Sinus Grafting

Sinus grafting ( Sinus lifting) is a procedure to increase the bone height in the back portion ( molar-premolar) of the upper jaw in patients with deficient bone height for the placement of implants.

Maxillary Sinus is a air filled cavity lined by thin mucus membrane situated in the back portion of the upper jaw above the root tips of molar-premolar teeth which helps in purifying and humidifying breathing air. When natural teeth are present floor of the sinus in maintained at a higher level. When these teeth are removed and if they are either unreplaced or replaced with removable denture or bridge for longer period the supporting alveolar bone height will be reduced because

• No stimulus is given to the supporting bone for its remodeling leading to bone resorption from the alveolar crestal region.
• Maxillary sinus begins to expand in all dimensions from above the alveolar bone.

Hence the overall height of the bone is reduced and if the bone height reduces significantly implant placement becomes impossible.

If the missing teeth are replaced by implant supported teeth sooner following extraction of teeth, the alveolar bone height and width can be preserved.

Normally there should be a minimum bone height of 8 mm and bone width of 6 mm present for the implant placement. Because of the Maxillary sinus expansion and alveolar bone resorption, the bone height is reduced to less than 8 mm. Sometimes the remaining bone height may be as low as 0.5 to 1 mm.

Sinus grafting is performed to increase the alveolar bone height to 8 mm or more by adding bone graft material between upper portion of alveolar bone and mucus membrane of the Maxillary sinus

Depending on the amount of bone height augmentation there are 2 types of sinus grafting procedures

• Indirect sinus grafting ( Crestal approach)
• Direct sinus grafting (Lateral window approach)

Indirect Sinus Grafting

When the remaining alveolar bone height is slightly less than 8 mm (Eg: 6 mm ) in the molar-premolar region then using a specially designed instrument the mucus membrane of the Maxillary sinus along with a thin section of upper portion of the alveolar bone is tapped and elevated by 2-3 mm from the crestal portion of the alveolar bone. Graft material is pushed into this elevated space and implant is placed. This procedure is called as Indirect sinus grafting.

Indirect sinus grafting procedure is a blind procedure of increasing the bone height that requires skill, precision and experience.

Dr. Lokesh is one of the very few surgeons who possess abundant experience and is technically skilled to perform this procedure.

Direct Sinus Grafting

Direct Sinus Grafting is done to increase the alveolar bone height when it is less than around 5 mm in the molar-premolar region.

In the Indirect sinus grafting technique there is a limitation in increasing the bone height by a maximum of around 3 mm. Any further increase in bone height will lead to tearing of the sinus mucus membrane and that results in failure of the grafting procedure.

But in Direct sinus grafting technique, more graft can be added and hence more bone height can be obtained compared to the Indirect technique.

In direct sinus grafting procedure, approximately 1 cm round or oval window is created on the side of alveolar bone at molar region about 1 cm above the alveolar crestal without perforating the mucus membrane using special surgical drills. Mucus membrane is gently separated from the surrounding bone. A cavity is created between mucus membrane and the upper portion of the alveolar bone. Bone graft is then added into the cavity.

Since we are separating the mucus membrane from the surrounding bone and bone graft is placed under direct vision this procedure is called as Direct sinus grafting .

Direct Sinus Grafting technique is more predictable than the Indirect Sinus Grafting technique. Once the bone graft is placed into the cavity created ,whether the implant can be placed simultaneously or at a later stage depends on the following criteria.

• If the alveolar bone height is about 4 mm or above, implant can be placed in the same appointment.
• If the remaining alveolar bone height is less than around 3 mm then bone graft is placed and implant is placed after 3-4 months of healing period.

Direct sinus grafting is a very delicate procedure which requires high levels of skill and experience.

Dr. Lokesh routinely performs this procedure in large numbers. In fact he himself modified the procedure and he specially designed the instruments required for the procedure.