Successful Management of Dental Implants in Postoperative Maxillary Cyst: A Case Report With a 13-Year Follow-Up

The postoperative maxillary cyst (POMC) is a well-documented delayed complication associated with various surgical interventions involving maxillary sinus diseases.¹  The occurrence of POMC is caused by entrapment of ciliated cells of the nasal mucosa or by obliteration of the sinus ostia during radical sinus surgery.²  Sinus surgeries shown to have developed POMC include the Caldwell-Luc operation,³  orthognathic surgery,^4,5  and maxillary sinus bone augmentation.⁶  After maxillary sinus bone augmentation for the purpose of dental implant placement, limited reports of POMC cases have been presented at various time points postoperatively: 6 months,⁶  3 years,⁷  and 10 years.⁸  Kim et al reported a case of postoperative maxillary cyst after the sinus bone graft procedure at a 10-year follow-up visit where radiologic and histologic analyses were performed.⁸  The authors believe that a tearing or perforation of the maxillary sinus membrane with subsequent entrapment of the membrane with a large amount of graft particles may contribute the development of such cyst.⁸  On rare occasions, the POMC can present as a skin tumor on the cheek as reported by Matsuzaki et al in a more recent publication.⁹  In management terms, marsupialization or enucleation of the cyst has been proposed as the effective treatment for POMC.¹⁰ 

This is a case report of a patient who had a dental implant installed 13 years ago in an area that was later found to be a POMC. Clinical presentations, histopathologic evaluation, and radiological manifestations of the implant and its associated complications are discussed in detail. Management of the cystic lesion and the involved implants with enucleation, explantation, and surface decontamination followed by guided bone regeneration are presented as well.

A 57-year-old female patient presented to the private clinic in Seoul, Korea, to receive full-mouth rehabilitation of her maxilla with dental implants in September 2004. The patient was a nonsmoker and had no systemic disease that would be contraindicated for implant therapy. However, a review of her medical history revealed that the patient had received a Caldwell-Luc operation for the treatment of chronic sinusitis 20 years ago.

The preoperative panoramic radiograph showed severe pneumatization of both maxillary sinuses. The limited volume of residual bone below the sinus floor due to pneumatization necessitated an augmentation procedure, but due to limited mouth opening by the patient, a transcrestal approach was chosen instead of the traditional lateral-wall sinus grafting (Figure 1a).

The patient received an oral administration of 2.0 g of amoxicillin for prophylactic antibiotic coverage 1 hour before the procedure. Under local anesthesia, a mucoperiosteal flap was reflected to expose the posterior alveolar ridge. At the site of tooth #2, Summer's osteotomes were used to elevate the sinus floor. The Schneiderian membrane was intact without any visible perforation, and there was no addition of any bone graft substitutes. Subsequently, the hydroxyapatite-coated implant (Zimmer TSV 4.8 × 10 mm) was inserted with proper mechanical stability and all 9 implants were submerged (Figure 1b). The flaps were sutured passively without tension and primary closure was achieved (Nylon 4-0, Ethilon 4.0, Ethicon, Cincinnati, Ohio). A panoramic radiograph was taken immediately after the surgery (Figure 1b). Postoperatively, antibiotics (ciprofloxacin, 500 mg, Ildong Pharmaceutical, Seoul, Korea) and nonsteroidal anti-inflammatory medication (Etodolac, 200 mg, Yuhan, Seoul, Korea) were prescribed for 10 days. The patient was also instructed to rinse with 0.12% chlorhexidine solution (Hexamedine, Bukwang Pharmaceutical, Seoul, Korea) for 30 seconds, 2 times a day for 1 week.

The healing was uneventful without any complication. After 6 months of healing, the second-stage surgery was performed to uncover all the implants. One of the implants, #4, was removed due to nonintegration. However, all implants had achieved proper osseointegration, and the final prosthesis was delivered after 2 months (Figure 1c). The patient was closely monitored annually.

In January 2018, 13 years after the implant placement, the patient complained of masticatory discomfort with gingival bleeding and swelling. Both panoramic radiograph and cone-beam computerized tomography (CBCT; rainbow CT, Dentium, Suwon, Korea) confirmed evidence of severe bone resorption around the area of implant #2 associated with clinical signs of peri-implantitis (Figure 1d, Figure 2). In addition, the panoramic, coronal, and sagittal views of the right maxillary sinus on the CBCT scan showed a unilocular radiolucency with a well-defined margin. The breadth of the nasal cavity was abnormally wide. The sinus was opacified and the natural ostia seemed to be obstructed (Figure 2a through c). The axial view further confirmed the expansive nature and the disappearance of the anterior lateral bone plate near what appeared to be a cystic lesion (Figure 2d). The decision was made to section the bridge and remove the implant #2.

Two weeks after the explantation, the patient presented with severe facial swelling. The buccal vestibule showed significant edema and active discharge of exudate with oro-antral communication at the site (Figure 3a). A re-entry procedure through the lateral wall of the sinus was necessary to evaluate and manage the site of active infection.

In the area of explantation, a fistulectomy was performed. The horizontal marginal incision and vertical incisions were used to reflect the facial mucoperiosteal flap. Upon reflection, the bone plate was noted to be missing and the proliferative granulation tissue was present (Figure 3b). The soft tissue mass was resected from the surrounding bony wall and the implant body was visible (Figure 3c). The removed specimen was fixed in neutral buffered formalin solution (Sigma Aldrich, St Louis, Mo) for histopathological examination.

A titanium brush (Genoss, Suwon, Korea) was used to debride and mechanically decontaminate the exposed implant surface (Figure 3c). The implant surface was further treated for chemical detoxification with tetracycline HCl (Oxymycin, 500 mg, Chong Kun Dang Pharmaceutical, Seoul, Korea) for 5 minutes at 100 mg/mL with saline solution (Figure 3d). The cystic cavity was thoroughly irrigated with saline solution. Then, biphasic calcium phosphate (Osteon III, Genoss) was condensed around the implant surface as well as the enucleated space, but without any barrier membrane (Figure 3e). The flaps were sutured passively with 4-0 Nylon (Figure 3f). The radiologic images confirmed that space was uniformly occupied by the bone graft as shown in Figures 3g, h, and i. Postoperatively, the patient was covered with ciprofloxacin, 500 mg (Ildong Pharmaceutical) and nonsteroidal anti-inflammatory drug (Etodolac 200 mg, Yuhan) for 2 weeks. The patient was also advised to rinse with 0.12% chlorhexidine solution (Hexamedine, Bukwang Pharmaceutical) for 30 seconds, twice a day for 2 weeks.

The specimen was confirmed histopathologically as POMC. Some cilia were observed, but ciliary loss due to chronic inflammation was also evident. The cystic lesion was lined with pseudostratified columnar epithelial cells with numerous inflammatory cells infiltrating into the connective tissue (Figure 4a). Proliferative granulation tissue was observed with innumerable lymphocytic cells (Figure 4b).

Within 2 weeks postoperatively, all clinical symptoms disappeared, and there was no recurrence during the first year (Figure 5a). At the 1-year visit, the CBCT showed increased bone density in the space and the grafted area showed a high degree of homogeneity (Figure 5b and c).

Traditionally, a radical surgical approach such as Caldwell-Luc operation was commonly used to remove the maxillary sinus mucosa in conjunction with inferior meatal antrostomy. In addition to POMC, other examples of delayed complications have been described, such as chronic maxillary neuralgia, infraorbital nerve hyperesthesia, and recurrent sinusitis.^11,12  As is evident with the patient in the current report, facial bone deformities have also been reported at long-term follow-ups.¹²  Because of these reasons, rather than the traditional approach, the more conservative surgical technique combined with endoscopes has gained popularity in recent years.^13,14  The authors also believe that any patient with a history of prior sinus surgery should be evaluated with proper CBCT imaging prior to any implant or sinus graft surgery.

Several reports of implant installation and maxillary sinus augmentation in cysts, mucoceles, polypoid mass, and severely thickened mucosal lining are available.^13–18  In these lesions, failures of dental implants and grafts were also frequently documented.¹⁹  However, to the best of authors' knowledge, there has not been any report of implant placement into POMC or the management of POMC-affected implant with decontamination and guided bone regeneration.

The patient reported in the present paper had been inaccurately diagnosed as having normal sinus at the time of implant placement. Because of radiographic misinterpretation, a transcrestal sinus elevation was undertaken in the area of POMC with subsequent implant placement. The osseointegration and masticatory function were maintained without any complications until the implant was removed 13 years postoperatively due to peri-implantitis. An episode of active infection after the implant removal necessitated a surgical entry, and this provided an opportunity to obtain the specimen for histological evaluation for a more definitive diagnosis of the lesion as POMC. In retrospect, the history of Caldwell-Luc operation for the treatment of chronic sinusitis 20 years prior to the implant surgery also prompted speculation of the lesion being POMC.

The common differential diagnosis of cyst near the maxillary sinus includes pseudocyst and mucous retention cyst. Pseudocyst does not have epithelial lining whereas mucous retention cyst presents as a dome-shaped cyst with epithelial lining.²⁰  The histopathologic finding of POMC is characterized by the lining of ciliated pseudostratified columnar epithelium.^8,10  In this patient's specimen, some ciliary loss was also found because the POMC lesion was influenced by the presence of peri-implantitis. This is consistent with the results of Gudis et al, where the loss of ciliary function was associated with disturbed mucociliary clearance and ventilation of the sinus.²¹  In particular, the unilocular lesion in the present patient was separated from the confine of the maxillary sinus and the facial bone plate was also nonexistent.

The accessibility for the POMC lesion enucleation and detoxification of the contaminated implant surface is significant. In this patient, at the time of implant #2 removal, it was decided that implant #3 was to be left in place due to lack of mobility and relatively well-maintained osseointegration. However, when the surgical entry had to be initiated when the patient returned with an active infection, the treatment of contaminated implant surface was also indicated. After numerous recommendations, although the efficacy is inconclusive, mechanical debridement with titanium brush and chemical detoxification with tetracycline HCl were used for this particular case.^22–24  Currently, there isn't any verification method to assess the completeness of detoxification and biofilm removal. Thus, the clinical decision largely depends on the expertise of individual clinicians. In this patient, a titanium brush was used until there was no visible debris attached to the implant surface and the implant surface appeared much shinier. Much effort was made to access and debride as many exposed threads as possible. Moreover, tetracycline HCl, 100 mg/mL, was applied onto the exposed surface for at least 5 minutes after using the titanium brush. Theoretically, tetracycline HCl should eliminate bacteria on the contaminated implant surface, remove endotoxins, and inhibit collagenase activities.^25,26  However, the clinical efficacy of tetracycline HCl, its appropriate concentration, and the duration of application to exert the proposed effect have not been extensively documented in the literature.

The successful outcome of guided bone regeneration around the enucleated cystic cavity and contaminated implants may not be warranted. The true re-osseointegration with newly formed bone is also questionable although promising outcomes have been described in some reports.^27,28  In this report, an attempt was made to regenerate the bone because the area was well-isolated, thorough enucleation was possible, and the detoxification of the implant surface was achievable. As shown in the 1-year CBCT, the grafted area was verified to have completely filled in with highly dense and homogenous bone.

Successful management and treatment of POMC and the affected implants can be achieved with thorough enucleation, mechanical debridement, and chemical detoxification followed by guided bone regeneration. The treated site is well-maintained for 1 year without any evidence of radiographic and clinical complications.

Abbreviations

CBCT:

cone-beam computerized tomography

HA:

hydroxyapatite

POMC:

postoperative maxillary cyst

The authors would like to thank Jung Sun Jang, Medical Device Evaluation Team Manager in Genoss (Suwon, Korea) for his work on histopathology.

The authors report no conflicts of interest related to this case report.