Pathology of the Head and Neck

106 P.J. Slootweg4Fig. 4.4. Epithelial lining of a radicular cyst containing manyRushton bodiesFig. 4.5. Cyst lining composed of squamous as well as mucous epithelium.This can be found in radicular cysts as well as in dentigerousor residual cysts4.3.1.2 Paradental CystThe paradental cyst is located on the lateral side of thetooth at the border between the enamel and root cementum.This cyst is secondary to an inflammatory processin the adjacent periodontal tissues that induces proliferationof neighbouring odontogenic epithelial rests, similarto the pathogenesis of the radicular cyst [88]. Histologically,it resembles the other inflammatory odontogeniccysts, the distinction being made by the specificclinical presentation. It is a rare lesion [128]. Treatmentconsists of excision with or without concomitant extractionof the involved tooth [45].4.3.2 Odontogenic Cysts –Developmental4.3.2.1 Dentigerous CystA dentigerous cyst surrounds the crown of an uneruptedtooth, mostly the maxillary canine or the mandibularthird molar tooth (Fig. 4.3). They are quite common.The cyst wall has a thin epithelial lining that maybe only two to three cells thick. In case of inflammation,the epithelium becomes thicker and will showfeatures similar to the lining of a radicular cyst. Also,mucous-producing cells as well as ciliated cells maybe observed (Fig. 4.6). The connective tissue componentof the cyst wall may be fibrous or fibromyxomatous.The cyst wall may also contain varying amountsof epithelial nests representing remnants of the dentallamina.Radiologically, a lot of jaw diseases associated withunerupted teeth may have an appearance similar to thatof a dentigerous cyst. Histologic examination, however,will be decisive in ruling out these possibilities amongFig. 4.6. Lining of a dentigerous cyst mainly composed of mucouscellswhich keratocyst and unicystic ameloblastoma (seeSects. 4.3.2.4 and 4.4.1.1) are the most prevalent. Moreover,the radiologic picture of the dentigerous cyst maybe mimicked by hyperplasia of the dental follicle, theconnective tissue capsule that surrounds the uneruptedtooth [33].Fibromyxomatous areas in the connective tissue wallof the dentigerous cyst may resemble the odontogenicmyxoma (see Sect. 4.4.2.1). The presence of odontogenicepithelial rests may lead to the erroneous diagnosisof one or another type of epithelial odontogenic tumour[71]. However, identification of the epithelial cyst liningwill rule out these alternatives.In most instances, dentigerous cysts are a fortuitousfinding on oral radiographs. Only when excessively largemay they cause swelling of the involved part of the jaw.If there is inflammation, they will cause pain and swelling.Removal of the cyst wall and the tooth involved willyield a permanent cure.The eruption cyst is a specific type of dentigerous cystlocated in the gingival soft tissues overlying the crown