Aim: This study aimed to clinically and radiographically evaluate the efficacy, predictability, and safety of combining a customized three-dimensional (3D) printed titanium mesh with a 'sticky bone' composite graft (particulate xenograft and Platelet-Rich Fibrin) for complex vertical and horizontal alveolar ridge augmentation in the posterior mandible, concurrent with dental implant placement. Patients and Methods: Eight systemically healthy patients (three males, five females, aged 34-65) presenting with severe atrophy of the posterior mandibular alveolar ridge were enrolled. A full digital workflow was employed, starting with Cone-Beam Computed Tomography (CBCT) to digitally plan the augmentation and design the patient-specific 3D titanium mesh. The surgical procedure involved full-thickness flap reflection, simultaneous placement of dental implants (n=16), stabilization of the customized mesh over the defect, and filling the space with a 'sticky bone' graft. Flap primary closure was achieved with tension-free suturing. Clinical assessment, post-operative pain (VAS), and radiographic evaluation (CBCT) for dimensional changes in height and width were performed over a 6-month period, after which the meshes were removed. Results: All surgical sites healed uneventfully, demonstrating a 100% implant and augmentation survival rate at 6 months. Postoperative radiographic analysis confirmed a highly significant increase in both dimensions: the mean alveolar ridge height increased by 47.1% ± 12.4% (p < 0.001), and the mean alveolar ridge width increased by 155.4% ± 62.1% (p < 0.001). The customized meshes exhibited excellent adaptation, with a mean deviation of only $0.3371 pm 0.1760 mm. Minimal, transient soft tissue dehiscence was observed in two cases, with no mesh exposure noted at the 6-month follow-up. Conclusion: The digital workflow utilizing a customized 3D titanium mesh in conjunction with a sticky bone graft is a highly effective, precise, and predictable technique for achieving significant vertical and horizontal augmentation of the severely atrophied posterior mandibular alveolar ridge, thereby ensuring a favorable and stable foundation for dental implant placement.