Closure of Schneiderian Membrane Perforation with the ‘Parachute’ Method and Placement of Two Implants During a Sinus Lift Surgery

The author:
Kobyakov Aleksandr Vladimirovich
A maxillofacial surgeon
The principal place of work:
N.I. Pirogov Regional Hospital,
the Division of Maxillofacial Surgery;
the Department of Dental Surgery and Maxillofacial Surgery of N.I. Pirogov Vinnitsa National Medical University

A sinus lift surgery is a method of a vertical dimension augmentation in a posterior maxillary alveolar process with the purpose of one-stage or deferred implantation upon its severe athrophy and/or significant pneumatization of the maxillary sinus. The method has been initially described by O.H.Tatum and P. Boyne (Tatum, O.H. (1986) Maxillary and sinus implant reconstruction. Dental Clinics of North America, 30, 207-229. ; Boyne, P. and James, R.A. (1980) Grafting of the maxillary sinus floor with autogenous marrow and bone. Journal of Oral and Maxillofacial Surgery, 17, 113-116.)

Now the sinus lift surgery is a well researched, safe, and documented procedure, which is highly popular among dentists. At the same time, separation of maxillary sinus mucous membrane from its walls is quite a delicate procedure and sometimes the membrane breakage during a surgery with defects happens. Literature shows that the percentage of Schneiderian membrane perforations during sinus lift surgeries varies from 11% to 56%. (Ardekian, et al. The clinical significance of sinus membrane perforation during augmentation of the maxillary sinus. J Oral Maxillofac Surg. 2006;64:277–382. [PubMed]).

This kind of an operative complication often bewilders surgeons and sometimes even makes them stop the surgery and proceed with it just in some time. But it should be clear that during the following attempts to repeat the surgery, the risk of the scar tissue perforation does not become reduced. Moreover, the size of the perforation hole can be significantly bigger because of the Schneiderian membrane elasticity loss. In view of this, some methods of mucous membrane defect closure have appeared providing an opportunity to continue and complete the surgery within one stage. Moreover, if mucous membrane defect closure iss conducted right, the mere fact of perforation does not affect the implant survival. ( Shwartz-arad D, Herzberg R, Dolev E. The prevalence of surgical complications of the sinus graft procedure and their impact on implant survival. J Periodontol. 2004;75:511–16.)

Various methods of Scheiderian membrane perforation closure during a sinus lift surgery have been suggested. Most of them are based on collagen membrane utilizing.
In the following clinical case a big perforation in mucous sinus membrane appeared. For that reason, the ‘parachute’ method has been applied for conducting the defect closure along with one-stage placement of Bio3 Progressive implants.

Clinical Case

A patient Ya., 32 years old, complained of missing teeth in the area of the left maxilla. The medical history showed that the teeth had been extracted because of caries complications 5 years ago. It also appeared that the patient had been smoking for 10 years. So the patient was warned about possible risks and complications of implantation and sinus lift surgery connected with smoking.

Objectively: During the oral cavity examination, a bounded edentulous space in the posterior left maxilla between the teeth 2.4 and 2.7 was found. CBCT of the maxilla and the defect area showed that the height of the bone tissue between the maxillary sinus floor and the jaw ridge bone was from 4 to 6mm, which was not enough for implant placement without penetration into the maxillary sinus space (pic. 1). The bone tissue volume presented was not enough for placement of a minimal implant without a sinus lift surgery, but the bone volume available permitted conducting sinus lift simultaneously with implant placement. The decision was taken to conduct a sinus lift surgery with simultaneous placement of 2 implants Bio3 Progressive 11,5/3,8.

The surgery process: Using local anesthesia with DS-Forte Ultracain solution, after the processing of the operative field with an antiseptic (Chlorhexidine bigluconate), and L-shaped cut was made on the mucous membrane, in the area of the alveolar process of the left maxilla, along the alveolar process top and through the gingival space near the teeth 2.4, 2.6 (pic. 2). The zygomatic alveolar crest was skeletonized with an elevator (pic. 3). The bone tissue was thinned with the help of a special diamond bur (pic. 4.) until its mucous membrane was seen (Schneiderian membrane) (pic. 5).

Then the attempt to separate the mucous sinus membrane from its bone walls was made with the help of an antral curette set (pic. 6), which resulted in a perforation appearance in the anterosuperior part of the space (pic. 7). Despite the complication, the separation of the Schneiderian membrane from the lower and medial sinus walls was continued, the sinus membrane was mobilized to the most in the area of the posterior, medial, and lower walls. The patient’s blood collection was made and PRF-membranes were prepared (pic. 8). The perforation hole was closed with PRF- and collagen membranes according to the 'parachute' method (pic. 9, 10). Implants Bio3 Progressive 3,8/11,5 were inserted into the preliminary prepared sockets for the alveolar process width (pic. 11). The space between the membrane and the bone walls of the sinus was partially filled with the mixture with PRF (pic. 12).

After that full insertion of implants into augmentate and bone tissue of the alveolar process, as well as filling of the residual cavity with the osteoplastic material were conducted (pic. 13). Some part of the collagen membrane was pulled out of the lateral window and covered with a mucoperiosteal flap, the wound was sewn up tightly with Nylon thread 4.0 (pic. 14). A comparison CBCT of the operative area was conducted (pic. 15).

For the postoperative period antibacterial and anti-inflammatory therapy as well as vasoconstrictive medication for the left side of the nasal cavity were prescribed, to prevent blocking of the natural anastomosis in the maxillary sinus.

Pic. 1. CBCT of the posterior left maxilla. The left maxillary sinus is significantly pneumatized, an alveolar opening in the area of the missing tooth 2.5 is observed
Pic. 2. The cut in the area of access to the alveolar process of the posterior maxilla
Pic. 3. The view of the released alveolar process and the lateral wall of the left maxillary sinus: the area of the sinus has more light grey contours and less bleeding points (marked with a dotted line)
Pic. 4. A ‘lateral window’ formation in the sinus wall with the help of a diamond bur
Pic. 5. Schneiderian membrane (the sinus membrane) with a small number of vessels in it is seen through the cut
Pic. 6. Separation of the mucous sinus membrane from its bone walls with the help of an antral curette
Pic. 7. The view of the perforation hole in the partially separated mucous membrane of the posterior sinus
Pic. 8. PRF-membranes and collagen membrane
Pic. 9. The view of PRF-membranes put under the Schneiderian membrane
Pic. 10. Collagen membrane put across the PRF-membranes and pulled outside

Pic. 11. Bio3 Progressive implants partially inserted for the purpose of further filling of the socket with the osteoplastic material

Pic. 12. Mixture mixed with PRF-blobs and PRP
Pic. 13. The view of the implant fully inserted and the final filling of the subantral space with the osteoplastic material
Pic. 14. Tight sewing up of the wound with Nylon thread. A healing abutment was placed into the implant in the area of the tooth 2.5 to prevent its displacement towards the sinus cavity
Pic. 15. The comparison CBCT of the sinus operated