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Defended by Ahmad Moustapha DIALLO on 13-10-2020

Thesis directors: Fani ANAGNOSTOU, Henri Michel BENOIST

Thesis in co-tutelle with the University CHEIKH ANTA DIOP, Dakar, Senegal


Oro-facial bone loss is a major problem in oral and maxillofacial rehabilitation. They have various and varied causes: cancer, cysts, cleft palates, infections or trauma. The management of such bone defects requires the use of bone grafts. Autogenous bone or autograft is the standard gold but has disadvantages: i) the need for a second surgical site, ii) morbidity, iii) increased operating time, iv) limited amount of bone to be removed. To overcome these pitfalls, alternative therapeutics to bone autograft are used, in particular bone substitutes derived from human (bone allografts), animal (xenografts) or synthetic (alloplastic) bone tissue. Bone allografts are a credible alternative to autografts and are nowaday widely used in reconstructive and regenerative surgery. These allografts are either mineralized (FDBA: Freeze-Dried Bone Allograft) or demineralized (DFDBA: Demineralized Freeze-Dried Bone Allograft) and come in powder or gel form depending on the support used in the case of DBM (Demineralized Bone Matrix). This PhD project aims to show the osteoformative potential of a new bone allograft formulation, partially demineralized as an injectable paste, in two different models for rat calvaria; it is a PDBM (Partially Demineralized Bone Matrix).
The 1st model is the rat calvarial defect model. Critical size defects (8 mm diameter) and sub-critical size defects (6 mm and 4 mm diameter) are performed on rat calvaria and then left empty or filled with the PDBM. Micro sacnner (μCT) and histological results showed the positive effect of PDBM in the bone repair of 6 and 8 mm diameter defects. Similarly, molecular biology (RT-PCR) showed the positive effect of PDBM in the early expression of genes involved in osteoformation.
The 2nd model is a vertical bone augmentation model. A bone chamber (custom-made cylinder of Polyetheretherketone) of 6 mm high and 5 mm in diameter is attached to the rat calvarias after perforating it with 3 small holes 1 mm in diameter. The bone chambers are filled with either PDBM or Bio-Oss®. The μCT and histological results revealed an osteoformative potential for PDBM in the bone chambers.
These results support the idea that bone allografts are a viable option for the treatment of periodontal and maxillofacial defects.

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