Superior Sinus Membrane Perforation Rates In Sinus Floor Elevation Procedures
Overview
This multicenter cross-sectional study aimed to assess the frequency of sinus membrane perforations during transcrestal sinus floor elevation (TSFE) using osseo-densification (OD) burs and identify associated risk factors. Conducted across six centers with ethical approval, the study included patients aged 18 and older who were missing maxillary posterior teeth with a crestal residual bone height (RBH) ranging from 2 to 6 mm. Preoperative assessments, including CBCT scans, were performed to evaluate bone dimensions and sinus health. A standardized surgical protocol for TSFE with OD burs was followed, and complications, particularly sinus membrane perforations, were documented and analyzed. Factors like the implant site (premolar or molar), socket type (healed or fresh), and initial RBH were examined for their impact on perforation rates, using descriptive statistics, χ², and logistic regression for analysis.
The study involved 621 patients with an average age of 57.9 years, undergoing sinus lifts at 670 sites with 621 implants placed in the maxilla. Most sinus lifts were performed in the molar region (76.87%) and in healed bone sites (74.33%), with an average RBH of 5.1 mm. Sinus membrane perforations occurred in 49 cases (7.31%). An RBH of 3 mm or less was identified as a significant risk factor for perforations, followed by an RBH between 3 and 5 mm. The tooth region and implant site did not significantly influence the risk of perforation. In conclusion, OD burs used in TSFE demonstrated a low rate of sinus membrane perforations, with severe posterior maxillary atrophy presenting as a higher risk factor for complications.
Introduction
After tooth loss, the posterior maxilla experiences considerable volume changes due to alveolar ridge resorption and sinus pneumatization, which can be exacerbated by age and additional tooth loss. This region has a notably high implant failure rate long-term, making successful rehabilitation challenging. Consequently, maxillary sinus augmentation is essential to enhance bone volume and improve implant success rates.
Several techniques address significant bone loss in the posterior maxilla, including sinus augmentation before or during implant placement to increase the sinus floor’s height and volume. These procedures involve either the lateral window technique or transcrestal sinus floor elevation (TSFE) with osteotomes, which is considered less invasive. However, both techniques frequently encounter complications such as sinus membrane perforation, which can lead to issues like graft migration, sinusitis, and overall procedure failure. Sinus membrane perforation is a serious concern, as an intact membrane is crucial for maintaining the osteogenic space and preventing infection.
Various methods have been suggested to assess sinus membrane integrity, such as the Valsalva maneuver and the nose-blow test. Risk factors for sinus membrane perforation include the thickness of the Schneiderian membrane, residual bone height (RBH), sinus width, surgical technique, operator experience, and anatomical variations.
The thickness of the sinus membrane, typically about 1 mm in healthy patients, is a major factor influencing perforation risk. Age affects sinus membrane thickness, while conditions like periodontitis and smoking can also impact it. The ability of the sinus membrane to stretch plays a significant role in the success of sinus grafting procedures.
Osseodensification (OD) is a non-excavating technique that uses specialized burs to expand bone in trabecular spaces without traditional cutting. Clinical studies have shown that OD can enhance implant stability and increase bone-to-implant contact compared to conventional drilling methods. OD also produces controlled hydraulic pressure on the sinus membrane, facilitating sinus floor elevation and reducing the risk of perforation.
In cases of severe maxillary atrophy, the OD technique has demonstrated success in improving implant stability and achieving sinus floor elevation with minimal membrane perforation. Patient-reported outcomes suggest that OD may be less invasive and offer better post-operative experiences compared to more traditional methods.
This multicenter clinical study aims to evaluate the effectiveness of OD in transcrestal sinus floor elevation, focusing on sinus membrane perforation rates and associated risk factors. The study hypothesizes that the OD technique will result in a lower rate of sinus membrane perforation compared to conventional methods.
Method
This multicenter cross-sectional study adhered to the ethical principles of the 1964 Declaration of Helsinki and received approval from the local ethical committees at six different centers under protocol ID ODSINUSPERF. It was registered with ClinicalTrials.gov (ID # NCT05954273).
The study focused on patients requiring dental implants for posterior maxillary edentulous spaces.
Preoperative evaluations included a thorough review of medical and dental histories, clinical examination, and CBCT scans to assess bone dimensions and sinus health.
Implant systems used included tapered screw-vent (ZimVie), tapered (Biohorizons), Anyridge (Megagen), Nobel Active (Nobel Biocare), IDCAM ST (Implant Diffusion International), and Bego Semandos RSX (Bego). Implants varied in diameter (regular: 3.75-5 mm, wide: 5 mm) and length (regular: 10-12 mm, long: 12 mm+).
The surgical procedure was standardized across all centers and performed under local anesthesia. A full thickness mucoperiosteal flap was reflected, and sinus grafting was performed according to the residual bone height (RBH). For RBH greater than 5 mm, the protocol involved using pilot drills and Densah burs to lift the sinus membrane and deposit autogenous bone. For RBH between 4 and 5 mm, additional bone graft materials were used. For RBH less than 3 mm, initial preparation skipped pilot drilling and directly utilized wider Densah burs for sinus membrane elevation and autogenous bone placement.
In cases of fresh sockets, if the apical width did not meet the minimum required, the sinus grafting was deferred to a second stage after socket healing. All cases followed the same protocols for both fresh and healed sockets, depending on the ridge width and bone height.
Post-surgical care included a soft, cold diet for the first three days, oral hygiene instructions, and a one-week course of antibiotics, along with anti-inflammatory and analgesic medications for three days.
Parameters investigated included surgical complications, especially sinus membrane perforations. Factors such as implant site (molar or premolar, immediate or healed) and initial RBH were analyzed to assess their impact on perforation rates. Descriptive statistics were used to summarize patient data, bone dimensions, and implant distribution, while sinus membrane perforation was assessed using chi-square tests and logistic regression analysis with a 5% significance level (IBM SPSS 23).
Inclusion Criteria
Inclusion criteria involved patients aged 18 or older with missing maxillary posterior teeth, a residual bone height (RBH) of 2 to 6 mm between the ridge crest and the sinus floor, and a maxillary alveolar ridge width of at least 4 mm.
Exclusion Criteria
Exclusion criteria included patients over 80 years old, those with sinus pathologies detected by cone beam computed tomography (CBCT), or systemic conditions such as uncontrolled diabetes, bleeding disorders, or recent radiation therapy. Excessive smoking, tobacco chewing, and alcohol abuse were also exclusion factors.
Result
This study involved 621 participants with a mean age of 57.9 years, undergoing sinus lifting and implant surgeries. The procedures were generally smooth, with no significant complications such as excessive bleeding, soft tissue issues, or infections. A total of 670 sinus grafting sites were performed across six centers, with 621 implants placed in the posterior maxilla. All implants were restored and monitored as part of routine maintenance.
Among the 670 sinus lifts, 515 were in the molar region and 155 in the premolar region. Of these, 498 were conducted in healed bone sites, while 172 were in fresh socket sites. The average residual bone height (RBH) was 5.1 mm, ranging from 2 to 7 mm. Specifically, 165 sites had an RBH of ≤3 mm, 256 sites had an RBH between 3 and 5 mm, and 249 sites had an RBH >5 mm. Bone grafting was necessary in 421 sites to augment the sinus before implant placement, while 249 sites required no additional grafting.
Sinus membrane perforations occurred in 49 sites (7.31%), confirmed through direct visualization. Statistical analysis revealed that the type of implant placement—whether in healed sites or immediate placements—did not significantly influence the incidence of perforations. However, a lower RBH (<5 mm) and the molar region were associated with a higher likelihood of sinus membrane perforation. Logistic regression identified an RBH of less than 3 mm (OR = 10.130, p < 0.001) and between 3 and 5 mm (OR = 3.726, p = 0.022) as significant risk factors for perforation. The location of the tooth, whether premolar or molar, and the implant site type did not significantly affect perforation risk.
Conclusion
This multicenter clinical study assessed the rate of Schneiderian membrane perforation and associated risk factors for sinus floor elevation (SFE) using a transcrestal approach with OD instrumentation. The study confirmed the hypothesis that the OD technique would result in a low sinus membrane perforation rate. Across 670 sites involving 621 patients from six centers, the overall perforation rate was 7.31%. Logistic regression revealed that challenging conditions, such as reduced buccal ridge height (RBH) of less than 3 mm (OR = 10.13) or between 3 to 5 mm (OR = 3.72), were linked to a higher risk of sinus membrane perforation.
OD instrumentation is recognized for its effectiveness in enhancing vertical dimension in the posterior maxilla with minimal invasiveness. Although the transcrestal technique, initially described by Summers, is widely adopted due to its minimally invasive nature, recent reviews have indicated that OD instrumentation achieves superior implant primary stability and allows for safer and earlier prosthetic reconstruction compared to the osteotome technique.
Prior studies have shown a 90% cumulative survival rate for implants placed in the posterior maxilla with conventional osteotome techniques, with reduced implant survival rates reported for RBH less than 4 mm. In contrast, OD instrumentation has demonstrated a 97% implant survival rate for RBH ranging from 3.5 to 7.3 mm. This method benefits from a hydrodynamic compression wave created by the OD burs, which aids in elevating the Schneiderian membrane and introducing autograft material effectively.
The study also noted an increased perforation rate with decreased RBH, aligning with previous findings that reduced RBH correlates with higher membrane perforation rates using both transcrestal and lateral window techniques. Despite this, OD instrumentation is considered advantageous in reduced RBH scenarios due to its reduced invasiveness and lower complication risk.
Recent research using OD burs in a goat model with lateral window techniques reported a 16% perforation rate, likely due to inadequate bone structure for effective sinus floor lifting. The current study highlighted that smaller incremental bur jumps led to increased perforation rates due to insufficient bone slurry for sinus membrane elevation. Larger diameter instrumentation and full flap reflection were suggested to improve the technique’s effectiveness.
The study utilized high magnification and careful suction to identify perforations, ensuring that even pinhole perforations were accounted for, with no observed sequelae such as sinusitis or oroantral communication. Although some studies have reported the safety of OD instrumentation, limitations include small sample sizes and lack of long-term follow-up. This multicenter study aimed to provide comprehensive insights into sinus membrane perforation rates with OD instrumentation, showing an overall perforation rate of 7.31%. Future prospective studies are needed to further explore the long-term performance of implants and restorations placed in sinus-grafted areas using the OD transcrestal approach.
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