Sinus Lifting

What is Sinus Lifting Surgery and Why is it of Vital Importance?

Sinus lifting (sinus augmentation) is a surgical procedure aimed at creating new bone volume in the upper jaw where bone atrophy has occurred due to the absence of posterior teeth (molars and premolars). The scientific name for this operation is “Maxillary Sinus Augmentation.” The success of dental implants largely depends on sufficient bone height and thickness to securely hold the implant.

In the posterior region of the upper jaw, there are air-filled cavities called the maxillary sinuses, located just above the jawbone. When a tooth is lost, the underlying bone begins to resorb (atrophy). Simultaneously, the sinus floor gradually sags downwards (pneumatization), further thinning the delicate bone barrier between the bone and the sinus.

This anatomical and pathological condition does not leave enough bone height for the placement of a standard-length dental implant. If an attempt is made to place the implant in a way that extends into the sinus cavity, the sinus membrane can be perforated, leading to a risk of implant failure or a sinus infection (sinusitis). Sinus lifting surgery intervenes at this critical point.

The surgical procedure involves gently raising the thin membrane lining the sinus cavity (the Schneiderian membrane) and placing a bone graft (bone substitute material) between this membrane and the existing jawbone. This placed graft gradually transforms into the patient’s own bone, preparing a strong and sufficient bone foundation for implant placement. In short, sinus lifting is a crucial preparatory phase that forms the basis for safe and long-lasting dental implant treatment in the posterior upper jaw areas.

Maxillary Sinus Anatomy and the Dynamics of Bone Loss

The maxillary sinuses are the largest of the four pairs of sinuses in the skull, located just behind the cheekbones on either side of the nasal cavities. In a healthy individual, these sinuses contain only air and are lined by a thin, mucosal membrane called the Schneiderian membrane. The floor of the sinus is often very close to the root tips of the upper back teeth. In some cases, the roots may even extend into the sinus cavity. Bone loss frequently encountered in dentistry is accelerated by two main mechanisms:

First, disuse atrophy: When a tooth is lost, the chewing force on the bone is eliminated. The bone, when not continually stimulated, is perceived as “unnecessary” by the body and resorbs, losing its volume. This process usually causes a reduction in vertical bone height.

Second, sinus pneumatization: As the upper jawbone resorbs, the sinus cavity begins to expand downwards due to the reduction in pressure. This results in the sinus floor descending towards the jawbone, leaving a bone wall so thin that it makes implant placement impossible. While the ideal bone height for implantation is typically at least 10 mm, it is common to encounter bone heights of between 1 and 5 mm in this region. These dynamics make the sinus lifting procedure indispensable for implants in this area.

Sinus Lifting Indications: Who Are the Candidates?

Sinus lifting surgery is not necessary for every upper jaw implant. The indications (application requirements) depend entirely on the existing bone height. Generally, a patient is determined to be a candidate for sinus lifting based on the following criteria:

1. Severe Bone Height Deficiency: Insufficient vertical bone height for placing a standard implant (typically 8-13 mm long). The criteria are generally as follows:
   • Closed Sinus Lifting Candidates (Crestal Approach): Typically patients with existing bone height of 5 mm and above. This technique is used when only a relatively small amount of bone augmentation is required.
   • Open Sinus Lifting Candidates (Lateral Window): Typically patients with existing bone height below 5 mm and requiring 4-6 mm or more of vertical bone gain. This method is usually mandatory for cases with very little bone height, such as 1-3 mm.
2. Healthy Maxillary Sinus: The sinus must not have pathologies such as chronic inflammation (chronic sinusitis), cysts, or polyps in its mucosa. If there is an infection in the sinus, it must first be treated in collaboration with an ear, nose, and throat specialist (ENT).
3. Sufficient Horizontal Bone Thickness: There must be enough horizontal bone thickness to support the diameter of the implant itself. Although sinus lifting increases vertical bone, horizontal bone grafting may be required simultaneously if there is a horizontal bone deficiency.
4. General Health Status: Systemic diseases that would negatively affect healing, such as severe uncontrolled diabetes, immune system diseases, or conditions affecting bone metabolism (e.g., bisphosphonate use), must be under control.

What are the Basic Types of Sinus Lifting Procedures?

Sinus lifting operations are primarily divided into two main categories based on the amount of existing bone and the desired amount of bone increase. This distinction directly affects the surgical technique used, the healing time, and even the timing of implant placement.

1. Lateral Window Technique (Open Sinus Lifting)

This technique is the most commonly used and provides the most radical bone augmentation. It is generally preferred when the existing bone height is less than 5 mm, meaning a significant amount of vertical bone gain is required.

Basic Procedure:

• Opening the Lateral Wall: Under local anesthesia, an incision is made in the gum on the outer surface of the jawbone facing the cheek (lateral wall).
• Creating the Bone Window: A round or oval bone window is carefully opened on this lateral wall, close to the cheekbone, using round burs (piezo surgery or special devices) to access the sinus cavity.
• Membrane Elevation: After the window is opened, the thin Schneiderian membrane lining the sinus cavity is gently and carefully separated and lifted from the bone floor using special instruments (curettes). This creates a space beneath the sinus floor for the graft material.
• Grafting: The prepared bone graft material (bone substitute) is placed into the created space. The goal is for the graft material to establish the height required for implant placement.
• Closure: The opened bone window is usually covered with an absorbable collagen membrane to ensure graft stability. The gum incision is closed with sutures.

In this technique, it is usually necessary to wait 6 to 9 months for the graft to mature and transform into new bone. Implants cannot be placed during this period. However, in some special cases (if 4-5 mm of existing bone is present), implants can be placed during the same session (simultaneous implantation).

2. Crestal Approach Technique (Closed Sinus Lifting)

This technique is used in cases where the bone height is 5 mm or more, and only a few millimeters (typically 2-3 mm) of additional bone augmentation is needed. It is less invasive than the open technique and has a shorter recovery time.

Basic Procedure:

• Implant Site Preparation: The preparation of the implant socket begins from the upper part of the bone (crestal) at the point where the implant will be placed.
• Use of Osteotomes: Progress is made with burs until very close to the sinus floor. Then, the final part of the implant socket is prepared using special blunt-tipped instruments (osteotomes) that gently push the thin bone plate and the membrane above it upwards from within the implant socket with light tapping or controlled pressure.
• Membrane Elevation: These instruments gently elevate the thin bone plate and the membrane above it upwards from within the implant socket by a few millimeters without tearing the membrane.
• Grafting and Implantation: After the membrane is raised, a small amount of bone graft material is placed into the implant socket, and the implant is immediately placed into this socket.

The biggest advantage of closed sinus lifting is that the implant can be placed in the same session. This shortens the patient’s total treatment time. However, since it provides only limited bone augmentation, it cannot be applied in cases of advanced bone deficiency.

Detailed Steps of the Surgical Procedure and Key Considerations

The success of a sinus lifting operation depends on the surgeon’s meticulousness and sensitivity to anatomical details. Open sinus lifting, in particular, requires advanced surgical skill.

Soft Tissue Management and Access Provision

The operation is performed entirely painlessly under local anesthesia. The first step is to make a careful incision in the gum to reach the lateral wall of the jawbone and gently lift the mucoperiosteal flap (the gum and bone covering membrane). Lifting this flap allows the surgeon to clearly view the lateral bone wall. Adequate and non-traumatic flap design is critical for rapid post-operative healing.

Creating the Lateral Window: The Advantage of Piezoelectric Surgery

Traditionally, the bone window was opened using high-speed burs. However, this method carried a high risk of tearing the sinus membrane. Today, piezoelectric surgery (piezo surgery) devices have revolutionized the procedure due to their ability to cut and abrade bone using ultrasonic vibrations. Piezo surgery affects only the hard tissue (bone) and stops working or causes minimal damage when it touches soft tissue (sinus membrane). This significantly reduces the risk of sinus membrane perforation. The window is usually opened in a “trap-door” fashion, leaving a hinge point, which allows the window piece to be used later to support the sinus floor.

Elevating the Schneiderian Membrane: The Most Delicate Stage

After the bone window is opened, the surgeon’s biggest challenge is to lift the membrane without perforating it. This is performed using specially designed round and blunt-tipped sinus curettes. The curettes advance slowly and gently along the bone floor beneath the sinus membrane, separating the membrane from the bone. Lifting the membrane creates sufficient space for the cavity beneath it to be filled with graft material. Membrane perforation (tearing) is the most common complication of sinus lifting surgery, and the surgeon’s skill is most tested at this point.

Bone Graft Materials: Which Materials are Used and Why?

The bone graft material placed into the sinus cavity serves as a scaffold for new bone formation. An ideal graft material must be biocompatible, absorbable by the body, and provide a structure upon which bone cells can grow. Graft materials are divided into four main groups based on their origin:

1. Autogenous Grafts: Bone harvested from the patient’s own body (usually from the chin, jaw angle, or hip bone).
   • Advantage: Contains living bone cells and is considered the “gold standard.” It has the highest healing potential.
   • Disadvantage: Requires a second surgical site, which means additional pain, swelling, and risk of complications.
2. Allografts: Bone materials taken from human cadavers and processed for sterilization.
   • Advantage: Does not require a second surgical site. Structurally similar to human bone.
   • Disadvantage: Theoretical risk of tissue rejection and disease transmission (although extremely low).
3. Xenografts: Bone materials taken from a different species (usually bovine or porcine) with organic components completely removed, leaving only the mineral structure.
   • Advantage: The most frequently used material. Can be obtained in high volume. Provides an excellent scaffold.
   • Disadvantage: Slowly resorbed by the body, which, while helping to maintain bone volume for a long time, may prolong the healing period.
4. Alloplasts: Synthetically produced materials such as calcium phosphate derivatives (e.g., tricalcium phosphate or hydroxyapatite).
   • Advantage: Unlimited supply and guaranteed sterilization.
   • Disadvantage: May have a weaker bone-forming potential compared to xenografts or autogenous grafts.

In modern surgery, combination grafting methods, such as mixing autogenous graft with xenograft or alloplast, are often preferred to achieve the best results. This combines the biological activity of the autogenous graft with the volume maintenance ability of the synthetic or xenograft.

Comprehensive Preparation and Diagnostic Imaging Before Sinus Lifting

The foundation of a successful sinus lifting operation lies in detailed and precise planning. The steps that must be taken before surgery include:

Cone-Beam Computed Tomography (CBCT)

Traditional two-dimensional X-rays (panoramic films) are insufficient for sinus lifting planning. CBCT (3D imaging) is essential for both accurately measuring vertical bone height in millimeter precision and examining the anatomical structure of the maxillary sinus itself. CBCT allows the surgeon to evaluate:

• Existing bone height and thickness.
• Pathologies within the sinus (thickened membrane, cysts, polyps, foreign bodies).
• Sinus septa (bony protrusions dividing the sinus cavity). These septa increase the risk of tearing the membrane during lifting and may require the surgeon to change their approach.
• The location of blood vessels (especially the posterior superior alveolar artery). Damage to this vessel can cause serious bleeding.

Evaluation of Sinus Health

If the patient has a history of chronic sinusitis or if CBCT shows thickening of the sinus mucosa, consultation with an ENT specialist is mandatory. Placing graft material into an infected or inflamed sinus can lead to the graft becoming infected and completely failing. If necessary, the sinus infection must be medically treated before the operation.

Post-Sinus Lifting Recovery Process: Step-by-Step Expectations

Sinus lifting is a relatively major surgical procedure, and the recovery process varies depending on the technique applied (open or closed).

Acute Healing Period (First Week)

The first few days immediately following the operation are when the most intense symptoms occur.

• Swelling (Edema): The most common situation. Significant swelling may occur in the cheek area. Cold compress application is critical for controlling this swelling during the first 48 hours.
• Pain: Pain is usually manageable with painkillers. Severe, uncontrolled pain may be a sign of infection or complication.
• Bleeding: Slight bleeding in the form of oozing is normal during the first 24 hours.
• Ecchymosis (Bruising): In addition to swelling, bruising may be seen on the cheek and sometimes under the eye. This usually resolves spontaneously within a few weeks.

During this period, antibiotics prescribed by the doctor must be used regularly, and actions that increase pressure on the sinus must be strictly avoided.

Graft Maturation Period (3 to 9 Months)

The actual healing involves the graft material being resorbed by the body and replaced by new, mineralized bone (osseointegration).

• Closed Sinus Lifting: Since implants are usually placed in the same session, the integration period for the implants with the jawbone (3-6 months) is awaited.
• Open Sinus Lifting: Because the graft volume is large, it may take 6 to 9 months for the graft to reach sufficient hardness and maturity for implant placement. This waiting period is vital for successful implant placement and long-term success.

During the recovery period, if the patient uses a denture, it may need to be adjusted so as not to put pressure on the graft area, or a temporary denture may need to be used.

What to Absolutely Avoid After Sinus Lifting Surgery?

Adherence to post-operative care instructions is just as important as the surgery itself in terms of graft stability and preventing the risk of infection.

Avoiding Actions That Increase Sinus Pressure

A sudden and severe increase in pressure inside the sinus can cause the newly lifted membrane to tear or graft particles to escape into the sinus. Therefore, the following actions should be avoided:

• Blowing the Nose: Avoid blowing your nose vigorously. If you need to sneeze, sneeze with your mouth open.
• Using Straws or Blowing: Strictly avoid actions that create negative or positive pressure in the mouth, such as smoking, using straws, or blowing balloons.
• Air Travel and High Altitude: Pressure changes can affect the sinus area. Air travel should be avoided for several weeks after the operation without the doctor’s advice.
• Heavy Lifting and Strenuous Exercise: Heavy physical activities that can increase blood pressure and the associated risk of bleeding should be avoided for the first few days.

Medication and Hygiene Management

• Antibiotics: Prescribed antibiotics must be used exactly for the specified duration to prevent the risk of infection.
• Painkillers: Painkillers should be used regularly, but those with blood-thinning effects (e.g., aspirin or some NSAIDs) should be avoided without doctor approval.
• Oral Hygiene: The operative site should not be brushed directly. Antiseptic mouthwashes recommended by the doctor can be used in the first week, but instead of spitting out the liquid vigorously, let it flow slowly out of the mouth.
• Nutrition: Soft and lukewarm foods should be preferred in the first few days, and care should be taken to chew on the opposite side of the surgical area.

What are the Possible Risks and Complications and How are They Managed?

Although sinus lifting generally has high success rates, like any surgical procedure, it carries some risks and complications. Awareness of these risks is important for early diagnosis and management.

Membrane Perforation (Tearing of the Membrane)

This is the most common complication. It is the situation where the thin and delicate sinus membrane is punctured or torn during lifting.

• Management: Small tears can be repaired using collagen membranes (patching), and the surgical procedure can continue. If the tear is large and irreparable, the grafting procedure may be canceled, the sinus is allowed to heal, and a second attempt is made after a few months. Even if membrane repair is successful, it slightly increases the risk of graft failure.

Sinus Infection (Postoperative Sinusitis)

This is when the graft material becomes infected with bacteria or fungi. This can manifest as severe pain, fever, nasal discharge (especially foul-smelling), and increased swelling.

• Management: It is usually treated with antibiotics and decongestants. If the infection cannot be controlled and the graft material is completely infected, the graft may need to be surgically removed.

Loss of Graft Material Support (Graft Failure)

This is when the graft material fails to transform into new bone due to inadequate blood supply, infection, or the patient’s systemic conditions. This means that the bone volume required for implant placement is not created.

• Management: When graft failure is detected (usually with a CBCT performed after 6-9 months), the failed graft material is cleaned, and planning for a second sinus lifting attempt is made.

Bleeding and Nerve Damage

Injury to the posterior superior alveolar artery during surgery can cause serious bleeding. Although rare, temporary affection of nearby nerves can cause numbness (paresthesia), but this condition is usually temporary.

Alternative Treatment Options for Sinus Lifting Applications

When some patients are hesitant about surgery or their general health condition is not suitable for sinus lifting, different implant approaches can be considered.

Short Implants

When the existing bone height is around 4-5 mm, shorter implants (6 mm or 8 mm) can be used instead of sinus lifting. These implants can show similar success rates to longer implants, provided they have sufficient diameter and special surface structures. This approach shortens the surgical time and completely eliminates the risk of sinus complications.

Angled Implants and Tilt Techniques

In fixed prosthesis techniques such as All-on-4 or All-on-6, posterior implants can be placed at an angle (tilt) to avoid the maxillary sinus. This is an effective method that bypasses the need for sinus lifting. Implants are placed in the anterior region where more bone is present, and angled to ensure force distribution.

Zygomatic Implants

In cases of very advanced bone loss where sinus lifting or short implants would be inadequate, implants are anchored directly to the cheekbone (zygoma). This is a highly invasive procedure and is only an alternative in the most severe cases of atrophy.

Success Rates and Long-Term Prognosis of Sinus Lifting Applications

Sinus lifting is one of the most researched procedures in dental literature, and when performed with modern techniques, its success rates are quite high. Success rates are generally reported to be between 90% and 98%. However, this success rate depends on the following factors:

• Amount of Existing Bone: The greater the existing bone height before surgery, the higher the success rate.
• Membrane Integrity: The absence of membrane perforation or its successful repair is critical for the graft to remain in place and for ossification.
• Graft Material: The use of autogenous bone is accepted to have a slightly higher success potential compared to other graft materials, but current xenografts also yield excellent results.
• Accuracy of the Surgical Technique: A meticulous approach by an experienced surgeon using modern tools like piezo surgery directly affects success.
• Patient Compliance: The patient’s adherence to instructions, such as not smoking, avoiding actions that increase sinus pressure, and regular use of prescribed medication, is key to long-term success.

In the long term, implants placed into the new bone created by sinus lifting have been proven to show similar stability and success rates as implants placed in natural bone. This demonstrates that sinus lifting is a reliable and permanent solution for implant-supported restorations.

Sinus Lifting: A Solution-Oriented Art in Modern Dentistry

The sinus lifting procedure is the art of regaining lost bone and has fundamentally changed the ability to restore function and aesthetics in dentistry. In the past, patients with insufficient bone were limited to using removable dentures, whereas thanks to sinus lifting, they can now have permanent, fixed, and comfortable dental implants.

This procedure not only replaces missing bone but also protects the anatomical structure of the maxillary sinus, thereby improving both the longevity of the implant and the patient’s overall oral health. Sinus lifting, as one of the most important innovations in modern oral surgery and implantology, plays a key role in improving the quality of life for patients. It is the most important step for patients to fully understand this process, potential risks, and the long healing period before starting treatment to achieve a successful outcome.