Abstract Reduction of morbidity in osseous reconstruction of cranio-maxillofacial bony defects could come from development of less invasive bone graft harvesting techniques or by elimination of bone graft donor sites using a bone graft substitute. This work studies outcomes and morbidity associated with these two approaches. A power-driven trephine was used to harvest bone from the anterior iliac crest using a minimally invasive surgical technique. Initially the safety of the technique was evaluated in a cadaver model. Twenty-five freshly preserved adult cadavers had a total of 250 cancellous cores of bone harvested from 50 anterior iliac crest sites. Twenty intentional perforations were made to the maximum depth possible with the instrumentation tested. No encroachment upon the peritoneum was found. A total of 84 patients had 333 cores of cancellous bone harvested using the same approach with a complication rate of 3.6% and a patient satisfaction rate of 98.8%. In a further 76 patients the motorized trephine method was compared to traditional open iliac crest corticocancellous block harvesting. The trephine group ambulated earlier, required fewer days of hospital stay and had significantly lower pain scores than the open iliac crest group. Coral-derived granules were used as a xenograft bone graft substitute to treat bony defects in the cranio-maxillofacial skeletons of 36 patients with 54 sites and followed for 12 to 36 months. The augmentations produced satisfactory results with the following complications noted: overt wound infection 1.8%, wound irritation 3.8% and clinically evident resorption in 9.3% of augmented sites. Coral-derived granules were then used to treat 48 dento-alveolar defects in 21 growing patients with trauma induced tooth-loss in the anterior maxilla and elective ankylosed tooth removal in the posterior maxilla and mandible. Coral granules were significantly more efficacious in reconstructing alveolar defects in the posterior maxilla or mandible (93.5%), than the anterior maxilla (17.6%). The minimally invasive technique using a power driven trephine was successful at reducing morbidity from bone graft harvesting at the anterior iliac crest. Coral-derived granules can be used in selected situations as a bone graft substitute and minimize post surgical morbidity by eliminating the bone graft donor site.

Anterior cervical discectomy and fusion (ACDF) is one of the most common cervical spine surgery procedures performed worldwide. ACDF utilizes autologous bone graft (autograft) from the iliac crest to induce fusion between neighboring vertebrae following the procedure. The iliac crest is widely considered the gold-standard autograft for ACDF procedures due to its osteoinductive, osteoconductive, and osteointegrative properties. However, harvesting from a second surgical site, as seen with iliac crest autograft, is commonly associated with short- and long-term complications. To mitigate iliac crest harvest site complications, a novel autograft location must be identified. The adjacent cervical vertebral body has been identified as a potential alternative donor site to the iliac crest. Previous studies have shown that this novel autograft site does not biomechanically compromise the vertebral body harvest site and has demonstrated clinically successful fusion rates comparable to those of the iliac crest. Despite prior successful fusion, a direct morphological and mechanical comparison between autograft from the adjacent cervical vertebra and iliac crest has not been thoroughly investigated. The primary goal of this thesis was to morphologically and mechanically compare the cervical spine and iliac crest. It was hypothesized that the cervical spine and iliac crest would not significantly vary in their morphological properties; however, due to daily physiological loading at each graft location, it was hypothesized that the two graft locations would differ mechanically. A clinical model utilizing iliac crest and cervical vertebral bone from human donors was characterized at the meso- and microscale to quantify morphological properties and collagen organization using micro-computed tomography (microCT) and second-harmonic generation (SHG) imaging modalities, respectively. A pre-clinical large animal model was used to characterize the mechanical and material properties of lumbar spine tissue, under similar physiological loading as the cervical spine, relative to the iliac crest through uniaxial compression testing. No significant difference was identified in the morphological and collagen organization properties in tissue from a human clinical cohort; however, directionality and anatomical location significantly impacted the mechanical and material properties in a bovine comparative anatomy model. Here, trabecular bone from the lumbar vertebra was found to be transversely isotropic whereas iliac crest trabecular bone was nearly isotropic; thus, directionality and anatomical location should be considered and quantified when selecting autograft tissue for future ACDF surgeries. Further characterization of the mechanical properties of cervical vertebral tissue and determination of correlations between directionality, anatomical location, and morphology through microCT and compression testing should be completed before adopting the cervical vertebra as the gold standard autograft for ACDF procedures. / Master of Science / Anterior cervical discectomy and fusion (ACDF) is a common upper spine surgery that helps to stabilize the spine by fusing two or more vertebrae together. To achieve this fusion, surgeons often use bone grafts taken from the patient's own hip, specifically the iliac crest. While this method is effective, it can lead to complications at the hip bone harvest site. To avoid these complications, researchers are exploring the possibility of using bone from a nearby vertebra in the upper spine as an alternative graft source. Early studies suggest that using bone from the upper spine does not weaken the spine and achieves similar success rates in fusion as the hip bone. However, a detailed comparison between both graft sites has not been thoroughly investigated until now. The main goal of this thesis was to compare the bone from the upper spine and the hip in terms of structure and strength. It was expected that the two types of bone would be similar in structure but different in strength due to difference forces they experience in the body. The research involved examining human bone samples from both the upper spine and hip using advanced imaging techniques to analyze their structure and collagen organization. Additionally, a large animal comparative model was used to test the strength and material properties of bone from the lower spine and hip, which experience similar forces as the human upper spine and hip. The findings showed no significant difference in the structure and collagen organization of the human bone samples. However, in the animal model, the strength and material properties of the bone significantly varied depending on the direction and location. Bone from the lower spine was found to be significantly stronger in one direction in comparison to two other directions in the lower spine and all three directions in the hip. These results suggest that when choosing bone for fusion in ACDF surgeries, it is important to consider the direction and location of the graft. Further research is needed to fully understand the mechanical properties of upper spine bone and to confirm its suitability as a standard graft for ACDF procedures.

No description available.

Dental caries and periodontal disease are the major causes for tooth loss. While dental caries commonly involve the posterior teeth in both jaws, the teeth most commonly lost due to periodontal problems are the first and second molars in the maxilla. As a consequence, the upper posterior jaw is frequently edentulous. Implant therapy today is a predictable treatment modality for prosthetic reconstruction of edentulous patient. Insufficient amounts of bone, due to atrophy following loss of teeth or due to the presence of the maxillary sinus, can make it impossible to insert implants in the posterior maxilla. During the 1970s and 1980s, Tatum, Boyne and James and Wood and Moore first described maxillary sinus floor augmentation whereby, after the creation of a lateral access point, autologous bone grafts are inserted to increase crestal bone height and to create the necessary conditions for the insertion of implants. This surgical procedure requires a two-stage approach and a double surgical site: first, bone is harvested from a donor site and transplanted to the recipient site; then, after a proper healing period of between 4 to 6 months, the implants are inserted. This kind of bone reconstruction, even if well documented, has its limitations, not least in the creation of two different surgical sites and the consequent increased risk of morbidity. In 2004, Lundgren et al. described a new, simplified technique for the elevation of the sinus floor. The authors showed that by lifting the sinus membrane an empty space was created in which blood clot formations resulted in the establishment of new bone. The implants were placed simultaneously to function as “tent poles”, thus maintaining the sinus membrane in a raised position during the subsequent healing period. An essential prerequisite of this technique is to obtain optimal primary implant stability from the residual bone in the sinus floor. An extremely resorbed maxillary sinus floor, with, for example, less than 2-3 mm of poor quality residual bone, could impair implant insertion. The aims of the present research project were (i) to evaluate the donor site morbidity and the acceptance level of patients when a bone graft is harvested from the anterior iliac crest, (ii) to evaluate implant stability, new bone formation inside the maxillary sinus and marginal bone resorption around the implants in long term follow up when maxillary sinus floor augmentation is performed through sinus membrane elevation and without the addition of any grafting material, (iii) to investigate new bone formation inside the maxillary sinus, in experimental design, using a resorbable space-maker device in order to maintain elevation of the sinus membrane where there is too little bone to insert implants with good primary stability. In Paper I, 70 consecutively treated patients were retrospectively evaluated in terms of postoperative donor site morbidity and donor site complications. With regard to donor site morbidity, 74% of patients were free of pain within 3 weeks, whereas 26% had a prolonged period of pain lasting from a few weeks to several months. For 11% of patients there was still some pain or discomfort 2 years after the grafting surgery. Nevertheless, patients acceptance was high and treatment significantly improved oral function, facial appearance, and recreation/social activities and resulted in an overall improvement in the quality of life of formerly edentulous patients. In Paper I and III, some differently shaped space-making devices were tested on primates (tufted capuchin - Cebus apella) in two experimental models aimed at evaluating whether a two-stage procedure for sinus floor augmentation could benefit from the use of a space-making device to increase the bone volume and enable later implant installation with good primary stability, without the use of any grafting material. An histological examination of the specimens showed that it is possible to obtain bone formation in contact with both the Schneiderian membrane and the device. In most cases the device was displaced. The process of bone formation indicated that this technique is potentially useful for two-stage sinus floor augmentation. The lack of device stability within the sinus requires further improvement in space-makers if predictable bone augmentation is to be achieved. In Paper IV, a total of 84 patients were subjected to 96 membrane elevation procedures and the simultaneous placement of 239 implants. Changes of intra-sinus and marginal bone height in relation to the implants were measured in intraoral radiographs carried out during insertion after 6 months of healing, after 6 months of loading and then annually. Computerised tomography was performed pre-surgically and 6 months post-surgically. Resonance frequency analysis measurements were performed at the time of implant placement, at abutment connection and after 6 months of loading. The implant follow-up period ranged from a minimum of one to a maximum of 6 years after implant loading. All implants were stable after 6 months of healing. A total of three implants were lost during the follow-up period giving a survival rate of 98.7%. Radiography demonstrated an average of 5.3 ± 2.1 mm of intra-sinus new bone formation after 6 months of healing. RFA measurements showed adequate primary stability (implant stability quotient 67.4 ± 6.1) and small changes over time. In conclusion, harvesting bone from the iliac crest could result in temporary donor site morbidity, but in 11% of patients pain or discomfort was still present up to 2 years after surgery. However, patient satisfaction was good despite this slow or incomplete recovery, as showed by the quality of life questionnaire. Maxillary sinus membrane elevation without the use of bone grafts or bone substitutes results in predictable bone formation both in animal design, where the sinus membrane is supported by a resorbable device, and in clinical conditions, where the membrane is kept in the upper position by dental implants. This new bone formation is accompanied by a high implant survival rate of 98.7% over a follow-up period of up to 6 years. Intra-sinus bone formation remained stable in the long-term follow-up. It is suggested that the secluded compartment allowed bone formation in accordance with the principle of guided tissue regeneration. This technique reduces the risks of morbidity related to bone graft harvesting and eliminates the costs of grafting materials.

No description available.

Les effets des agents anti-ostéoporotiques sur le tissu osseux sont évalués au niveau de la crête iliaque (CI) mais les réponses aux traitements peuvent varier selon le site osseux. Le but de cette étude était de comprarer les effets de l’acide zolérodronique (ZOL) et du tériparatide (TPTD) au niveau de la crête iliaque et de la vertèbre lombaire L1 (VL1) chez la brebis âgée. Le ZOL a induit une forte diminution du remodelage osseux et une augmentation des microendommagements au niveau des deux sites et une modification des crosslinks du collagène surtout au niveau de l’os cortical de la CI. Trois mois de TPTD ont augmenté le remodelage osseux uniquement au niveau de la VL1. En conclusion, les délais et les amplitudes de réponses au ZOL ou au TPTD diffèrent entre la CI et la VL1 chez la brebis. Ces résultats montrent l’importance de prendre en compte le site osseux pour évaluer les effets des agents anti-ostéoporotiques / The effects of anti-osteoporotic agents on bone tissue are evaluated on iliac crest (IC) but the answers to treatments may vary according to the skeletal site. The purpose of this study was to compare the effect of zoledronic acid (ZOL) and teriparatide (TPTD) on IC and lumbar vertebrae (LV1) in ewes. ZOL has induced a high decrease of bone remodeling, an increase in microdamages in both sites and a modification of collagen crosslinks mainly in cortical bone of IC. Three months of TPTD has increased the bone remodeling only in LV1. In conclusion, the delays and the magnitudes of responses to ZOL or to TPTD differ between IC and LV1 in ewes. These results show that the distinction of bone sites to study the early effects of antiosteoporotic therapies appears meaningful