Comparison of extraction sites versus artificial defects with xenogenic bone substitute in minipigs

Objectives The preclinical evaluation of bone substitutes is frequently performed in artificially created defects. However, such defects do not reflect the predominant clinical application of bone substitutes for socket preservation. Hence, the goal of this animal study was to compare the performance of a xenogenic bone substitute in extraction sites versus artificial defects. Material and Methods Four study sites each were created in the mandibles of four minipigs in the region of the third premolars and first molars, respectively. On one side, fresh extraction sockets were established while contralaterally trephine defects were created in healed alveolar bone. All sites were augmented using a particulate xenogenic bone substitute, covered by resorbable membranes and allowed to heal for 12 weeks. The amounts of new bone, non-bone tissue and remaining bone substitute granules were quantified through histological and micro-CT analysis. Comparative statistics were based on t-tests for two samples and ANOVA with the level of significance set at α = 0.05. Results Histomorphometric data from only two animals could be quantitatively analyzed due to difficulty with identifying the surgical sites. The percentage of newly formed bone ranged between 53.2% ± 5.6% for artificial defects and 54.9% ± 12.4% for extraction sites. With the exception of ANOVA indicating a greater amount of non-bone tissue in extraction sites as compared to artificial sites (p = 0.047), no statistically significant differences were observed. Micro-CT scans showed patterns similar to the ones observed in histomorphometry. As extraction sites could be identified only in two micro-CT reconstructions, quantitative assessment was not undertaken. Conclusions Despite the comparable performance of bone substitute material in artificial defects and extraction sites found here, the data gathered with this experiment was insufficient for showing equivalence of both approaches

Evaluation of anodized surfaces designed for improved soft tissue integration

A rapid and stable integration of dental implant systems into a given tissue is achieved by enabling optimal migration, adhesion, proliferation and differentiation of surrounding cells at the implant and abutment surfaces. The design of abutments requires the careful evaluation and optimization of their surface to provide a strong attachment for the connective tissue and epithelium. In this work the effect of surface anodization on soft tissue integration was evaluated by comparing anodized (Xeal™) and machined surface titanium discs as culture substrates for human gingival epithelial cells (HGEPp) and primary human gingival fibroblasts (HFIB-G). HFIB-G cells did not show any significant preference between the two surfaces whereas HGEPp cells showed significantly faster growth on the Xeal™ surface

A non-contact impedimetric biosensing system for classification of toxins associated with cytotoxicity testing

© 2019 We report on a novel impedance spectroscopy measurement and data analysis technique for cytotoxicity testing. The technique combines non-contact measurement with real-time impedance data analysis based on the toxin dose dependency of the outputs, making it suitable for high throughput screening. A multi-electrode array was designed and fabricated such that a standard well plate could be positioned above the electrodes, negating the requirement for bespoke culture wells with integrated electrodes. For cytotoxicity testing, endothelial cells, type ECV304, within the wells were exposed to various concentrations of 3 toxins, dimethyl sulphoxide, cadmium chloride and saponin, which exhibit different modes of action on cells. Impedance spectra were recorded every 30 min over a 24 h period. From the spectra ‘toxin maps’ were produced which presented the correlation between impedance output and dose of toxin versus frequency and time. The results demonstrated characteristic toxin maps for each toxin and significantly differences between the three toxins studied. Using complementary measurement methods, we showed that these differences in toxin maps related to morphological and physiological changes in the cells due to the differing mode of action of each toxin

Rational design and in vitro characterization of novel dental implant and abutment surfaces for balancing clinical and biological needs

BACKGROUND Long-term success and patient satisfaction of dental implant systems can only be achieved by fulfilling clinical as well as biological needs related to maintenance, aesthetics, soft tissue sealing, and osseointegration, among others. Surface properties largely contribute to the biological and clinical performance of implants and abutments. PURPOSE To decipher the clinical and biological needs in implant dentistry. To address identified needs, next-generation dental implant and abutment surfaces are designed and characterized in vitro. MATERIALS AND METHODS Novel implant and abutment surface designs were produced and characterized using surface chemical analysis, surface topography analysis, scanning electron microscopy, contact-angle measurements, and cell-culture experiments. RESULTS The novel anodized implant surface was gradually anodized, increasing the surface roughness, surface enlargement, and oxide-layer thickness from platform to apex. The surface was phosphorus enriched, nonporous, and nanostructured at the collar, and showed micropores elsewhere. The novel anodized abutment surface was smooth, nanostructured, nonporous, and yellow. Pristine surfaces with high density of hydroxyl-groups were protected during storage using a removable cell-friendly layer that allowed dry packaging. CONCLUSIONS A novel anodized implant system was developed with surface chemistry, topography, nanostructure, color, and surface energy designed to balance the clinical and biological needs at every tissue level

Mechanical and Biological Advantages of a Tri-Oval Implant Design

Of all geometric shapes, a tri-oval one may be the strongest because of its capacity to bear large loads with neither rotation nor deformation. Here, we modified the external shape of a dental implant from circular to tri-oval, aiming to create a combination of high strain and low strain peri-implant environment that would ensure both primary implant stability and rapid osseointegration, respectively. Using in vivo mouse models, we tested the effects of this geometric alteration on implant survival and osseointegration over time. The maxima regions of tri-oval implants provided superior primary stability without increasing insertion torque. The minima regions of tri-oval implants presented low compressive strain and significantly less osteocyte apoptosis, which led to minimal bone resorption compared to the round implants. The rate of new bone accrual was also faster around the tri-oval implants. We further subjected both round and tri-oval implants to occlusal loading immediately after placement. In contrast to the round implants that exhibited a significant dip in stability that eventually led to their failure, the tri-oval implants maintained their stability throughout the osseointegration period. Collectively, these multiscale biomechanical analyses demonstrated the superior in vivo performance of the tri-oval implant design