1,720,959 research outputs found
Effects of titanium oxide surface properties on bone-forming and soft tissue-forming cells
No full textFull text access from Treasures at UT Dallas is restricted to current UTD affiliates (use the provided Link to Article). Non UTD affiliates will find the web address for this item by clicking the "Show full item record" link, copying the "dc.relation.uri" metadata and pasting it into a browser.Background: Previous studies have concluded that certain titanium oxide (TiO₂) surface properties promote bone-forming cell attachment. However, no comprehensive studies have investigated the effects of TiO₂ surface and film morphology on hard and soft tissues. Purpose: The aim of this study is to understand the effects of TiO₂ morphology on the proliferation and differentiation of murine preosteoblasts (MC3T3-E1) and proliferation of human gingival fibroblasts (HGF-1) using in vitro experiments. Materials and Methods: Samples were fabricated with several TiO₂ thickness and crystalline structure to mimic various dental implant surfaces. in vitro analysis was performed for 1, 3, and 7 days on these samples to assess the viability of MC3T3-E1 and HGF-1 cells in contact with the modified oxide surfaces. Results: Results showed that HGF-1 cells exhibited no significant difference in viability on modified oxide surfaces versus a titanium control across experiments. MC3T3-E1 cells exhibited a significantly higher viability for the modified oxide surface in 1 day experiments, but not in 3 or 7 day experiments. Alkaline phosphatase expression in MC3T3-E1 was not significantly different on modified oxide surfaces versus the control across all experiments. A slight positive trend in viability was observed for cells in contact with rougher modified oxide surfaces versus a titanium control in both cell types. Conclusions: These observations suggest that crystallinity and thickness do not affect the long-term viability of hard or soft tissue cells when compared to a cpTi surface. Therefore, treatments like anodization on implant components may not directly affect the attachment of hard or soft tissue cells in vivo. © 2018 Wiley Periodicals, Inc.Erik Jonsson School of Engineering and Computer Scienc
Effect of Ionic Liquid Coatings on Early Healing and Osseointegration of Titanium Implants
No full textAlthough titanium (Ti) dental implants are known to achieve high success rates and
osseointegration in vivo, a higher incidence of implant failures have been recently reported.
Implant failures are caused by several factors; however, the nature and intensity of the
inflammatory response at the titanium-tissue interface determines the healing outcome of an
implant. Surface modifications performed on titanium implants have attempted to directly
address both patient and external factors that interfere with constructive inflammation, but often
do not address multiple complications that impact osseointegration while maintaining
regenerative healing. Dicationic imidazolium-based ionic liquids (IonL) have demonstrated low
toxicity, antimicrobial, lubricant, and anticorrosive activities in vitro making them a potential
candidate as a multifunctional dental implant coatings. However, the biological response to these
coatings in vivo is unknown. The goal of this dissertation was to evaluate the effect IonLs have
on inflammation, healing, and osseointegration of titanium dental implants. This research is
divided into three aims (i) to investigate the biocompatibility of IonL in a subcutaneous model,
(ii) to define and validate success criteria for an oral implantation model and (iii) to investigate
the impact of IonL on early healing and osseointegration in an oral implantation model. In each
aim a combination of clinical evaluation, histopathology, immunohistochemistry, molecular
analysis, and MicroCT was used to track inflammation and healing from 2-30 days (d) in the
Lewis rat.
In aim 1, an initial evaluation of both IonL-Phe and IonL-Met indicated that IonL appeared in
peri-implant tissues and increased acute inflammation at 2d compared to uncoated Ti. At 14d,
inflammation receded with more developed peri-implant tissue in coated and uncoated samples
with no foreign body giant cells. IonL was no longer observed at 14d, suggesting elution or
resorption by macrophages. This aim demonstrated that medium dose IonL-Phe does not
significantly interfere with Ti foreign body response in an aseptic environment.
In aim 2, a new pre-clinical oral implantation model defined an appropriate baseline for
successful Ti osseointegration. Healing was similar to other rodent models: hematoma and acute
inflammation at 2d, initial bone formation at 7d, advanced bone formation and remodeling at
14d, and bone maturation at 30d. Overall, this model resulted in a 78.5% osseointegration
success rate (>60% bone-to-implant contact (BIC)), similar to human osseointegration.
Therefore, This model combines the advantages of a rodent model while maximizing BIC,
making it an excellent candidate for evaluation of IonLs. Following aim 2, a pilot in vivo
assessment determined medium dose IonL-Phe demonstrated the best histogical response and
BIC for the remaining evaluation. In aim 3, IonL-Phe-coated and uncoated cpTi screws were
implanted into several demographic groups of rats to represent biological variations that could
affect healing. Molecular and histological analysis indicated IonL heightened acute inflammation
compared to uncoated Ti. However, the coating was released/resorbed by 7 days and did not
negatively affect subsequent bone remodeling in all demographics. Overall, IonL-Phe coating
did not disturb oral Ti osseointegration and may provide additional control over the healing
environment in scenarios known to be challenged by bacteria, such as peri-implantiti
Investigation of Titanium Oxide Characteristics on Healing Abutments: Retrieval Characterization and Soft-Tissue Compatibility
No full textTitanium implant healing abutments (IHAs) are a temporary component of the dental implant system that have a vital role in soft tissue healing and shaping after implant body placement. A large amount of studies have been dedicated to investigating dental implant body performance, however little focus is placed on the IHA. Unlike the implant body, these devices are exposed to both the oral environment and acute inflammation post-implantation, producing conditions known to cause early implant failure. In addition, they are color coded with anodization during manufacturing, with no regard to how this surface modification affects the stability or efficacy of the device. Therefore, it is crucial to understand the behavior of IHA during implantation, and the response of soft tissue to these modified titanium oxide surfaces. Anodized IHAs were subjected to surface characterization pre-and post-implantation in patients to elucidate the effects of the oral environment on HA surfaces. Changes in surface crystallinity, morphology, elemental composition, and electrochemical properties were monitored to assess HA surface stability.
To evaluate soft tissue response to these materials, titanium oxide samples were fabricated to have varied titanium oxide thickness and crystalline structure to mimic IHA surfaces. In vitro analysis was performed on these samples to assess the viability of HGF-1 cells in contact with the modified oxide surfaces
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
