Odontoma is a benign odontogenic tumor of developmental origin first described by Paul Broca in 1867. It is a hamartomatous tumor resulting from the growth of completely differentiated epithelium and mesenchymal cells that give rise to ameloblast and odontoblast. These tumors are made up of enamel and dentin, but they can also have the inconsistent amount of pulp tissue. Odontomas in most cases are asymptomatic and rarely require any kind of intervention. Two-dimensional imaging of these entities usually does not give a complete picture, especially the mediolateral dimension and their proximity to vital structures. Assessment of the relationship of these masses to vital structures such as inferior alveolar nerve canal, mental foramen, incisive canal and nerve, maxillary sinus, and adjacent teeth can be challenging using conventional periapical and panoramic radiographs.,, The role of three-dimensional (3D) imaging such as cone beam computed tomography (CBCT) in such cases is invaluable as it substantiates diagnosis and increases operator confidence and the overall safety margin of the treatment procedure all at a fraction of the radiation dosage of a CT scan. In this report, we would like to emphasize the validation of advanced imaging even in cases that appear straightforward as it could be the difference between a complete cure and permanent morbidity as a treatment outcome.
A 39-year-old female patient reported with a complaint of pain in her left temporomandibular joint (TMJ) region. Following a thorough clinical examination, the patient was advised a panoramic radiograph to rule out any osseous change involving the TMJ. The panoramic image showed no bony remodeling in the TMJ region but revealed a well-defined radiopaque mass within the body of the mandible on the left side in the region of missing 36 and 37, extracted before 2 years due to mobility, surrounded by a radiolucent rim [Figure 1]. The mass appeared to extend close to the superior border of the mandibular canal. A provisional diagnosis of complex odontome was agreed on and following consultation with maxillofacial surgeons, and considering the benign appearance of the mass, it was best deemed fit to leave the mass untouched, with only periodic recall and review of the site. The patient reported after 3 months and expressed a desire to replace missing lower left posterior teeth. CBCT of maxilla and mandible was advised to assess if the radiopaque mass was operable and also for qualitative and quantitative assessment of bone for implant planning in the edentulous sites.
An inhomogeneous radiopaque mass of varying density was noted in the molar region on the left side of the mandible measuring 28.7 mm anteroposteriorly, 13 mm superoinferiorly, and 9.4 mm buccolingually at its maximum dimensions. The radiopaque mass was located immediately beneath the crest of the alveolar ridge causing some superior bowing of the ridge in relation to missing 37 closer to the buccal cortical plate. The conglomerate mass was well defined and clearly demarcated from the adjoining normal bone. A distinct radiolucency was seen bordering the entire mass indicative of a soft tissue capsule, best visualized in the tangential sagittal sections [Figure 2]. The actual extent of the lesion was significantly larger than the size of the mass initially noted on the digital orthopantomogram; anteriorly, the mass was less dense than the posterior segment indicating varying stages of differentiation within the same lesion [Figure 3] and [Figure 4].
Indentations of the buccal cortical plate were noted with mild expansion of the buccal and lingual cortices. On comparison with the cortex on the opposite, an expansion of 1.8 mm was noted [Figure 5]. At its inferior most convexity, the mass was approximating the superior border of the inferior alveolar canal and approximately 7 mm above the lower border of the mandible.
A radiographic differential diagnosis of complex odontome and periapical cemental dysplasia (remnant postextraction of 37) was arrived at. Osteoid osteoma, calcifying epithelial odontogenic tumor, cemental dysplasia, cementoblastoma, ameloblastic fibro-odontoma, odontoameloblastoma, and cemento-ossifying fibroma were the differentials taken into consideration.
Following adequate localization of the mass, a left mandibular nerve block using 2 ml of lignocaine with 1:100,000 dilution adrenaline was given, local buccal infiltrations were also given, site was entered using a crestal incision, and mucoperiosteal flaps were opened. Roughly, 1 mm of crestal bone was removed enabling visualization of the mass which was found to be more dense and yellowish in comparison with the surrounding bone. The mass was quite tenaciously adherent to the surrounding bone, additional bone guttering was performed, and retention slots (undercuts) were prepared on the anterior portion of the mass which was engaged with the beak of a cryer, rotational movements using the cryer gently elevated and separated the mass from the surrounding bone [Figure 6]. The flap was then repositioned and sutured with 3-0 silk sutures.
Examination of decalcified sections of the excised mass revealed a mineralized tissue with the presence of disorganized dentinal tubules, areas, and lines of basophilic deposition similar to dental cementum and hyaline material of prismatic structure corresponding to enamel matrix. In addition, cavities sometimes contained loose connective tissues resembling the dental papilla were noted [Figure 7] and [Figure 8]. The features were suggestive of complex odontome.
The patient was recalled after 1 week for suture removal and was assessed to be asymptomatic, 3-month recall of patient also found the patient to be asymptomatic with no evidence of sensory loss or paresthesia and a well-healed-rounded edentulous ridge.
Odontomas are benign tumors which contain various component tissues of the teeth, and they are the most common odontogenic tumors which constitute 22% of all the odontogenic tumors of the jaws. There are two types of odontomas, complex odontomas and compound odontomas – the latter being twice as frequent as the former. Compound odontomas show a predilection in the anterior section of the upper maxilla, while complex odontomas are typically found in the posterior mandibular region, the present case conforms to this pattern.
Compound odontoma is composed of agglomerated tooth-like structures, so-called denticles, while complex odontoma is formed by an irregular mass where tissues are present in a more or less disorderly pattern as seen in this case.
The WHO classification defines complex odontome as follows: “A malformation in which all the dental tissues are represented, individual tissues being mainly well formed but occurring in a more or less disorderly pattern.” The etiology of complex odontomas is unknown. Several theories have been proposed, including local trauma, infection, family history, and genetic mutation as in Gardener's and Harmann's syndrome., It has been suggested that odontomas are inherited from a mutant gene or interference, possibly postnatal with the genetic control of tooth development. Chen et al. suggested that the two variants of odontomas seem to be pathogenetically different. The complex odontoma, having an expected higher age at the time of diagnosis and a predilection for the posterior mandible regions, may be considered the terminal stage of hamartomatous lesions, whereas compound odontomas may be the result of multiple schizodontia because of a local hyperactivity of the dental lamina.
The relative frequency of complex odontome among odontogenic tumors varies between 5% and 30%. The majority of cases (83.9%) occurs before the age of 30 with a peak in the second decade of life, <10% of them are found in patients over 40 years of age.
Complex odontomas are usually asymptomatic and are associated with changes such as malformation, impaction, delayed eruption, malposition, cyst formation, displacement, resorption, or devitalization of the adjacent teeth, and expansion of the cortical plate, this expansion though minute could be identified on CBCT cross-sectional planes. Symptoms that may be present include numbness in the lower lip, frontal headaches, swelling in the affected areas, and facial asymmetry, none of which were present in our case. In the present case given, the history of existing teeth being extracted before 2 years due to mobility and the eventual location of the mass just beneath the ridge causing some superior bowing of it, when it was discovered, is suggestive that the mass had the propensity to erupt and would possibly have if left untreated.
Odontomas are occasionally identified during routine radiographic examinations. In some situations, the diagnosis of these lesions using radiographic images is challenging because of the presence of several anatomical structures.
Panoramic radiography can be used for the detection of odontomas, but it cannot give enough information for the management and treatment planning; hence, CBCT is the better imaging method to evaluate this type of masses for the management and treatment planning. CBCT provides several advantages regarding diagnosis and treatment planning because of its capacity to enable the 3D multiplanar reconstruction of the scanned site. With the aid of specific software and according to protocols based on individual requirements, the digital volume may be converted into images in three planes of sections: axial, sagittal, and coronal, making the visualization of the anatomical structures possible from all viewpoints. The software tools facilitate the creation of reports and diagnosis, enabling the measurements related to bone structures and soft tissues assessments.
The radiological appearance of complex odontomas depends on their development stage and degree of mineralization. The first stage is characterized by radiolucency due to a lack of calcification. Partial calcification is observed in the intermediate stage, while in the third stage, the lesion usually appears radiopaque with amorphous masses of the dental hard tissue surrounded by a thin radiolucent zone corresponding to the connective capsule histologically.
In this case, qualitative assessment of the sections showed that the posterior segment was more radiopaque with amorphous masses of dental hard tissue and a radiolucent zone surrounding the lesion, while the anterior smaller portion was less dense in comparison and could only be identified on the CBCT sections; hence, the present lesion was considered to be an intermediary stage between partially and completely mature.
The use of CBCT scans in the diagnosis of maxillofacial pathology, especially mandibular, is imperative as previously the surgeons used to rely on panoramic radiographic signs such as narrowing or diversion of mandibular canal and degree of interruption of white lines outlining the mandibular canal to assess the proximity of mandibular canal to an entity. The associated incidence of damage to the mandibular canal was as high as 8% which can significantly hamper quality of life and is unacceptable, especially when a low radiation dose imaging modality can significantly reduce this risk. CBCT can also be used to evaluate the size and contour of pre- or post-operative deformities and thus help in determining the volume of bone necessary for reconstructive procedures.
It also allows generation of images of all conventional radiographs used in dentistry as per the requirement of the interpreter into panoramic, periapical, bitewing, occlusal radiographs, and lateral and frontal cephalograms.
The degree of opacity, location, well-defined border, and zone of lucency differentiate complex odontomas from other opaque lesions within the jaw. The lesions that may share radiographical features with complex odontomas include cementoblastoma, osteoid osteomas, cemento-ossifying fibromas, and focal cemento-osseous dysplasias.
In this case report, CBCT analysis enabled an accurate diagnosis, treatment planning, and additional qualitative and quantitative assessment for the future implant planning at the edentulous site.
The surgical treatment consists of complete enucleation and curettage of the lesion and the surrounding area. Recurrence is occasional but uncommon. A careful histological and radiographical examination of these tumors is necessary because these lesions may resemble a much more aggressive neoplasm, the odontoameloblastoma.
Conventional images for the evaluation of the structures of the maxillofacial complex are often inconclusive, and additional radiographic evaluation is necessary. CBCT is an important auxiliary tool in the case reported here, aiding a correct diagnosis, accurate treatment planning, and therefore prevents a possible neoplastic transformation or a second surgical procedure.
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