with a maxillary permanent lateral incisor: Case report and literature review. J Indian Acad Oral Med Radiol [serial online] 2008 [cited 2020 Jan 25];20:141-5. Available from: http://www.jiaomr.in/text.asp?2008/20/4/141/52829
| Introduction|| |
Dentigerous simply means 'containing teeth'.  Dentigerous cysts are most common benign odontogenic cysts of developmental type that are usually single in occurrence. However multiple dentigerous cysts are also reported.  They are generally associated with an impacted tooth and develop after the complete formation of the crown.  They most commonly involve the mandibular third molars or the maxillary canine, followed by the mandibular premolars. The involvement of incisors is rare. Males are more commonly affected than females. The condition may occur at any age, but the greatest incidence is reported in the second and third decades of life.
A dentigerous cyst is one which encloses the crown of an unerupted tooth by expansion of its follicle and is attached to the neck. It is important that this definition is strictly applied and the diagnosis of a dentigerous cyst is not made uncritically on radiographic evidence alone; otherwise, keratocyst of the envelopmental variety, follicular keratocyst and unilocular ameloblastoma involving the adjacent unerupted teeth are liable to get misdiagnosed.  The classification by the World Health Organization of epithelial cysts related to odontogenic apparatus refers to the dentigerous or follicular cyst as an epithelial developmental odontogenic cyst. 
The diagnostic hypothesis of a dentigerous cyst depends on a correct radiological examination of the space between the dental crown and the folliculus, as well as on the identification of such a space during surgery.  The final diagnosis is possible after histopathological examination.
This article reports a case of a dentigerous cyst in an 8-year- old boy, involving an unerupted maxillary lateral incisor.
| Case Report|| |
A young boy aged about eight years presented with a chief complaint (as told by the child's father) of swelling in the left upper front region of the face, of two months' duration. It was initially small, but gradually increased in size. The swelling was associated with occasional dull pain (on pressure).
There was history of trauma, i.e. he had had a fall two years ago. He had bleeding from the upper front teeth region. Four months later the deciduous tooth (61) exfoliated. The permanent tooth which erupted six months later was displaced. The patient also gave a history of difficulty in breathing, since the swelling developed.
General examination showed the boy to be apparently healthy with normal growth and development for his age. He had gross asymmetry of the face due to the swelling on the left side. Single left submandibular lymph node, oval in shape measuring about 1.5 cm, was palpable, mobile and non tender. Extra oral examination showed a diffuse swelling measuring about 3 × 4 cm, extending from the midline and left lateral wall of the nose, mildly obliterating the naso-labial fold and philtrum of the lip to about 1 cm inferior to the infraorbital margin and outer canthus of the eye. Mild obliteration of left nares was observed, as also incompetent lips. Swelling was mildly tender, hard in consistency [Figure 1].
Intra-oral examination revealed a well-defined swelling, both palatal and buccal, to 21, 62, 63, 64, with expansion of cortical pates. Buccally, the swelling measured about 5 × 3 cms, obliterated the labial vestibule and raised the upper lip. The overlying mucosa showed a bluish discoloration in the region of 62. Palatally, the swelling extended to the midline of the palate and measured 2.5 × 3 cms. Swelling was hard in consistency, except with respect to 62 on the buccal aspect, where it was soft. The swelling was mildly tender, margins were well defined. There were no visible or palpable pulsations. 62, 63 were mobile. Associated teeth were non tender. Midline diastema, extruded and distally displaced 21 was present. There was spacing between 21, 62, and 63. Eruption was observed at 12; however 22 had not erupted at the time of examination [Figure 2] and [Figure 3].
Based on the history and clinical examination, a provisional diagnosis of radicular cyst involving 62, 63 was established. Differential diagnosis of dentigerous cyst involving 22, adenomatoid odontogenic tumor, unicystic ameloblastoma, traumatic bone cyst, aneurysmal bone cyst, calcifying odontogenic cyst, and odontogenic myxoma were considered.
Radiographs were advised. IOPA and Occlusal radiograph [Figure 4] and [Figure 5] showed an unerupted 22. Unilocular well defined radiolucency involving the crown of 22 was noted. Mesially displaced and extruded 21 was found. The panoramic radiograph showed the developing tooth bud of 23 to be superiorly displaced to near the floor of the orbit. Routine blood investigations were within normal limits. Aspiration of the lesion yielded a straw colored cystic fluid. Cytologic examination showed needle shaped cholesterol crystals. Under Hematoxyllin and Eosin (H&E) smear, inflammatory cells and RBCs were seen. Under general anesthesia, complete enucleation of the cyst was done with extraction of 62 and displaced 23 [Figure 6] and [Figure 7]. Considering the patient's age and the fact that it had a favorable path of eruption, 22 was retained.
The enucleated specimen was sent for histopathological examination, which under H/E stain showed 2-3 layers of flattened epithelium resembling reduced enamel epithelium. Connective tissue showed dense collagen fibers and dense inflammatory infiltrate of predominantly lymphocytes and plasma cells. Areas of hemorrhage were also seen in the connective tissue [Figure 8].
Correlating the clinical, radiological and histopathological features, a final diagnosis of dentigerous cyst involving 22 was established. Follow-up after a month showed that the swelling had resolved and healing was satisfactory, with erupting 22 [Figure 9]. Panoramic radiograph showed formation of bone with trabeculation, suggestive of bony healing [Figure 10]. Further orthodontic management was planned for the displaced and extruded teeth.
| Discussion|| |
Dentigerous cyst is a cyst arising by separation of the follicle from around the anatomical crown of an unerupted tooth within the jaws.  It is the second most common odontogenic cyst , and represents 33% of all odontogenic cysts.  Its frequency in the general population has been estimated at 1.44 cysts for every 100 unerupted teeth.  Though present in the first decade of life, it is more common in the second and third decades of life. ,, It has a slight male prediction. [4,6] Studies by Shear showed that 62% of the subjects studied were males and 38% females, with a ratio of 1.6: 1.  Whites were more commonly affected than blacks, with a ratio 4.7:1. 
Cysts involve impacted, unerupted permanent teeth, supernumerary teeth, odontomes and, rarely, deciduous teeth.  Seventy five percent of the cases are located in the mandible.  They are most commonly reported in the mandibular third molar, maxillary canine, mandibular premolar and maxillary third molar, in that order. The involvement of incisors is very rare. , Studies by Shear  have shown an incidence of 1.6% involving the lateral incisors, as compared to 45.9% involving the mandibular third molars. A study by Mourshed has reported that 1.44% of impacted teeth may undergo dentigerous cyst transformation.  Hence, the involvement of lateral incisors is rare. Studies by Daley and Wysocki have reported 0.1%, and by Bernick 2.1%. 
Pathogenesis is still controversial. Various hypotheses have been suggested. Shear  advocates an Intra follicular theory in the development of dentigerous cyst, wherein he presumes that it starts with the accumulation of fluid between the reduced enamel epithelium and the enamel, or between the layers of reduced enamel epithelium and enamel. Al-Talabani and Smith suggested two types of dentigerous cyst, with different causes arising at different stages of tooth development. 1) Degeneration of the stellate reticulum at an early stage of development, associated with enamel hypoplasia. 2) Development after crown completion by accumulation of fluid between layers of reduced enamel epithelium (REE), hypoplasia is not common. 
Another theory advocated by Benn and Main in their study is that inflammation at the apex of a deciduous tooth can lead to the development of an inflammatory follicular cyst around the permanent teeth.  Toller postulated that follicular proliferation occurs, which would eventually lead to impaction; however, the induction of proliferation is not known. Killian et al. , postulate that trauma to the deciduous teeth leads to disturbances in the odontogenesis of the permanent teeth. This can usually give rise to hypoplastic defects, crown/root disruptions in permanent teeth and deviation from (N) eruption direction.
The case reported also has a history of trauma to the deciduous incisors. This could have caused proliferation of REE and the permanent tooth enamel to develop the cyst.  Another concept suggested by Shear and Lustmann is that the crown of the permanent teeth erupts into a radicular cyst of deciduous teeth. This phenomenon may occur, but is rare. A drawback is that such an erupting tooth may indent rather than penetrate.  The cyst develops between the REE and the crown of an unerupted tooth in certain cyst-prone individuals, and it is likely that a genetic factor contributes to the process; this is yet to be demonstrated at a molecular level. 
Regarding the development of cyst, Main (1970) suggested that pressure exerted by a potentially erupting tooth on an impacted follicle obstructs the venous outflow and thereby induces transudation of serum across capillary walls. Increase in hydrostatic pressure of this pooling fluid results in separation of follicle from the crown with or without REE. Capillary permeability is altered so as to permit the passage of greater percentage of protein. Immunoglobulins and immunoglobulin containing cells in the cyst wall may also play a role in fluid formation. 
Growth of cyst, presence of glycosaminoglycans (hyaluronic acid, heparin, chondroitin-4 sulphate) in the walls and fluids increase the osmolality of cyst fluid which leads to an increase in internal hydrostatic pressure which results in cyst expansion. Recent studies have shown presence of potent bone resorbing factors Prostaglandin E 2 (PGE 2 ) and Prostaglandin E 3 (PGE 3 ) bring about bone resorption and cyst expansion. 
Clinically, a small dentigerous cyst may be asymptomatic and may be discovered on routine examination. However, it can increase to potential size by expansion of bone and, rarely, bone destruction. Large cysts cause asymmetry of the face. Displacement of impacted teeth, adjacent teeth and root resorption is common.  Maxillary cysts may displace and obliterate maxillary antrum and nasal cavity. 
On a radiograph, it typically presents as a unilocular radiolucent area associated with the crown of unerupted teeth. , It is usually well-defined with sclerotic borders, though not always - an infected cyst may show ill-defined borders.  Radiographically, follicular space >2.5 mm is suggestive of fluid gathering.  Radiolucencies greater than 4 mm are to be considered cystic, until otherwise proven.  Depending on the crown-cyst relation, three variants have been described. 1) In the central variety the cyst surrounds the crown symmetrically and the crown projects into the cyst. The tooth may be pushed away from its direction of eruption. 2) The lateral variety is usually associated with mesio-angular impacted molars that have partially erupted and there is dilation of follicle on one aspect of the crown. (3) In the circumferential variety, the cyst surrounds the crown and extends for some distance along the root, so that a significant portion of the root appears to lie within the cyst. It has to be differentiated from the envelopmental type of keratocyst. 
In cases of extensive bony involvement and presence of a complex cystic lesion, a CT (computerized tomography) becomes necessary. It helps to rule out solid and fibro-osseous lesions, displays bony detail and gives exact information about the size, origin, content and relationship of the lesion with adjacent structures. An MRI (magnetic resonance imaging) may fail to show the bony detail but will precisely display the lesional contents and provide information about the cyst fluid. The cystic lesion appears homogeneously hypointense on T1-weighted images and hyperintense on T2-weighted images. 
Microscopic examination of the cyst shows a thin fibrous cyst wall, epithelial lining of 2-4 cell layers of flattened non-keratinizing cells - and epithelium-connective tissue interface is flat. Focal areas of the mucous cells may be seen in the epithelial lining; capsule/fibrous wall shows inflammatory cell infiltrate. 
Treatment basically consists of enucleation with removal of unerupted tooth. Enucleation of cyst with retainment of the involved teeth after the lining is carefully dissected is done in young individuals, where the eruption is favorable; marsupialization is done in case of large cyst. ,, Cysts rarely recur, except when the lining is not completely removed.  Metaplastic and dysplastic changes may occur. An ameloblastoma, mucoepidermoid carcinoma or squamous cell carcinoma may develop from the lining epithelium of the cyst. , Carcinoma arising from a dentigerous cyst is extremely rare. Gardner has put forward three criteria for the diagnosis of carcinoma arising from a dentigerous cyst: 1) a microscopic transition area from benign cystic epithelial lining to invasive malignant squamous cell carcinoma, 2) no carcinomatous change(s) in the overlying epithelium, and 3) no source of carcinoma in the adjacent structures. The average age of patients with carcinoma in a dentigerous cyst is 58.8 years, with a range from 25 to 84 years. 
Multiple dentigerous cysts have also been reported in the literature. They are reported in patients with syndromes like basal cell nevus syndrome,  mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome) and cleidocranial dysplasia. , Bilateral mandibular dentigerous cysts have been reported after prolonged concurrent use of cyclosporine and calcium channel blockers. 
| Conclusion|| |
Dentigerous cysts are one of the most common developmental odontogenic cysts, which are usually detected in routine radiographic examination. Developing dentigerous cysts are difficult to distinguish from normal follicle. Pericoronal radiolucencies greater than 4 mm are to be considered cystic, until proven otherwise.  Diagnosis requires an accurate radiographic image to be further confirmed by a histological examination. The radiographic image should identify the enhancement of the pericoronal space just around the crown of the impacted tooth and will complement the histological examination of the odontogenic cyst.  Daley and Wysocki have recommended the following guidelines for the diagnosis of a dentigerous cyst: 1) a pericoronal radiolucency >4 mm in greatest width, 2) histologically, fibrous tissue lined by nonkeratinized stratified squamous epithelium, and 3) a surgically demonstrable cystic space between the enamel and the overlying tissue. Of these, the third is the most critical, but all the three must be satisfied. 
| Acknowledgments|| |
Dr. T. K. Ramamurthy, Reader, Dr. T. A. Deepak, Senior Lecturer, Department of Oral Medicine and Radiology, and my colleagues.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10]