**7. Complications of sinus lifting**

A variety of complications can happen during and after sinus lifting. As all the other surgical techniques, this procedure is prone to all common complications of oral surgery but in this chapter we will focus on complications of this procedure.

#### **7.1. Membrane perforations**

The most common complication during sinus graft surgery is tearing of the sinus membrane. Causes of this condition include: Pre-existing perforations, tearing during scoring of the lateral wall window, existing or previous pathologic condition, and elevating of the membrane from the bony walls. This complications occurs about 10% to 34% of the time. The perforation of the sinus membrane should be sealed to prevent contamination of the graft from the mucus and the contents of the sinus and to prevent the graft materials from extruding into the sinus proper. The surgical correction of a perforation is initiated by elevating the sinus mucosal regions distal from the opening. Once the tissues are elevated away from the opening, the membrane elevation with a sinus curette should approach the tear from all sides so that the torn region may be elevated without increasing the opening size. The antral membrane elevation techni‐ que decreases the overall size of the antrum, thus folding the membrane over itself and resulting in closure of the perforation.

If the sinus membrane tear is larger than 6 mm and cannot be closed off with the circumele‐ vation approach, then a resorbable collagen membrane, but of a longer resorption cycle, may be used to seal the opening. The remaining sinus mucosa is first elevated as described previously. A piece of collagen matrix is to cut to cover sinus tear opening and overlap the margins more than 5 millimeters. Because no antibiotic is used on the collagen to make this procedure easier to perform, additional antibiotic is added to the graft material. Once the opening is sealed, the sinus graft procedure maybe completed in the routine fashion. A sinus perforation may cause an increased risk of short-term complications. A torn membrane may increase the risk of bacterial penetration into the graft material. Furthermore, mucus may violate the graft influencing the amount of bone formation. Drip of the graft material into the sinus proper may occur as a result of torn membrane, travel to and through the ostium and either be abolished through the nose or block the ostium and prevent normal sinus drainage. Ostium obstruction is also possible from swelling of the membrane related to the surgery. These conditions increase the risk of infection. However, despite these potential complications, the risk of infection is low (less than 5%)

#### **7.2. Antral septa**

IAN repositioning also presents many disadvantages. The technique does not recover the alveolar ridge anatomy and temporarily weakens the mandible. Mandibular fractures associated with endosseous implants have been documented and are generally related to high levels of resorption in edentulous mandibles. Also, nerve mobilization leads to many factors that can increase the occurrence of fractures. [7, 9] A large portion of the buccal cortex is removed, reducing the structural integrity of a region that is under constant stress during chewing. [8] In addition to that, sites that have been prepared and subsequently abandoned due to bad angulation or insufficient initial stability are areas of bone fragility susceptible to fracture. [7] Poor nutrition as a consequence of blood perfusion changes associated with this nerve mobilization can also be a cause of fracture. [10] Another disadvantage of IAN reposi‐ tioning is the risk of nerve damage. The duration and degree of neurosensory disturbance has been related directly to the amount of compression and tension applied to the nerve during the procedure, [11] or to chronic distension/compression of the nerve after the surgery. [12] Hypoesthesia, paresthesia, and hyperesthesia are the most common complications. [13]

The success rate of the lateralization procedure, regarding the osseointegration process, varies from 93.8% to 100%, and thus both patients and surgeons believe this to be a safe procedure; however, a small percentage of patients will have nerve damage for the rest of their lives. [14] Concerning the use of materials as barriers between the implant and nerve, there is controversy in the literature, because while some authors consider the use of resorbable membranes to be helpful, [4] others have observed faster healing of the bone wound without barriers, followed by the restoration of the mandibular canal. [15] One advancement is the utilization of piezo‐ electric devices, which allow the surgeon to perform the osteotomy without damaging soft tissue, because piezoelectric devices only affect mineralized tissues. In vitro tests have shown a lower risk of injury when piezoelectric devices are used compared to conventional rotary

A variety of complications can happen during and after sinus lifting. As all the other surgical techniques, this procedure is prone to all common complications of oral surgery but in this

The most common complication during sinus graft surgery is tearing of the sinus membrane. Causes of this condition include: Pre-existing perforations, tearing during scoring of the lateral wall window, existing or previous pathologic condition, and elevating of the membrane from the bony walls. This complications occurs about 10% to 34% of the time. The perforation of the sinus membrane should be sealed to prevent contamination of the graft from the mucus and the contents of the sinus and to prevent the graft materials from extruding into the sinus proper. The surgical correction of a perforation is initiated by elevating the sinus mucosal regions distal from the opening. Once the tissues are elevated away from the opening, the membrane

devices. [16]

**7. Complications of sinus lifting**

578 A Textbook of Advanced Oral and Maxillofacial Surgery Volume 2

**7.1. Membrane perforations**

chapter we will focus on complications of this procedure.

Antral septa are the most common osseous anatomical variant seen in the maxillary sinus. Sinus septa may create added difficulty at the time of surgery. Maxillary septa can prevent adequate access and visualization to the sinus floor; therefore inadequate or incomplete sinus grafting is possible. These dense projections complicate the surgery in several ways. After scoring the lateral-access window in the usual fashion, the lateral-access window may not fracture and rotate into its medial position. The strut reinforcement is also more likely to tear the membrane during the releasing of the access window.

#### **7.3. Management of septa based on location**

The septa maybe in the anterior, middle, or distal partof the antrum. When the septum is found in the anterior section, the lateral access window is divided into sections: one in front of the septa and another distal to the structure. This permits the release of each section of the lateral wall after tapping with a blunt instrument. The elevation of each released section permits investigation into the exact location of the septa and to continue the mucosal elevation.

When the strut is located in the middle region of the sinus, it is more difficult to make two separate access windows within the direct vision of the surgeon. As a result, one access window is made in front of the septa. The sinus curette then proceeds up the anterior aspect of the web, towards its apex. The curette then slides toward the lateral wall and above the septum apex. The curette may slide over the crest of septum approximately 1 to 2 mm. A firm pulling action fractures the apex of the septum. Once the septum is separated off the floor, the curette may proceed more distal along the floor and walls.

When the septum is in the posterior compartment of the sinus, it is often distal to the last implant site. When this occurs, the posterior septum is treated through the posterior wall of the sinus.
