Aim: To describe a clinical case, a rare complication, in which two mandibular incisors became discoloured following bone harvesting for pre-implant augmentation. Summary: A 57-year-old woman was referred by her general dental practitioner regarding discolouration of her mandibular right central and lateral incisors. A segmental osteotomy was performed in the vicinity of these incisors about 4 weeks previously to harvest bone, which was grafted to provide support for the placement of an implant to replace the missing maxillary right canine. Although both incisors were symptom-free, they were non-responsive to sensitivity tests. Non-surgical root canal treatment was carried out to both of these non-vital teeth, followed by intracoronal bleaching to improve their colour. Key learning points: 1. Pre-implant bone grafting procedures may risk disrupting the blood supply of teeth situated close to the harvesting site. 2. If the blood supply of teeth is compromised, this may lead to loss of vitality and tooth discolouration. 3. The length, morphology and position of the roots of teeth should be carefully evaluated using periapical radiographs, and if necessary, tomographic imaging techniques to avoid this iatrogenic sequelae. 4. The consequences of loss of vitality and tooth discolouration are managed conservatively by root canal treatment and internal bleaching. Keywords: bone augmentation, bone grafts, root canal treatment, surgical complications, tooth bleaching, tooth discolouration