This lecture, presented by Dr. George Anastasov, Maxillofacial Surgeon, provides a comprehensive overview of techniques for the reconstruction of the severely atrophic mandible tailored for dental implantology. Dr. Anastasov outlines the primary goals of reconstruction (restoring form, function, and occlusion) and the causes of defects (age-related atrophy, trauma, malignancy, osteonecrosis). He emphasizes a systematic evaluation process, including assessing soft tissue viability, and detailing a treatment algorithm based on bone availability and local donor sites. The core of the presentation compares and contrasts various autogenous bone graft donor sites—including local sites (symphysis, extended ramus-coronoid process), calvarium, rib, iliac crest (the optimal source for volume), and tibial plateau—listing their advantages, morbidity, and ideal applications. The presentation concludes by advocating for the use of high-definition imaging (CBCT) and adjunct techniques like Platelet-Rich Plasma (PRP) to maximize bone graft consolidation and long-term restorative predictability.
Reconstruction of the Atrophic Mandible for Dental Implantology
0:16 Goals of Reconstruction: The primary goals for treating severe mandibular atrophy include restoring continuity, shape, form, lower facial contour, optimal occlusion, and masticatory function, aiming to return the patient to their pre-morbid state.
4:28 Causes of Defects: Defects are most frequently age-related (due to periodontal disease and tooth loss), but can also be congenital, infectious (osteomyelitis, ONJ), traumatic (gunshot wounds), or neoplastic/post-radiation.
6:05 Evaluation and Timing: Evaluation must assess soft tissue (vascular supply, scarring, contamination) and hard tissue (size and location of the defect). Key Takeaway: If salivary contamination is present, a composite vascularized bone graft is preferred; if contamination is minor/absent, a free bone graft may be used.
7:57 Reconstruction Options: Options range from titanium gap bridging plates (for immediate temporary bridging or compromised patients) to various bone grafts (autogenous being preferred) and vascularized bone flaps (fibula, iliac crest, scapula) for large, complex, or compromised defects.
12:02 Principles of Grafting (Two-Phase Theory): Success depends on the quality of the autograft (viable osteocompetent cells) and the recipient site’s vascularization. Phase 1 (Day 1 – Week 4) involves initiation by transplanted osteocytes; Phase 2 (starts at Week 2, continues indefinitely) involves consolidation through capillary ingrowth, oxygenation, and remodeling based on functional load.
16:26 Predictability and Longevity: Treatment planning must prioritize maximizing the predictability and longevity of the restoration while minimizing complications, duration, and cost.
21:45 Imaging Necessity: High-quality imaging is essential; Cone Beam CT (CBCT) is highlighted as optimal due to its high definition, precise anatomic data, and low radiation dose compared to medical CT.
24:31 Local Donor Sites: For limited defects, local sites like the mandibular symphysis and ramus are favored. Dr. Anastasov highlights the Extended Ramus Coronoid Process Graft (28:42), which provides a large volume of bone for reconstruction without requiring extra-oral donor sites.
30:21 Calvarial Grafts: The parietal bone is a decent option, especially for onlay grafting, offering minimal donor site pain and high resistance to infection/resorption, but the bone is rigid and less cancellous.
40:00 Iliac Crest Grafts (Optimal Source): The iliac crest is considered the best source for free bone grafts due to its large volume and abundant cortical/cancellous bone. Posterior harvest yields 100-120 cc, but anterior harvest may limit cosmetic deformity. Case Example (42:52): Using an allogenic cadaveric mandibular crib filled with hip graft to drastically increase height.
47:50 Tibial Plateau Grafts: Provides a good source of cancellous bone chips (up to 40 cc) with low morbidity, but aggressive harvest risks tibial plateau fractures.
51:03 Adjunctive Techniques (PRP): Platelet-Rich Plasma (PRP) is highly recommended for accelerating healing and increasing graft density (up to 10-40%) by providing concentrated growth factors (PDGF, TGF-β) and stimulating angiogenesis and stem cell proliferation.
57:37 Final Goals: Successful dental rehabilitation requires restoring adequate occlusal relationships, ensuring sufficient masticatory force and stable restorations, promoting oral hygiene, and restoring the patient's self-esteem and identity (e.g., adequate lip support).