13: CONTEMPORARY SUBANTRAL SINUS SURGERY AND GRAFTING TECHNIQUES

CHAPTER 13 CONTEMPORARY SUBANTRAL SINUS SURGERY AND GRAFTING TECHNIQUES

The atrophic edentulous posterior maxilla often poses problems for implant placement. Following loss of teeth there is a gradual loss of alveolar bone and in many patients the sinus floor dips close to the alveolar ridge, leaving less than optimal bone height or width for placing implants. In some patients the loss of alveolar bone coupled with increased antral pneumatization may result in only a 2- to-3 mm thickness of alveolar bone height. The result is insufficient bone to place implants.1 For these patients the sinus lift procedures represent a treatment of choice.

Sinus lift subantral augmentation has produced excellent results with few complications.2,3 Autogenous bone alone or in combination with particulate allografts, xenografts, or alloplasts has provided excellent results.4 More recently, to reduce donor site morbidity, blood loss, operative time, and postoperative complications, allografts, xenografts, and/or alloplasts alone or in combination have been used as the graft of choice without the addition of autogenous bone.5 The grafts are combined with the patient’s blood, platelet-rich plasma, bone marrow aspirate, aqueous antibiotics, or sterile saline.6 In some cases, depending on the volume of alveolar bone, simultaneous sinus lift subantral augmentation and implant placement can be accomplished for the patient.7,8

image Historical Perspective

As far back as the 18th century successful sinus surgeries were performed using calcium sulfate as the graft material.9 In 1893 American physician George Caldwell and French laryngologist Henry Luc accessed the maxillary sinus by creating a lateral window providing access to lift the sinus membrane. Hilt Tatum, in 1975, introduced a technique to increase alveolar bone height that placed graft material under the maxillary sinus membrane prior to placing implants.10 In 1980 Boyne and James, using the Caldwell-Luc procedure, grafted autogenous bone between the sinus membrane and antral floor.11 Smiler and Holmes reported a series of five successful subantral grafts performed via a lateral window approach using porous hydroxyapatite alone as the graft material in 1987.12

image Biologic and Anatomic Considerations

Morphology

The adult maxillary sinus, or antrum of Highmore, lies within the body of the maxilla. It is the largest of the paranasal sinuses, measuring on average 34 × 33 × 23 mm with a 15 mL volume. It can occupy the body of maxilla from the tuberosity to the canine fossa. The root apices of molar teeth can extend into the sinus with only a thin sheet of bone or connective tissue separating the antrum from the oral cavity.13 With age and loss of maxillary posterior teeth there is progressive alveolar atrophy, increased pneumatization of the sinus, and thinning of the buccal wall.

The maxillary sinus is shaped as a quadrangular pyramid. The sides are directed superiorly, inferiorly, posteriorly, and anteriorly. The apex of the pyramid is pointed laterally into the zygomatic process. The base is directed medially toward the lateral wall of the nose. The medial wall of the sinus is the most complex, containing the nasolacrimal duct, which lies on average 4-to-9 mm anterior to the maxillary ostium. This duct drains tears and runs from lacrimal fossa in the orbit, down the posterior aspect of the maxillary vertical buttress, and empties into the anterior aspect of the inferior meatus.

The ostium of the maxillary antrum is located in the superior aspect of the medial wall of the sinus and empties mucus into the posterior aspect of the hiatus semilunaris. The anterior wall contains the infraorbital foramen with the infraorbital nerve running over the roof of the sinus and exiting through the foramen. The thinnest portion of the anterior wall is just above the canine fossa. The posterior wall is located behind the pterygomaxillary fossa and is pierced by the posterior superior alveolar nerves. It lies in proximity to the internal maxillary artery, the sphenopalatine ganglion, the foramen rotundum, and the greater palatine nerve.

The superior wall of the maxillary sinus is the floor of the orbit, through which runs the infraorbital canal and nerve. The floor of the sinus is approximately 1.00-1.25 cm below the level of the nasal cavity.

The mucosal lining of the sinus has a rich vascular network of complex vascular loops that help warm and filter inspired air. This layer of peudostratified columnar ciliated epithelium and connective tissue lines the maxillary sinus. The rapid, rhythmic sweeping movements of the cilia remove the mucus that goblet cells secrete, with the debris and bacterial contaminants, toward the ostium to the middle meatus of the nose.1417

Vascular Supply, Lymphatic Drainage, and Innervation

image Quadrilateral Buccal Osteotomy

Although the hinge osteotomy was one of the first approaches for sinus lift grafting, this procedure worked well only when there was sufficient vertical maxillary bone height.12 The quadrilateral buccal osteotomy is indicated for either normal or minimal vertical maxillary bone height. An advantage of quadrilateral osteotomy is that it permits the sinus membrane to be elevated higher than the superior horizontal osteotomy. The surgery proceeds after reflection of the mucoperiosteal flap and exposure of the lateral wall of the maxilla, the canine fossa, the malar buttress, and the infratemporal fossa. An inferior horizontal osteotomy begins 2-to-3 mm above the floor of the antrum in the area of the first molar using a #6 or #8 round bur and copious irrigation23 (Figure 13-2). A small round bur or a fissure bur must not be used because either will most likely cause tearing of the schneiderian membrane.

The osteotomy is done with a light touch, stripping away bone until the membrane is exposed. The anterior limit of the osteotomy is the anterior limit of the sinus. If bicuspid teeth are present the anterior limit is 3-4 mm distal to the tooth. The osteotomy extends to the region of the second molar as the posterior limit of the bone cut.

The anterior vertical bone cut is begun from the inferior horizontal osteotomy and extended as high as access permits. The superior horizontal osteotomy extends from the superior limit of the anterior vertical bone cut posterior to approximate the length of the inferior horizontal osteotomy. A posterior vertical osteotomy connects the inferior and superior horizontal bone cuts to complete the quadrilateral osteotomy (Figure 13-3).

image Elevation of the Schneiderian Membrane

The quadrilateral osteotomy exposes the schneiderian membrane circumferentially around the bone cuts. The membrane is first lifted along the superior horizontal osteotomy using broad-based freer elevators or curettes (Figure 13-4, A) The membrane can be elevated higher than the superior bone cut (Figure 13-4, B). This is especially important when the anatomy and resorption patterns restrict visibility and exposure.

With the sharp border of the dissection elevators placed on bone, and its broad base supporting the membrane, the membrane is lifted from its anterior and posterior walls (Figure 13-4, C). Further dissection exposes the medial wall of the sinus (Figure 13-4, D). The buccal osseous window stays attached to the schneiderian membrane as elevation continues. The bony wall turns inward and is positioned horizontally in the superior aspect of the dissection.

Piezosurgery with the diamond-coated insert or saw insert will cut a precision osteotomy (Figure 13-5, A). The quadrilateral osteotomy (Figure 13-5, B) can be removed, exposing the sinus membrane (Figure 13-5, C). Using the noncutting smooth insert, the membrane is elevated (Figure 13-5, D). The elevated membrane exposes the medial, inferior, and posterior bone walls of the sinus (Figure 13-5, E).

image Grafting the Osseous Cavity

Graft material is placed under the membrane within the osseous cavity in an anterior inferior direction and with a loose compaction. It is important that the graft is in contact with the medial osseous wall (Figure 13-6, A). Graft is added until the cavity is loosely filled, reconstituting the buccal wall (Figure 13-6, B). Overpacking the site and/or pressure in a superior direction is avoided because this might tear the membrane. Also, overcompressing the graft restricts blood flow into the material, inhibits angiogenesis, decreases oxygen tension, and compromises success. The mucoperiosteal flap is then repositioned and sutured. If the periosteum is torn a hemostatic collagen wound dressing or a guided bone regenerative membrane can be placed over the buccal window to inhibit fibrovascular growth into the graft (Figure 13-6, C).

Jan 7, 2015 | Posted by in Implantology | Comments Off on 13: CONTEMPORARY SUBANTRAL SINUS SURGERY AND GRAFTING TECHNIQUES
Premium Wordpress Themes by UFO Themes