Figure 4.

Defect classification according to an intra-operative assessment (adapted from Schwarz et al. [27]). Class 1a—facial view (a); Class 1a—occlusal view (b); Class 1b—buccal dehiscence + semicircular bone resorption to the middle of the implant body (c); Class 1c—buccal dehiscence + circular bone resorption with the lingual wall (d); Class 1d—circular bone resorption with lack of buccal and lingual walls (e); Class 1e—circular bone resorption with the presence of buccal and lingual wall; (f) Class 2: supra-crestal bone resorption.