When a tooth has been missing for a long time, the jaw bone will have remodeled itself, and reduced in height and width. This can lead vital anatomical structures like sinuses and nerves to come closer to the surface of the bone. If any of these anatomic landmarks are injured during implant placement, it can cause major complications.
What is a sinus lift?
A sinus lift is one of the most common augmenting procedures performed prior to or during dental implant surgery. It is done to raise the level of the maxillary sinus in the upper jaw, which facilitates the placement of an implant in the back region of the jaw.
- In patients whose upper teeth have been missing for a long time, the jaw bone reduces in height, causing the sinus to come closer to the surface.
- The opposite can also happen in patients suffering from sinusitis for a long time; the sinus cavity is enlarged. In such cases too, a sinus lift may be required.
- Anatomical variations where the sinus is larger than expected or closer to the surface than usual may also make a sinus lift procedure necessary.
Types of sinus lift surgeries
Prior to any implant surgery, the dentist advises you to undergo a 3D bone scan. This helps the dentist determine the exact bone height available in your jaw for implant placement. Depending on the existing dimensions of the upper jaw bone, the surgeon will advise you to undergo either an indirect sinus lift or a direct sinus lift procedure.
- If the bone height is about 7-8 mm, the dentist requires only about 3-4 mm of additional bone to get good stability of the implant. In such cases, an indirect sinus lift is advised.
- When the existing bone is less than 5 mm, the dentist will advise you to go for a direct sinus lift, in order to gain more bone height.
Differences between a direct and an indirect sinus lift
1. Degree of invasiveness
An indirect sinus lift is a minimally-invasive procedure when compared to a direct sinus lift procedure.
To perform a direct sinus lift, the surgeon needs to cut open an additional site, on the side of the upper jaw bone, and create a window through which the sinus can be accessed and then the artificial bone is placed to increase the overall height of the jaw bone.
In an indirect sinus lift, the sinus is accessed from the same site that is drilled to place the implant. After drilling the bone for implant placement, as the sinus is approached, the surgeon uses specialized instruments to gently fracture the bony wall between the drilled site and the sinus. The membrane is then lifted using blunt instruments to the required height.
In some cases, if the surgeon feels necessary, they may add artificial bone during indirect sinus lifts too.
2. Implant in the same sitting
Indirect sinus lift and implant placement are always done at the same time, hence the patient doesn’t need to undergo a second surgery. In certain cases of direct sinus lift, it is often (but not always) necessary to delay the implant placement for a few months, in order to allow for satisfactory healing.
3. Post-operative complications
Although complications are sometimes unavoidable in any surgical procedure, an indirect sinus lift is associated with relatively fewer complications like tearing of the sinus membrane or secondary infection of the sinus. Also, there is a lower risk of uncontrolled bleeding during an indirect sinus lift procedure.
Post-operatively, a direct sinus lift is generally associated with slightly more swelling and pain compared to an indirect sinus lift. The additional bone cutting and the invasive nature of a direct sinus lift surgery come with an increased number of complications for patients.
However, the care to be take after surgery in both the techniques is similar.
4. Access to the sinus
Direct sinus lift has an advantage of providing good visibility of the surgical site and the sinus membrane to the performing surgeon. On the other hand, an indirect sinus lift is basically a blind procedure, relying more on the tactile sensation of the surgeon.
5. Cost
Direct sinus lift is a costlier procedure when compared to indirect sinus lift because of the increased complexity of the procedure, a much larger amount of artificial bone needed, and the use of resorbable membranes to protect the graft.
6. Gain in bone height
The amount of bone height gained is less in indirect sinus lift is less. An indirect sinus lift is advised when the amount of height gain needed is 2-3 mm. A direct sinus lift can help the surgeon achieve a gain in bone height of around 8-10 mm.
7. Success rates
Both techniques have an excellent and comparable success rate of more than 95 percent. The selection of the cases for the appropriate surgery is very important otherwise the chances of complications and failure will rise rapidly.
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