Cystic lesions of the jaws are a relatively commonly encountered pathology. Fortunately, approximately 86% of them are periapical lesions and their treatment is not complex (1). Large cysts of the jaws are rare and mainly result to be follicular cysts and keratocysts. Scientific community still continues to use the term 'odontogenic keratocyst' more favorably than 'keratocystic odontogenic tumor' although both terms remain acceptable synonyms (2). However, radicular and residual cysts can also grow substantially in size, thus causing considerable osseous defects (3).
Residual (radicular) cysts develop from epithelial remnants which are stimulated to proliferate by the inflammatory response originating from the necrotic pulp of previously extracted non-vital teeth (4). In fact, these are radicular cysts that remain in the jaw after removal of the affected tooth and continue to grow in an autonomous manner. In the course of time, the cysts may undergo regression, remain static in size, or grow, but unfortunately little is known about their evolution and expansion and why they develop in the first place (3). Compared to other large cysts such as radicular cysts, follicular cysts and keratocysts, residual cysts are rare amounting only to 10% to 18% of dental cysts (1). The diagnosis of a residual cyst is often established inadvertently, either during routine radiography or when the cyst is infected (5, 6).
Surgical treatment of cystic lesions of the jaws can be accomplished by means of enucleation or marsupialization (7). Marsupialization or decompression is a technique that releases pressure from the cyst, allowing for bone formation and reduction of the cystic cavity in order that later in the course of treatment enucleation can be accomplished more easily and with less risk to vital structures. This technique requires close patient cooperation, frequent visits, maintenance of cystic cavity hygiene and subsequent enucleation not earlier than three months after the initial surgery (8). The method of choice for the treatment of cystic lesions of the jaws is enucleation of the lesion and biological treatment with organization of coagula and new bone formation. The treatment is carried out completely in one session, which accounts for faster cystic cavity reduction due to centripetal healing of bone (4). This usually happens after enucleation of small cysts, while enucleation of large cysts of the jaws creates substantial osseous defects.
The aim of this case report was to present spontaneous bone regeneration after enucleation of a large sized residual cyst in the maxilla, evaluated by clinical examination and panoramic radiography.
A 36 year- old female patient was referred to the Department of Oral Surgery, University Dental Clinical Center of Kosovo – Prishtina with a chief complaint of swelling in the right upper molar region, observed before one month. Her medical history did not reveal any health problems. Dental examination revealed the absence of the first molar (tooth 16 FDI) accompanied with a firm tumefaction located buccally to the molar region of the right maxilla. Discoloration of the agonist teeth was noted, namely second molar and second premolar. During intraoral palpation of the tumefaction deep in the fornix, Dupuytren's phenomenon was detected.
Panoramic radiography revealed a radiolucent lesion on the right side of the maxillary molar region, approximately 35 mm in size in antero-posterior and 50 mm in cranio-caudal direction (Figure 1). In order to fulfill the complete set of diagnostic criteria, aspiration with sterile syringe was performed and straw colored fluid, rich in cholesterol crystals, a characteristic of cystic fluid, was acquired (Figure 2).
Pulp vitality testing (by electric pulp tester – Parkell Inc., Edgewood, New York) of the second molar and second premolar revealed that both of them were vital.
The surgical procedure was performed under local anesthesia (Lidocaine-Adrenalin, 40mg/0.025, 2ml, Alkaloid Skopje). Reflection of the mucoperiosteal flap, followed by removal of buccal cortical bone which was considerably thin, and exposure of the cystic membrane was carried out. The cystic membrane was carefully separated from the surrounding bone and was completely removed. Inspection of the remaining osseous defect following cystectomy displayed expansion of the cyst in all directions, buccally as well as in the direction of the sinus, thus causing exposure of the intact Schneiderian membrane of the intact maxillary sinus (Figure 3). The large osseous defect produced after enucleation of the cystic lesion was rinsed with sterile saline solution (0.9% Sodium Chloride). Considering our lack of suction tools for the drainage of the accumulated fluids such as blood and serum in the cystectomy osseous defect, we used handmade wound dressing of iodoform gauze tape, consisting of a cotton gauze strip immersed in sterile saline solution (0.9% Sodium Chloride) and impregnated with iodoform powder (PPH Cerkamed – Varna, Bulgaria) .
The iodoform gauze tape was inserted and folded with compression inside the bone defect (Figure 4) with one loose end for communication with the oral cavity through the primary closure of the repositioned and sutured mucoperiosteal flap (3-0, Coated VICRYL®, polyglactin 910, Suture-Ethicon- GMBH, Germany). This gauze tape remained inside the defect for 2 (two) days postoperatively, accomplishing the effect of compressive hemostasis inside the remaining bone defect and, simultaneously, serving for drainage of the accumulated fluids inside the osseous defect.
Antibiotics were administered (Amoksiklav 625mg tablets, Lek, Ljubljana) every 8 hours for 6 days and the patient was advised to refrain from hot beverages and solid foods for 24 hours after the surgical procedure. During the routine postoperative follow up visit next day, the gauze tape was partially removed and the day after (48 hours postoperatively) it was removed completely. Postoperative edema was minor and the patient declared that she had slight pain; hence she used only one tablet of Ibuprofen 400 mg (Farmavita, Sarajevo). The sutures were removed on the seventh postoperative day. Histopathological microscopic examination of the bioptic material (enucleated cystic lesion) displayed a cystic wall coated with stratified squamous epithelium and effusion of fibrotic tissue, dense infiltrates of inflammatory and hyaline particles, and presence of extravasated erythrocytes. (Figure 5) Hence, the final histopathological report with diagnosis of "radicular cyst" was confirmed.
The postoperative course of the case was followed with routine visits made at certain time intervals as follows: after 24 hours, two days, one week, one month, six months and twelve months.
During routine examination one month after the surgical procedure, the patient did not report any problems or concerns, but the pulp vitality test (Electric Pulp Tester, Parkell Inc, Edgewood, New York) of the neighboring teeth revealed loss of the second molar vitality, which was afterwards treated by an endodontist. On a follow-up examination after one year, the patient did not report any particular problems. Panoramic image revealed intense bone opacity indicating sufficient formation of new bone from the margins to the center of the defect, significantly reducing the remaining osseous cavity when compared to the preoperative radiograph. (Figure 6)
Defects of various sizes and shapes remain after enucleation of bone cysts. The remaining small surgical defects after enucleation of cysts commonly heal spontaneously by the physiological appositional mechanism of bone growth. The residual bone cavities are replenished with blood clots, which become the scaffold for new bone formation. However, in case of large surgical defects caused by enucleation, a blood clot in the bone defect is a considerable risk as it can easily become infected or lead to the formation of a large hematoma as a result of uncontrolled accumulation of blood in the bone cavity.
Aiming to reduce the postoperative osseous defect volume and to prevent the above mentioned complications, different methods of surgical treatment and drainage of the large jaw cysts are used, depending on the experience and preference of the surgeon.
One of the treatment methods is closed method cystectomy with postoperative bone cavity drainage by iodine gauze tape, which was used in our case, or by suction which works by means of negative pressure created in the bone cavity within a period of 5-7 postoperative days. The suction acts by pulling the soft tissue towards the center of the osseous defect, which decreases the volume of the defect and supports primary wound healing as in cases of small bone cavities. This method of treatment is simple for treating large bone cysts, resulting in a shorter rehabilitation time and complete regeneration of the bone tissue within 2-6 months (9).
Hern and Milijavec (10) have found that large osseous defects created after enucleation of large jaw cysts show slower postoperative spontaneous regeneration than small osseous defects. Their results show that the final bone density formed after 12 months, in small defects (20-30mm) was 97%, while in large defects it was 84%, compared with healthy neighboring bone density (10). Therefore, enucleation of large cystic defects creates a dilemma of whether to fill the osseous defect with bone substitutes or not.
There are different views about the application of bone grafts for the treatment of osseous defects after enucleation of large cysts of the jaws (11-13). Many authors have concluded that the use of autogenous bone grafts (3, 14), and alloplastic grafts (15) can help with healing of osseous defects by reducing the risk of possible fractures of the jaws and shorten the recovery period.
Although autogenous bone grafts are considered the gold standard for the reconstruction of defects in the maxillofacial region, considering they are biologically compatible, they become vascularized and osseointegrated with surrounding bone with minimal risk of infection and dislodgement, their use has disadvantages and limitations. These disadvantages include: prolonged time of operation considering the time for graft harvesting, donor site morbidity, graft resorption, limited availability with the small amounts being insufficient for replenishing large defects etc. (16).
Consequently, alloplastic graft materials and xenograft bone for filling bone defects after cyst enucleation are used as an alternative to autogenous grafts (14, 17-19). Thus, the study of Khaled (15) shows that bone density 3 and 6 months after cyst enucleation, with lesions measuring from 1.5 to 3.5 cm, was higher in the group of patients whose osseous defect was filled with Agipore granules (corals) and in the group treated with lower laser intensity, than in the control group where the bone defects remained empty. Despite the fact that usage of alloplastic material lowers morbidity and complications, and their usage is unlimited (16), these materials have shown reduced osteogenic activity since they first have to be resorbed and then replaced with new osteogenic tissue (8, 19). Recovery delays are also observed due to slow resorption or exposure of graft and infection afterwards (9). Horowitz and Bodner (19) have found failure in 20% of cases with large bone defects associated with xenograft bone recommended for promotion of bone regeneration. It is considered that the use of bone grafts reduces the risk of spontaneous fractures after enucleation of large cysts (3, 14, 20).
Ettl et al. (12) found that the use of bone grafts in lesions after cyst enucleation showed no superiority and that simple cyst enucleation with blood clot healing shows low complication rates and sufficient bone regeneration even in large defects. Chiapasco et al. (11) and Wagdargi SS et al. (21) also found that spontaneous bone regeneration could occur in large mandibular cysts without the aid of any filling materials.
Numerous investigations have documented spontaneous healing of bone defects after large cyst enucleations, without the use of bone graft (10, 13, 22). Shokier et al. (22) have observed spontaneous healing without the use of bone grafts in 20 patients, out of which 10 were keratocysts, 5 follicular cysts and 5 radicular cysts, with monocortical bone defects ranging from 2.5 to 6 cm. The authors evaluated bone density formed at intervals of 6, 12 and 24 months and found gradual reduction of the size of osseous defects in all cases, with bone density increasing significantly. The bone density increase was significantly higher in the first 6 months compared to the subsequent months (23).
Also, Wagdargi et al. (21) have found a bone density increase with statistical significance of 90.8%, 6 months after enucleation and primary closure of 16 odontogenic cysts ranging from 3 to 10 cm in size. Authors have noted higher bone density in mandibular osseous cavities than those in the maxilla.
Schmitz and Hollinger (24) divided bone defects into critical and non-critical size defects, depending on the number of walls that surround them. The authors found that defects with two missing walls are uncritical sized defects and can heal spontaneously regardless of the size of the defect, while the defects that have only one wall with all the other walls missing are critical size defects, reconstruction of which is necessary. From a study performed in rabbits, it was observed that spontaneous healing of osseous defects was superior when the defect was unicortical and not greater than 8mm, and failed when defects were bicortical and greater than 15mm in diameter (25).
Results in the literature show that residual bone defects after cystic enucleation regenerated spontaneously despite the size of the cavity, histological type, gender and age, whenever it was possible to conserve residual bone plates provided by periosteum and endosteum (10, 23, 26).
In contrast, Hern and Miljavec (2008) found that increased patient age had a negative effect on healing and that the shape of the osseous defect was a more important healing factor than the volume (10).
Our study case presents the subjective and radiographic assessment of healing of residual bone defect sized 35 to 50mm, surrounded by sufficient bone plates and primarily closed with mucoperiosteal flap after enucleation of large cyst in maxilla, without using any graft material.
One year after cystectomy, the panoramic image revealed increased bone opacity suggestive of new bone formation from the margins to the center of the bone defect, showing significant reduction in size of the residual bone defect when compared to the preoperative radiograph.
The presented case depicts successful spontaneous healing of osseous defect after large cyst enucleation without the use of any filling materials, thus confirming the results from the literature relating to spontaneous healing of large osseous defects without bone substitutes (21, 22, 26, 27).
The course of the presented case and results from the literature provide compelling evidence in support of the surgical approach of treating large radicular cysts with the primarily closed method without use of any graft materials.
Based on our clinical case and data from the literature, it can be concluded that spontaneous bone healing after enucleation of large cysts should be the treatment of choice even in large cystic cavities where the residual bone defect is walled with sufficient amount of bone. This surgical treatment modality is noncomplex, with low financial and biological costs. It decreases the overall cost of surgery and reduces the risk of postoperative complications associated with grafting.