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Maxillary sinus floor augmentation (also termed sinus lift, sinus graft, sinus augmentation or sinus procedure) is a surgical procedure which aims to increase the amount of bone in the posterior maxilla (upper jaw bone), in the area of premolar and molar teeth, by sacrificing some of the volume of the maxillary sinus.
When a natural tooth is lost, whether through dental decay, periodontal disease or dental trauma, the alveolar process begins to remodel. The edentulous (toothless) area is termed a ridge, which over time usually loses both height and width. Furthermore, the level of the floor of the maxillary sinus gradually becomes lower. Overall, this leads to a loss of volume of bone which is available for implantation of dental implants, which rely on osseointegration. The goal of the sinus lift is to graft extra bone into the maxillary sinus, so more bone is available to support a dental implant.
While there may be a number of reasons for wanting a greater volume of bone in the posterior maxilla, the most common reason in contemporary dental treatment planning is to prepare the site for the future placement of dental implants.
Sinus augmentation (sinus lift) is performed when the floor of the sinus is too close to an area where dental implants are to be placed. This procedure is performed to ensure a secure place for the implants while protecting the sinus. Lowering of the sinus can be caused by: Long-term tooth loss without the required treatment, periodontal disease, trauma.
Patients who have the following may be good candidates for sinus augmentation.
Prior to undergoing sinus augmentation, diagnostics are run to determine the health of the patient’s sinuses. Panoramic radiographs are taken to map out the patients upper jaw and sinuses. In special instances, a computed tomography or CT scan is taken to measure the sinus’s height and width, and to rule out any sinus disease or pathology. Generally, the material which is used to add bone volume to the sinus floor is:
There are multiple ways to perform sinus augmentation. The procedure is performed from inside the patient’s mouth where the surgeon makes an incision into the gum, or gingiva. Once the incision is made, the surgeon then pulls back the gum tissue, exposing the lateral boney wall of the sinus. The surgeon then cuts a "window" to the sinus, which is covered by a thin membrane. The membrane is carefully lifted away, and bone graft material is placed into the newly created space. The bone material can be allogenic (from a tissue bank) or autogenous (taken from the patient). Synthetic materials may also be used.
As an alternative, sinus augmentation can be performed by a less invasive osteotome technique, in which the sinus membranes are lifted by gentle tapping of the sinus floor with the use of osteotomes. The amount of augmentation achieved with the osteotome technique is usually less than what can be achieved with the lateral window. The goal of this procedure is to stimulate bone growth and form a thicker sinus floor, in order to support dental implants.
Straumann implant placed in site of maxillary left permanent first molar. Sinus floor provided approximately 6.8 mm of apico-coronal height whereas placement of a 10 mm implant was desirable. The sinus floor was thus lifted using the osteotome approach and packing bone into the osteotomy to lift the floor of the sinus. The dome of bone graft can be seen apical to the implant. Today, there are several variations of sinus graft procedure, these are the most common:
Lateral Window approach (opening a window in the anterolateral sinus wall) - done by Tatum in February, 1975.- A crestal incision is made with vertical extensions and the lateral aspect of the maxilla is exposed. Then the osteotomy aka anthrostomy is completed. The sinus membrane, aka Schneiderian Membrane, is then detached from the bony walls of the internal aspects of the sinus, utilizing various curettes. Once properly detached, the lateral wall window with the sinus membrane is rotated medially into the sinus. The sinus membrane can fold on itself when reflected medially. Implant sites can be prepared and implants placed at this stage. The medial part of the sinus is grafted first. The graft material used can be either and autograft, an allograft, a xenograft, an alloplast a growth-factor infused collagen matrix, or combinations thereof. After the implants have been placed, the remaining lateral part of the sinus defect is grafted. The flaps are relieved and closed primarily. The graft is left for 6–9 months. Implant placements should be delayed if they cannot be properly stabilised, to prevent complications. Tatum does not recommend implant placement into the grafts at the time of sinus grafting. For most patients, he recommends a uniform lining elevation off all axial walls to a height necessary to result in a healed height of 18–20 mm bone. The Osteotome approach - First done by Tatum in 1974 and published by Summer in 1994 - A crestal incision is made, and the crestal ridge is exposed. A sharp osteotome is used to "chisel" a rectangle in the crestal ridge of the maxilla, then a sinus-lift osteotome is used like a mallet to fracture the bone, and punch a hole through where the rectangle was created into the sinus floor. The sinus is then raised with bone grafting material and implants are placed. Though this was the technique used by Tatum in 1974, he currently prefers a closed (floor elevation without sinus entry) technique.
The crestal approach sinus kit is a tool that provides 97% succes rate, minimizing Schneiderian membrane perforation.
This technique was invented in 1996, by Dr. Leon Chen. Unlike the traditional methods of sinus lifts, which typically use an osteotomy of the lateral aspect of the maxilla, the HSC technique uses an osteotomy on the lateral aspect of the crestal ridge of the maxilla. The HSC technique has shown to have much shorter recovery times than traditional methods, and does not require a hospital visit, or a bed rest recovery time. A dental implant is placed at the same time as the HSC technique, also reducing the healing time.
A local anesthetic with vasoconstrictor is infiltrated into the gums, and a crestal incision is made. An osteotomy is initiated on the crestal ridge with a 5mm Chen Sinus Bur, or a Chen Peizo tip. Drilling ceases about 1mm short of the sinus floor. The surgeon then downsizes to a 2mm Chen sinus bur for the purpose of forming a narrower conical shape at the end of the osteotomy. Constant pressure is applied to the foot pedal of the high speed hand piece to apply hydraulic pressure to the osteotomy while drilling.
While rotating, the 2mm Sinus bur is gently tapped through the cortical bone of the sinus floor, just hard enough form a pinhole through the bone. Hydraulic pressure is introduced to the surgical site at this stage, providing just enough force to begin atraumatically dissecting the membrane from the sinus floor. Once the membrane is loosened, the hydraulic pressure is ceased. The membrane will be at rest, but slightly detached.
The patient is now ready for the initial lifting of the sinus. A bone grafting mixture is then packed through the pinhole and pushed gently against the membrane using a 3mm Chen sinus condenser. This will slightly raise the sinus, resting it on the newly placed bone.
Once the initial lift in complete, the surgeon switches to a regular sized implant drill and bores through the 2mm conical shape. This opens full access to the sinus cavity. The secondary list introduces more bone graft mixture for the permanent sinus augmentation. The bone grafting material is added until the sinus has been lifted to the proper height for implant placement.
Once a sufficient amount of bone grafting material is condensed under the membrane, the surgeon will place a dental implant by drilling directly into the newly placed bone grafting material, and placing the implant fixture. The crestal incision is then sutured closed.
Generally speaking this surgery has a very high success rate. Over an 8 year study of 1,557 implants in 1,100 patients using the Hydraulic Sinus Condensing technique, only 8 implants failed, resulting in a 99.99% success rate.
The majority of patients whose implants failed were smokers, or had an abnormally small amount of cortical bone, and in every one of those cases the second attempt at the surgery was successful.
In addition, this procedure allows implant placement with less than 1mm of crestal bone. The sinus is able to be lifted with the presence of a sinus septum or sinus slope, unlike other lift techniques.
Because this procedure fortifies the natural barrier between the sinus and the oral cavities, and can also relieve pressure within the sinus, several patients were referred by Otolaryngologists for this study in an attempt to cure the patients sinusitis. In all such cases the patients reported improvement of their sinus problems, including fewer or no headaches, improved breathing, improved drainage, and elimination of sinus pressure. None of the patients in the study complained of worsened sinus problems, or newly formed sinusitis.
A major risk of a sinus augmentation is that the sinus membrane could be pierced or ripped. Remedies, should this occur, include stitching the tear or placing a patch over it; in some cases, the surgery is stopped altogether and the tear is given time to heal, usually three to six months. Often, the sinus membrane grows back thicker and stronger, making success more likely on the second operation.
Besides tearing of the sinus membrane, there are other risks involved in sinus augmentation surgery. These risks include:
It takes about three to six months for the sinus augmentation bone to become part of the patient's natural sinus floor bone. Up to six months of healing is sometimes left before implants are attempted. However, some surgeons perform both the augmentation and dental implant simultaneously, to avoid the necessity of two surgeries.
The first maxillary sinus floor augmentation procedure was performed by Oscar Hilt Tatum, Jr. in 1974.
A sinus-lift procedure was first performed by Dr. Hilt Tatum Jr. in 1974 during his period of preparation to begin sinus grafting. The first sinus graft was done by Tatum in February, 1975 in Lee County Hospital in Opelika, Alabama. This was followed by the placement and successful restoration of two endosteal implants. Between 1975–1979, much of the sinus lining elevation was done using inflatable catheters. After this, suitable instruments had been developed to manage the lining elevation from the different anatomical surfaces encountered in sinuses. Tatum first presented the concept at The Alabama Implant Congress in Birmingham, Alabama in 1976 and presented the evolution of technique during multiple podium presentations each year until 1986 when he published an article describing the procedure. Dr. Philip Boyne was introduced to the procedure when he was invited, by Tatum, to be "The Discusser" of a presentation on sinus grafting given by Tatum at the annual meeting of The American Academy of Implant Dentistry in 1977 or 1978. Boyne and James authored the first publication on the technique in 1980 when they published case reports of autogenous grafts placed into the sinus and allowed to heal for 6 months, which was followed by the placement of blade implants. This sequence was confirmed by Boyne before the attendees at The Alabama Implant Congress in 1994.