Large Schneiderian Membrane Perforation Repair During Sinus Lift Surgery: A Case Report

1. Introduction

The rehabilitation of the atrophic posterior maxilla with dental implants remains a clinical challenge due to the progressive reduction of alveolar bone volume and height following tooth loss, often resulting in insufficient bone availability for implant placement.[1] In these cases, maxillary sinus floor elevation using the lateral window approach has become a predictable surgical procedure to achieve vertical bone augmentation and enable implant placement. [1]

The lateral window technique has demonstrated high long-term implant survival rates – 95.6% after 5 years and 93.1% after 10 years. [2] However, the procedure remains technique-sensitive and may be influenced by several anatomical and surgical factors, including sinus septa, membrane thickness, residual ridge height, sinus pathology, and operator experience. [3,4]

Among the reported complications associated with sinus floor elevation procedures, Schneiderian membrane perforation is considered the most common intraoperative event, with incidence rates reported around 20-25% depending on the surgical approach and anatomical conditions. [4] Large membrane perforations may compromise graft stability, increase the risk of sinus contamination and postoperative complications, and potentially affect treatment outcomes if not adequately managed. [4]

Several techniques have been proposed for the management of Schneiderian membrane perforations, including direct suturing, use of resorbable collagen membranes, and stabilization approaches designed to isolate the defect and maintain graft containment.[4] The use of stabilized collagen membranes has shown promising clinical outcomes in the management of extensive perforations, allowing continuation of the augmentation procedure without interruption. [5,6]

This case report describes the management of a large Schneiderian membrane perforation (>10 mm) occurring during lateral window sinus augmentation using a stabilized collagen membrane technique, as well as the clinical and radiographic outcomes following 1 year after the implant rehabilitation.

2. Case Presentation

A 67-year-old male patient presented to a private clinic seeking an implant-supported rehabilitation of the maxilla. The patient expressed a strong preference for a full fixed rehabilitation, as he had previously experienced difficulties adapting to a removable prosthesis and was dissatisfied with its comfort, stability and function.

The patient was classified as ASA I, with no relevant systemic diseases and reported being a non-smoker. No known drug allergies or ongoing medications were reported. The patient presented with a fully edentulous maxilla, with a history of tooth loss attributed to dental caries and periodontal disease.

2.1. Diagnostic Assessment

Initial radiographic assessment included panoramic radiography and cone-beam computed tomography (CBCT). Three-dimensional evaluation demonstrated severe vertical bone deficiency in the posterior maxilla (second quadrant), with a residual bone height of approximately 5 mm (Figure 1), precluding predictable implant placement without prior sinus augmentation. A sinus retention cyst was also detected during the preoperative assessment.

2.2. Therapeutic Intervention

A lateral window sinus augmentation procedure was planned and performed under local anesthesia using articaine with epinephrine (Artinibsa^® 40 mg/mL + 0.01 mg/mL, Inibsa^®, Llissá de Vall, Spain). Following anesthesia, a mid-crestal incision with buccal releasing incisions was performed, and a full-thickness mucoperiosteal flap was elevated to expose the lateral wall of the maxillary sinus. The dimensions and location of the lateral window were determined preoperatively using CBCT evaluation. After preparation of the lateral window with a piezoelectric surgical device (VarioSurg™, NSK, Tokyo, Japan), careful elevation of the Schneiderian membrane was initiated using sinus curettes (Hu-Friedy^®, Chicago, IL, USA) (Figure 2).

During membrane elevation, a large perforation (>10 mm) of the Schneiderian membrane occurred (Figure 3). Instead of aborting the procedure, Schneiderian membrane elevation was cautiously completed.

Following the technique described by Testori et al. [6], a resorbable collagen membrane (Bio-Gide^®, Geistlich^®, Wolhusen, Switzerland) was used to reconstruct the perforated Schneiderian membrane. The membrane was stabilized externally and folded inward to create a protected compartment for graft containment. A xenogeneic bone substitute (Bio-Oss^® S, Geistlich^®, Wolhusen, Switzerland) was placed within this compartment, and a second collagen membrane was positioned over the lateral window and secured with fixation pins (Figure 4). Tension-free primary closure was obtained using interrupted sutures (Supramid^®, B. Braun^®, Melsungen, Germany).

The postoperative regimen included amoxicillin/clavulanic acid (875/125 mg) twice daily for 8 days, a systemic corticosteroid (60 mg/day) for 3 days, paracetamol (500 mg) combined with codeine phosphate hemihydrate (30 mg) twice daily for 3 days for pain control, and a 0.12% chlorhexidine mouthwash three times daily for 10 days.

2.3. Follow-up and Outcomes

Postoperative healing was uneventful, with no signs of infection, sinus complications, or graft exposure. Clinical follow-up visits were conducted at 1 week, 2 weeks and 1 month, with sutures being removed at 2 weeks.

CBCT evaluation after a 6-month healing period (Figure 4) confirmed successful graft containment and volume stability (Figure 5).

Implant placement was subsequently performed, with six Nobel Biocare Replace (Nobel Biocare^®, Kloten, Switzerland) implants inserted in the augmented maxilla according to the prosthetically driven treatment plan. The implants were distributed to maximize anteroposterior spread and provide adequate support for the planned full-arch rehabilitation. (Figure 6). All implants achieved satisfactory primary stability at the time of placement, allowing progression to the prosthetic rehabilitation phase.

At 1-year follow-up after successful osseointegration, a full-arch fixed implant-supported metalacyclic rehabilitation was performed, restoring function and aesthetics (Figure 7).

At the 1-year follow-up after the rehabilitation, the patient reported a high level of satisfaction with the rehabilitation, expressing confidence during mastication and the absence of pain or discomfort. In the patient's own words, “I am very happy with the rehabilitation.”.

Figure 6. Case Report Timeline.

Figure 6. Case Report Timeline.

3. Discussion

Maxillary sinus floor augmentation using the lateral window technique is considered a predictable and well-documented procedure for the rehabilitation of the atrophic posterior maxilla, particularly in patients with limited residual bone height [7]. In the present case, the residual bone height was approximately 3 mm, which justified the indication for sinus augmentation before implant placement. Despite the high success rates reported for this procedure, perforation of the Schneiderian membrane remains the most common intraoperative complication associated with sinus lift surgery. [4]

The incidence of membrane perforation reported in the literature varies considerably, ranging from 6% to 42%, although most studies describe rates between 20% and 25%. Several factors have been associated with an increased risk of perforation, including sinus anatomy, membrane thickness, the presence of septa, retention cyst, and reduced residual bone height [8]. In particular, residual bone heights below 3.5 mm appear to increase the likelihood of membrane perforation during elevation [9,10].

The management of Schneiderian membrane perforations depends largely on the size and extent of the defect. Small perforations can often be managed conservatively, whereas larger defects usually require additional measures to stabilize the membrane and protect the grafted area [4]. The use of resorbable collagen membranes has been widely described as a reliable option for repairing large perforations and maintaining graft containment. However, in extensive defects, some authors still recommend interrupting the procedure and performing a second surgery after healing of the membrane [4].

In the present case, although a large perforation (>10 mm) occurred during membrane elevation, the procedure was not interrupted. Instead, careful continuation of the membrane elevation was performed, followed by stabilization with a resorbable collagen membrane. By partially adapting the membrane externally and folding it internally, it was possible to create a contained compartment capable of supporting and isolating the graft material from the sinus cavity. This approach is consistent with the technique originally described by Testori et al. 2008 [6] for the management of large Schneiderian membrane perforations, which was subsequently refined by Tian et al. 2026 [5]. This strategy appeared to provide sufficient stability for the xenogeneic graft material and helped maintain the augmented space during healing. In addition, the placement of a second collagen membrane over the lateral window may have contributed to graft protection and stabilization, in line with guided bone regeneration principles.

Although membrane perforations have been associated with increased risks of postoperative complications such as sinusitis, graft contamination, and graft instability, these complications were not observed in the present case [10]. Healing progressed uneventfully, with no signs of infection, graft exposure, or sinus-related symptoms during follow-up. Radiographic evaluation demonstrated maintenance of graft volume, allowing implant placement after 6 months with satisfactory primary stability. Previous studies evaluating similar techniques have also reported favorable histologic outcomes, demonstrating new bone formation and successful graft integration despite the occurrence of large Schneiderian membrane perforations [6]. Furthermore, successful osseointegration and definitive full-arch implant-supported rehabilitation were achieved after 1 year.

The present case reinforces the idea that large Schneiderian membrane perforations do not necessarily compromise the outcome of sinus augmentation procedures when appropriately managed. Careful handling of the membrane and adequate stabilization of the grafted compartment appear to be critical factors for achieving favorable healing and successful implant rehabilitation, even in challenging clinical situations with severe maxillary atrophy.

Nevertheless, the limitations inherent to a single case report should be acknowledged, including the limited follow-up period. Further clinical studies with larges samples of patients are necessary to better clarify the predictability of different management approaches for extensive Schneiderian membrane perforations during sinus augmentation procedures.

4. Conclusions

The stabilized collagen membrane technique appears to be a predictable option for the management of large Schneiderian membrane perforations (>10 mm), allowing successful graft containment, continuation of the sinus augmentation procedure, and subsequent implant rehabilitation. Nevertheless, this is a technically demanding surgical approach that requires adequate clinical experience and meticulous execution.