This randomized controlled clinical trial evaluated the effectiveness of platelet-rich fibrin (PRF) and a simvastatin/PRF composite combined with a xenogeneic bone graft during alveolar ridge splitting with simultaneous implant placement in patients with horizontal alveolar ridge deficiency. Twenty-one participants were randomly allocated into three groups: a control group receiving xenogeneic bone graft alone, a PRF group receiving xenogeneic bone graft blended with PRF, and a simvastatin/PRF group receiving xenogeneic bone graft blended with a simvastatin/PRF composite. Clinical and radiographic outcomes were assessed to compare horizontal and vertical bone gain, bone density, and keratinized tissue width after treatment.