Peri-implant bone histology plays a crucial role in understanding the mechanisms underlying implant failure. This article presents a case report of a failed dental implant in a 72-year-old male patient, with a focus on the histological evaluation of the peri-implant bone. The patient underwent an All-in-4 implant-based denture treatment plan, which initially showed promising results but later resulted in implant failure. A trephine core biopsy was performed to assess the histology of the failed implant site and determine the cause of failure at the microscopic level. Histological analysis revealed the presence of graft material acting as a scaffold, surrounded by dense fibrosis and chronic inflammatory infiltrate. These findings indicate a failure of osseointegration and suggest possible causes for implant failure, such as inadequate tissue integration and host response. Factors contributing to implant failure, including occlusal overload, peri-implantitis, and systemic conditions, were discussed in the context of the case. Understanding the histological changes associated with implant failure is crucial for improving treatment outcomes and developing preventive strategies. Preoperative assessment, including evaluation of bone density and identification of systemic risk factors, is essential for successful implant placement. Retrieval and histological analysis of failed implants provide valuable insights into tissue responses and areas for improvement in implant design and surgical techniques. This case report highlights the significance of peri-implant bone histology in diagnosing and managing implant failure, with implications for enhancing implant success rates and patient care in implant dentistry. Further research in this field will contribute to advancements in implantology and the development of evidence-based protocols for implant treatment.