Oroantral fistula (OAF) is an unnatural epithelialized communication between the oral cavity and the maxillary sinus. When an oral maxillary sinus fistula occurs, foreign substances and bacteria in the oral cavity enter the maxillary sinus through the fistula and may cause chronic maxillary sinusitis. If inflammation of the maxillary sinus persists, the fistula is not naturally blocked, resulting in a vicious cycle in which sinusitis persists1). If the natural ostium is intact to spontaneous drainage in the sinus cavity, surgical success largely depends on primary closure of the defect.
Although various techniques used to close oroantral fistula include the buccal advancement flap, palatal rotation flap, combination flaps, bone grafts, and buccal fat pad, long-term successful closure of oroantral fistulas is still one of the most difficult problems confronting the surgeon working in the oral and maxillofacial region2). A combination flap of buccal fat pad and buccal advancement has also been utilized, however, this technique can lead to a mucosal healing without correction of the bone defect which makes implant-supported prosthetic rehabilitation very difficult3). If the sinus membrane can be adhered to the gingiva or scar tissue, the second approach become challenging4,5).
Therefore, the use of bone autografts for closing OAFs has been recommended especially for the defects larger than 10 mm or in the case of failure of conservative methods to close the defect6). Block type autogenous bone harvested from alveolar bone, ramus, or iliac crest is effective to reconstruction of maxillary defect and OAF closure. A monocortical block graft is harvested by using a burr with matching the size of the round bony defect. However, considerable effort is required to match the size, and in some cases, block bones require additional treatment for fixation. A sandwich or pouch graft technique, wrapping bone substitutes by using absorbable collagen membrane, yielded a more promising closure of OAF by provision of a more biologically apt base in terms of regeneration of lost bone structure at the floor of the maxillary sinus7,8). The aim of this case report is to suggest particulated autogenous bone graft with pouch graft technique to address disadvantage of block-type autogenous bone and to enhance bone quality and rapid bone healing.
A 51-year-old female healthy patient presented with a persistent foul odor and pus discharge from the right side of her mouth, which began after implant treatment two years ago. She had previously undergone endoscopic sinus surgery a year ago, but continued to experience the symptoms. Radiographic images confirmed a mucosal thickening on maxillary ostium and revealed sinusitis on the right side and a bone defect in the area of teeth #16-17 (Fig. 1). She reported that one implant fixture was removed during the initial implant treatment due to poor bone quality.
The author suspected the presence of an oroantral fistula, which was concealed by the prosthesis, so the prosthesis was removed first. Upon oral examination, a small fistula was observed, but it was not of significant size (Fig. 2A). Considering the oral symptoms were likely caused by the defect in the maxillary bone, autogenous bone grafting was planned. She was prescribed Pseudoepedrine HCl 60 mg tid (Koreapharma., Seoul, Korea), Roxithromycin 150 mg bid (Ildong Pharma., Seoul, Korea), Acetaminophen 350 mg tid (Bukwang Pharma., Seoul, Korea), Almagate 500 mg bid (Yuhan Pharma., Seoul, Korea) for one month before the surgery and one week after the surgery.
Under general anesthesia, caution was taken to gently detach the scar tissue adhering to the gingiva (Fig. 2B). The maxillary Schneiderian membrane was lifted with additional ostectomy (Fig. 2C). The author utilized a recently suggested harvesting technique, which involved making sagittal, coronal, and axial osteotomies with micro-saws to acquire cortical bone chips in a grid pattern. The harvested cortical bones were then crushed using a bone mill into fragmented bone particles (Fig. 3A∼C)9). To ensure the stability of the graft, a pouch-type graft with a collagen membrane (Remaix, Matricel GmbH, Herzogenrath, Germany) was performed by wrapping the autogenous bone to cover both the sinus membrane and the gingiva sides (Fig. 3D). The wound was closed with interrupted sutures using 4/0 Vicryl (Ethicon/Johnson-Johnson, New Brunswick, NJ) and horizontal mattress sutures using 3/0 Prolene (Ethicon/Johnson-Johnson) (Fig. 3E). The wound healed without any complications (Fig. 3F). The sinus-related symptoms were resolved (Fig. 4A, B), and the prosthesis was reinstalled two weeks after the surgery. The bone graft showed stable results at two months postoperatively (Fig. 4C). She has not reported any recurrence symptoms related her sinus.
The management of oroantral fistula (OAF) poses a significant challenge to oral and maxillofacial surgeons. Various techniques have been employed to close OAFs, including buccal advancement flap, palatal rotation flap, combination flaps, bone grafts, and buccal fat pad10). However, long-term successful closure with only soft tissue closure remains elusive. In this case, the author utilized an autogenous bone graft to resolve the long-standing oroantral fistula with sinusitis. To overcome the drawbacks of block-type autogenous bone grafts, the author used particulated bone with a pouch graft technique11,12). The graft was then wrapped with an absorbable membrane, resulting in successful closure of the fistula and resolution of sinus related symptoms.
The successful closure of the OAF not only alleviated the patient's symptoms but also allowed for the reinstallation of the prosthesis. It is crucial to promptly address OAFs to prevent complications such as chronic sinusitis due to the persist invasion of the oral bacteria. Specifically, when suturing OAF with soft tissue, clinicians face the challenge of prolonged treatment duration due to the difficulty of treating additional bone defects that needed additional graft surgery for implant placement including sinus lift through the dissection between the adhesion on the schneiderian membrane and gingiva13,14). As autogenous bone is the most recommended option, extensive research has been conducted on its use for closing oroantral fistulas. To ensure graft stability, surgeons should carefully design the size of the harvested autogenous bone to precisely fit the defect and secure it with screws and platelet-rich fibrin11,12,15,16). The method described in this manuscript could offer better accessibility by utilizing autogenous bone regardless of the defect size and applying it with the collagen membrane. However, complete coverage of the graft may impede blood supply and result in incomplete graft incorporation17). Since this patient did not undergo additional implant surgery at the bone graft site, the histological confirmation of the bone graft's outcome could not be obtained. Nevertheless, even in the presence of maxillary sinusitis, the autogenous bone grafts demonstrated effective filling of the bone defect without any side effects such as infection. Further studies will be required to assess the bone regeneration capability for implant placement with particulated autogenous bone graft using this technique.
This case report demonstrates the successful closure of an oroantral fistula using a particulated autogenous bone graft with a pouch graft technique. This approach addressed the limitations of block-type autogenous bone grafts and resulted in the resolution of sinus-related symptoms. Prompt management of oroantral fistulas is crucial to prevent complications and the proposed technique offers an accessible and effective solution for closing these fistulas. Further research is needed to evaluate the long-term bone regeneration capability of this method.