Radiographic and Nasal Endoscopic Observation of Accidentally Perforated Anterior Nasal Cavity With Dental Implants: Case Reports with 5–23 Years of Follow-Up

Nasal floor elevation is an effective and safe procedure for implant placement in the atrophic premaxilla and has a similar success rate compared to the sinus lift technique.¹  Both nasal and sinus floor elevations are predictable procedures that allow long-term implant survivability.^2–4  Many studies on sinus membrane perforation have been published and prevailing opinions suggested that the maxillary sinus perforation has negatively influenced the success of maxillary sinus grafting and implant survival rates.^5–7  On the contrary, Park et al reported that clinical and radiological results did not actually show any difference in the success rate between the perforated group and non-perforated group.⁸  The authors concluded that the result of sinus membrane perforation was tremendously heterogenic.⁸  In the case of anterior nasal floor perforations with dental implants, there are only a few case reports available that described the occurrence of rhinitis and maxillary sinusitis in anterior nasal floor perforation as associated complications.^9,10 

Surgical treatment of anterior nasal floor perforation has been reported, which removes the portion of the implant exposed to the nasal cavity through the nasal endoscope.^9,10  However, no reports were showing that perforated implants were clinically and radiologically satisfactory over a long period. In this case report, long-term clinical, radiologic, and nasal endoscopic effects of perforated anterior implants on nasal floor perforation are examined.

Seven patients were identified as having nasal floor perforations among patients who had implants installed in the maxillary anterior region between 1996 and 2018. Four of 7 patients were followed-up, and cone-beam computerized tomography (CBCT; Rainbow CT, Dentium, Suwon, Korea) and nasal endoscopic examination were performed. The remaining 3 patients dropped out because of 1 death and 2 relocations. Patients signed written informed consent before the examination. CBCT was obtained with a cross-sectional and sagittal image at the perforated implant site. Nasal endoscopic examination was performed and recorded by one otolaryngologist. The patient's demographic data such as age, sex, smoking, and follow-up period were also recorded (Table 1).

A 39-year-old male patient presented to the private clinic in Seoul, Korea, to receive full-mouth rehabilitation of maxilla and mandible with dental implants. The patient was a smoker and had no systemic disease that would be contraindicated for implant therapy. After 6 months of following bilateral sinus graft procedures, implants were placed. Six months after the surgery, after confirmation of osseointegration, the final prostheses were delivered (Figure 1a) and the post-insertion panoramic radiograph was taken. Fifteen years later, a new panoramic radiograph and CBCT were also obtained and evaluated. Furthermore, the otolaryngologist also performed nasal endoscopy to evaluate the area.

A healthy 35-year-old male had multiple implants placed and restored in the private clinic in Seoul, Korea in November of 1996 (Figure 2a). The patient was a non-smoker who didn't present with any systemic diseases. All implants achieved osseointegration successfully, and segmentalized prostheses were delivered. The post-delivery panoramic radiograph was taken. The patient was routinely examined twice per year for 23 years. At a 23-year follow-up visit, a new panoramic radiograph and CBCT were also obtained and evaluated. Furthermore, the otolaryngologist also performed nasal endoscopy to evaluate the area.

A 37-year-old male with smoking habit presented to the private office in Seoul, Korea. The patient did not have any systemic disease that would be contraindicated for implant therapy. A pre-operative panoramic radiograph revealed severe ridge resorption and severe bone loss around the poster mandibular dentition due to periodontal disease (Figure 3a). In 2000, during implant placement, simultaneous transcrestal sinus augmentation around the upper left quadrant was performed. Inadvertently, nasal mucosa was perforated, but the procedure continued with the placement of 4.0 × 10 mm hydroxyapatite-coated fixture (Steri-Oss Steri-Oss Inc) with bovine bone mineral matrix (Bio-Oss Geistlich) near the apical extent. Six months later, the final prosthesis was delivered after confirming the osseointegration of all the implants. The patient was closely monitored for 18 years with a routine examination and maintenance twice per year. At his 18-year follow-up visit, a new panoramic radiograph and CBCT were also obtained and evaluated. Furthermore, the otolaryngologist also performed nasal endoscopy to evaluate the area.

This 45-year-old systemically healthy female patient had the SLA-textured implant (3.8 × 12 mm, Implantium, Dentium) placed at #6 site in November 2013 in the private clinic (Figure 4a). The fixture extended beyond the nasal floor, but all implants were successfully integrated and subsequently restored with a splinted prosthesis. The patient was closely followed up for 5 years with a routine examination and maintenance twice per year. At her 5-year follow-up visit, a new panoramic radiograph and CBCT were also obtained and evaluated. Furthermore, the otolaryngologist also performed nasal endoscopy to evaluate the area.

The patient did not show any complications postoperatively. The radiograph revealed that the resorbable blast media (RBM)-textured 4 × 10 mm implant (Restore, Keystone Dental, Inc) installed at #11 site inadvertently penetrated through the nasal floor. There were no clinical symptoms of nasal floor perforation except transient nasal bleeding. On a panoramic radiograph taken 15 years later, no bone resorption around the #11 implant was observed (Figure 1b). The CBCT taken at the same time showed that #11 implant was perforated into the nasal cavity, but did not show any signs of mucosal thickening around the fixture (Table 1, Figures 1c–e). The images of nasal endoscopy also demonstrated that the perforated implant was not covered with mucosa and the surrounding tissues did not appear to be inflamed (Table 1, Figure 1f). The protruded implant, however, did show minor debris accumulation on the fixture surface and the inferior turbinate was observed to be free of direct contact with the tip of the implant (Figure 1f–g).

The patient was asymptomatic for 23 years. One of the implants was a machined surface fixture with a dimension of 3.75 × 11.5 mm (3i Implant Innovations) at #11 site and the panoramic radiograph revealed that the tip appeared to have penetrated through the surrounding nasal floor (Figure 2a). The 23-year follow-up panoramic radiograph revealed that there was moderate bone loss combined with clinical signs of peri-implantitis around #11 implant (Figure 2b). The CBCT images taken after 23 years also showed the implant tip appeared to be located inside the nasal cavity (Figure 2c). A slight mucosal thickening was observed around the part of the fixture that extended beyond the nasal floor (Table 1, Figure 2d and e). The nasal endoscopy images revealed that nasal crust was observed in the mucosa surrounding the implant tip (Table 1, Figure 2f). The nasal crust was located inferior to the inferior turbinate. After removing the nasal crust, mucosal thickening and bleeding were observed (Figure 2g). Initially, the implant tip appeared to be covered with mucosa, but after the removal of the proliferative mucosa, the tip became visible (Figure 2h). The patient did not show any signs of complications after the procedure.

Postoperatively, there were no complications other than transient nasal bleeding. The 18-year follow-up panoramic radiograph did not show any remarkable marginal bone loss around #11 fixture (Figure 3b). The CBCT taken at an 18-year visit revealed that the implant tip had penetrated intranasally, but there was no mucosal thickening around the perforated site. (Table 1, Figure 3c–e). Subsequently, the nasal endoscopy confirmed that the protruding implant tip was covered with healthy mucosa with particles of bone grafts that were partially visible through the thin tissue (Table 1, Figure 3f and g).

The patient did not report any postoperative complications other than transient nasal bleeding immediately after the surgical placement. After 5 years of the nasal floor perforation, the patient was still asymptomatic and there was no marginal bone loss around the implant as observed from the panoramic radiograph (Figure 4b). Mucosal thickening around the perforated site was not observed on the CBCT scan either (Table 1, Figures 4c and d). The nasal endoscopy confirmed that the protruding implant surface was covered with mucosa that was slightly elevated with minor inflammation (Table 1, Figure 4e and f).

Implant placement in the atrophic maxilla is a challenge for the surgeon. As an alternative, nasal floor augmentation or bicortical stabilization combined with implant placement has been described in the past.^2,11,12  However, nasal floor perforation may occur during bicortical stabilization and as a result, the implant tip may be protruded into the nasal cavity.¹³  Although the long-term implant survival rate has been shown to be similar when compared to sinus floor augmentation, reliable data is lacking due to limited number of nasal floor augmentation cases compared to sinus grafting procedures.² 

The most common type of intraoperative complication during nasal cavity or maxillary sinus grafting procedure is the membrane perforation.^14–16  The studies have shown that the perforation was more common during maxillary sinus augmentation than nasal floor elevation.^14–16  As a result, the protruded implant inside maxillary sinus may contribute to thickening of the Schneiderian membrane leading to maxillary sinusitis.^17,18  On the contrary, there are also reports showing that long-term exposure of the implant tip into the maxillary sinus does not affect clinical and radiological outcomes.¹⁹  Jung et al reported that there was sinus mucous thickening in 14 of the 23 implants exposed inside the sinus cavity, and all patients remained asymptomatic.²⁰  Similarly, in animal experiments, Zhong et al showed that the tips of the implants with penetrating depth of 1 mm and 2 mm were fully covered with newly formed membrane and partially with new bone.²¹  The tips that extended more than 3 mm were exposed in the sinus without any membrane or bone coverage, but still without any differences in implant stability, bone-to-implant contact, and bone volume around the implant threads.²¹  The authors concluded that despite the protrusion, penetration of dental implant into the maxillary sinus with membrane perforation did not compromise the sinus health and the implant osseointengration.²¹  The heterogenicity of this result can be attributed to the type of sinus mucosal lesion, extent of Schneiderian membrane perforation, location of fracture or injury of the cortical layer of the sinus floor, skillfulness of the surgeon, and duration of postoperative antibiotic administration.¹⁹  However, there are not many available reports of complications associated with implant placement with anterior nasal floor perforation.¹⁷ 

Anatomically, the nasal cavity and maxillary sinus are lined with the same pseudostratified ciliated columnar epithelium. The maxillary sinus communicates with nasal cavity through the maxillary ostium and ethmoid infundibulum, and is drained to the middle meatus.^22–24  The sinus floor perforation is known to be the main cause of dysventilation and ostium obstruction due to mucosal thickening. In the case of nasal floor perforation with implant extension into the nasal cavity, rhinosinusitis can be induced by the irritation of the nasal mucosa with altered nasal airflow and debris accumulation on the exposed implant surface.^9,10  In addition, nasal clearance could be disturbed by implant blockage of the mucociliary pathway, leading to inflammation.^9,10  However, the effect of penetration depth and the extent of exposed implant inside the nasal cavity on implant stability is still undetermined.

The nasal floor perforation can be accurately assessed using nasal endoscopy. It can also be used to evaluate the inside of maxillary sinus through the surgically expanded ostium. Maru and Gupta²⁵  suggested that nasal endoscopy was a better diagnostic tool than conventional CT scans for observation of middle meatus secretion, condition of mucosa, and synechiae. In the present cases, the mucosal covering of the protruding implant and the inflammation of the nasal mucosa were accurately identified using nasal endoscope. The findings from nasal endoscopy and CBCT positively correlated to each other as well, but the ability to assess the nature of surrounding tissues near the extended implant tip was far superior with endoscopy.

In the current report, four patients had nasal floor perforation during bicortical stabilization and implants penetrated into the nasal cavity. Nevertheless, these implants successfully achieved osseointegration and were restored with prosthesis without any symptoms of complications long-term. Based on the CBCT evaluations, 3 implants appeared to be without any mucosal thickening around the protruding tips, whereas in nasal endoscopy, 2 implant tips were found to be covered with nasal mucosa. In the nasal endoscopy, mucosal thickening was observed around 3 implants with only 1 implant showing visible inflammation. One implant had the tip exposed inside the nasal cavity without any tissue coverage, but there was no peripheral mucosal proliferation or inflammation. Given the limited number of cases evaluated, findings must be interpreted with caution and better controlled with appropriate sample sizes for future studies.

Based on clinical, radiological, and nasal endoscopy evaluations, dental implants extending into nasal cavities through anterior nasal floor perforation did not affect implant stability nor did they show any signs of complications long term.

Abbreviations

CBCT:

cone beam computerized tomography

RBM:

resorbable blast media

The authors report no conflicts of interest with this report.