The Association Between Dental Implant and Bone Graft Failure and the Levels of Vitamin D and LDL Cholesterol: Retrospective Clinical Study

Background/Objectives: Dental implant and guided bone regeneration (GBR) procedures rely on successful bone healing and remodeling. Systemic metabolic factors, including vitamin D deficiency and elevated low-density lipoprotein cholesterol (LDL-C), may adversely affect osseointegration and bone regeneration. This study aimed to investigate the association between implant/GBR failure and serum vitamin D and LDL-C levels. Methods: A retrospective clinical study was conducted on 40 patients treated with dental implants and/or GBR procedures between 2023 and 2025 in the Eastern Province of Saudi Arabia. Twenty patients with failed outcomes and twenty patients with successful outcomes were included. Smokers, immunocompromised patients, individuals with a history of radiotherapy or chemotherapy, and patients with uncontrolled diabetes mellitus (HbA1c > 6.5%) were excluded. Failure was defined as progressive bone loss, loss of osseointegration, implant mobility, graft resorption, or persistent infection and was categorized as early or late failure. Serum vitamin D and LDL-C levels were obtained after treatment and analyzed using bivariate and exploratory multinomial logistic regression analyses. Results: Significant differences in serum vitamin D and LDL-C levels were observed among failure groups. Mean vitamin D levels were highest in the non-failure group (91.3 ± 47.9 nmol/L), followed by early failure (53.3 ± 33.7 nmol/L) and late failure (28.3 ± 11.3 nmol/L) (p = 0.001). Mean LDL-C levels increased progressively from the non-failure group (107.0 ± 26.8 mg/dL) to early failure (137.6 ± 47.3 mg/dL) and late failure groups (161.3 ± 57.0 mg/dL) (p = 0.003). Vitamin D status and LDL-C category were significantly associated with failure type (p = 0.001 and p = 0.012, respectively). Conclusions: Lower serum vitamin D levels and higher LDL-C levels were associated with implant and GBR failure, particularly in late failure cases. However, because serum vitamin D and LDL-C levels were measured after treatment outcomes and the study was limited by its retrospective design and relatively small sample size, these findings should be interpreted with caution and do not establish a causal relationship. Larger prospective studies are needed to determine whether preoperative assessment and optimization of vitamin D and lipid status may improve implant and regenerative treatment outcomes.