Parmar PD, et al. - Using 2-dimensional (2D) and 3-dimensional (3D) imaging techniques, authors investigated 32 candidates to examine the consequence of collagen membrane on the healing of through-and-through periapical lesions. They calculated 2D healing according to Molven's criteria whereas 3D healing was evaluated using modified PENN 3D criteria, RAC indices and the B index, 12 months after surgery. A significant reduction in the size of lesions [92 ± 12% (control) and 86 ± 14% (GTR) in 2D and 85 ± 19% (Control) and 82 ± 13% (GTR) in 3D] was noticed. They found periapical surgery with or without GTR predictable and viable for through-and-through lesions with no advantage of using a collagen membrane. They suggested both cone beam computed tomography (CBCT) and periapical radiographs (PA) comparable in assessing the healing after periapical surgery.