Primary wound closure is difficult in the posterior mandible when insufficient soft tissue is available. Primary wound closure using a buccinator musculomucosal flap after implant placement and guided bone regeneration was performed in a patient with an atrophic alveolar ridge in the posterior mandible. Implants were placed at the bone level of neighboring teeth to protect the inferior alveolar nerve, and exposed threads were covered using guided bone regeneration. A posterior-based buccinator musculomucosal flap was raised and placed over the alveolar crest, which resulted in a satisfactory clinical outcome.