July 2, 2019
by Arun K. Garg, DMD; Gregori M. Kurtzman, DDS, MAGD
Normal pneumatization of the maxillary sinus frequently when combined with the loss of teeth provides inadequate volume of bone, specifically related to height to house an implant. This process is further complicated with periodontally failing posterior teeth are to be extracted. To achieve sufficient bone height to allow implant usage, augmentation of the maxillary sinus may be required. A crestal approach for sinus augmentation may be utilized when sufficient height is present to allow stability of the implant but greater height is indicated. Yet, clinical situations arise where minimal bone height is present and greater height is required to support the planned implants wherein a lateral sinus approach is indicated.
Lateral wall sinus augmentation has traditionally consisted of creation of a window in the lateral osseous wall below the zygoma with a round diamond or carbide in a surgical handpiece. The desired window is outlined with a round diamond/carbide and the surgeon keeps tracing it until the membrane is visualized. As an alternative to use of the bur for window preparation piezo has been utilized, but this is a slower process. Some potential clinical challenges present with this approach as depth is surgeon dependent, with possible risk of membrane damage. Various kits have been developed that utilize larger carbide burs that are designed to minimize potential membrane damage when this delicate tissue is contacted with depth stops to increase procedure safety. Yet, these kits still require other instrumentation to complete the procedure and ready the elevated sinus for graft placement. A kit has been developed incorporating sinus safe lateral window burs both in carbide and diamond, with depth stops, a rotary instrument to laterally enlarge the window without tearing the sinus membrane and hand instruments to complete the elevation process.
Lateral sinus instrumentation
Rotary instruments are required when a lateral sinus augmentation is planned for access through the lateral osseous wall of the sinus. Additionally, hand instruments are required to elevate the sinus membrane from the boney floor and lateral/medial walls to create an area that will accommodate the graft augmentation to be placed. For convenience, a kit has been developed with all instrumentation required for the lateral approach for sinus augmentation (Fig. 1).
Thickness of the lateral bone varies both by patient as well as location on the lateral wall. During lateral wall access the underlying membrane has the potential of tearing and depth rings for the kits rotary carbides and diamonds improving procedure safety while decreasing complication potential during lateral wall development. Lateral Access (LA) stoppers are provided in increments of 0.5 mm to 3.0 mm, in half mm increments. This indicates how much of the rotary instrument is exposed and how much depth penetration may occur before stopping further penetration (Fig. 2). The authors recommend that lateral access begin with the 0.5 mm LA stopper outlining the window desired, then increasing in depth by half mm increments until the membrane is visualized, decreasing membrane tearing potential.
The “Island” burs, (Fig. 3 left) are rotary instruments utilized when it is desired to have an osseous window that can be replaced over the completed lateral window following completion of the sinus augmentation or rotated to become the new sinus floor. The Island burs are provided as a diamond coated cylinder and as a serrated end cylinder in an 8.0 mm diameter. Depth penetration is controlled utilizing the LA stoppers and decrease potential of membrane tearing.
“Rotary” carbides and “Diamonds” (Fig. 3 middle) are utilized with the LA stoppers to create a lateral window in the sinus. Use of these is practitioner preference with some surgeons preferring use of a diamond, while others like the feel of the carbide when accessing the sinus membrane. The diamond is provided in an 8.0 mm diameter with a rounded end (domed) or flat end. This rotary tool allows more precision when cutting the window as it “sands” the bone verses cutting found with the carbide. The carbide sinus burs are provided in a 6.0 and 8.0 mm diameter cutting bone more aggressively than the diamond and may be indicated when sinus wall is denser and thicker. When a thick lateral osseous wall is noted prior to initiating window creation the carbide may be utilized to start window preparation and continued with the diamond when the wall thickness has been decreased sufficiently. This approach will help in shortening time required to create the lateral window.
“Widener” burs, have a smooth wider head with a narrower diamond covered shaft and are utilized following access into the sinus to widen the window based on the geometric shape of the sinus (Fig. 3 right). The smooth head is pressed into the sinus membrane elevating it to prevent membrane damage while enlarging the window with the diamond coated shaft. The bur is rotated at slow speed while contacting the edge of the window with the diamond covered shaft, moving the instrument to the anterior (right side sinus) or posterior (left side sinus) moving in the direction that the instrument is rotating.
Once the membrane has been exposed and initial elevation around the margin of the osseous window has occurred, further membrane elevation is performed with hand instruments along the floor and medial wall of the maxillary sinus. These is performed with four double ended instruments labeled TOLA II 01 to 04 (Fig. 4). The TOLA II -01, 02 and 03 are curved end curettes that allow the practitioner to utilize the curved end to elevate the membrane as the tips edge separates and elevates the membrane at the boney surface working from the osseous window internally within the sinus. One end of the TOLA II -01 is similar to the Widener with a rounded blunt end adding in initiation of separation of the membrane from the bone. The TOLA II -4 has a wide scoop at one end and is utilized to carry graft material to the elevated sinus and a condenser at the opposing end aids in compacting the graft into the areas needed.
A 60-year-old male presented interested in replacing the missing posterior teeth in the left maxillary quadrant. Radiographs were taken and it was determined insufficient alveolar height was present at the missing premolars and molars. As the crestal height was minimal a lateral approach sinus augmentation was required to create sufficient bone to house the planned implants. The patient agreed with the treatment plan presented and was scheduled for treatment.
Local anesthesia was administered with a crestal incision made and a mesial vertical releasing incision created (Fig. 5) with elevation of a full thickness flap to expose the lateral osseous wall of the sinus (Fig. 6).
A 1mm LA stopper was placed on the carbide in the handpiece (Fig. 7). The carbide was applied to the lateral wall of bone with water until the depth stopper contacted the osseous wall. The stopper was replaced with the 1.5mm stopper and continued until the membrane could be visualized (Figs. 8 & 9). Examination of the site for visualization of the underlying membrane was performed and the process repeated increasing the depth stopper in half mm increments until the membrane could be visualized (Fig. 10). The domes end of the TOLA II -01 hand instrument was used to detach the membrane from the bone at the windows margins. The spoon end of the TOLA II -01 instrument was next used to continue the membrane separation at the windows margins. The rotary Widener was placed on the handpiece and used to enlarge the osseous window.
TOLA II hand instruments were utilized to detach and elevate the sinus membrane keeping the membrane intact and free of tearing (Fig. 11). Membrane elevation should extend along the entire sinus floor, the mesial wall of the sinus, the medial wall, distal to ensure augmentation posterior to where the most distal implant would be placed and superior so that sufficient height would be attained.
Following membrane elevation, sinus membrane integrity is tested by having the patient gently inhale and exhale through their nose. An intact membrane will demonstrate movement of the membrane in the sinus visible through the lateral window with each breath. When the membrane is perforated (torn) movement of the membrane will not be observed. If the membrane is not intact, sealing of the damaged membrane will need to be performed prior to augmentation placement to prevent distribution of the graft material throughout the sinus during the healing phase. If the torn membrane can not be sealed, the procedure will need to be aborted and the membrane allowed to heal before augmentation can continue.
Various augmentation materials have been advocated and the authors preference is the use of allograft particles mixed with PRP to create “sticky bone”. To create PRP, blood is drawn from the patient at the start of the surgical appointment and centrifuged. PRP membranes are created, which will be placed in the sinus covering the elevated sinus membrane prior to graft placement to aid in containing the graft during healing and over the lateral window before flap closure (Fig. 12). Liquid is then drawn from the tube and added to the allograft particles in a sterile dish (Fig. 13).
A disposable syringe that has had the end cut off is used to introduce the graft material into the elevated sinus. The syringe is loaded with the graft material and slowing expressed into the space created between the elevated sinus and surrounding bone of the maxillary sinus (Fig. 14). A condenser is used to compress the graft against the medial, mesial and distal walls of the sinus to avoid potential voids within the graft or between the graft and walls of the sinus (Fig. 15). Additional graft material is added with the syringe and compressed until the entire sinus area is filled to the level of the lateral window (Fig. 16).
The PRP clots that had been placed in the box for compression have formed membranes (Fig. 17). A PRP membrane is placed over the lateral window to limit soft tissue ingrowth into the sinus augmentation during graft organization and healing (Fig. 18). Additionally, this also provides patient stem cells to aid in the graft organization and maturation process. The flap is repositioned to achieve primary closure of the site and sutured (Fig. 19). The maxillary sinus augmentation surgical procedure is complete and healing will process with implant placement after several months.
When insufficient available alveolar height presents in the posterior maxilla, sinus augmentation may be indicated when implants are planned. This may present when in situations where the teeth have been missing for periods of time and resorption has occurred or teeth are being extracted as part of treatment. The lateral window approach to sinus augmentation to create sufficient height for implant placement has been avoided by practitioners with less experience at complex osseous surgery. The simplified approach outlined with the kit makes use of lateral sinus augmentation less complex with greater safety and should be considered when implants are planned in the posterior maxilla and insufficient alveolar height is needed and a crestal approach cannot be utilized.
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About the Author
Dr. Garg is an internationally recognized dental educator and surgeon, who for more that 20 years served as a full-time professor of surgery in the department of Oral and Maxillofacial Surgery and as director of residency training at the University of Miami Leonard M. Miller School of Medicine. He can be reached at email@example.com. Dr. Kurtzman is in private general dental practice in Silver Spring, Maryland, USA and a former Assistant Clinical Professor at University of Maryland in the department of Restorative Dentistry and Endodontics and a former AAID Implant Maxi-Course assistant program director at Howard University College of Dentistry. He has earned Fellowship in the AGD, American College of Dentists (ACD), International Congress of Oral Implantology (ICOI), Pierre Fauchard, ADI, Mastership in the AGD and ICOI and Diplomat status in the ICOI, American Dental Implant Association (ADIA), International Dental Implant Association (IDIA). He can be reached at firstname.lastname@example.org.