Augmentation of the maxillary sinus floor (also called sinus lift, 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 lifting 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.
Indications
While there can be many reasons for desiring more bone volume in the posterior maxilla, the most common reason in contemporary dental treatment planning is to prepare an area for a dental implant.
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 safe implant placement, while protecting the sinus. Sinus sagging 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
Significant bone loss in the posterior maxilla
Missing teeth due to genetic or birth defects
Missing most 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 the use of shorter implants to reduce the number of artificial teeth or implant failure one year after implant placement.
technique
Before performing sinus augmentation surgery, a diagnostic 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 at the gumline. Once the incision has been made, the specialist removes the gum tissue, exposing the lateral 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 in the newly created space. The gum is then sutured tightly and the graft is left 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 blood clot formation could result in new bone due to the principles of guided bone regeneration. The long-term prognosis of the technique is estimated at 94%.
Osteotome technique
As an alternative, sinus augmentation can be performed with a less invasive procedure, the osteotome. There are several variations of this technique and they all originate from Dr. Tatum’s original technique, first published by Drs. 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 gingival tissue and making a socket in the bone at a distance of 1-2 mm from the sinus membrane. The floor of the sinus is then raised by pressing it down with the help of osteotomes.
The amount of augmentation obtained by using this technique with osteotomes is usually less than that which can be obtained by 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 to support the replacement of teeth with implants.
The size and shape of the sinus significantly influence the formation of new bone after transcrestal sinus floor elevation: with 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 as a crucial parameter when choosing sinus floor elevation with transcrestal approach as a treatment option.
Drs. 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 the bone directly above the sinus, but the bone on the medial wall, and can be used in more severe cases of bone resorption, which would normally require to be treated 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.
Complications
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 the surgery is interrupted so that the perforation has time to heal, usually between three and six months. Often, the sinus membrane grows back thicker and stronger, making success more likely with a second operation. Although rarely reported, such a secondary operation can also be successful when the primary operation is limited to lifting the membrane without the insertion of additional material.
Besides perforation of the sinus membrane, other risks are involved in sinus lift surgery. The most notable of these concerns the close relationship between the augmentation of the sinonasal complex area which can lead to the development of sinusitis, with its chronicization and severe symptoms.
Sinusitis resulting from maxillary sinus enlargement is considered a class 1 sinonasal complication according to Felisati classification and should be treated surgically with a combination of endonasal endoscopy and endo-oral approach. In addition to sinusitis, other risks associated with sinus lift are: infection, inflammation, pain, allergic reactions, tissue or nerve damage, scarring, hematoma, graft failure, oro-antral communication/ oro-antral fistula, implant displacement or mobility, bleeding.
Recovery
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 placed. However, some surgeons perform sinus elevation and dental implant placement at the same time to avoid the need for 2 operations.
History
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 Tatum, Jr. in 1974, during the preparation period to perform sinus grafting. 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 accomplished with inflatable catheters. After this, appropriate instruments were developed to manage mucosal elevation of the various anatomic surfaces encountered in the sinuses.
Atum first presented the concept at the Alabama Implant Congress in Birmingham in 1976 and expounded on the evolution of the technique in several podium presentations each year until 1986, when he published a paper describing the procedure. Dr. Philip Boyne first became acquainted with 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 were the authors of 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 before attendees of the Alabama Implant Congress in 1994.
Cost-effectiveness
The slightly higher efficacy (implant integration) of the lateral sinus lift technique has to be weighed against the substantially higher cost compared to the trans alveolar sinus lift technique. From the patient’s perspective, the greater 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 implantation site.
Summary
Sinus lift procedure in dental surgery
The sinuses are pneumatic cavities of the facial mass that serve several roles, including purifying air entering through the nasal passages, maintaining upper floor pressure and fluidizing secretions.
The maxillary sinuses are in close proximity to the maxillary dental arch, and dental pathology is often transmitted to them by the neighboring relationship of the dental roots to the sinuses.
Inflammation of the sinuses is known as sinusitis and may have several causes.
In principle, 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 irritating factors.
Odontogenic, this 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, most often 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 found in the vicinity of the alveolar ridges. 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 would result in chronic maxillary sinusitis.
In this situation, in order to create the necessary bone support for dental implants, a procedure called sinus lift, a surgical procedure in which bone is added to the upper jawbone in the lateral areas, is performed.
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 either autogenous or allogenic (synthetic or bovine).
The procedure itself is not painful as it can be performed under local anesthesia, so the patient will not feel any discomfort.
There are two types of sinus lift:
Internal sinus lift – this procedure takes place in cases where the sinus is not very close to the bony crest, so the membrane does not need to be lifted significantly, just slightly pushed superiorly. After lifting the membrane, bone will be 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 ridge and during the procedure the membrane has to be elevated significantly. With external sinus lift, a window is created in the vestibular bony cortex through which the sinus membrane will be directly visualized.
Following the sinus lift procedure, regardless of the modality chosen, the operated area may become swollen. Slight nosebleeds are normal.
It is important for the patient to follow the instructions that will help the patient heal quickly and 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 medication should be strictly followed as well as visits to the dentist for check-ups.
Bibliography
Felisati, Giovanni, Chiapasco, Matteo, Lozza, Paolo, Saibene, Alberto Maria, Pipolo, Carlotta, Zaniboni, Matteo, Biglioli, Federico & Borloni, Roberto (July 2013).”Sinonasal complications resulting from dental treatment: outcome-oriented proposal of classification and surgical protocol”. American Journal of Rhinology and Allergy.
Bruschi, G. B.; Scipioni, A.; Calesini, G.; Bruschi, E. (March 1998) “Localized management of sinus floor with simultaneous implant placement: a clinical report”. The International Journal of Oral & Maxillofacial Implants.
Albrektsson, Tomas; Berglundh, Tord; Lindhe, Jan (2003) “Osseointegration: Historic Background and Current Concepts”. In Lindhe, Jan; Karring, Thorkild; Lang, Niklaus P. (eds.). Clinical Periodontology and Implant Dentistry. Oxford: Blackwell Munksgaard. p. 816. ISBN 1-4051-0236-5.
Bell, G. W.; Joshi, B. B.; Macleod, R. I. (February 2011). “Maxillary sinus disease: diagnosis and treatment”. British Dental Journal.
Rosen PS; Summers R; Mellado JR; et al. (1999) “The bone added osteotome sinus floor sinus floor elevation technique: Multicenter retrospective report of consecutively treated patients”. Int J Oral Maxillofacial Implants.
Summers, Robert B. (1994) A new concept in maxillary implant surgery: the osteotome technique. Compendium.
