Introduction Collagraft® has been widely used in orthopaedic since 1993 as a bone substitute both alone (osteoconductive) and with autogenous bone marrow (osteoinducive). It is a combination of purified bovine dermal fibrillar collagen with approximately 65% hydroxyapatite and 35% tricalcium phosphate. In this study its use in the management of large odontogenic cysts is reviewed. The cases have a here possibility of pathological fracture in the perioerartive period or delayed healing with bone cavity due to intraoral wound dehiscence occurs. Its use avoids bone harvest operative sites or the use of autograft. Collagraft® is presented in strips measuring 45 x 10 x 3 mm and is packaged in boxes of three or six strips. The packaging includes a well for the collection of autologous blood to constitute the strips prior to use. See figure 1. Materials and Method All the patients presented with odontogenic mandibular cyst which when enucleated resulted in significant bone cavities often in edentate areas. The patients were at risk from delayed healing and pathological fracture. All cysts were enucleated under general anaesthesia. Collagraft® was used to fill the surgical defect after being hydrated in autologous blood harvested from patient just prior to use. See figure 2. Wound closure by continuous suture using 3/0 Vicyl. Periooperative antibiotics were given a loading dose followed by a five day course. Good oral hygiene was encouraged supported by the use of chlorhexadine mouthwash. See figure 3 for results. Radiographs were obtained preoperatively, one day postoperative and three months postoperative. See figure 4. Conclusion Collagraft® is a useful addition to the materials available as a bone substitute in management of bone defects in Oral and Maxillofacial surgery. We have used Collagraft® in cases of mandibular odontogenic cyst management. All the patients had a significant cyst cavity which would have been slow to heal if solely enucleated and was considered for bone grafting technique. Collagraft® was easy to handle and resulted in good healing with minimal complications. Two cases had small wound dehiscence and extrusion of graft material. The defects healed uneventfully good oral hygiene was maintained and an extended curse of antibiotics was prescribed (Penicillin 250mg one week course). A Study of the use of ‘Collagraft’® in the Repair of Mandibular Bone Defects Following Enucleation of Odontogenic Cysts Davidson M.J.C., Davidson F.C., Pilcher R. Department of Oral and Maxillofacial Surgery, Taunton and Somerset Hospital. UK PatientSex / AgeApproximate volume Pathological Complications of Collagraft diagnosis of cyst used in cc M.S.  6110Dentigerous cyst 38 None J.P  505Dentigerous cyst 48None E.R.  638Dentigerous cyst 38None J.H  583Dentigerous cyst 38None P.R  453Dentigerous cyst 48Small wound dehiscence J.C.  506Dentigerous cyst 48Small wound dehiscence G.H  294Dentigerous cyst 38None G.D  754Recurrent keratocystNone Results Figure 1. Presentation of Collagraft® Figure 2. Operative sequence of enucleation of cyst & use of Collagraft® Collagraft ® registered trademark Zimmer Inc Figure 4. Radiographic sequence of cyst enucleation. 1- preoperative, 2- immediate post-operative, 3 - Three months post-operative Figure 3.