Treatment Possibilities in Mandibular Defect Reconstruction Based on Ameloblastic Fibro-Odontoma Treatment—Does Small Bone Defects Heal without Bone Grafting?

Abstract

The occurrence and manifestation of each ameloblastic fibro-odontoma (AFO) is quite rare and uncommon. Mentioned odontogenic tumor classification had changed over the years; however, the treatment possibilities for this lesion remain the same. In most cases surgical enucleation is sufficient enough; however, bigger lesions might require bone curettage with sometimes performed bony ostectomy, which is a quite sufficient and effective method of treatment. In the presented case report, a panoramic radiological evaluation indicated an impacted molar tooth surrounded with mixed radiolucent/radiopaque areas. The 10-year-old Caucasian girl was scheduled for an incisional biopsy. The bone cavity in the mandible after tumor removal might be left for spontaneous healing or grafting techniques, depending on the shape and size of the defect. In the presented case report, the usage of PRF/iPRF in the mandibular bone cavity, and healing improved the overall final result.

1. Introduction

Ameloblastic fibroodontoma (AFO) is one of the odontogenic tumors (OT), present in the oral cavity and is considered one or rare lesion in the oral cavity, estimated 0.1–3.4% (0.3–2.3%) in some studies [1,2]. Since the WHO classification in 1992, some crucial changes in OT studies had changed [1,2]. AFO is common in children and young adults (one to two decades of life) and it might be related to odontogenesis. In almost all cases it grows slowly without any symptoms or other clinical manifestations and is mostly diagnosed on radiographs [2]. Santos et al. conclude that it is still unclear if AFO is an early stage of odontoma [3,4]. In both cases, impacted teeth at different stages of eruption might be found [5,6]. In the old World Health Organisation classification (2005), AFO was classified in the same group as ameloblastic fibroma (AF), ameloblastic fibrodentinoma (AFD), and others, characteristic of the presence of odontogenic epithelium with odontogenic ectomesenchyme with or without hard tissue formation [7,8]. Their shape, size, and advancement might vary greatly. Back in 2017, the new WHO classification changed AFO and AFD (ameloblastic fibrodentinoma) from two separate entities, since they represent the early stages of complex odontoma development (developing odontoma group) [9,10]. This fact was related to little clinical evidence of AOF, and AFD classifying them as independent entities. Similar changes influenced odontoameloblastoma (OA), since its more characteristic of an odontoma with coexisting ameloblastoma but with clinical signs as ameloblastoma [9,10]. The new classification divides OT and classifies them into epithelial, mesenchymal (ectomesenchymal), or mixed forms depending on which component of the tooth germ gives rise to the neoplasm [7,8,9,10].

Nowadays AFO is considered a benign mixed odontogenic lesion, most present in the mandible, and less commonly in the maxillary region. This origin is related to the presence of hard odontoid tissue with a great variety in the spectrum of developing odontoma [11,12,13]. In most cases, an asymptomatic swelling, followed by delayed teeth eruption with well-defined lesion borders remains the most typical symptom of this pathology [8,9,10,11,12]. More advanced lesions might rarely displace surrounding teeth and the lesion might exceed the cortical bone layer towards the soft tissues [8,9,10,11,12,13,14,15]. The inferior alveolar nerve is not involved in the lesion and its function loss is not common, similar to surrounding teeth resorption [8,9,10,11,12,13,14,15]. Bigger lesions might lead to facial disfigurement, mandibular asymmetry, bone swelling, and problems with biting and chewing. Malignant transformation is not common; however, long-term follow-up is necessary. Problems with tooth eruption might arise, or their displacement.

In radiological assessment, the lesion is mostly well-defined, unilocular, radiolucent mass with areas of radiopaque material, and teeth-like structures, with no, erupted teeth in the lesion cavity. Irregularity of size and shape of radiolucent areas might correspond with the growth phase of the lesion. Its well-defined margins with the presence of radiopaque areas might suggest its entity; however, other larger lesions might require a biopsy at first to establish the biology of the tumor before any final surgery will take place.

The current classification of AFO describes this lesion as of mixed origins of ameloblastic fibroma and a complex odontoma with ectodermal and mesenchymal components and odontogenic tissue such as enamel, dentin with the common presence of an ectopic impacted/retained teeth [7,8,9,10,11,12,13,14]. Some correlation with the scope of present different types of dental hard tissues is worth remembering [15,16]. This mixed benign neoplasm is also built of various dental hard tissues with different calcification stages. It seems that cone-beam computerized tomography might be very useful in the diagnosis of tumors and teeth-like masses [14,15,16,17,18]. The presented lesion is also quite often tooth eruption related. In most cases, ameloblastic cells are present with various fibrous tissues and parts of calcified masses. Additionally, types of extraosseous odontogenic tumors can occur. Those findings are very similar to our case, presenting combined radiolucent-radiopaque images on radiographs [19].

The most common occurrence of this lesion is the posterior mandible and the area of the third molar; however, other mandible areas might be also affected [2,3,4,5,6,7,8,9,10,11,12,13,14,15,16]. Buchner et al. performed a study on 114 cases of AFO worldwide [20]. The authors concluded that the mandible was involved in 65%, with 80% occurrence in the posterior part of the mandible and more than 92% was associated with impacted and/or unerupted teeth [21,22]. The maxillary location remains somehow rare [19,20,21,22,23].

Studies performed worldwide suggest that hybrid odontogenic tumors can be found [15,16,17,18,19,20]. AFO in most cases is a small lesion; however, cases with a great variety of shapes and sizes are describing occurrence both in the maxilla and mandible [8,16,17,18,19,20,21,22,23,24,25]. The recurrence rate is highly related to the surgical approach, localization, and structures involved in its composition [1,2,3,4,5,18,19,20,21,22,23,24,25].

Differential diagnostics should include pathologies with similar mixed radiological appearances such as calcifying epithelial odontogenic tumor (CEOT), calcifying odontogenic cyst (COC), immature complex odontoma, adenomatoid odontogenic tumor (AOT), ameloblastic fibrodentinoma (AFD) [7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22]. During clinical differentiation, bone swelling should be distinguished from odontogenic cysts (OC), eruption cysts, OKC (odontogenic keratocysts), cyst-related pathologies, and rarely with PHP, primary hyperparathyroidism tumors, namely Brown tumors related to the parathyroid gland adenomas or related lesions [8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25].

After the removal of each pathology from the bone, an empty intraosseous bony cavity is present. Not all cases require bone grafting or GBR (guided bone regeneration) procedures. A bone graft could be performed with calvarial, iliac, or fibula graft, while GBR is performed with autogenous and/or synthetic biomaterials. Recovery after regenerative interventions may be related to a period after surgery of delayed or complicated healing [26,27,28]. Shape, size, localization, and close proximity to an esthetic area in the oral cavity, along with the ability to support bone ridge/stable teeth stability in the oral cavity are considered the most important factors. In the presented paper, a rare case of AFO lesion and its treatment with blood cloths/PRF will be presented and discussed

2. Case Report Presentation

A 10-year-old Caucasian female was referred to with an asymptomatic right mandibular molar area lesion. The lesion was incidentally discovered by a dentist on a routine panoramic radiograph. The image consisted of a well-defined radiolucent area with various amounts of surrounding radiopaque areas in various shapes, and sizes, and with the presence of retained molar teeth. The presence of some irregular hard, radiopaque material included the differentiated diagnosis with PHP primary hyperparathyroidism or any other endocrine diseases but the findings were irrelevant. On further examination, the medical, social and family histories were unremarkable, as were the results of a review of systems and a physical examination. There was no history of local trauma or infection. Oral inspection revealed good oral hygiene. Examination revealed a slight swelling of the vestibule on the right side of the mandible, extending from the permanent first molar to the ramus of the mandible on the same side. The mucosa was unaffected and the swelling was bony-hard and there was no tenderness on palpation. The lower right permanent mandibular molar was non-mobile, non-tender, and vital. The right mandibular second permanent molar had not erupted in the oral cavity. There were no neurological deficiencies related to the trigeminal and facial nerves. Submandibular lymph nodes were nonpalpable and non-tender. Panoramic radiography exhibited an expansive, unilocular radiolucent, well-circumscribed lesion with scattered foci of calcified material which contained several radiopaque bodies of varying sizes and shapes (Figure 1 and Figure 2). The right lower first molar was associated with the lesion and had been displaced inferiorly to the caudal border of the mandibular body. CBCT scans revealed a mixed radiolucent-radiopaque lesion size of about 20 mm × 26 mm × 25 mm at the right angle of the mandible with features of bone expansion of the buccal cortical plate (Figure 3). The lingual plate remains untacked and without any tumor spread (Figure 4).

Decisions were made, to perform a surgical approach. No adjacent teeth required additional endodontic treatment, Before surgery patient was then scheduled for a dental hygienist in preparation for surgery. The surgical plan consisted of tumor removal, followed by bone curettage and if needed and guided bone regeneration-GBR or simple blood-cloth iPRF tumor cavity feeling because of their small size.

Under general anesthesia, and orotracheal intubation the right mandibular angle was exposed by vestibular mucoperiosteal incision. The surgical field was covered by sterile drapes. The oral cavity was rinsed with 0.1% CHX (chlorhexidine gluconate)(Eludril, Pierre-Fabre Oral care, France) solution for 30 s. Additionally, lips and skin surrounding the operating field were scrubbed with alcohol–ethanol 96% solution-AHD 1000 solution (MediLab, Lysoform, Berlin, Germany). Protective sterile Vaseline (Unilever, London, UK) cream was applied to the lips. Local injection of mixed 0.25% solution consisted of Lignocaine with Norepinephrine 2% (ampule, 2 mL, Polfa-Warszawa, Poland) with a mixture of Natrium Chlorate 0.9% (Natrium Chloratum 0.9% Fresenius KabiClear, Bad Homburg vor der Höhe, Germany) was used. A blade No 15c B (Swann Morton, WR Swann, Owlerton Grn, Hillsborough, Sheffield, England) was used for the incision. A modified USSO-unilateral sagittal-split osteotomy of the mandible approach incision was used. After elevating full-thickness mucoperiosteal flaps, the entire tumor and the retromandibular triangle of the mandible were exposed. The thin, buccally expanded cortical plate was removed and the lesion was removed by enucleation, followed by some bone curettage, and by removal of the impacted lower right molar, leaving the inferior alveolar nerve intact (Figure 5).

The cyst was not present. Tumor masses were colored light-red (strawberry-like) and were easily bleeding. After removing all calcified tooth-shaped structures with different hardness degrees impacted molar was removed. Fibrous tissues were present along various calcified bodies (Figure 6). The bony defect was filled with collagen sponges and blood-PRF feelings (platelet-rich fibrin-PRF, delivered from local laboratory from patients’ blood and gathered on a laboratory centrifuge-MPW-352, MPW Med Instruments, Warszawa, Poland). Since no pathological fractures were present no wire fixation, nor titanium mini plates were used. Because of a stable cortical lingual plate and good bone volume in the inferior mandibular margin of the mandible, a prophylactic titanium plate was not used.

Flaps were sutured onto the desired position with 4-0 Vicryl single sutures (Ethicon, Johnson & Johnson Medical N.V., Machelen, Belgium). No dressings nor rubber drains were used in the bony cavity). The surgery went uneventful, with standard antibiotics and anti-inflammatory drugs.

After discharge, the patient continued intra-oral antibiotics 1 g Amoxicillin (Sandoz Poland, Novartis Division-Basel, Switzerland), 200 mg Ibuprom (Ibuprofenum, USP PHARMACIA, Ziębicka 40, Wrocław, Poland). The oral cavity was rinsed with 0.1% CHX (chlorhexidine gluconate) (Eludril, Pierre-Fabre Oral care, France) solution three times per day after its mixture with mineral water 1:5.

Histological examination revealed a tumor composed of odontogenic epithelium areas embedded in a background of primitive connective tissue and dentin (Figure 7).

The follow-up examination was made two years after surgery, and the clinical and radiological appearance of the bone and surrounding soft tissue was normal. Panoramic radiography exhibited ossification at the original place of the lesion. Intraoral examination revealed complete healing without bone expansion.

Routine follow-ups took place every week for six weeks, then every month for six months. Now after 24 months post-op an overall good final surgical outcome was achieved (Figure 8 and Figure 9). Future controls were not enrolled because of the COVID-19 pandemic and changes in the Surgical Ward Localization.

3. Discussion

The occurrence of various OTs varies greatly. Their shape, size, location, and growth in time require not only some diagnostic steps but also great individualism in each case of bigger lesions. This situation is mostly associated with the scope of the surgical approach and the degree of excised structures. Small defects might heal quite well on their own, if surrounding bone walls are present, which enables a good final outcome from healing. Larger defects that might cause some defects in the bone anatomy, its function, and morphology might require one of the known regenerative procedures. Furthermore, the occurrence of both maxillary and mandible bones of different OT might result in a different approach and excision of tumor resection. In some cases, the scope of the first surgical approach might greatly influence later tumor reoccurrence or even malignant transformation reoccurring and not fully healed lesions [9,10,11,12,13,14,15,20,21,22,23,24,25,26,27,28,29].

The aggressiveness of AFO is still unclear; however, its malignant transformation is possible [22,23,24,25]. If present, a surgical removal should be performed; however, surgical margins and radicalism of the procedure still are discussable [29]. Authors confirm that because of its great similarity to other odontogenic tumors AFO can be easily misdiagnosed [30,31]. Mummolo et al. conclude that AFO can be easily misdiagnosed with AF (ameloblastic fibroma) or AFD (ameloblastic fibrodentinoma) [26]. However, today because of the new WHO classification of OT, the presence of AFO has been moved towards the odontoma section, which also resulted in changes in its treatment, such as enucleation with curettage, and rarely ostectomy in bigger lesions [20,21,22,23,24,25,26,27,28,29,30].

Treatment modalities are mostly related to conservative approaches such as enucleation and curettage since AFO is a non-aggressive lesion. Unlike AF (ameloblastic fibroma), which requires a more radical approach, AFO is not likely to suspect any malignant transformation towards AFS (ameloblastic fibrosarcoma); however, a rare possibility is also possible. This is yet another reason to separate AF from AFO/AFD and their potential malignant formation.

Treatment of choice is conservative, In well-defined lesions with clear borders, enucleation with or without curettage is enough. Destructive lesions without clear borders might even require surgical resection, marginectomies, or even in some extreme cases maxillectomies/mandibulectomies. Many papers describe possible approaches, with a great correspondence with the shape, size, location, and cortical bone loss, and are focused on [10,11,12,13,14,15,16,17,18,25,26,27,28,29,30,31,32,33,34,35,36,37]:

-

Conservative approach with enucleation alone

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Conservative approach with enucleation and bone curettage

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Surgical curettage with bony cavity ostectomy

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Surgical marginectomy in bigger lesions with/without reconstruction;

Regardless of the type of uses treatment, re-occurrence is rare [22,23,24,25,26,29,30,31,32,33,34,35,36]. The main question should be focused on the type of possible restoration and defect support to ensure adequate healing and bone regeneration. Bigger lesions might require some bone grafting protocols to restore some bone, while smaller lesions might heal on their own. Fresh-frozen allogenic bone grafts or PRF with xenograft bone materials seem to have good healing potential in defects where the cortical walls tend to improve bone stability [35,36]. A recent meta-analysis by Xiang et al. on PRF usage after third molar surgery highlights that it reduces some postoperative complications, but does not prevent all of them; however, it improves pain relief and swelling after lower third molar removal [37]. On the other hand, PRF mixed with a commercial spongious bone substitute, as reported in two case reports by Zhou et al., grants good results. Authors suggest that PRF serves as a bone scaffold in four-wall bony defects alone, nevertheless, it also can be combined with a xenograft in three-wall bony defects and presents excellent biocompatibility and good soft and hard tissue healing [38]. Those findings seem to confirm the Authors’ approach after AFO removal to combine collagen sponges with PRF/Blood cloths to the well-defined defects surrounded with intact bony cortical walls [36,37,38,39,40,41]. It seems that PRF and its modification are sufficient enough to promote healing in small bone defects when adjacent bony walls are untacked for better healing promotion [38,39,40,41,42,43]. Those small bone defects are hard to describe in size; however, lesions not larger than 15 mm seem to have good healing potential.

Small bone cavities after cyst enucleation are left for spontaneous healing. PRF usage is quite beneficial in oral cavity defects. Bone healing with PRF, based on blood gyration and various degree of centrifuge functions improve bone healing [35,36,37,38,39,40,41,42]. When some small cyst cavities tend to heal on their own it might take some time, while PRF or GBR procedures enable that effect much faster with a low rate of complications. Bigger lesions might require bone from fresh-frozen allogenic banks or perhaps the usage of a secondary surgery side for harvesting the proper amount of bone to ensure more improved bone defect healing. Such harvesting side might include calvaria bone, tibia, iliac bone crest, mental area, external oblique ridge, mandibular ramus, retromolar area, and others [37,38,39,40,41,42,43]. In all cases, stable defect suturing ensures its integrity if the sutures are tight enough and enable suturing without tension. Bigger reconstruction might include bone stabilization with titanium mini plates, meshes, or other titanium devices to ensure their stability for good healing promotion [37,38,39,40]. GBR techniques are useful in larger defects or those lacking a good volume of bone, and the shape of and presence of cortical walls surrounding the defect in either the mandibular or maxillary bones.

Last but not least, AFO in the past was derived from AF tumors, which has also a great potential for malignisation. This fact requires special attention. In the past, an ameloblastic fibro-odontosarcoma could arise from AF. If diagnosed early an extended surgical approach might lead to a great functional and therapeutic result. A differential diagnosis between AF and AFS has a great impact on the therapy plan. AFS should be always differentiated between forms of ameloblastoma, odontogenic fibroma, ameloblastic fibrodentinoma, ameloblastic fibroma, and ameloblastic fibro-odontoma. In some cases, we report that there is a very thin histological barrier and a greater differential diagnosis is the key to a greater therapeutic outcome. Gilani et al. agree that differential diagnosis should consist of other odontogenic sarcomas, ameloblastic carcinosarcoma, and spindle cell carcinoma. Khalili et al. point out that only the mesenchymal component represents sarcomatous alterations. Chemotherapy after surgical excision is a good treatment method and should be also taken under consideration in young patients and young adults in order to minimize its recurrence. A study performed by Pontes et al. suggests that Ki67 AND Bcl-2 proteins in AFS could be useful markers [44,45,46,47,48,49,50,51].

4. Conclusions

The presence of AFO requires curettage at most. A more radical surgical, ostectomy or even resection should be used in very big lesions, and those require some sort of bone grafting to restore the missing bone. Small defects should heal on their own or can be successfully treated with PRF usage. The overall success rates for AFO treatment remain good. The shape, size, and localization of the lesion greatly influence the type of surgical approach and possible reconstruction methods. We also conclude that macroscopic findings related to various numbers of tooth-like odontogenic tissues removed from the cavity could be very good additional information in recognizing the type of tumor.