No abstract

We sought to assess the ability of nanotopographically complex titanium surfaces to accelerate osteoconduction. For this, 130 miniature bone ingrowth chambers (called "T plants"), fabricated from either commercially pure titanium (cpTi) or titanium alloy (Ti6Al4V or Ti64), with microtopographically complex surfaces were used in the study, of which 50 were further modified by the discrete crystalline deposition (DCD) of calcium phosphate (CAP) nanoparticles that superimposed a nanotopographic complexity on each implant surface. Thus, four experimental groups were generated (cpTi, cpTi-DCD, Ti64, and Ti64-DCD), and the Tplants were implanted bilaterally in the femora of Wistar rats for 9 days. After harvesting, the femora were trimmed, and multiple-mounted samples were embedded in PMMA. The blocks produced were ground and block faces observed by back-scattering electron imaging (BSEI) at different planes through the chambers. Osteoconduction was assessed, as a function of bone-implant contact, on a total of 1087 BSEI micrographs and submitted to rigorous statistical analyses. Our results showed both the important effects of anatomic location on bone ingrowth and the significant increase in osteoconduction (p < 0.001) as a function of the enhanced surface nanotopography obtained by the CAP nanocrystals.

No abstract

The regeneration of tissues affected by periodontal disease is a complex process; it encompasses the formation of bone, cementum and periodontal ligament. We developed a semi-rigid PLGA (polylactide-co-glycolide acid)/CaP (calcium phosphate) bilayered biomaterial construct to promote periodontal regeneration, which has a continuous outer barrier membrane and an inner topographically complex component. Our experimental model compared periodontal prophylaxis alone with prophylaxis and biomaterial implantation in the treatment of class II furcation defects in dogs. Clinical evaluation, micro-computed tomography, histology and backscattered electron imaging were used for data analysis. Healing occurred uneventfully and bone volumetric values, trabecular number and trabecular thickness were all significantly greater in the treated group; while trabecular separation was significantly greater in the control group. New cementum, bone, and periodontal ligament with Sharpey fibre insertions were only seen in the treated group. Although periodontal regeneration has been reported elsewhere, the advantages of employing our bilayered PLGA + CaP construct are twofold: 1)it did not collapse into the defect; and, 2) its inner side was able to retain the blood clot throughout the buccal defect. The result was greater periodontal regeneration than has previously been reported with traditional flexible membranes.

We have developed a biodegradable composite scaffold for bone tissue engineering applications with a pore size and interconnecting macroporosity similar to those of human trabecular bone. The scaffold is fabricated by a process of particle leaching and phase inversion from poly(lactideco-glycolide) (PLGA) and two calcium phosphate (CaP) phases both of which are resorbable by osteoclasts; the first a particulate within the polymer structure and the second a thin ubiquitous coating. The 3-5 μm thick osteoconductive surface CaP abrogates the putative foreign body giant cell response to the underlying polymer, while the internal CaP phase provides dimensional stability in an otherwise highly compliant structure. The scaffold may be used as a biomaterial alone, as a carrier for cells or a three-phase drug delivery device. Due to the highly interconnected macroporosity ranging from 81% to 91%, with macropores of 0.8∼1.8 mm, and an ability to wick up blood, the scaffold acts as both a clot-retention device and an osteoconductive support for host bone growth. As a cell delivery vehicle, the scaffold can be first seeded with human mesenchymal cells which can then contribute to bone formation in orthotopic implantation sites, as we show in immune-compromised animal hosts. We have also employed this scaffold in both lithomorph and particulate forms in human patients to maintain alveolar bone height following tooth extraction, and augment alveolar bone height through standard sinus lift approaches. We provide a clinical case report of both of these applications; and we show that the scaffold served to regenerate sufficient bone tissue in the wound site to provide a sound foundation for dental implant placement. At the time of writing, such implants have been in occlusal function for periods of up to 3 years in sites regenerated through the use of the scaffold.