Characteristics, Diagnosis and Treatment of Compound Odontoma Associated with Impacted Teeth

Compound odontoma is a malformation typical of young adults below the age of 20, with a slight preference for the male gender and the anterior region of the maxilla. Clinically asymptomatic, it can be detected during a radiological investigation in connection with the persistence of deciduous dental elements and the impaction of definitive ones. The treatment of choice is excisional surgery and recurrence is a rare event. The need for orthodontic therapy for impacted elements is usually not necessary because in most cases, odontomas are small, circumscribed lesions the size of a permanent tooth. In this article, the diagnostic and therapeutic surgical excision procedure is presented in three patients at developmental age with large compound odontomas associated with at least one retained canine, and in two of the cases, with serious transmigration to the impacted tooth elements.


Introduction
Odontomas are hamartomatous developmental malformations of the dental tissues [1]. According to the World Health Organization (WHO), a compound odontoma is defined as "a malformation in which all dental tissues are represented in a more orderly pattern than in the complex odontoma, so that the lesion contains many tooth-like structures. Most of these structures do not morphologically resemble the teeth in the normal dentition; however, enamel, dentin, cementum and pulp are arranged as in the normal tooth" [2,3].
Odontomas are developmental anomalies consequential to the growth of totally differentiated epithelial and mesenchymal cells that generate ameloblasts and odontoblasts [4]. These cells and tissues can look either normal or not fully developed in structure. The level of differentiation in the formed tissues can be variable, and both enamel, dentin, cementum, and pulp may be present within the compound odontoma [3]. The complex odontomas are characterized by non-descript masses of dental tissues, while compound odontomas by multiple, well-formed tooth-like structures [3].
Typically asymptomatic, they are revealed on routine radiographs or upon assessing the origin of delayed tooth eruption [1,[5][6][7][8]. Radiographically, depending on the development stage, they may appear as radiolucent in the initial phase and as a radiopaque form at progressive stages [5]. The diagnosis is based on clinical examination and radiographic images, and following surgical removal, it must be further confirmed by histological examination. Differential diagnosis is made with all other ossified bone lesions, such as ossifying fibroma, odontoameloblastoma, ameloblastic fibroma or fibro odontoma, osteoma and fibrous dysplasia; or florid osseous dysplasia [5] to decide the most appropriate treatment [9].   overlapping presence of a compound odontoma, which in its evolution blocked the eruption of the corresponding permanent canine; (B) A cross-section image highlights the permanent canine that has been displaced vestibular due to the presence of an odontoma that is palatal to the canine; (C,D) Parasagittal images that show that the odontoma completely occupies the entire thickness of the bone between the buccal and palatal cortex. Absence of bone trabeculae and displacement of the permanent canine towards the vestibulum.       (C) various fragments of the removed odontoma are recognizable, the neoformation is organized in variously cusped denticles. The structures of the compound odontoma with crowns and roots are recognizable.

Case Number 2
The second clinical case concerns a 14-year-old male patient who was referred for consultation to our paediatric oral surgery unit. The patient was operated on in November 2021 ( Figures 5-8). The diagnosis of odontoma was made in conjunction with routine radiographic control, motivated by the lack of teeth 32 and 33 in the dental arch.

Case Number 2
The second clinical case concerns a 14-year-old male patient who was referred for consultation to our paediatric oral surgery unit. The patient was operated on in November 2021 ( Figures 5-8). The diagnosis of odontoma was made in conjunction with routine radiographic control, motivated by the lack of teeth 32 and 33 in the dental arch.   During the surgical phase, the emergence of the nerve is highlighted in order to ensure its preservation. It is again possible to highlight the denticles; they are arranged with various degrees of angulation. The whole odontoma is positioned superiorly with respect to the permanent canine, which is in the inferior portion of the mandible; (B) The presence of the neoformation in the bone structure of the mandible. The vestibular cortex is thinned, absent in some places; (C) Axial slices showing lesion-thinning cortical plates and the compound odontoma occupying the entire sagittal thickness of the mandible in the upper part. Visible are the tooth-like structures, some fused together, others not fused, with different sizes. Canine 33 and lateral incisor 32 have been moved towards the mandibular caudal cortex in a more horizontal position, certainly raised by canine 33, presenting with hyperplastic dental follicle.
R PEER REVIEW 7 of 14 Figure 6. Series of images from cone beam computed tomography (CBCT). (A) The localization of the neoformation is anterior to the emergence of the mandibular nerve, which is at the level of element 34. During the surgical phase, the emergence of the nerve is highlighted in order to ensure its preservation. It is again possible to highlight the denticles; they are arranged with various degrees of angulation. The whole odontoma is positioned superiorly with respect to the permanent canine, which is in the inferior portion of the mandible; (B) The presence of the neoformation in the bone structure of the mandible. The vestibular cortex is thinned, absent in some places; (C) Axial slices showing lesion-thinning cortical plates and the compound odontoma occupying the entire sagittal thickness of the mandible in the upper part. Visible are the tooth-like structures, some fused together, others not fused, with different sizes. Canine 33 and lateral incisor 32 have been moved towards the mandibular caudal cortex in a more horizontal position, certainly raised by canine 33, presenting with hyperplastic dental follicle.

Case Number 3
The third case presented here is that of a 15-year-old male patient. The surgery was performed in July 2021 (Figures 9-13).  consisting of an ensemble of calcified structures, some like mini-teeth, some denticles appear as single-rooted, others as multi-rooted, some even fused, with no complete root formation and enamel, dentin, and cement being identified as dental tissues. (D) The orthopanoramic image after 6 months showing the progressive reconstruction of the bone anatomy of the area. The odontoma resulted in both dislocation and subsequent inclusion of 32 and 33, but also caused root displacement of 31, 41, and 34. Any type of orthodontic therapy is postponed; not only is bone formation required at all the entire area resulting from the surgical removal of the odontoma, but it is also necessary to check the vitality of the dental elements adjacent to the area itself.

Case Number 3
The third case presented here is that of a 15-year-old male patient. The surgery was performed in July 2021 (Figures 9-13).

Case Number 3
The third case presented here is that of a 15-year-old male patient. The surgery was performed in July 2021 (Figures 9-13).     The crown is fully exposed; (D-E) To make it possible to extract the impacted canine, the tooth is cut, then the crown is extracted first and then the root; (F) After completing the extraction, the residual bone cavity and dental structure, if visible, is analysed. In this case, the root apex of 41 is visible and the vitality of this tooth will be evaluated during the   The crown is fully exposed; (D-E) To make it possible to extract the impacted canine, the tooth is cut, then the crown is extracted first and then the root; (F) After completing the extraction, the residual bone cavity and dental structure, if visible, is analysed. In this case, the root apex of 41 is visible and the vitality of this tooth will be evaluated during the   The crown is fully exposed; (D-E) To make it possible to extract the impacted canine, the tooth is cut, then the crown is extracted first and then the root; (F) After completing the extraction, the residual bone cavity and dental structure, if visible, is analysed. In this case, the root apex of 41 is visible and the vitality of this tooth will be evaluated during the the tooth is cut, then the crown is extracted first and then the root; (F) After completing the extraction, the residual bone cavity and dental structure, if visible, is analysed. In this case, the root apex of 41 is visible and the vitality of this tooth will be evaluated during the follow-up; (G) The denticles of the odontoma begin to be exposed. In this case, there are only 4 single neoformations positioned in the bone structure and detached from each other, thus being even more difficult to find because they were not all four fused together.
R PEER REVIEW 10 follow-up; (G) The denticles of the odontoma begin to be exposed. In this case, there are o single neoformations positioned in the bone structure and detached from each other, thus even more difficult to find because they were not all four fused together.
The studies included (Table 1) in the present review of the literature were publi between 2002 and 2015. The total sample size of the analysed odontomas was 1279 (ra 11-163). All cases were given the subclassifications of complex or compound odont and the ratio was 1:0.92. No gender predilection was seen in the overall sample, wher male to female ratio was 1:0.98. Information on the management of the involved could not be obtained, as there were not available reports.

Author
Year Analysed Odontomas Compound Complex Female M
The studies included (Table 1) in the present review of the literature were published between 2002 and 2015. The total sample size of the analysed odontomas was 1279 (range: 11-163). All cases were given the subclassifications of complex or compound odontoma, and the ratio was 1:0.92. No gender predilection was seen in the overall sample, where the male to female ratio was 1:0.98. Information on the management of the involved teeth could not be obtained, as there were not available reports.

Discussion
Compound odontoma is a benign odontogenic tumour and it is usually diagnosed in young adults during regular radiological examination performed to assess the reason of a missing or mispositioned tooth in permanent dentition [33].
At the clinical level, compound odontoma can often be associated with anterior teeth misalignment and tooth eruption disorders, with possible impaction and delayed tooth eruption. One quarter of patients are asymptomatic, but compound odontoma can also be characterized by pain (13.3%) and swelling (8.9%) [34]. The preferred localization of compound odontomas is the anterior maxilla (81.8%) [33].
Surgical removal is the usual treatment and recurrence is rare [35].
In the clinical cases presented here, it was possible to refer the patient for orthodontic treatment of the impacted canine only in the first case, when the inclusion concerned the upper left canine. In this case, the odontoma blocked the physiological eruption of the canine, but did not cause it to be misaligned. In fact, the canine position was vertical, even if slightly vestibular, placed above the odontoma.
In the remaining two cases, the position of the odontoma was in the front part of the mandible and was associated with the inclusion of the canine, which was unfavourable for orthodontic treatment. In fact, in both cases, we proceeded with both the surgical enucleation of the odontoma and the extraction of the impacted canine, and in one case, also the extraction of the lateral impacted transmigrated incisor. In both cases, the large volume occupied by the odontoma, and late diagnosis certainly contributed to the displacement of the canine from its physiological site towards the mesial position, almost completely horizontal towards the bottom of the mandible on the inferior cortex, in line with the entire symphysis area of the chin.
This type of tooth displacement is called transmigration. Transmigration most commonly concerns the permanent canines and is characterized by the movement of a nonerupted tooth that crosses the median line of the mandible and goes to position itself in the opposite part of the anterior mandible, as in cases 2 and 3 of this report [36]. Transmigration is rare, with an incidence of 0.007-0.08% and a 1.3:1 female predilection [37]. Interestingly, in this report, both cases of compound odontoma associated with transmigration of the left lower canine and lateral incisor were observed in male patients at developmental age.
The presence of cysts and tumours can alter the eruption pathway and cause tooth transmigration. The transmigrated teeth typically present unilaterally with a certain degree of angulation. In case 2, the angulation was almost horizontal to the lower jawline, while the transmigrated canine in case 3 presented a 60-degree angulation to the corresponding long axis of the first lower premolar [38,39].
The treatment of choice for transmigrated canines in association with vast compound odontoma is extraction. Orthodontic reposition of transmigrated canines is usually reserved for mild cases [40].
Few cases in the literature could be found with transmigrated canines being transplanted following endodontic therapy [41].
However, the management of bone gaps after surgical excision treatment of large lesions may require regenerative approaches using a combination of three-dimensional structures and new therapeutic means [42].

Conclusions
This article has documented three cases of compound odontomas: one in the upper premaxilla and two in the mandible in patients at developmental age. All the cases were associated with canine impaction; however, only the maxillary-impacted canine underwent orthodontic treatment after surgery. The two mandibular canines associated with compound odontoma were transmigrated and no orthodontic therapy was possible due to the challenging near-horizontal position at the lower portion of the anterior mandibula.
Although the radiological and macroscopic features following surgical removal are pathognomonic, histological examination is always performed. As a diagnostic investigation in preparation for surgery, CBCT offers details on the morphology of the odontoma, its relationship with the surrounding dental structures, and the cortical bone profiles of the affected jaws. Informed Consent Statement: All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. Informed consent was obtained from all subjects involved in the study.