Faculty Bibliography

This study investigated the effect of undersized preparations with two different implant macrogeometries. There were four experimental groups: group 1, conical implant with an undersized osteotomy of 3.2mm; group 2, conical implant with an undersized osteotomy of 3.5mm; group 3, cylindrical implant with an undersized osteotomy of 3.2mm; group 4, cylindrical implant with an undersized osteotomy of 3.5mm. Implants were placed in one side of the sheep mandible (n=6). After 3 weeks, the same procedure was conducted on the other side; 3 weeks later, euthanasia was performed. All implants were 4mmx10mm. Insertion torque was recorded for all implants during implantation. Retrieved samples were subjected to histological sectioning and histomorphometry. Implants of groups 1 and 2 presented significantly higher insertion torque than those of groups 3 and 4 (P<0.001). No differences in bone-to-implant contact or bone area fraction occupied were observed between the groups at 3 weeks (P>0.24, and P>0.25, respectively), whereas significant differences were observed at 6 weeks between groups 1 and 2, and between groups 3 and 4 (P<0.01). Undersized drilling affected the biological establishment of bone formation around both dental implant macrogeometries.

Tissue engineering endeavors to create replacement tissues and restore function that may be lost through infection, trauma, and cancer. However, wide clinical application of engineered scaffolds has yet to come to fruition due to inadequate vascularization. Here, we fabricate hydrogel constructs using Pluronic((R)) F127 as a sacrificial microfiber, creating microchannels within biocompatible, biodegradable type I collagen matrices. Microchannels were seeded with human umbilical vein endothelial cells (HUVEC) or HUVEC and human aortic smooth muscle cells (HASMC) in co-culture, generating constructs with an internal endothelialized microchannel. Histological analysis demonstrated HASMC/HUVEC-seeded constructs with a confluent lining after 7 days with preservation and further maturation of the lining after 14 days. Immunohistochemical staining demonstrated von Willebrand factor and CD31(+) endothelial cells along the luminal surface (neointima) and alpha-smooth muscle actin expressing smooth muscle cells in the subendothelial plane (neomedia). Additionally, the deposition of extracellular matrix (ECM) components, heparan sulfate and basal lamina collagen IV were detected after 14 days of culture. HUVEC-only- and HASMC/HUVEC-seeded microchannel-containing constructs were microsurgically anastomosed to rat femoral artery and vein and perfused, in vivo. Both HUVEC only and HUVEC/HAMSC-seeded constructs withstood physiologic perfusion pressures while their channels maintained their internal infrastructure. In conclusion, we have synthesized and performed microvascular anastomosis of tissue-engineered hydrogel constructs. This represents a significant advancement toward the generation of vascularized tissues and brings us closer to the fabrication of more complex tissues and solid organs for clinical application.

PURPOSE: The aim of this study was to assess the effect of implant coating with laminin-1 on the early stages of osseointegration in vivo. MATERIALS AND METHODS: Turned titanium implants were coated with the osteoprogenitor-stimulating protein, laminin-1 (TL). Their osteogenic performance was assessed with removal torque, histomorphometry, and nanoindentation in a rabbit model after 2 and 4 weeks. The performance of the test implants was compared with turned control implants (T), alkali- and heat-treated implants (AH), and AH implants coated with laminin-1. RESULTS: After 2 weeks, TL demonstrated significantly higher removal torque as compared with T and equivalent to AH. Bone area was significantly higher for the test surface after 4 weeks, while no significant changes were detected on the micromechanical properties of the surrounding bone. CONCLUSIONS: Within the limitations of this study, our results suggest a great potential for laminin-1 as a coating agent. A turned implant surface coated with laminin-1 could enhance osseointegration comparable with a bioactive implant surface while keeping the surface smooth.

In this study, the physicochemical characteristics of calcium phosphate based bioactive ceramics of different compositions and blends presenting similar micro/nanoporosity and micrometer scale surface texture were characterized and evaluated in an in vivo model. Prior to the animal experiment, the porosity, surface area, particle size distribution, phase quantification, and dissolution of the materials tested were evaluated. The bone regenerative properties of the materials were evaluated using a rabbit calvaria model. After 2, 4, and 8weeks, the animals were sacrificed and all samples were subjected to histologic observation and histomorphometric analysis. The material characterization showed that all materials tested presented variation in particle size, porosity and composition with different degrees of HA/TCP/lower stoichiometry phase ratios. Histologically, the calvarial defects presented temporal bone filling suggesting that all material groups were biocompatible and osteoconductive. Among the different materials tested, there were significant differences found in the amount of bone formation as a function of time. At 8weeks, the micro/nanoporous material presenting ~55%TCP:45%HA composition ratio presented higher amounts of new bone regeneration relative to other blends and a decrease in the amount of soft tissue infiltration.

PURPOSE: Imaging is important to identify subclinical changes and for treatment planning in patients with osteonecrosis of the jaw (ONJ) exposed to antiresorptive therapy. The aim of this study was to compare the findings at radiography with those at fluorodeoxyglucose (FDG) positron emission tomography (PET) with computed tomography (CT) for patients with ONJ related to antiresorptive therapy. MATERIALS AND METHODS: A cross-sectional retrospective analysis of patients with clinically identified ONJ lesions of the mandible was performed. Two imaging modalities were evaluated for each patient: plain radiography (ie, panoramic or periapical) and FDG PET/CT with 1-mm sections. Outcome variables for the radiographic findings were osteolytic and osteosclerotic bone changes. Outcome variables for FDG PET/CT images were localization of FDG uptake. Maximum standard uptake values (SUVmax) of abnormal FDG jaw uptake were recorded, in addition to the mean SUV of the contralateral normal mandible, and used to calculate the target-to-background ratio. Radiographic changes and FDG uptake were classified as local (ie, corresponding to exposed cortical bone) or diffuse (ie, local changes and changes extending beyond the margins of exposed bone) for each imaging technique. Local and diffuse changes detected by each imaging modality were described and the difference in detection was compared with the McNemar test. RESULTS: Twenty-three patients with 25 clinically identified ONJ lesions were analyzed using radiography and FDG PET/CT. Differences were found in how radiography and FDG PET/CT detect local and diffuse changes associated with ONJ. Radiography showed local changes in 17 patients (68%), diffuse changes in 3 patients (12%), and no changes in 5 patients (20%), whereas FDG PET/CT imaging showed local changes in 17 patients (68%) and diffuse changes in 8 patients (32%). The McNemar test indicated that FDG PET/CT imaging was less likely to miss a lesion (P < .001). Mean SUVmax was 6.59, and the mean target-to-background ratio was 5.37. CONCLUSION: The results of this study show that FDG PET/CT detects local and diffuse metabolic changes that may not be represented by plain radiography for patients with ONJ related to antiresorptive therapy. The target-to-background ratio allowed the discrimination between ONJ lesions and background changes. Future studies are necessary to determine whether FDG PET/CT can determine risk and facilitate management of ONJ.