Volumetric and linear assessment of maxillarymandibular and zygomatic bone as donor sites foralveolar ridge augmentation using cbct : a crosssectional stud / Aya Rabie Abdeltawab ; Mushira Mohamed Dahaba , Salma BelalEiid

Thesis (Ph.D)-Cairo University- Faculty of Oral and Dental Medicine - Department of Oral and Maxillofacial Radiology

Bibliography: p. 167-179.

Autogenous bone grafts remains the gold standard in the repair of alveolar atrophy and in bone defects reconstruction Intraoral bone grafts from the mandible and maxilla can be applied. The maxilla provides only small amounts of mainly cancellous autograph like zygomatic buttress and maxillary tuberosity. However, Mandibular bone grafts have been used for alveolar repair to allow implant placement with extremely favorable results in bothhorizontal and mainly vertical bone deficiency. Mandibular block can be harvested from the ramus, the mandibular symphysis, or edentoulous areas. The obvious advantages associated with intraoral harvesting includes: easy and convenient surgical accessibility, The close proximity of donor and recipient sites can reduce operative and anesthesia time, making them ideal for outpatient implant surgery, low rate of morbidity, decreased cost and not result in avisible scar. An important advantages in implant cases is that Autogenous graft obtained from intramembranous bone has been demonstrated to be more resistant to resorption than bone grafts obtained from endochondral bones i.e minimal resorbtion, good volume maintenance, and high concentration of bone morphogenetic proteins. CBCT imaging is a well-established radiographic modality in treatment planning for dental implants and for the individual patient has to be used primarily for presurgical planning and transfer to implant placement. The justification for CBCT use during the preoperative planning phase is based on the need for specific anatomic considerations, esthetic challenges in the anterior maxilla, insufficient bone volume, shape and quality, the use of more advanced surgical techniques and the integrated Autogenous bone grafts remains the gold standard in the repair of alveolar atrophy and in bone defects reconstruction Intraoral bone grafts from the mandible and maxilla can be applied.The maxilla provides only small amounts of mainly cancellous autograph like zygomatic buttress and maxillary tuberosity. However, Mandibular bone grafts have been used for alveolar repair to allow implant placement with extremely favorable results in bothhorizontal and mainly vertical bone deficiency. Mandibular block can be harvested from the ramus, the mandibular symphysis, or edentoulous areas. The obvious advantages associated with intraoral harvesting includes: easy and convenient surgical accessibility, The close proximity of donor and recipient sites can reduce operative and anesthesia time, making them ideal for outpatient implant surgery, low rate of morbidity, decreased cost and not result in avisible scar. An important advantages in implant cases is that Autogenous graft obtained from intramembranous bone has been demonstrated to be more resistant to resorption than bone grafts obtained from endochondral bones i.e minimal resorbtion, good volume maintenance, and high concentration of bone morphogenetic proteins. CBCT imaging is a well-established radiographic modality in treatment planning for dental implants and for the individual patient has to be used primarily for presurgical planning and transfer to implant placement. The justification for CBCT use during the preoperative planning phase is based on the need for specific anatomic considerations, esthetic challenges in the anterior maxilla, insufficient bone volume, shape and quality, the use of more advanced surgical techniques and the integrated presurgical planning and virtual patient approach. In our study, the planmeca promax 3D Mid machine were used to assess the four intraoral graft sites in-vivo using linear and volumetric measurements (manual or semi-automatic segmentation techniques). Linear measurments are important for identifying the bounderies and anatomical structures very well Manual segmentation was done for 3 donor site and semiautomatic segmentation only for maxillary sinus. Usually a small defect is 7 mm in width, 5 mm depth, and 12 mm length and it requires a volume of 0.42ml. Maxillary donor sites in this current study, with the resultant widths (6.68±0.44 and 19.12±3.47) and volumes (0.31±0.07 and 0.49±0.06) may conform to such small deficiencies. According to our findings, for medium and large defects, the ramus might be adequate with width and volume of 29.87±6.17 mm and 0.99±0.19 cm3 respectively, whereas, the symphysis may cover large defects, since it supplies a mean graft width and volume of 40.17±0.96 mm and 1.56±0.44 cm3. the mandibular symphysis is dominating the other areas regarding the volume as was observed in the mesio-distal dimension, The thinnest graft was the zygomatic buttress, care should be taken in consideration to avoid schneiderian membrane perforation. The volume in the current study was done in two ways, volumes calculated from linear measurements and volumes extracted by the segmentation tool. The error between the two volume techniques in the four groups was relatively wide ranging from 23 to 61 %, where segmentation showed underestimated values.