Pathology of the Head and Neck

Maxillofacial Skeleton and Teeth Chapter 4 117as those as already mentioned (see Sect. 4.4.3.1). Ameloblasticfibro-odontomas can be distinguished from ameloblastomasby the presence of cellular myxoid tissueand of dentin and enamel.Most cases of ameloblastic fibro-odontoma presentas painless swelling or are discovered due to disturbancesin tooth eruption. Radiographically, the tumourpresents as a well-demarcated expansive radiolucencywith a radiopaque centre. Treatment consistsof enucleation and curettage. Recurrence is rarely seen[46].Fig. 4.22. Ameloblastic fibro-odontoma combines the soft tissueelements of an ameloblastic fibroma with the deposition of thedental hard tissues enamel and dentin. Cavities in the homogeneouseosinophilic dentin contain high-columnar ameloblasts lyingdown enamel matrix (deep purple)Fig. 4.23. Panoramic radiograph showing radiodense mass inconnection with a tooth germ, a picture typical of complex odontomaAmeloblastic fibro-odontomas are rare [34, 127].They occur primarily within the first two decades andhave the posterior jaw areas as sites of predilection, themandible more often involved than the maxilla [118,153].The soft tissue component is identical to that of ameloblasticfibroma. Dentin may be formed either as eosinophilicmineralised material containing tubuli, justas in normal teeth, but it may also form as an homogeneouseosinophilic mass with sparse cells included.It always lies in close association with adjacent epitheliumand forms the scaffold for the deposition of enamelmatrix that is laid down at the epithelial–dentin interfaceby columnar epithelial cells that have reachedtheir terminal differentiation as ameloblasts. The dentalhard tissues are arranged haphazardly without any reminiscenceof the orderly structure characterising normalteeth (Fig. 4.22).Hyperplastic dental follicles may also show focal areaswith the appearance of ameloblastic fibro-odontoma.Differential diagnostic considerations are the same4.4.3.3 Odontoma –Complex TypeICD-O:9282/0Complex odontoma is a lesion composed of a haphazardconglomerate of dental hard tissues. This hamartoma isone of the more common odontogenic lesions [34, 127].The posterior mandible is the favoured site (Fig. 4.23).Ages at which this lesion occurs are difficult to determineas lesions may be present unnoticed for a longtime, the age distribution mentioned reflecting the agewhen the lesion was found rather than the age at whichit formed. This explains the enormous range in age distributionreported: 2–74 years [118].Complex odontomas consist of a usually well-delineatedmass of dental hard tissues in a haphazard arrangement.The bulk of the lesion consists of dentinrecognisable by the presence of tubuli. Enamel plays aminor role, usually confined to small rims in cavities inthe dentin mass. The stroma consists of mature fibrousconnective tissue.Sometimes, odontomas may contain areas identicalto the calcifying odontogenic cyst includingghost cells [22, 61, 80]. Odontoma-like structuresmay also occur in the hyperplastic dental follicle (seeSect. 4.4.2.1).Complex odontomas may reveal their existence bydisturbances in tooth eruption, missing teeth or jawexpansion. Quite often, they are incidental findings onradiographs taken for other purposes. In those cases,an amorphous calcified mass is seen that may be connectedwith the crown of an unerupted tooth. Treatmentconsists of conservative removal. Recurrences arenot seen.4.4.3.4 Odontoma –Compound TypeICD-O:9281/0Compound odontoma is a malformation consistingof tiny teeth that may vary in number from only a fewto numerous. These teeth do not resemble the normal