FIGURE 3.

Bone defects classification: (A) Class 1: ideal alveolar bone condition: implants can be placed in an ideal, restoration-driven location without augmenting the volume of alveolar ridge. Although soft tissue grafts are sometimes recommended; (B) Class 2: a moderate horizontal atrophy: a dehiscence or a fenestration of the buccal plate is present. Implants are placed combined with hard tissue augmentation procedures; (C) Class 3: large degree of horizontal defects: residual alveolar ridge allows for a two-stage implant placement. Sufficient bone graft volume and adequate healing time are indispensable; (D) Class 4: severe atrophy on height and width: the remaining alveolar bone is in poor condition and there are commonly two alternatives: (i) onlay bone grafting; (ii) GBR with autogenous particulate bone and/or xenogeneic bone using Ti mesh.