Tehran University of Medical Sciences Journal of Craniomaxillofacial Research 2345-5489 4 3 2017 10 08 406 409 EN Mehran Bahrami Dental Research Center, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. Roya Hashemi Dentist. Seyed Mehran Falahchai Dental Research Center, Department of Prosthodontics, Tehran University of Medical Sciences, Tehran, Iran. 2017 10 07 2017 10 07 Prosthetic rehabilitation of patients with unfavorable-implant-position or problematic implant angulation is complicated. A completely-edentulous-patient with lower lip squamous-cell-carcinoma had undergone resective surgery twice. After radiotherapy of a total dose of 60cGy of 30 sessions for about 3 months, moderate trismus was developed. Mouth commisurotomy was accomplished in order to insert three implants in the mandibular-anterior-region. Two distal implants were excessively tilted to achieve better biomechanical advantages and to obtain greater anterior-posterior- distance which made prosthetic rehabilitation of the patient challenging. In the mandibular-custom-tray a lingual “window” was designed to accommodate the open-impression-copings. Trial-denture-bases were tried-in. A putty index was recorded from arranged-mandibular-teeth. According to this index, a zigzag bar similar to letter “M” was designed using custom abutments. So that three ball anchors were placed on this “M-designed-bar” (MDB) more labial than the inserted implants to support the mandibular-implant-supported-overdenture. Using MDB permits teeth-set-up with minimal interfere with tongue function. The major disadvantage of this design is its inevitable-buccal-cantilever. Distolingual areas of mandibular tray were border-molded excessively in order to overcome this problem and to increase stability and also to reduce detrimental-lateral forces to implants. Key words: Dental Implants, Implant-Supported Denture Prosthesis. https://jcr.tums.ac.ir/index.php/jcr/article/view/174 https://jcr.tums.ac.ir/index.php/jcr/article/download/174/191