Purpose: The aim of this retrospective study was to compare long-term (≥ 5 years) outcomes of implants placed in patients treated for chronic periodontitis versus those placed in periodontally healthy patients. In both groups, the implants were placed in alveolar ridges that were laterally augmented with autogenous bone block grafts using a split bone block technique. Materials and Methods: Two hundred ninety-two patients were screened in the course of supportive periodontal treatment examinations. Nonsmoking patients without any severe systemic diseases who had adhered to regular supportive periodontal treatment for a minimum of 5 years after undergoing autogenous lateral grafting (using the split bone block technique), implant placement, and prosthetic reconstructions were classified into two groups based on their presurgical status: periodontally healthy patients (PHP) and periodontally compromised patients (PCP). Results: Clinical outcomes for 77 patients, 38 PHP and 39 PCP, were examined. All had been successfully treated for severe lateral atrophy and received a total of 241 endosseous implants between 2002 and 2008. At the final examination, mean bleeding on probing was 7.08% ± 7.27% in PHP and 14.49% ± 18.14% in PCP, a statistically significant difference. Significantly higher Plaque Index and more recession were associated with a narrow ( 2 mm) width of keratinized mucosa. Conclusion: Implants in alveolar ridges laterally augmented using a split bone block technique revealed similar clinical peri-implant conditions in both PHP and PCP. Using autogenous bone block grafts without biomaterials resulted in long-term peri-implant tissue stability. Schlagwörter: autogenous bone augmentation, CIST, lateral augmentation, peri-implant disease, periodontally compromised patients, split bone block grafting