For decades, titanium mesh has been used effectively in various clinical settings due to its biocompatibility and unique mechanical characteristics. In these scenarios, the clinical variables include the types of bone grafts chosen, the configuration of the titanium mesh (including preoperative computerized shaping), and biologic surface conditioning.
To use titanium mesh effectively in bone grafting procedures performed in preparation for dental implants, clinicians must understand the unique features of titanium mesh, how it compares with other grafting materials and techniques, how it is typically used in a variety of different clinical cases (including preoperative procedures and complications management), and the potential for future applications of titanium mesh in bone grafting.Indications for Bone Grafting with Titanium Mesh
Ideally, dental implants are placed in alveolar bone of optimal quality and quantity to achieve primary stability and to facilitate the esthetic and functional restoration of surrounding gingival tissues. When implants are treatment planned in alveolar ridges that have been compromised in height or width (or both) due to edentulism, tooth extraction, trauma, periodontitis, or infection secondary to caries, alveolar bone volumes must be restored via procedures such as ridge splitting, distraction osteogenesis, bone plates/ pins, onlay bone grafting, or guided bone regeneration (GBR). Titanium mesh offers the dental implant surgeon the stiffness necessary to prevent bone graft resorption from soft tissue contraction and a bone-restoring option that is simple to plan and execute and relatively affordable for patients.
Once a bone grafting framework is prepared in and around the compromised bone, biocompatible resorbable or nonresorbable barrier membranes can be used to create an insulated space that protects it from the migration of epithelial and connective tissue cells but may not provide adequate rigidity to prevent bone graft resorption from soft tissue contraction.6 In addition, the membranes simultaneously attract osteoblasts and osteocytes to the compromised bone, thus facilitating bone regeneration. Perhaps even more critical than its capacity to mediate cell-migration patterns to the bone defect, a barrier membrane must possess adequate firmness not only to isolate and preserve the mediating space within the healing/restoration area but also to defend the integrity of the bone graft from pressure exerted by resident mechan- ical forces (including, for example, micromotion) as well as by contraction of the soft tissue during healing of the raised flap. Generally, the larger the bone defect to be restored, the more robust the barrier membrane should be to maintain the spatial requirements in the bone defect area.8 Due to its physical properties (including mechanical rigor and mediation of cell migration), a titanium mesh membrane is often ideal in cases where bone grafting is indicated for three or more missing teeth (and alternative procedures are difficult or impossible) and particularly in cases of extreme vertical/horizontal bone defects in the alveolar ridge. By understanding the properties of titanium mesh and how it compares with other membrane barriers, surgeons can provide their patients with the best alternatives for bone grafting and subsequent dental implant success.
Physical Properties of Titanium Mesh
For over 50 years, titanium has been used for various surgical procedures because of its good mechanical strength and firmness, low density/weight, and resistance to high temperatures and corrosion. Its corrosion resis- tance is due mainly to its ability to produce a protective oxide layer via passivation.13–15 The strength and rigidity of titanium mesh allows it to create and maintain sufficient space for bone regeneration in an alveolar bone defect while also protecting bone grafts from encroachment pressures from the surrounding soft tissues.16 At the same time, it is sufficiently malleable and widely avail- able in different thicknesses (0.01–0.06 mm) to cover bone defects of various sizes and locations.7,8 Membrane thickness (generally 100–200 μm to balance strength and plasticity and to avoid membrane exposure) appears to affect the quantity of restored bone, while membrane porosity affects bone quality via free migration of blood and bone cells and the occlusion of soft tissue cells. While pores also appear to help prevent membrane exposure, determining optimal pore size regarding cell migration/ occlusion in titanium mesh for bone regeneration has remained elusive.2,20,21 GBR with titanium mesh reliably produces horizontal and vertical bone augmentation whether implants are placed at the same time as the bone grafts, or in a delayed procedure. Titanium mesh has very rarely been shown to lead to bone resorption caused by infection
Titanium Mesh and Barrier Membranes
Barrier membranes used with GBR are classified into resorbable and nonresorbable categories. The premier membranes in each category are the resorbable collagen membrane and the nonresorbable expanded polytetra- fluoroethylene (ePTFE), titanium-reinforced PTFE, and titanium mesh membranes. Because of their absorp- tion/degradation rates, enhanced collagen membranes generally do not preserve the space surrounding a bone defect to sufficiently prevent cell migration/occlusion and often require bone pins (see chapter 14), bone plates (see chapters 15 and 16), the adjacent root eminences, tenting screws, or titanium mesh (as described in the following section) to prop them up. As a result, there is often more significant vertical bone gain where titanium mesh is used due to its combined moldability and structural shape- holding properties when compared with collagen, PTFE, or other membranes alone (although some studies have found no significant differences). Unlike resorbable and other nonresorbable membranes, titanium mesh does not promote restoration site infection, probably due to its bacteria-resistant density and surface characteristics and a pseudoperiosteum layer of tissue that often forms beneath it, which insulates the augmented bone.
Some disadvantages of titanium mesh include the need to remove it at a future stage of treatment, along with any nonresorbable fixation devices, necessarily introducing the potential for additional trauma at the restoration/implant site. The rigidity of titanium presents other drawbacks; for example, shaping a membrane to fit the bone defect can be a clinically challenging task, and sharp edges from the membrane may result in soft tissue tears and lead to mesh exposure caused by the membrane’s protruding edges. However, such exposure (particularly when it occurs late in the healing process) generally does not lead to infection like it does with PTFE membranes, which require timely removal. Titanium mesh may require removal only when exposed in the early weeks after the initial procedure.
Protocols for Using Titanium Mesh Membranes for Bone Grafting
Standard perioperative clinical procedures should be followed to achieve successful bone grafting with titanium mesh. The patient’s general condition should be evaluated, along with the site(s) for the operative procedure; antibi- otic and site disinfection regimens should be followed before and after the procedure, along with maintenance of sterile conditions in the area of operation. Surgical flaps should be employed to ensure sufficient blood supply and proper closure.
The clinician should firmly affix the titanium mesh by placing fixation screws at the corners to keep it tented up into the designated shape and to prevent any movement and the potential for subsequent perforation of the membrane edges into the overlying soft tissue and possible exposure. The titanium mesh should also be bioactively coated or covered with freeze-dried bone allograft (FDBA) or a thick membrane to promote bone regeneration and minimize overlying soft tissue perforation prior to buccal periosteal release and tension-free closure with deep mattress and single interrupted sutures. Detailed postoperative instructions for oral care should be provided to the patient. The last 25 years of using titanium mesh for dental implants include bone grafting or bone regeneration with immediate or delayed implant placement, usually depending on the severity of the horizontal or vertical bone defect in the future implant site
Immediate implant placement
Combining bone grafting with titanium mesh and immediate implant placement offers a number of clear advantages, including avoidance of the additional time, cost, and trauma associated with secondary procedures, with apparently no significant differences in desired outcomes compared with delayed implant placement.40 Crucial for immediate implant placement success are patient case selection (minimal horizontal/vertical defects and minimal bone dehiscences/fenestrations) and choice of grafting material (autogenous particulate bone, FDBA allografts). Mild to moderate, single-direction bone defects appear to yield the best results16,26,28,29,41 (Fig 17-1).
Delayed implant placement
Delayed implant placement with bone grafting and titanium mesh appears to be more common among bone regeneration case studies due to the procedure’s reliable osteogenic effects to optimize ideal implant placement, particularly in cases with widespread single-direction bone defects, despite the increased instances of membrane exposure in many cases
In addition to applications for vertical and horizontal reconstruction of severe bone defects in the alveolar ridge44 (Fig 17-2), delayed implant procedures with bone grafting and titanium mesh extend adjunctive bone augmentation procedures such as onlay bone grafting45,46 (Fig 17-3). Such cases employ autogenous bone onlay grafting in conjunction with particulate autogenous bone to add vertical and horizontal volume before application of the titanium mesh to stabilize and protect future sites of implantation. Generally, less autogenous bone onlay grafting is required in such cases, showing that bone grafting and titanium mesh procedures can be used when prior onlay grafting has failed
Bone Graft Materials with Titanium Mesh
Bone graft materials for GBR with titanium mesh membranes most often include particulate forms of autogenous bone (Fig 17-4) or FDBA allografts because these materials’ bone regeneration properties (osteoin- duction and osteogenesis) can initiate and then facilitate a complete filling-in of the asymmetric spaces of bone defects beneath the titanium mesh. While autogenous bone particulates are often still consid- ered the gold standard for bone regeneration procedures,many clinicians opt to use FDBA allografts or a combination of both materials9–12,20,21,24,28,29,49–54 (Fig 17-5). Another alternative to autogenous bone grafts is the use of osteoinductive recombinant human bone morphogenetic proteins (rhBMPs) carried on an absorbable collagen sponge (ACS) in conjunction with autogenous bone (Fig 17-6) or FDBA allografts55–62 (Fig 17-7).
Fixation of Titanium Mesh
Sturdy fixation of the titanium mesh to the alveolar bone graft can facilitate blood clot formation, which can other- wise be adversely affected by micromotion and a corre- sponding disturbance of proper migration of healing cells. The titanium mesh’s tight fixation, with adequate numbers and proper placement of titanium fixation screws, appears to promote an occlusive effect on connective tissues.20,21,63 Titanium fixation screws remain the optimal choice for the stabilization of titanium mesh to prevent movement and to maintain its tented shape, though various methods have been used to fixate titanium mesh to recipient bone depending on the size of the bone defect and whether an immediate or delayed protocol is used for placing implants. Methods have included absorbable sutures (single tooth, immediate placement),64 titanium pins and tacks (single/multiple teeth, delayed placement56,65; see Fig 17-7), and even implant cover screws16 (see Fig 17-1).
Healing Complications Associated with Titanium Mesh
Healing complications associated with titanium mesh include wound dehiscence and subsequent titanium mesh exposure (early and late) due mainly to the manual shaping of the rigid titanium membranes, whose sharp edges often pierce mucosal flaps.7,8 Because of the risk of fibrous tissue proliferation and reduced bone formation, the clinician should remove any membrane exposed in the first several weeks following the proce- dure and treat the patient for infection.20,21 Though soft tissues often form beneath the porous structure of the titanium mesh membrane, efforts to counter such growth by placing an absorbable collagen membrane over the mesh have proven unsuccessful.66,67 However, covering the sharp edges with sticky bone or hydrated FDBA, when possible, significantly decreases the risk of soft tissue perforation.
The effects of membrane exposure after the first several weeks are less concerning, and studies report acceptable rates of bone resorption and reduced risks of infection (though infection protocols should nonethe- less be followed).31,68 Rough edges of the membrane can be tidied. Still, the mesh should remain in place because a pseudoperiosteum layer will have formed beneath the mesh by this time, preventing it from causing serious bone resorption or infection
Future Application of Titanium Mesh Membranes with GBR
In addition to the advancements in CBCT imaging technol- ogies and the developments in digital manufacturing of preformed titanium mesh membranes enabled by those technologies, clinicians can hope for further progress in bioactive and similar coating techniques for titanium mesh membrane surfaces to facilitate the bone regeneration process. The most widely used and studied adjunctive therapies for titanium mesh membranes are concentrated growth factors, including platelet-rich plasma (PRP) membranes, which, when layered between the titanium mesh and the gingival tissues in the defect area, promote angiogenesis and the differentiation of fibroblasts (Fig 17-8). This not only decreases inflammation and speeds healing of gingival tissues but also shields the titanium mesh and the bone grafts it covers. 
Conclusion
To use titanium mesh effectively for bone grafting in preparation for dental implants, clinicians must recognize the unique mechanical features of these nonresorbable “membranes,” how they differ completely from barrier membranes, their typical clinical use, and what the future holds. Bone graft success rates have been increased by the effective use of titanium mesh in various clinical cases because of its biocompatibility and mechanical charac- teristics, extending surgeons’ decades-long reliance on them to restore and prepare alveolar ridges as sites for dental implant.
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