Minimally Invasive Sinus Elevation Surgery

What Is Minimally Invasive Sinus Elevation Surgery?

The maxillary sinus floor elevation surgery for bone graft and for increasing residual bone height is employed for dental implantation. Minimally invasive sinus floor elevation can be done now without going through the lateral window approach.

Why Is There a Need for Minimal Invasive Surgery?

The maxillary sinus floor elevation surgery is mainly done to increase the alveolar bone height and improve osseointegration (bone-implant contact) in upper molars or posterior teeth. The minimally invasive approach is made through the lateral window approach and is most preferred over the older sinus lift procedure. However, these predictable and traditional approaches often pose postoperative complications and challenges like septal and alveolar artery damage as well to an extent.

Minimally invasive surgery is not only beneficial to the patient for faster wound healing postoperatively but can also reduce the risk of damage to anatomic structures like the alveolar arteries and the septum. In adapting the lateral window minimal approach compared to the conventional trapezoidal flap, the operator can achieve better results, especially in terms of the treatment time or surgery time.

What Are the Inclusion Criteria of Minimally Invasive Sinus Lift Surgery?

Maxillary sinus floor elevation represents a predictable and effective surgical procedure to increase bone volumes in clinical conditions of atrophic alveolar bone, allowing the insertion of implants of adequate length; the lateral approach is a well-known surgical technique to gain access to the maxillary sinus. Although it is considered to be more invasive than crestal or trans alveolar techniques, it provides a suitable clinical solution for severely resorbed maxillae, where residual alveolar bone height is minimal, and a large amount of bone reconstruction is needed.

Patients with active periodontal disease are treated until adequate periodontal health has been maintained. All the patients are treated with multiple sessions of oral hygiene instructions until they can demonstrate adequate inflammation control. Periodontal patients are treated by scaling and root planing and, if necessary, by a surgical approach. They were included only if, at three months follow-up, they had periodontal pockets less than 5 mm deep.

What Are the Exclusion Criteria of Minimally Invasive Sinus Lift Surgery?

The following exclusion criteria are considered:

• Systemic or immunological diseases.

• Recent acute myocardial pathology.

• Coagulation disorder.

• Metabolic disorders.

• Bisphosphonates therapy.

• Heavy smoking (more than ten cigarettes per day).

• Alcoholism.

• Maxillary sinus pathology.

• Former sinus surgery.

What Is the Procedure for Minimally Invasive Sinus Lift Surgery?

1. Antibiotic therapy (Amoxicillin 2 g) is started 2 hours before every surgical intervention.

2. Prior to surgery, patients are asked to rinse with a 0.2 % Chlorhexidine solution for one minute. Under local anesthesia, a full-thickness mucoperiosteal envelope flap is elevated.

3. The flap is designed as a horizontal incision on the buccal wall of the maxillary sinus, positioned at the mucogingival line. When improved visualization of the surgical site is needed, two small releasing incisions of usually approximately 2 mm in length are performed at the mesial and distal ends of the flap.

4. Horizontal and releasing incisions are beveled so that an increased connective surface would be available for sutures and for collagen membrane stabilization.

5. Once the flap is raised, a bone window of 6*6 mm is opened, using the piezosurgery system to gain access to the maxillary sinus.

6. Bone window dimensions are recorded using a periodontal probe. The bone wall is reduced using a bone shaving device until the sinus membrane becomes evident and the bone window dimension is approximately 6*6 mm. All surgical procedures are performed with great accuracy to avoid damage and perforation of the membrane.

7. The sinus is filled with deproteinized bovine bone. The membrane is sutured to the exposed connective surface in the peripheral area of the flap, and a periosteal releasing incision flap is sutured with sling sutures.

8. Antibiotic therapy is continued for 5 days (2 g Amoxicillin per day). Painkillers (Ibuprofen 600 mg) are prescribed, to be taken as long as required.

9. Chlorhexidine mouthwashes are prescribed twice daily for the following 21 days. Sutures are removed after 14 days. Dentures are not permitted for use until they are adjusted and refitted and not before two weeks. After surgery, patients are recalled for the follow-up visit at 1, 7, 14, 30, 180 days intervals.

What Is the Post-surgical Follow-up or Intervention for Minimally Invasive Sinus Lift Surgery?

Maxillary grafted sites are left to heal six months before implant placement; after the 180 days follow-up, CT (computed tomography) scans (with surgical template) are performed in order to assess the augmented bone volume where the implants are planned to be inserted.

Peri-implant marginal bone level changes are assessed with periapical radiographs taken with the paralleling technique at implant placement, at the definitive restoration delivery, and four months after prosthesis loading.

• Height and Width of Residual Alveolar Bone: Measurements are recorded in correspondence to radiopaque reference on CT scans.

• Intrasurgical Measurements: Once the flap is designed, the length of the horizontal incision is measured with a periodontal probe (CPC15).

• Bone Window Dimensions: These are recorded using a periodontal probe. Bone window length and height are measured, and bone window area is calculated.

What Are the Complications of Minimally Invasive Sinus Lift Surgery?

The following are the complications of minimally invasive sinus lift surgery:

1. Prosthetic Failure:

• All planned prostheses could not be delivered because of implant failure.

• Loss of prosthesis due to implant failure.

• Replacement of a definitive prosthesis for any reason.

2. Implant Failure:

• Implant mobility.

• Implant removal due to progressive marginal bone loss.

• Any mechanical complications (such as implant fracture) that render the implant not usable. The stability of each implant is tested after removing the healing abutment (6 months after implant placement, before starting the prosthetic stage) and four months after the initial loading of the definitive prostheses.

• After the prosthesis is removed, clonal measurements are recorded, and periapical radiographs are taken.

3. Biological or Mechanical Complications.

Conclusion:

These tested surgical approaches, along with a small bone window and an envelope flap, could represent a minimally invasive procedure to gain access to the sinus cavity without influencing the safety of the surgical intervention. Less discomfort at sites are subject to minimally invasive flap procedure during the first week after surgical intervention and hence is more operator and patient-friendly.