Bone matrix derived from mandibular periosteal cells and cultivated by tissue engineering on a polymer fleece has recently been used for sinus floor elevation and augmentation. This case report focuses on clinical and histologic results after lateral ridge augmentation of a localized non-space-maintaining defect in the right posterior area of the mandible using tissue-engineered bone. Implant-supported prosthetic rehabilitation of a partially edentulous 32-year-old woman was planned involving a fixed partial denture. Preoperative investigations revealed a transversely reduced alveolar ridge width on the right side of the posterior mandible. Lateral augmentation was performed using tissue-engineered bone obtained by autogenous periosteum cells from the same area. Six months after augmentation 2 implants were placed and a bone biopsy was obtained from the augmented area. Transverse ridge dimensions were found to be enhanced. Histologic examination of the biopsy revealed dense lamellar bone. Wound healing was uneventful after all surgical interventions. This case report demonstrates the successful clinical application of tissue-engineered bone for lateral augmentation of the transversely reduced alveolar ridge. The results suggest that periosteum-derived tissue-engineered bone can be used to create a sufficient implant site not only for the sinus floor elevation and augmentation procedure for vertical bone enhancement but also for lateral augmentation. Schlagwörter: alveolar ridge augmentation, bone biopsy, dental implants, tissue engineering