Special surgical interventions in implantology
Sinus lift procedure in dental surgery
Augmentation of the floor of the maxillary sinus (also called sinus lift, sinus graft, sinus augmentation, sinus elevation) is a surgical procedure that aims to increase the amount of bone in the posterior maxilla, in the area of the premolar and molar teeth, by raising the Schneiderian membrane (sinus membrane) and placing a bone graft.
When a tooth is lost, the alveolar process begins to remodel. The remaining tooth socket disappears as the bone heals, resulting in an edentulous area called the ridge.
This process causes a reduction in the height and width of the surrounding bone. In addition, when a maxillary molar or premolar is extracted, the maxillary sinus pneumatizes in this region which will subsequently decrease the thickness of the adjacent bone. In general, this leads to a loss of bone volume which is valid for the insertion of dental implants, which rely on osseointegration to replace missing teeth. The purpose of the sinus lift is to graft additional bone into the maxillary sinus, so more bone is available to support the dental implant.
While there may be several reasons for wanting more bone volume in the posterior jaw, the most common reason in contemporary dental treatment planning is for preparing an area for a dental implant.
Sinus augmentation (sinus lift) is performed when the sinus floor is too close to an area where dental implants are to be placed. This procedure is performed to ensure a safe implant placement with protection of the sinus. Sinus subsidence can be caused by: old extractions without further treatment, periodontitis, trauma.
Patients with the following may be good candidates for sinus augmentation:
Loss of more than one tooth in the posterior maxilla
Loss of a significant amount of bone in the posterior maxilla
Missing teeth due to genetic or birth defects
Missing the majority of maxillary teeth and the need for a complex sinus lift for multiple implants.
It is not known whether the use of sinus lift techniques are more successful than using shorter implants to reduce the number of artificial teeth or implant failure one year after placement.
Before sinus augmentation surgery is performed, a diagnosis is performed to determine the health of the patient’s sinuses. Panoramic radiographs are taken to map the patient’s upper jaw and sinuses. In special cases, cone-beam computed tomography is preferred to measure the height and width of the sinuses and to rule out any sinus disease or pathology.
There are several variations of the sinus lift technique.
Traditional sinus augmentation or side window technique
There are multiple ways to perform sinus lift surgery. This procedure is performed from inside the patient’s oral cavity, where the surgeon makes an incision in the gum. Once the incision has been made, the specialist removes the gum tissue, exposing the side wall of the sinus bone. Next, a lateral window is created in the sinus, which will expose the Schneiderian membrane. This membrane is separated from the bone, and bone graft material is placed into the newly created space. The gum is then sutured tightly, and the graft is allowed to heal for 4-12 months.
The graft material used can be either autograft, allograft, xenograft, alloplast, synthetic variants or combinations of these. Studies have shown that simply lifting the sinus membrane, creating a space and forming blood clots could lead to new bone due to the principles of guided bone regeneration. The long-term prognosis of the technique is estimated at 94%.
As an alternative, sinus augmentation can be performed by a less invasive procedure using the osteotome. There are several variations of this technique and all originate from Dr Tatum’s original technique, first published by Dr Boyne and James in 1980.
Dr. Robert B. Summers described a technique that is normally performed when the sinus floor needs to be elevated less than 4 mm. This technique is performed by elevating the gum tissue and making a socket in the bone at a distance of 1-2 mm from the sinus membrane. The sinus floor is then raised by pressing it down with the help of osteotomes.
The amount of augmentation achieved using this osteotome technique is usually less than that which can be achieved using the lateral window technique. A dental implant is normally placed in the socket formed by the sinus lift procedure and allowed to integrate with the bone. Bone integration takes around 4-8 months. The purpose of this procedure is to stimulate the bone to grow and form a thicker sinus floor so that it can support the implant tooth replacement.
The size and shape of the sinus significantly influence the formation of new bone after transcrestal elevation of the sinus floor: through this technique, the regeneration of a significant amount of new bone is a predictable outcome only in narrow sinus cavities. During preoperative planning, the bucco-palatal width of the sinus should be considered a crucial parameter when choosing transcrestal sinus floor elevation as a treatment option.
Dr Bruschi and Scipioni described a similar technique that is based on a partial-thickness flap procedure. This technique increases the malleability of the bone crest and does not use bone directly above the sinus, but bone on the medial wall, and can be used in more severe cases of bone resorption that would normally require treatment with the lateral wall technique. The healing period is reduced to 1.5- 3 months. Recently, an electric hammer has been introduced to simplify the application of this and similar techniques.
A major risk of sinus augmentation is that the sinus membrane could be perforated or ruptured. Remedies, if this happens, include suturing the perforation, and in some cases, surgery is discontinued so that the perforation has time to heal, usually between three and six months. Often, the sinus membrane rebuilds thicker and stronger, making success more likely with a second operation. Although rarely reported, such secondary surgery can also be successful when the primary operation is limited to lifting the membrane without the introduction of additional material.
In addition to perforating the sinus membrane, there are other risks involved in sinus lift surgery. The most notable one concerns the close relationship between the area augmentation and the sinonasal complex, which can lead to the development of sinusitis, its chronicization, and the appearance of severe symptoms.
Inflammation of the sinuses, resulting from maxillary sinus augmentation, is considered a class 1 sinonasal complication according to the Felisati classification and should be treated surgically with a combination of endoscopic and endo-oral approaches. In addition to sinusitis, other risks associated with sinus lift include infection, inflammation, pain, allergic reactions, tissue or nerve damage, scarring, hematomas, graft failure, oro-antral communication/fistula, implant displacement or mobility, and bleeding.
It takes 3 to 6 months for the sinus bone augmentation to become a natural part of the sinus floor. Up to 6 months of healing is the period that is left until the implants are applied. However, some surgeons perform sinus elevation and dental implant placement simultaneously to avoid the need for 2 operations.
The first maxillary sinus floor augmentation procedure was performed by Oscar Hilt Tatum, Jr. in 1974.
A sinus floor augmentation procedure was first performed by Dr. Hilt Tatum, Jr. in 1974 during the period of preparation to perform the sinus graft. The first sinus graft was performed by Tatum in February 1975 at Lee County Hospital in Opelika, Alabama.
This was followed by the successful placement and restoration of two endosteal implants. Between 1975 and 1979, much of the sinus mucosal elevation was performed using inflatable catheters. After this, appropriate instruments were developed to manage mucosal elevation on the various anatomical surfaces found in the sinuses.
Tatum first presented the concept at the Alabama Implant Congress in Birmingham in 1976 and showcased the evolution of the technique in several podium presentations each year until 1986, when he published a paper describing the procedure. Dr. Philip Boyne was introduced to the procedure when he was invited, by Tatum, to be “The Discussant” of a presentation on sinus grafting given by Tatum at the annual meeting of the American Academy of Dental Implantology in 1977 or 1978. Boyne and James authored the first publication on this technique in 1980, when they published case reports of autogenous grafts placed in the sinus and allowed to heal for 6 months, which were followed by placement of blade implants. This sequence was confirmed by Boyne to attendees at the Alabama Implant Congress in 1994.
The slightly higher effectiveness (implant integration) of the lateral sinus lift technique has to be weighed against the substantially higher costs compared to the trans alveolar sinus lift technique. From the patient’s perspective, the higher invasiveness of the lateral technique will also be an important decision criterion. However, the trans alveolar approach is unlikely to be effective in advanced levels of bone resorption at the site of implantation.
Sinus lift procedure in dental surgery
Sinuses are pneumatic cavities of the facial mass that serve several roles, including purifying air entering through the nasal cavity, maintaining upper-stage pressure and fluidizing secretions.
The maxillary sinuses are located close to the maxillary dental arch, and dental pathology is often transmitted to them through the close proximity of the dental roots to the maxillary sinuses.
Inflammation of the sinuses is known as sinusitis and can have several causes.
Basically, it can be of two kinds:
Rhinogenic, when it is not related to the teeth and can be a complication of a cold or constant exposure to irritants.
Odontogenic, is the type of sinusitis that develops in relation to a tooth root that has suffered an infection and the treatment plan should aim to treat the causative factor, often the extraction of the root that caused the sinusitis.
There are some situations in which the upper arch, partially or totally edentulous, changes its conformation and the bone height is reduced so that the sinus is in the vicinity of the alveolar ridge. This situation is unfavorable when the patient opts for the insertion of dental implants.
Insufficient bone height would lead to the insertion of implants into the maxillary sinus, a situation that will result in chronic maxillary sinusitis.
In this situation, to create the bone support needed for dental implants, a procedure called a sinus lift, a surgical procedure in which bone is added to the upper jawbone in the lateral areas, is used.
In order to add bone, the sinus membrane must be carefully lifted to create the necessary space.
The bone used in sinus augmentation can be autogenous or allogenic (synthetic or bovine).
The procedure itself is not painful, as it can be performed under local anesthesia, so the patient will feel no discomfort.
The sinus lift procedure can be of two types:
Internal sinus lift – this procedure takes place in cases where the sinus is not very close to the bone crest, so the membrane does not need to be lifted significantly, just slightly pushed superiorly. After the membrane is lifted, bone is added to the newly formed cavity and the implant can be inserted.
External sinus lift – this procedure is necessary when the maxillary sinus is very close to the alveolar crest and during the procedure the membrane has to be elevated significantly. With the external sinus lift procedure, a window is created in the buccal bone cortex through which the sinus membrane can be directly visualized.
Following the sinus lift procedure, regardless of the modality chosen, it is possible that the operated area may become swollen. Slight nosebleeds are normal.
It is important for the patient to follow the instructions that will help a rapid healing without complications:
Avoid pressure variations – sneezing, blowing the nose or drinking through a straw are completely contraindicated.
Use nasal decongestants for 5 days after surgery to prevent inflammation of the sinus mucosa.
Antibiotic and anti-inflammatory administration should be strictly followed as well as visits to the dentist for check-ups.