Articles - Forum Implantologicum

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Feature Article

Nov 18, 2021 // 19 min read

An Update on Vertical Bone Augmentation

Abstract

Several techniques have been reported to obtain vertical bone gains, such as guided bone regeneration, distraction osteogenesis, onlay block grafts, interpositional grafts and the use of titanium mesh. According to the ITI SAC Classification (Dawson et al. 2021), these techniques are considered to be advanced to complex level procedures, and technique-sensitive to the experience of the operator. To date there is no technique that clearly provides better outcomes than others. However, there is a consensus in the literature that smaller augmentations are more predictable to obtain and are less invasive.

Our purpose is to present an update of the currently used surgical techniques for vertical ridge augmentation, and a rationale for assisting clinicians in choosing the most appropriate technique for a specific situation.

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Introduction

Bone augmentation techniques are widely used in preparation for or in conjunction with dental implant placement. In order to be successful, many technical and biological aspects have to be considered. Bone regeneration primarily depends on an adequate vascular supply to deliver cells that will ultimately produce bone and regenerate the defect. The regenerated bone volume should allow placement of a dental implant in the preferred position to support a prosthesis under loading conditions and provide long-term function.

Cordaro and Terheyden (2014) stated that the ideal ridge augmentation material should maintain the contour of the dimensions being reconstructed while keeping space for bone formation, provide osteogenic potential, optimize vascular supply and remain stable over the healing time.

The vascular supply for bone regeneration primarily originates from the surrounding bone walls. Hence, the morphology of the defect can directly influence the choice of technique, material, and the outcome of a vertical augmentation procedure. Stability of the graft, prevention of soft tissue ingrowth, maintained soft tissue coverage, adequate healing time and infection control are also very important factors for success (Lundgren & Sennerby 2008).

When discussing vertical bone augmentation, it is important to make a distinction between intrabony defects inside the bone contour or extrabony defects outside the bone contour. The challenge is greater when there is a need for vertical bone augmentation outside of the osseous boundaries. There is an increased distance from the basal bone with a lack of osseous walls for graft containment. It is also more difficult to achieve and maintain graft stability. The soft tissue flap must be mobilized and advanced to attain primary closure over the graft site and at the same time maintain an optimal vascular supply (Urban et al. 2018). In addition, the remaining basal bone is mainly composed of dense and more poorly vascularized cortical bone.

Simultaneous implant placement and bone grafting versus a staged bone graft and late implant placement is also a point of discussion. As a rule, a minimum of 4 mm of apical bone height is needed to achieve good primary stability of the implant. If an 8-mm-long implant is planned, there may be a need for a smaller bone augmentation. Simultaneous bone grafting of up to 4 mm can be attempted using the GBR technique using the implant as a tent-pole. However, there is greater risk when attempting bone augmentation with simultaneous dental implant placement. If there is a complication during healing or the bone regeneration is incomplete, the implants may heal with marginal bone loss and exposed threads. When less than 4 mm of bone height is available, bone augmentation is performed as a staged procedure.

For the purposes of this review, we will address the techniques for vertical augmentation outside of the alveolar bone envelope, performed in a staged approach.

Fig. 1a: Clinical preoperative view showing posterior mandible vertical deficiency. Free gingival grafts were performed before bone grafting to improve the condition of the soft tissue

Fig. 1b: Preoperatory panoramic view, vertical deficiency on posterior mandible

Fig. 1c: Intraoperative view, flap mobilization and bone exposure

Fig. 1d: Autogenous particulate graft scraped from mandible + DBBM (75/25 ratio) with non-resorbable titanium-reinforced membrane prepared to cover the defect

Fig. 1e: Non-resorbable E-PTFE membrane with titanium reinforcement covering the graft, stabilized with tacks and titanium screws

Fig. 1f: Intraoperative view of implant placement, 6 months after grafting

Fig. 1g: Occlusal view of two implants placed (Straumann Tissue Level, SLA, 4.1 x 6 mm)

Fig. 1h: Periapical radiograph of final restoration showing adequate marginal bone level

Fig. 2a: Preoperatory view showing left posterior mandible vertical deficiency

Fig. 2b: Preoperatory panoramic radiograph

Fig. 2c: Preoperative CBCT cross section

Fig. 2e: CAD/CAM custom-made titanium mesh, buccal view

Fig. 2f: CAD/CAM titanium mesh with particulale autogenous + DBBM graft + PRF

Fig. 2g: Titanium mesh placed with bone graft, and screw-retained. Note adaptation of mesh

Fig. 2h: Titanium mesh covered with resorbable collagen membrane

Fig. 2i: PRF membranes applied over the resorbable membrane

Fig. 3a: Preoperatory panoramic view, vertical deficiency on posterior mandible

Fig 3b: Preoperative CBCT showing posterior mandible deficiency

Fig. 3c: Preoperative CBCT showing posterior mandible deficiency

Fig. 3d: Intraoperative view, flap mobilization decortication of host bed, ramus graft harvest site

Fig. 3e: Autogenous block graft, screw-retained to posterior mandible

Fig. 3f: Particulated autogenous chips + DBBM bone substitute packed around block. Collagen membrane prepared to cover graft

Fig. 3g: Double layer of collagen membrane covering graft

Fig. 3h: Postoperative radiograph showing graft integration 4 months after grafting

Fig. 3i: Postoperative radiograph after implants placed (Straumann TL, SLActive, 3.3 x 8 mm RN and 4.1 x 8 mm RN)

Fig. 3j: Final restorations, single crowns, screw-retained (restorations done by Dr. Dudu Pittas do Canto, Porto Alegre, Brazil)

Fig. 4a: Preoperatory view, showing anterior maxilla vertical deficiency, secondary to trauma

Fig. 4b: Preoperatory 3D CBCT view, showing vertical deficiency

Fig. 4e: Intraoperatory view, iliac crest block grafts for 3D reconstruction, including vertical block

Fig. 4f: CBCT crosscut, 5 months after grafting

Fig. 4g: Clinical view, buccal aspect, 5 months after grafting, pre-operatory of implant placement

Fig. 4h: Intraoperative view, buccal aspect, at implant placement (Straumann TE, 3.3 x 12 mm for central incisors, Straumann Narrow Neck 3.3 x 10 mm for lateral incisor)

Fig. 4i: Buccal view, final screw-retained restorations, 5 years after loading. Single crowns (restoration by Dr. Joao Emilio Roehe Neto, Porto Alegre, Brazil)

Fig. 4j-1: Periapical radiographs, 5 years after loading

Fig. 4j-2: Periapical radiographs, 5 years after loading

Fig. 5a: Preoperative buccal view. Note large vertical defect

Fig. 5b: Preoperative panoramic view. Note large vertical defect

Fig. 5c: Intraoperative view of extra-alveolar distraction device placed, movement and vector of the segment being checked

Fig. 5d: Panoramic view of vertically distracted segment, after completion of movement

Fig. 5e: Horizontal bone augmentation with ramus block graft, done at time of distractor removal, 3 months after end of distraction. Implants were placed 4 months after horizontal block grafting

Fig. 5f: Panoramic view with implants and provisional restoration

Fig. 6: Decision tree on extraosseous vertical bone augmentation: VBA (vertical bone augmentation); GB (guided bone regeneration); BG (block graft); TM (titanium mesh); IG (interpositional graft); DO (distraction osteogenesis); TR (titanium-reinforced); BS (bone substitute); d-PTFE (dense polytetrafluoroethylene); rhBMP-2 (recombinant human bone morphogenic protein-2)