February 2014, Volume 10, Issue 2
Published by AEGIS Communications
A Simplified, Safer Approach to Lateral Sinus Augmentation
Lateral sinus elevation adds osseous height needed for implant placement
A common clinical problem with implants that are to be placed into the posterior maxilla when teeth have been extracted at an earlier date is loss of osseous height sufficient to place implants. Some patients showing resorptive patterns and sinus enlargement are left with minimal bone height to accommodate implant usage.
Maxillary sinus augmentation with various bone graft materials has become a routine treatment over the past 18 years. Numerous studies have reported highly successful survival rates of implants placed into an augmented sinus.1-3 Transalveolar sinus floor elevation—also known as subantrial augmentation—was first described by Tatum4 and was later modified by Summers.5-7 It uses a series of osteotomes with a mallet to create an osteotomy and fracture the sinus floor while elevating the Schneiderian membrane into the sinus cavity. Following manipulation, the membrane is then lifted and the space created in the sinus is augmented with bone particulate graft material, increasing the volume and height of bone available for implant placement.
Numerous studies show that when 5 mm of residual alveolar bone is present, simultaneous implant placement can achieve preformed adequate primary stability.6,8,9 Yet, when there is less than 5 mm of residual alveolar bone height, a delayed two-stage approach is recommended for improved implant success.10,11
The most common complication of the lateral sinus elevation approach is tearing of the Schneiderian membrane, which could allow for bacterial contamination or enable loose particles to gain access to the sinus cavity. A safer lateral window approach to sinus augmentation procedure using safe-end specialized drills with vertical stoppers for osseous window formation and subsequent membrane elevation is described.
Material and Methods
The Lateral Approach Sinus Kit (LASK) (Hiossen, www.hiossen.com) provides a “Dome” drill, “Core” drill, metal stoppers, a Side Wall drill, and a bone separator tool.
The Dome drill is a unique osseous drill allowing removal of the lateral wall of the maxillary sinus while collecting autogenous bone to be added to the material to be placed into the sinus. Macro and micro cutting blades provide excellent cutting of the lateral wall without tearing of the sinus membrane. These Dome drills, which are available in both 5.0- and 7.0-mm diameters, are run at 1,200 to 1,500 rpm with irrigation in an implant surgical handpiece. The provided metal depth control stoppers fit on the Dome drills, limiting depth of penetration (to 0.5, 1.0, 1.5, 2.0, 2.5, and 3.0 mm) and are used sequentially to safely expose the sinus membrane.
The Core drill, which is also available in 5.0- and 7.0-mm diameters, differs from the Dome drill in that the center does not cut, with bone removal resulting in a core of bone being left over the sinus. This bony lid is removed due to its small size and can be ground to be added to the graft material being placed into the sinus. This particular drill follows the same design of the crestal augmentation sinus (CAS) drills and is also used at 1,200 to 1,500 rpm.. The metal drill stoppers fit these drills as well, allowing controlled sequential depth preparation. The bone separator tool is used to separate the osseous core created with the Core drill.
The Side Wall drill may be used to enlarge the osseous window created by the Dome drill if desired. The tip of this drill is smooth and designed to safely push the sinus membrane away from the cutting portion of the drill, which starts 1 mm from the safe end. Osseous cutting is performed at 1,500 rpm using the side of the rotating drill to enlarge the osseous window. The metal drill stoppers from the LASK may be used on these side wall drills to limit accidental penetration too far into the sinus and tearing of the membrane during this drill’s use. As with the other drills in this kit, irrigation is used during its operation.
A 65-year-old man presented with the desire for rehabilitation of the maxillary arch involving the placement of an implant in the posterior maxillary left quadrant, which had been missing teeth for an extended period of time. Radiographically, enlargement of the maxillary sinus was noted with insufficient height in the molar region for implant placement (Figure 1 and Figure 2). Sinus augmentation was discussed to assist in achieving the patient’s desired treatment goal. As less than 5 mm of crestal height was available, implant placement would not be possible at the time of sinus augmentation because primary stability would not be achievable.
Following administration of local anesthetic, crestal and vertical releasing incisions were made and a full-thickness flap was elevated. Elevation of the flap extended superiorly to expose the lateral wall of the maxillary sinus up to the inferior aspect of the zygoma (Figure 3). Endosseous implants were placed in the posterior right and anterior segments, which had sufficient bone in height and width for fixture placements.
A 5-mm-wide Dome drill was placed onto the surgical handpiece with a 0.5-mm drill stopper. This would allow initiation of the window without the possibility of excessive penetration and subsequent damage to the sinus membrane. The Dome drill with stopper was placed on the lateral sinus wall at a height superior to the current height of the available bone as measured radiographically (Figure 4). This was done to ensure that the window created had elevatable membrane circumferentially. When maximum depth was achieved with the 0.5-mm drill stopper, the surgeon switched to a 1.0-mm drill stopper and continued drilling. The drill stopper size was sequentially increased, checking for membrane exposure (Figure 5). When bone over the sinus membrane was removed, the area changed in color from the light color of the bone (ivory) to a darker grey as the dark sinus began to show clinically at the window. The bone material collected with the Dome drill was periodically removed to be used with the osseous graft.
Final window creation was made with the Dome drill with a 2.5-mm drill stopper (Figure 6). Some patients may require deeper drilling, which is dependent on the thickness of the lateral maxillary sinus wall. The intact sinus membrane showed no bone over the membrane at the window that was created on the lateral wall (Figure 7). An osseous septum was noted to run vertically at the middle of the window created. The presence of the septum would preclude use of the Core drill, because it would be very difficult to remove the window core created without tearing the sinus membrane.
Sinus curettes were used to start the sinus membrane elevation at the inferior aspect, teasing the membrane from the osseous wall of the sinus interiorly (Figure 8). Because this case had a septum, the anterior and posterior aspects of the sinus in relation to the septum were elevated separately, with attention to teasing the membrane from the septum as part of the elevation process. It was important for the elevation to also include the medial wall of the sinus to fill a volume great enough that the placed implant would be surrounded by bone (Figure 9).
Failure to elevate the medial wall aspect could cause the placed implant to have no osseous contact, which could decrease clinical success following loading. Additionally, the authors advise elevation to a greater height than the length of the implant to be placed when a delayed fixture placement is to be performed. This would allow for possible graft settling during healing that could yield less height than was planned.
An absorbable collagen membrane (Resorbable Collagen Tape, Ace Surgical, www.acesurgical.com) was inserted into the sinus to thicken the sinus membrane and seal any micro-tears that might be present (Figure 10). The Resorbable Collagen Tape was cut to size and placed into the sinus dry, using the patient’s blood in the site to wet it as it was placed. Once wetted with blood, the Resorbable Collagen Tape becomes sticky, attaching itself to the sinus membrane.
Autogenous bone collected from the Dome drill was mixed with Regenaform® Cortical Cancellous Bone Chips (Exactech, Inc., www.exac.com) in a sterile dappen dish. The osseous graft mixture was carried to the oral cavity and introduced into the elevated sinus, where it was gently condensed with a large plugger, pushing the mixture to the medial and filling in a lateral direction until the entire cavity was filled (Figure 11). The process was repeated in the cavity anterior to the septa. Sufficient osseous graft was placed until the sinus was augmented to be flush with the outer aspect of the lateral sinus wall at the window that had been created (Figure 12).
A long-term resorbable membrane (Guidor®, Sunstar, www.guidor.com) was cut to extend beyond the outline of the lateral window and placed over the osseous graft that had been placed into the sinus (Figure 13). The flap was repositioned and initially closed with a horizontal mattress suture using Cytoplast™ ePTFE, (Osteogenics Biomedical, www.osteogenics.com) to achieve primary closure at the crest (Figure 14). This suture served to resist soft tissue tension that may result due to inflammation and the resulting swelling following surgery. Additional sutures were placed to close the incision line using a simple interrupted technique. The radiograph showed initial graft placement and the elevation achieved to create a site that could accommodate implant placement at a later date (Figure 15).
The patient returned 6 months following sinus augmentation for implant placement. Soft tissue in the site on the lateral aspect demonstrated no inflammation, and incision lines were not discernable on the gingiva (Figure 16). A radiograph was taken to check and verify the organization of the osseous graft that had been placed into the sinus and to determine if the site was ready for re-entry for the implant fixture placement (Figure 17 and Figure 18). A full-thickness flap was made, and the lateral aspect of the maxillary sinus where the window had been created demonstrated good integration of the graft with the surrounding native bone of the patient (Figure 19).
The use of a crestal approach to sinus elevation when additional osseous height is required for implant placement is now being emphasized. This approach works well when at least 5 mm of osseous height is present for immediate implant placement. Yet when less bone height is present, a lateral window approach may be a more prudent technique to increase crestal height so that implant fixtures may be placed.
The lateral sinus augmentation approach can be challenging, as tearing of the sinus membrane often necessitates abandoning the procedure and re-entering at a later date after the membrane has healed. Previous techniques involved use of diamonds or carbides in a high-speed handpiece or the use of piezo surgical units. These approaches had potential for membrane damage (burs in a high-speed handpiece) or were very slow (piezo). The LASK from Hiossen uses specially designed drills that greatly minimize tearing of the membrane and improve the safety of the procedure.
Douglas F. Dompkowski, DDS, received honorarium from Hiossen for this article.
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About the Authors
Douglas F. Dompkowski, DDS
Private Practice,Periodontology and Implantology
University of Maryland
Department of Periodontology
Gregori Kurtzman, DDS, DICOI, DADIA
Silver Spring, Maryland