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Method for insuring parallelism of implants placed simultaneously with maxillary sinus bone grafts
J Oral Maxillolac
Surg
49:435-437,1991
Method for Insuring Parallelism of lmplan ts Placed Simultaneously With Maxillary Sinus Bone Grafts MICHAEL S. BLOCK, DMD,’ AND J. STEVEN WIDNER, DDSt
flaps, with the periosteum attached to the medial and lateral ilium. A cancellous block measuring approximately 4 mm x 10 mm x 25 mm (two for bilateral cases) is removed from the exposed area, along with underlying cancellous particles. Cortical bone is not obtained except in unusually thin or osteoporotic hips. The periosteal and overlying fascial layers are closed, followed by closure of the skin. Attention is then directed to the exposed sinuses. The cancellous block is fitted into the sinus through the antral window. A pilot hole is then drilled through the thin alveolar crest at the most posterior implant site and into the cancellous block, while stabilizing the block from above with a retractor or periosteal elevator (Fig 1). An intermediate spade drill is used to enlarge the hole. A guide pin is then inserted into the implant site through the bone block. Additional anterior holes are drilled in similar fashion using the guide pins to maintain paral-
When there is less than 2 or 3 mm of alveolar bone present, there can be difficulty in maintaining implant parallelism when cylindrical implants are placed simultaneously with bone grafts within the maxillary sinus. We have used the following technique in five patients, using a cancellous block of bone, rather than particulate cancellous or cortical bone to stabilize the implants and ensure parallelism. Technique After preoperative treatment planning, the patient is placed under general anesthesia via a nasal endotracheal technique. The left hip and face, including the oral cavity, are prepared with Betadine and isolated in separate surgical fields. Exposure of the anterolateral maxillary wall is performed bilaterally via alveolar crest incisions. The sinus lift procedure is performed as described by Kent and Block.’ The inferior osteotomy is placed approximately I to 2 mm above the sinus floor. The sinus membrane is gently elevated from the floor and walls of the antrum, and the lateral maxillary wall is rotated medially and superiorly. The anterior superior portion of the iliac crest is then exposed. Periosteal incisions are made in the middle of the crest along its greatest length, and then horizontally at the anterior and posterior limits of the crest. Soft-tissue attachments on the crest are maintained. A straight osteotome is used to create a crestal osteotomy approximately 6 cm long with horizontal cuts at each end. The medial and lateral cortical plates of the crest are out-fractured as bone From the Department of Oral and Maxillofacial Surgery. Louisiana State University School of Dentistry, New Orleans. + Associate Professor. t Senior Resident. Address correspondence and reprint requests to Dr Block: Department of Oral and Maxillofacial Surgery, LSU School of Dentistry. 1100 Florida Ave, New Orleans. LA 70119. 0 1991 American geons
Association
of Oral and Maxillofacial
FIGURE 1. The cancellous block of bone placed into the sinus is held with a periosteal elevator against the intact, thin maxillary floor while the pilot drill is used to prepare the implant site.
Sur-
0278-2391/91/4904-0022$3.00/O
435
436
FIGURE 2. Use of the final drill to prepare the implant site through the cancellous block of bone.
TECHNIQUE
FIGURE 4.
FOR IMPLANTS IN SINUS GRAFTS
Implants placed, stabilizing the bone graft.
Discussion
lelism. The final holes are drilled (Fig 2) and the implant body try-ins are placed to stabilize the graft while this is being done (Fig 3). A hydroxyapatite (HA)-coated implant is then inserted into the most posterior site. Cancellous bone particles are packed around the implant, filling the posterior portion of the sinus. The next implant is then inserted and the sinus packed with more bone. Additional implants are placed in the same fashion (Fig 4). Typically, the most anterior implant is placed into the paranasal alveolar bone. When the ridge is narrow, cancellous bone particles combined with demineralized bone are then packed on the lateral surface of the alveolar crest (Fig 5). The mucoperiosteal flap is undermined, horizontally scored, if necessary, and primary closure is obtained.
The use of a block of bone for maxillary sinus grafting is not new. Threaded implants can be placed into a corticocancellous block of bone to stabilize it as well as promote maintenance of implant position. However, there has been about a 25% loss of titanium implants immediately placed into bone grafts because of lack of integration.’ We, therefore, prefer to use HA-coated implants with grafts. The use of cancellous particulate grafts with simultaneous placement of HA-coated implants has proved successful, without loss of implants due to nonintegration. ’ Inserting posterior maxillary implants into the thin sinus floor of an atrophic maxilla results in an
FIGURE 3. The implant body try-in placed into the prepared site to stabilize the bone graft for preparation of additional implant sites.
FIGURE 5. Particulate cancellous bone firmly packed into the sinus, completely covering the implants.
implant ,with little stability that is easily displaced during surgery or the healing period. In the technique described, the block of cancellous bone serves as a means to maintain a vertical, parallel position. As more implants are engaged into the bone wafer, greater three-dimensional stability is attained, mechanically locking the implants into place. The implants remain stable as bone is packed around them and parallelism is more readily preserved (Fig 6). Essential for the described technique
are an adequate block of cancellous bone and a sufficiently large antral window to allow placement of the graft. References 1. Kent JN, Block MS: Simultaneous maxillary sinus floor bone grafting and placement of hydroxylapatite-coated implants. J Oral Maxillofac Surg 47:238, 1989 2. Keller EE, Van Roekel NB, Desjardins RP, et at: Prosthetic surgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int J Oral Maxillofac Implants 2: 155. 1987
Surg
49:435-437,1991
Method for Insuring Parallelism of lmplan ts Placed Simultaneously With Maxillary Sinus Bone Grafts MICHAEL S. BLOCK, DMD,’ AND J. STEVEN WIDNER, DDSt
flaps, with the periosteum attached to the medial and lateral ilium. A cancellous block measuring approximately 4 mm x 10 mm x 25 mm (two for bilateral cases) is removed from the exposed area, along with underlying cancellous particles. Cortical bone is not obtained except in unusually thin or osteoporotic hips. The periosteal and overlying fascial layers are closed, followed by closure of the skin. Attention is then directed to the exposed sinuses. The cancellous block is fitted into the sinus through the antral window. A pilot hole is then drilled through the thin alveolar crest at the most posterior implant site and into the cancellous block, while stabilizing the block from above with a retractor or periosteal elevator (Fig 1). An intermediate spade drill is used to enlarge the hole. A guide pin is then inserted into the implant site through the bone block. Additional anterior holes are drilled in similar fashion using the guide pins to maintain paral-
When there is less than 2 or 3 mm of alveolar bone present, there can be difficulty in maintaining implant parallelism when cylindrical implants are placed simultaneously with bone grafts within the maxillary sinus. We have used the following technique in five patients, using a cancellous block of bone, rather than particulate cancellous or cortical bone to stabilize the implants and ensure parallelism. Technique After preoperative treatment planning, the patient is placed under general anesthesia via a nasal endotracheal technique. The left hip and face, including the oral cavity, are prepared with Betadine and isolated in separate surgical fields. Exposure of the anterolateral maxillary wall is performed bilaterally via alveolar crest incisions. The sinus lift procedure is performed as described by Kent and Block.’ The inferior osteotomy is placed approximately I to 2 mm above the sinus floor. The sinus membrane is gently elevated from the floor and walls of the antrum, and the lateral maxillary wall is rotated medially and superiorly. The anterior superior portion of the iliac crest is then exposed. Periosteal incisions are made in the middle of the crest along its greatest length, and then horizontally at the anterior and posterior limits of the crest. Soft-tissue attachments on the crest are maintained. A straight osteotome is used to create a crestal osteotomy approximately 6 cm long with horizontal cuts at each end. The medial and lateral cortical plates of the crest are out-fractured as bone From the Department of Oral and Maxillofacial Surgery. Louisiana State University School of Dentistry, New Orleans. + Associate Professor. t Senior Resident. Address correspondence and reprint requests to Dr Block: Department of Oral and Maxillofacial Surgery, LSU School of Dentistry. 1100 Florida Ave, New Orleans. LA 70119. 0 1991 American geons
Association
of Oral and Maxillofacial
FIGURE 1. The cancellous block of bone placed into the sinus is held with a periosteal elevator against the intact, thin maxillary floor while the pilot drill is used to prepare the implant site.
Sur-
0278-2391/91/4904-0022$3.00/O
435
436
FIGURE 2. Use of the final drill to prepare the implant site through the cancellous block of bone.
TECHNIQUE
FIGURE 4.
FOR IMPLANTS IN SINUS GRAFTS
Implants placed, stabilizing the bone graft.
Discussion
lelism. The final holes are drilled (Fig 2) and the implant body try-ins are placed to stabilize the graft while this is being done (Fig 3). A hydroxyapatite (HA)-coated implant is then inserted into the most posterior site. Cancellous bone particles are packed around the implant, filling the posterior portion of the sinus. The next implant is then inserted and the sinus packed with more bone. Additional implants are placed in the same fashion (Fig 4). Typically, the most anterior implant is placed into the paranasal alveolar bone. When the ridge is narrow, cancellous bone particles combined with demineralized bone are then packed on the lateral surface of the alveolar crest (Fig 5). The mucoperiosteal flap is undermined, horizontally scored, if necessary, and primary closure is obtained.
The use of a block of bone for maxillary sinus grafting is not new. Threaded implants can be placed into a corticocancellous block of bone to stabilize it as well as promote maintenance of implant position. However, there has been about a 25% loss of titanium implants immediately placed into bone grafts because of lack of integration.’ We, therefore, prefer to use HA-coated implants with grafts. The use of cancellous particulate grafts with simultaneous placement of HA-coated implants has proved successful, without loss of implants due to nonintegration. ’ Inserting posterior maxillary implants into the thin sinus floor of an atrophic maxilla results in an
FIGURE 3. The implant body try-in placed into the prepared site to stabilize the bone graft for preparation of additional implant sites.
FIGURE 5. Particulate cancellous bone firmly packed into the sinus, completely covering the implants.
implant ,with little stability that is easily displaced during surgery or the healing period. In the technique described, the block of cancellous bone serves as a means to maintain a vertical, parallel position. As more implants are engaged into the bone wafer, greater three-dimensional stability is attained, mechanically locking the implants into place. The implants remain stable as bone is packed around them and parallelism is more readily preserved (Fig 6). Essential for the described technique
are an adequate block of cancellous bone and a sufficiently large antral window to allow placement of the graft. References 1. Kent JN, Block MS: Simultaneous maxillary sinus floor bone grafting and placement of hydroxylapatite-coated implants. J Oral Maxillofac Surg 47:238, 1989 2. Keller EE, Van Roekel NB, Desjardins RP, et at: Prosthetic surgical reconstruction of the severely resorbed maxilla with iliac bone grafting and tissue-integrated prostheses. Int J Oral Maxillofac Implants 2: 155. 1987