Immediate Insertion of Dental Implants Immediate Insertion in Bilateral Traumatic Bone Cysts With or Without a Bone Grafting Material: A 5-Year Follow-Up Case Report

A traumatic bone cyst (TBC) is characterized by the presence of a bone cavity with a well-defined radiolucent area and no epithelial lining.¹  Its etiology remains contradictory,²  despite the fact that the relationship of the lesion to previous traumatic episodes has been reported.^3,4 

The occurrence of TBCs in the maxillary bones is rare,⁵  but if it does occur it is most likely to present in the posterior region of the mandible.²  Bilateral cases are poorly described in the literature.⁶ 

The treatment for TBCs consists of the exploration and curettage of the walls of the bone, during which it is possible to establish the final diagnosis and define the treatment to be followed.^1,4,7 

Although an uncommon lesion, TBCs are often diagnosed accidentally during a routine radiological examination.^4,7  With dental implants becoming more commonly used, it is important to know the alternatives for rehabilitation with implants of TBC areas with a view of defining a standardized protocol of treatment in the future. Thus, prosthetic rehabilitation with dental implants in a patient with bilateral traumatic bone cysts in the mandible with 2 distinct therapeutic approaches is described.

A 24-year-old male patient sought dental care in a private practice complaining about bilateral mandibular second premolar agenesis.

The clinical examination showed the absence of the mandibular second premolars. A cone beam computerized tomography (CBCT) scan was performed for the planning of the rehabilitation with dental implants. The image confirmed the absence of the mandibular second premolars, which showed orthodontic components and revealed 2 broad, well-delineated radiolucent areas in the mandible body stretching from the second molar to the canine bilaterally. Tomographic sections presented with residual alveolar cervical bone of approximately 4 mm in both mandibular regions (Figure 1).

Although the patient stated that he did not have trauma in the region, the diagnostic hypothesis was traumatic bone cysts. To confirm the diagnosis, surgical access was planned to inspect the cavities.

Bilateral local anesthesia was performed, followed by mucoperiosteal incision and detachment in the alveolar ridge region to identify the bone and dental limits.

With an electric motor-mounted reducer, the alveolar occlusal region on both sides was perforated. The thickness of the alveolar bone and the depth of the bone cavity were measured. In both areas, there were spaces without bone trabeculation, and the coating epithelium was partially filled with light yellow liquid, confirming the diagnosis of a traumatic bone cyst.

The treatment option was to perform a wider surgical approach with a relaxing incision and a bone window opening on the lateral wall of the trephine on the left side of the mandible (Figure 2). On the right side, the side access window was not made.

Bone preparation for fixation of the implants was complimented. Following this, bleeding and filling of the cavities by a local blood clot was promoted. An implant with a treated (oxidized) surface (Neodent, Curitiba, Brazil) was inserted into the interior of the cystic area and fixed on each side with an initial stability of 25N. On the left side, the cystic space was filled with a bovine bone substitute graft (Bio-Oss; Geistlich Pharma do Brasil, São Paulo, Brazil) and a local blood clot. On the right side, visual inspection and probing with a 15 mm probe (Hu-Friedy Mfg Co, LLC, Chicago, Ill) were performed through the osteotomy site of the implant to observe the lesion limits. Then bleeding was induced for blood clot formation. The implant was only in contact with the cortical bone and the local blood clot.

The patient was advised about postoperative care and was given antibiotic therapy with amoxicillin, 500 mg, 3 times a day for 7 days and analgesics. The suture was removed after 7 days. The clinical control of healing was performed through a visual inspection, where the gingiva was perceived to be a good color and there was no bleeding, probing with a depth within the acceptable limits and without bleeding and an implant without mobility. The bone formation was also monitored radiographically.

After 5 months of clinically and radiographically controlled bone repair, new surgical access was made to adapt the implant healers (Neodent), followed by the installation of the implant-supported prostheses.

The radiographic control images of the 5-year follow-up showed trabecular bone on both sides of the mandible (Figure 3). The patient gave his written consent before the beginning of the treatment, as well as authorizing the use of his case in a report.

The pathogenesis of traumatic bone cyst remains uncertain.³  Although in the present case, the patient did not recall any traumatic episodes in the region of the TBC, the most widely reported and accepted hypothesis is that they occur from intramedullary hemorrhage secondary to trauma and consequent bone cavitation.² 

TBCs usually present with no complications and may present with spontaneous resolution. However, simply waiting for spontaneous regression is not recommended due to the possibility of a misdiagnosis leading to complications such as the pathological fracture of the mandible.^1,3  There were no complications associated with the cysts in this case; however, due to their dimensions, the pathological fracture of the mandible could occur. Moreover, as the absence of the premolars was an issue for the patient, waiting for the spontaneous regression of the cysts was not a feasible solution, as it is not possible to predict when it would happen.

As the patient presented with an installed orthodontic appliance, it can be inferred that the radiolucent images in the mandible body may not have been as visible in the initial panoramic radiograph as they were in the CBCT.⁸  Another hypothesis is that the radiolucency could have been caused by anatomical bone variation due to the positioning of the submandibular glands.^9,10 

Most of the TBC cases are asymptomatic and are discovered in routine radiological investigations.^2,7  In the present case, the TBC was discovered in a CBCT scan performed for the planning of the rehabilitation with dental implants. It is known that CBCT and 3D CBCT images provide more detailed information for evaluating implant-related treatments.⁸ 

Filling the cavity with platelet-rich plasma,⁵  a bone graft or hydroxyapatite⁷  are suggested alternative treatments. In this case, one TBC cavity was filled with bovine hydroxyapatite. The use of bone substitutes in areas where there is inflammation and a lesion has been successfully performed and confirmed by histological analysis previously.¹¹ 

The exploration of the cavities confirmed the diagnosis of bilateral TBCs as the cavities were hollow and uncoated when curetted. As there was the plan for rehabilitation with dental implants, the bone window opened in the left side was used for the placement of the bone graft after the fixation of the implant on that side. On the right side, access was made to the bone cavity only at the implant preparation site, leaving the implant in contact only with the blood clot. No collagen membrane was used to cover the bone defect because it had enough soft tissue for closure.¹² 

The installation of the implants simultaneously with the surgical exploration of the TBC was performed taking into consideration a previous study that evaluated the filling of bone cavities with a blood clot associated or not with autogenous bone.¹³  In the study by Palma et al,¹³  the osseointegration of the dental implants with a treated surface and bone formation were histologically similar with or without the presence of bone associated with a blood clot.

This case report confirmed those findings since the clinical and radiographic follow-up showed osseointegration despite the use of the graft. The installation of implants in bone cavities solely filled with a blood clot presents the advantages of a lower chance of infection, lower morbidity, a lower financial cost and a better acceptance by the patient.¹⁴ 

Surgical exploration followed by the immediate installation of dental implants in areas affected by traumatic bone cysts may be considered a viable, safe, and low-cost alternative. In this case report, the cavity filled with a local blood clot in contact with the implant presented clinical and radiographic success similar to the filling with a bone graft in the same patient after 5 years.

Abbreviation

CBCT

cone beam computerized tomography

TBC

traumatic bone cyst

Authors state that they have no conflict of interest