This is a case report describing a 35-year-old woman who had had an expanded polytetrafluoroethylene chin implant inserted 13 years previously through an intraoral incision. She complained of pain in her chin and lower anterior teeth. A cephalogram showed severe bone erosion and upward displacement of the implant. The patient underwent removal of the chin implant and at surgery, >5mm bone erosion of the labial cortex was found beneath the chin implant and the implant was found to have become severely embedded in the chin bone. This patient had vertical maxillary excess and mandibular retrognathia and microgenia. There was noticeable chin dimpling caused by mentalis muscle hyperactivity when she tried to close her mouth at rest. The authors describe how an expanded polytetrafluoroethylene is usually considered a good choice for alloplastic chin augmentation with less bone resorption compared with a solid silicone implant. The authors propose that the severe bone resorption was due to mentalis muscle hyperactivity, rather than the implant material. Some bone resorption occurs with any alloplastic augmentation, but severe cases have been described in the literature involving impingement on dental roots and on the mental nerve. The authors advise that if a patient has labial incompetence and mentalis muscle hyperactivity caused by a dentofacial deformity, then chin alloplastic augmentation should be avoided and genioplasty should be considered instead. This paper contributes to the literature on complications of alloplastic facial implant augmentation and gives an indication that facial analysis and likely long-term effects of implant position on underlying bone must be taken into account before offering this option to patients.