Schneiderian Membrane Perforation Rate During Sinus Elevation Using Piezosurgery: Clinical Results of 100 Consecutive Cases

Stephen S Wallace. DDS;Ziv Maior. DMD; Stuart J. Froum, DDS;Sang-Choon Cho, DDS;Dennis R Tarnow, DDS

The lateral window sinus elevation procedure has become a routine and highly successful preprosthetic procedure that it used to increase bone volume in the posterior maxilla for the placemant of dental implants. Many surgical techniques have been proposed that provide access to the maxillary sinus through the lateral wall to allow for elevation or the sinus mem­brane. Among these are the multiple variations of the hinge and complete osteotomy tech-niques, which make use of rotary cutting, instruments for the antrostomy The most common intraoperatrve complication with these surgical approaches is perforation of the schneiderian membrane, with perforation rates of 14% to 56% reported in the literature  In most instances, perforation occurs either while using rotary instruments to make the window or when using hand instruments to gain initial access to begin the elevation of the membrane from the sinus walls. This article presents an alternative approach that uses a piezoelectric instrument for the sinus elevation procedure. Although new to the United States, the approach has been used succestfully in Europe for many years The membrane perforation rate in this series of 100 consecutive cases using the piezoelectric technique has been reduced from the average reported rare of 30% with rotary instrumentation to 7%. Furthermore, all perforations wiih the piezoelectric technique occurred during the hand instrumentation phase and not with the piezoelectric inserts(Int J Penodom.cs Restorative Dent 20O7;27.413-419 J
'Clinical Associate Professor. New York University Department of Periodontics and Implant Dentistry, New York, New York.
^Pnvate Practice. Ra'anano, \srsel. 3Clinic»l Professor, Director of Clinical Research, New York University Department of
Periodontics and Implant Dentistry. New York, New York. 'Assistant Clin.cal Professor, Associate Director of Omical Research, New York University
Department of Pariodontics and Implant Dentistry, New York, New York. ^Professor arid Chairman, New York University Department of Periodontics and Implant
Dentistry, New York, New York.

Correspondence to: Dr Stephen Wallace, 140 Grandview Avenue, Waterbury, CT O670B. e-mail: sswdds.sinut9sbcglobal.net.

Sinus augrnentation surgery has become a well-accepted preprosthetic procedure for creating sufficient bone volume for the placement of endosseous implants in the atrophic posterior maxilla.1"' This technique, first presented by Tatum5 in 1977 and first published in 1980 by Boyne and James,* has since undergone many modifications The lateral window approach today uses many antrostomy designs. The procedure is most often initiated with various forms of rotary surgtcal instrumentation, such as an electric or air-driven handpiece with diamond or carbide burs. The actual elevation of the schneidenan mem­brane, performed prior to placement of the bone graft, is typically performed with hand instrumentation.

The piezoelectric stnus elevation technique uses an improved and sophisticated ultrasonic (piezoelectric) device (Piezosurgery Inc). The device operates at a variable modulated fre­quency (24.7 to 29.5 KHz) that is designed to cut or grind bone but not damage adjacent soft tissues. It uses specifically designed osteotomy (cut­ting) and osteoplasty (grinding) inserts for making the antrostomy.

Initial membrane elevation is per­formed with a unique blunt elevator that further protects the integrity of the membrane by providing a cavitat-ing saline spray.

The most frequent intraoperative complication with sinus elevation surgery is the perforation of the schnei-denari membrane. This paper presents
the intitial clinical experiance with regard to perforation rates observed in consecutive lateral window sinus ele­vations performed in the private prac­tices of five expenenced surgeons, all but one of whom were new to the piezoelectric sinus elevation technique

Method and Materials

Clinical data for this study were obtained from the private practices of the participating clinicians. The data include the initial lateral window entries using the Piezosurgery device, which were performed following a single trial case used to gain familiarity {learning curve) with the device. All patients required maxillary sinus elevation for the placement of endosseous implants, were medically qualified to receive such therapy, and signed appropriate consent forms.

A database was established to report observed sinus membrane per­forations. Occurrences of perforations were recorded, as were the types of inserts used Membrane thickness as measured by computerized tomo-graphic (CT) analysis was also recorded, because this anatomic fac­tor has been linked to perforation rates. A total of 100 grafted sinuses were included in this case series.

Results

One hundred sinus elevations were performed, and there were seven per forations. None of the perforations occurred during the antrostomy and initial membrane elevation with the piezo inserts. The seven perforations that occurred upon continued mem-hand instruments were related to the presence of a septum (n = 4) and an extremely thin membrane (n - 3). The overall membrane perforation rate was 7%. The perforation rate with the piezoelectnc inserts was 0%.

Because the number of perfora­tions was limited to seven, it was not possible to attribute any statistical dif­ference to the perforation rates of thick (> 1 mm) versus thin (< 1 mm) mem-branes. Eighty-seven of the lateral walls were > 1 mm in thickness; these win­dows were created with the OP-3 and OT-1 inserts The remaming 13  were< 1 mm in thickness, and these windows were made using osteoplasty instru­ments such as the OT-5 diamond ball or the OT-1 diamond scalpel

Discussion

Piezoelectric bone surgety has been used for many intraoral dental and implant procedures. The use of this technique for sinus elevation surgery has been described by Vercelioth and coworkers.7'8 Not only is this tech­nique clinically effective, but histo-logic and histomorphometric evi­dence of wound healing and bone formation in the dog model has been presented to show that the tissue response is more favorable to Piezo-surgery than it is to diamond Of car­bide rotary instrumentation.

The piezoelectric ultrasonic device used in this study (Piezosurgery) is designed to operate at a low frequency of 24.7 to 29.5 KHz. producing microvi-brations (20 to 60 um) that are ideal for ostectomy and osteoplasty but allow for the preservation of soft tissue. The various inserts used in this study were specifically designed for sinus elevation surgery. Light handpiece pressure and an integrated saline coolant spray keep the temperature low and visibility of the surgical site high It is claimed that inad-vertent perforations of the sinus merri" brane are unlikely when piezosurgical techniques are appropriately applied. In a series of 21 bony windows anC membrane elevations performed with piezoelectric surgery, only 1 perforation was reported.

Both hinge and complete antros-tomies can be performed with thii device using the sinus inserts shown in Figs 1 to 4. When the lateral wall is thin, it may be convenient to use the dia­mond ball smoothing insert (OT-5) or the diamond scalpel (OT-1) to outline the window (Fig 5). If the wall is thick, it is less time consuming to first reduce the thickness of the wall with the osteo­plasty insert (OP-3) and then refine the window with the diamond-coated smoothing insert (OT-1) (Fig 6). The bone removed by osteoplasty can be harvested and incorporated within the sinus graft. The initial release of the membrane from the antrostomy edges is performed with a dull, rounded, non-cutting elevator (EL-1) that works with saline cavitation to safely create a small internal elevation (Fig 7). The proce­dure is complete with conventional sinus membrane elevators (Fig 8).

The most common intraoperative complication ofsinus elevation surgery is perforation of the schneidenan membrane. A review of the literature reveals that schneidenan membrane perforation rates in lateral window sinus elevation surgery vary from 14% to 56%.10 The perforation rate in the present case series was 7% (7 of 100 sinuses), which is significantly lower than that reported in the literature. It is the experience of our research group that the expected membrane perfora­tion rate is in the range of 25% to 30%. Further, the occurrence of perforations appears to be equally attributable to rotary instrumentation, initial release of the membrane at the antrostomy margin with hand instruments, and the continued elevation of the membrane from the internal sinus walls. In this series of cases, perforations were com-pletely eliminated during the antros­tomy preparation and during the initial membrane release phases of the surgery. If this trend continues, Piezosurgery offers a 75% reduction in the expected perforation rate to the 7% observed in this series.

There is some debate in the liter­ature as to whether membrane perfo-rations affect the outcome of sinus ele­vation surgery as measured by vital bone formation and/or implant sur­vival. Data from Proussaefs et al" showed vital bone formation of 33.6% versus 14.2% and implant survival of 100% versus 70%, respectively, for nonperforated and perforated cases. Khoury12 reported 14 of 28 implant failures (statistically high) in cases with perforations. Of 164 implant failures included in the Sinus Consensus Conference clinician survey,1 79 involved perioperative complications, of which 38 had identified sinus per­forations. In contrast to these findings are reports by Schwartz-Arad et al'3 and Ardekian et al,14 which showed no difference in implant survival with respect to membrane perforations.

Regardless of the effect on out­come parameters, perforations must still be repaired to complete the graft­ing procedure. Repairing perforations may be simple, difficult, or perhaps impossible. If the perforation cannot be repaired, procedures using partic-ulate graft materials will most likely have to be abandoned.

Membrane repair techniques using bioabsorbable collagen barrier membranes have been reported by Pikos,15 Vlassis and Fugazzotto,1617 Proussaefs and Lozada,18 and Wallace et al." A recent clinical report by Teston et al10 provided clinical, histo-logic, and histomorphometric evi­dence of successful therapy when very large perforations have been ade­quately repaired.

At best, even a simple repair with a bioabsorbable collagen barriermem-brane increases the cost of the proce­dure. More involved repairs, however, increase the time necessary to com­plete the procedure and may therefore result in increased patient morbidity, including postoperative edema and sinus congestion. The increased oper­ative time may also result in a higher sinus graft infection rate, as it offers more opportunity for contamination of the graft or repair membrane from intraoral bacteria.

A second intraoperative compli­cation of sinus elevation surgery is the profuse bleeding that sometimes occurs when performing the antros-tomy with rotary cutting instruments. This occurs when the ansstamosis of the lower branch of the posterior supe-rior alveolar artery and the infraorbital artery is severed, usually with the ver­tical osteotomy cuts. This artery is pres-ent in 100% of cadaver specimens^0 and can be located in 52% of CT stud­ies.21 Figure 9 shows the clinical appearance of a relatively large artery, and Fig 10 shows its location in the lat­eral wall in a paraxial CT view. Bleeding from this artery is usually minimal, but sometimes it can be of a magnitude that makes it impossible to continue the procedure until the bleeding is con­trolled. In some instances this can take 20 minutes or more, again increasing the operative time and likewise increas­ing the likelihood of postoperative edema and ecchymosis. The use of piezoelectric inserts allows for antros-tomy preparation without injury to the vessels in the lateral wall, as the inserts do not cut soft tissue. Figures 11 and 12 show preservation ot this artery using piezoelectric surgical techniques.

Conclusions

While piezoelectric surgery is relatively new in the United States, rt has been used with excellent results in Europe for more than 10 years. The following ad­vantages have been shown in sinus elevation surgery usirvg piezoelectric techniques:

1. Reduced membrane perforation rate
2. Improved intraoperative visibility
3. Reduced intraoperative bleeding
4. Reduced surgical trauma

References

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