Purpose: To define the role played by a suspended external-internal (SEI) suture in reducing marginal flap tension after bone augmentation in the maxilla and in enhancing primary wound healing. Materials and Methods: Twenty partially edentulous patients requiring bone augmentation (either guided bone regeneration or autogenous bone block placement) before or simultaneous with implant insertion in the maxilla were enrolled in this clinical prospective cohort study. Flap tension was measured by a dynamometer, which was accurate to within 1 g. The force recorded was that needed to enable the vestibular extensible flap to reach the edge of the palatal nonextensible flap. Flap tension was recorded after the periosteum-releasing incision was made (before application of any suture; T1), and after the SEI suture was applied (T2). Final marginal flap adaptation was accomplished via horizontal mattress sutures and simple stitches. Wound healing was monitored at 1, 2, 4, and 16 weeks and classified as "obtained primary closure" or "compromised" as a result of dehiscence or marginal flap necrosis. Results: The mean flap tension measured at T1 was 32.9 ± 7.7 g. After the SEI suture was applied, the mean marginal flap tension decreased to 4.1 ± 1.5 g. The marginal flap tension was reduced by 87.6% compared to the initial strain. All patients healed uneventfully, and no complications such as dehiscences or marginal flap necrosis were recorded. Conclusion: The application of the SEI suture reduced the tension on the margins of the flaps and played a decisive role in obtaining primary wound healing. In case of passive wound closure (strain 5 g), the type of augmentation procedure (guided bone regeneration or autogenous block) was revealed to have no impact on the quality of wound healing. Keywords: bone augmentation, internal suture, primary wound closure, wound dehiscence