Sinus Augmentation is a complex but predictable surgery. When implant placement is added, they can become very interesting procedures with multiple moving parts. With science-based regenerative bone graft materials, areas with minimal bone and lost membranes can be successfully treated. When there is a minimal amount of crestal bone, integration in the area of the graft is required and the material must maintain volume to fully cover the implant body over time. Various studies have demonstrated that approximately 25% of sinus augmentations are compromised by torn membranes. A modern science-based bone graft material needs to perform without a sinus membrane in these situations. This presentation will cover a few sinus augmentations performed in the last few months and the decisions that were needed to produce a successful outcome.
Sinus Augmentation withImplant Placement: Always Interesting
Due to buccal resorption and a minimal amount of crestal bone, the osteotomy for the sinus augmentation and implant was repositioned to the lingual. A number of excellent devices have been developed for exposing the membrane without damage and they are highly recommended. However, in this case, the majority of bone was removed with a standard round bur and when the membrane was close to being exposed, a multifluted round bur was used to expose the membrane.
The membrane was dissected a few millimeters around the osteotomy and 2cc of Sinus Graft was injected, raising the membrane and filling the floor of the sinus. A few characteristics of this radiograph are notable. When the membrane is properly elevated, there will be no radiolucency between the graft material and the sinus bone. If the membrane is not detached from the bone, there will be a distinct radiolucent line between the bone and the graft material. Also, when the graft material is homogeneous and dense, it ensures that the membrane is elevated because the pressure of the membrane condenses the graft material.
After the implant placement of #12, the remaining defects around the implant were grafted with Immediate Graft to fill the voids between the implant and the bone. This radiograph shows the extent of the membrane (arrows). Before both implants are placed, the last drill is made to the full length of the implant. The material is beginning to set, so the osteotomies are created to the full length of the implant, and then the implants are placed. Sinus Graft sets in about 30 minutes.
2-week post-op. Shortly after grafting, Sinus Graft sets and becomes bonded to the sinus wall and implant surfaces. Because Sinus Graft ‘sets’ in the sinus, the volume of the graft site is maintained through the regenerative period. At two weeks, cellular migration is occurring into the graft material causing the graft material to lose density around the sinus floor. The mesial wall has a significant amount of cancellous bone. However, the posterior wall adjacent to the molar has very little cancellous bone to supply regenerative cells. Therefore, the decrease in graft density is occurring primarily around the mesial implant with minimal decrease in density around the distal implant.
4-week post-op. The regenerative process begins at the border between the sinus wall and bone graft. As osteoblasts migrate from the bone into the bone graft, the density of the bone graft is reduced by the presence of the invading cells. At first, the radiographic density in the graft is reduced as vital tissue replaces the bone graft. However, the second stage shows an increase in density as the immature bone mineralizes. At this visit, the patient is scheduled for placement of healing abutments and impressions at three months after implant placement.
Sinus Bump Technique
Three months after sinus augmentation and implant placement, the healing abutment is placed and the patient is scheduled for an impression. At this time, the graft is fully mineralized with the grafted site presenting with a greater degree of mineral density than the preexisting alveolus. The original floor of the sinus is no longer distinguishable as the increase in mineralization moves into the preexisting bone.
Dissection of the sinus membrane is made with a micro instrument as pictured. The dissection is very minimal. The dissection begins with this instrument which is placed against the bone under the membrane only releasing the membrane apical to the osteotomy. After releasing the membrane apical to the osteotomy, a ball instrument is used to dissect the membrane to the floor of the sinus and to the medial wall of the sinus with a minimal amount of dissection in the medial and distal direction. No dissection in the cranial direction is needed. The dissection is only performed to allow the graft material to flow to the bottom of the sinus and when that space is filled, hydraulic pressure raises the membrane.
The following patient was referred for implant replacement of his first molar (#3). During the examination, a visible mass was noted on the left sternocleidomastoid muscle. The mass was examined and appeared to be a swollen lymph node. The patient reported that he was previously treated for cancer. The patient was referred to an ENT and instructed not to return for implant placement until cleared by the physician. The patient had a biopsy of the mass and was cleared by his physician for implant placement. He did not yet have a diagnosis. The decision was made to proceed with implant placement even though the diagnosis had not been made. If the diagnosis is favorable, then all is well. However, if the diagnosis is cancer, then the therapy could compromise his left occlusion making his right occlusion all the more critical. Also, if treatment should involve radiation to the head and neck, his ability to have a sinus augmentation and implant might be contraindicated. Due to these factors, the decision was made to proceed with sinus augmentation and implant placement. The patient was a 56-year-old male in otherwise good health. At the consult appointment, the patient’s blood pressure was 124/81. However, after his biopsy and while he was waiting for his diagnosis, he presented for surgery and his blood pressure was 179/83. This change in blood pressure was deemed stress-related and not related to cardiovascular disease. Therefore, the surgery proceeded as planned.
A ct scan was taken before surgery and the decision was made to do a crestal osteotomy for access to the sinus membrane. However, the sinus membrane was torn when the membrane was exposed (maybe one of those new sinus augmentation instruments is indicated). An attempt to inject Sinus Graft under the membrane failed as shown on this radiograph with no graft material on the floor of the sinus. The decision was made to remove the membrane from the floor of the sinus and inject Sinus Graft without a membrane.
2-week post-op. Even without a membrane covering the graft material, the graft material bonds to the implant and the sinus walls and sets in the sinus. The removal of a torn membrane and injection of the graft material onto the floor of the sinus is the treatment of choice. At the post-op appointment, the patient reported his diagnosis was squamous cell carcinoma originating from the left posterior tongue. He was referred by his diagnosing ENT to a university hospital for robotic aided surgery. When the sinus membrane is damaged, our protocol is to remove the membrane from the floor of the sinus and fill the floor of the sinus with Sinus Graft. The following case outlines this procedure from start to finish.
A lateral wall osteotomy was planned. However, the bone was no more than an eggshell thickness. During the preparation of the osteotomy for sinus augmentation, the membrane tore as soon as the bur contacted the bone. The sinus membrane was very fragile and therefore, the decision was made to remove the membrane from the floor of the sinus. The membrane was removed and the floor of the sinus was filled with Sinus Graft prior to implant placement.
One year after the implants were restored. These implants have now been in function for 8 years. When using modern science-based graft materials that set in the sinus and resist displacement and infection, the sinus membrane is optional. Dentistry should rethink the need for the sinus membrane. For more information on the procedure, follow the link:
For 50 consecutive sinus augmentation procedures done in a private practice, following the link:
American Society for Bone and Mineral Research (ASBMR) Tissue Engineering and Regenerative Medicine International Society (TERMIS)