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Sep 10 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: September 17, 2014 (Wednesday)

Time: 12:45 p.m. to 1:30 p.m.

Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Mr. Ekambaram Manikandan, PhD Candidate

Title: Aspects of solvent on dentin bonding

Abstract: Degradation starts at the resin-dentin bonded interfaces within a few months of adhesive bonding.  The simplified dental adhesives that are routinely used in the contemporary clinical dental practice are extremely hydrophilic and are prone to hydrolytic degradation. Matrix metalloproteinases (MMP) and cysteine cathepsins (CC) are the two types of proteolytic enzymes that have been shown to degrade the un-infiltrated demineralized collagen at the bottom of the hybrid layer in the bonded interfaces. These enzymes are hydrolases; therefore, the presence of water in the hybrid layer will be a favourable factor for degradation of the dentin-bonded interfaces. Ethanol-wet bonding (EWB) with hydrophobic adhesive could prevent the hydrolytic degradation of dentin bonded interfaces. In vivo and in vitro studies have shown that chlorhexidine (CHX) treatment of demineralized dentin prior to resin bonding preserved resin-dentin bond durability by inhibition of dentin-matrix bound MMP and CC. However, water in the hybrid layer could lead to easier removal of CHX from demineralized dentin, when compared to ethanol. 1-Ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride (EDC) is a dentin collagen cross-linker shown to preserve dentin bond durability in vitro. EDC solution for dentin collagen crosslinking is routinely prepared in water, though water incorporation in the hybrid layer would lead to dentin bond degradation. Our research experiments aimed to study the role of alternative solvents in the current experimental strategies for the enhancement of resin-dentin bond durability. Within the limitations of our research work, it could be concluded that solvents play a significant role in the enhancement of dentin bond durability. The choice of solvent depends on the bonding protocols applied. In general, ethanol and acetone are better than water for preservation of resin-dentin bond durability.

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Aug 28 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: September 4, 2014 (Thursday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Ms. Zhuang Longfei, PhD Candidate (12:45 p.m. to 1:15 p.m.)
Title: Periodontal and peri-implant microbiota in subjects with healthy and inflamed tissues

Abstract: Bacteria, in the form of biofilm, has been shown to play a critical role in the etiology and pathogenesis of periodontal and peri-implant infectious diseases. Studies have shown that distinctively different dental plaque is commonly found in healthy versus inflamed gingivae and mucosa. It should be noted, however, that in most of these studies, the healthy and diseased plaque samples were collected from different individuals. To address this important issue, subjects who were periodontally involved and/or had inflamed peri-implant tissues, and also had equivalent healthy control sites were recruited in my studies. The results indicated that there were larger differences in the composition of the microbial communities found in different individuals, than the differences in microbial composition found between the two sites with different probing depths in the same individual. The putative periodontal pathogens were identified both in healthy and inflamed tissues within the same subjects.

Presenter: Mr. Yau Tak Wai David, MPhil Candidate (1:15 p.m. to 1:45 p.m.)
Title: Bayesian Longitudinal Polytomous Item Response Models for Child Perception Questionnaire

Abstract: Traditional approach to measuring latent constructs is simple yet involving unrealistic assumptions. The item response theory (IRT) not only can circumvent the unrealistic assumptions, useful item and test properties can also be revealed. CPQ11-14 is a pioneer and widely adopted oral health-related quality of life (OHRQoL) instrument for children aged 11 to 14. This study aims to explore the CPQ11-14 psychometric properties by IRT and investigate factors affecting changes in OHRQoL over time. Of particular interests are the identification of potentially biased items, investigation of the reliability under the IRT framework and item discriminatory power.

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Aug 14 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: August 21, 2014 (Thursday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Dr. Yeung Wai Kan Andy, MPhil Candidate (12:45 p.m. to 1:15 p.m.)
Abstract: The perception of taste has been investigated by neuroimaging studies with the use of various liquid delivery systems. However, existing systems compatible with functional magnetic resonance imaging (fMRI) have limitations including limited tongue coverage and discontinuous liquid delivery. The aim of this study is to develop a delivery system which can deliver multiple solutions to a major portion of the dorsal and lateral surfaces of the tongue with a stable and continuous flow and a user-friendly interface. Results from a pilot study will also be shown to demonstrate the ability to detect brain activations triggered by taste stimuli.

Title: Development of a taste liquid delivery system for functional magnetic resonance imaging

 

Presenter: Miss Wu Lingli, MPhil Candidate (1:15 p.m. to 1:45 p.m.)

Title: Motivational Interviewing and Interactive Risk Assessment in Changing Adolescents’ Oral Health Behaviours: Process Evaluation and Randomized Controlled Trial

Abstract: The prevention of common oral diseases highly depends on one’s adoption of healthy behaviors. Conventional (oral health) education (CE) often fails to elicit sustainable changes in oral health behaviors. In this study, motivational interviewing (MI) and interactive risk assessment (RA) will be introduced for changing adolescents’ oral health behaviors. Through a randomized controlled trial, the effectiveness of three intervention schemes (CE, MI, and MI + RA) in enhancing adolescents’ oral health self-efficacy, improving their oral health habits (diet and oral hygiene), and preventing dental caries will be compared. Through process evaluations, the feasibility, acceptance, and quality of delivery of the respective interventions will be determined, whereas process factors that affect the effectiveness of the interventions will be identified. This study will involve 450 adolescents recruited from 15 secondary schools. Data will be collected at baseline and after 6, 12, and 24 months.

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Jun 17 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: June 23, 2014 (Monday)

Time: 12:45 p.m. to 1:30 p.m.

Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

 

Presenter: Ms. Ma Xiaomin, PhD Candidate

Title: Effects of Silver Diamine Fluoride in Preventing Dental Caries in Patients Wearing Removable Partial Dentures: A Randomized Double-blind, Placebo-controlled Study 

Abstract: Removable partial dentures (RPDs) are commonly used to replace missing teeth in adult patients. However, patients wearing dentures may have an increased rate of dental decay. The effect of topical fluoride on caries prevention in RPD wearers have not been evaluated in previous studies. The aim of this study is to compare the effectiveness of semi-annually applied silver diamine fluoride versus placebo on dental caries prevention and the quality of oral flora in patient wearing RPDs over a two-year period.

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Jun 12 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: June 18, 2014 (Wednesday)
Time: 12:45 p.m. to 1:30 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Mr. Yang Ning, PhD Candidate

Title: The stringent response in Staphylococcus aureus and related bacterial pathogens

Abstract: The stringent response is a coordinated regulatory process initiated by all bacterial species in response to starvation or environmental challenges, such as oxidative stress or antibiotic administration. In this talk, I will give an overview of the mechanisms underlying the stringent response, with particular emphasis to the major bacterial pathogen Staphylococcus aureus. I will outline the key molecular processes that remain to be fully elucidated, and will indicate how these issues may be addressed.

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May 28 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: June 4, 2014 (Wednesday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Miss Wang Shuai, PhD Candidate (12:45 p.m. to 1:15 p.m.)

Title: Effects of Enterococcus faecalis and Lipoteichoic Acid from Enterococcus faecalis on osteoblasts and osteoclasts

Abstract: Enterococcus faecalis is considered a major pathogen related to refractory root canal infection. E. faecalis colonize dentin and form biofilms in endodontically treated teeth with periapical lesions. Lipoteichoic acid (LTA) is a principal component of bacterial membrane and a major virulence factor of E. faecalis. LTA can cause apoptosis in osteoblasts and osteoclasts and stimulates leukocyte to release pro-inflammatory cytokines and bone resorption. Semaphorin 4D (Sema4D), is a mediator of osteoclast-osteoblast communication. Sema4D-Plexin-B1 bidirectional signaling plays a critical role in the suppression of osteoblast differentiation. In our present study, we for the first time have found that E. faecalis LTA induced the immune-inflammatory response of human macrophages via TLR-2 dependent NF-κB and p38 signal transduction. Furthermore, E. faecalis enhanced osteoclastogenesis with upregulation of Sema4D expression. Further studies are needed to explore the mechanisms of E. faecalis and E. faecalis LTA involved in osteogenensis, osteoclastogenesis and bidirectional signaling in bone remodeling.

 

Presenter: Mr. Jin Xiaozhuang, PhD Candidate (1:15 p.m. to 1:45 p.m.)

Title: Universal primers: Development and adhesion aspects for resin-metal bonding

Abstract: Currently, no single bonding agent could bond universally dental acrylic-based resin to metals. Recently, the novel silane system (NSS) primers were reported by Matinlinna and co-workers that could promisingly to promote the bonding between the resin and some dental biomaterials e.g. titanium and amalgam. NSS primers sought to provide a durable and hydrolytic stable bonding permanently. However, the adhesion mechanism and optimal formulation of NSS primers are not yet studied. Thus, in the current study, the mechanical, chemical and physical properties of such NSS primers would be studied in order to understand fundamentally the adhesion mechanism, and improve the NSS primers performance in acrylic-based resin to metal bonding. In addition, optimized NSS primers formulations which could universally enhance the bonding between acrylic-based resin and metals in both dental and medical systems are targeted. 

No responses yet| 109 views

May 27 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: June 3, 2014 (Tuesday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

 

Presenter: Miss Xie Shujie, PhD Candidate (12:45 p.m. to 1:15 p.m.)

Title: Functional Characterization of a Phage-derived Exonuclease and DNA Recombination Protein from an Oral Neisseriaceae

Abstract: Two-component DNA homologous recombination systems comprising a DNA exonuclease and single strand DNA annealing protein (SSAP) are widely distributed throughout the prokaryotic world. Such DNA homologous recombination systems have been utilized in in vivo genetic engineering procedures – termed ‘recombineering’ – which can be used to modify plasmid or genomic DNA within bacterial cells. Based on their amino acid sequences, ‘YqaJ’ proteins have been predicted to comprise a distinct type of DNA exonuclease, within the large Lambda-Exo family of exonucleases. However, no YqaJ protein homologue has yet been functionally characterized. Here, I describe the comprehensive characterization of a YqaJ protein (KO-YqaJ) and partnering SSAP protein (KO-RecT) from Kingella oralis, a commensal species of oral Neisseriaceae. My experiment results clearly show that the KO-YqaJ and KO-RecT proteins have DNA recombination activities in bacterial cells, thus demonstrating their potential for use in recombineering applications. Taken together, data indicates that ‘YqaJ’ family exonuclease proteins are functionally equivalent to ‘Exo’ family proteins, but have several notable differences. Thus, my work shows that YqaJ proteins constitute a distinct class of DNA exonuclease.

 

Presenter: Mr. Li Peng, PhD Candidate (1:15 p.m. to 1:45 p.m.)

Title: Survival mechanism of microbial biofilm persisters and their interaction with the host

Abstract: Biofilm has been recognized as the predominant mode of microbial growth and exhibits higher drug resistance compared to its planktonic counterpart. The ability of pathogens to form biofilms is a leading cause for persistence of infections and failure of antibiotic therapy. A subpopulation of biofilms named “persisters” can survive from killing of lethal-dose antimicrobials. Persisters are phenotypic variants which are highly tolerant to multiple antimicrobials without acquiring genetically heritable resistance. The biological basis of persisters has been elusive and little is known about the interaction between biofilm persisters and the host cells. The present study focuses on the bacterial and fungal biofilm persisters of P. gingivalis and C. albicans to investigate the survival mechanism of microbial biofilm persisters and their interactive profiles with the host.

No responses yet| 61 views

May 23 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: May 30, 2014 (Friday)

Time: 12:45 p.m. to 1:30 p.m.

Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

                                                          

Presenter: Miss Zhang Shinan, PhD Candidate

 

Title: Oral health status, knowledge and behaviors of Dai and Bulang ethnic minority groups in Yunnan Province, China

 

Abstract: An oral health survey was conducted on a sample of 5- and 12-year-old Dai and Bulang children in Yunnan, China. The dental caries prevalence among the 5-year-old Dai and Bulang children was 89% and 85%, respectively. Most of the decay were left untreated. The caries experience of the 5-year-old Dai children was associated with gender, father’s education, bottle feeding habits, snacking habits, dental visit behaviour, and oral hygiene status. The caries experience of the 5-year-old Bulang children was associated with their snacking habits, dental visit habits and oral hygiaene status. The dental caries prevalence of the 12-year-old Dai and Bulang children was 40% and 35%, respectively and most of the caries were untreated. Dental caries among the 12-year-old Dai and Bulang children and associated with gender and dental attendance. Their oral health-related knowledge was moderate. Most of them had gingivitis and around half of them had dental calculus.

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May 22 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: May 29, 2014 (Thursday)

Time: 12:45 p.m. to 1:30 p.m.

Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

 

 

Presenter: Mr. Hamama Hamdi Hosni Hamdan Eldesouki, PhD Candidate

Title: Chemomechanical Caries Removal : Is it a Fact or a Science Fiction?

 

Abstract: Chemomechanical caries excavation is an excellent example of conservative caries removal methods due to its ability to reliably preserve a greater thickness of caries-affected dentine. Chemomechanical caries removal agents dissolve the denatured collagen fibrils leaving the sound and partially-degraded fibrils intact. Also, one of the main advantages of the CMCR method is its characteristic visual excavation end point sign, after this point, the solution fails to become turbid. The aim of this PhD project was to evaluate the efficacy of currently available chemomechanical caries removal  methods and its effects on tooth substrate, residual bacteria, and bonding to dentine.

No responses yet| 65 views

Mar 21 2014

Dental Research Seminar

Published by Dental Library under Dentistry
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Date: March 28, 2014 (Friday)

Time: 12:45 p.m. to 1:15 p.m.

Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

 

Presenter: Ms. Epasinghe Don Jeevanie, PhD Candidate

 

Title: Potential Applications of Proanthocyanidin for Reparative Therapies in Dentistry

 

Abstract: In dentistry, repair and restoration of tooth structure to regain its mechanical properties is the ultimate aim of caries management. Since collagen is the major part of dentine it is necessary to strengthen and preserve collagen matrix when repairing lesions involved in dentine. Proanthocyanidin is a naturally derived collagen cross linker which can strengthen and protect the collagen fibers from degradation. The present study aimed to investigate the potential applications of proanthocyanidin in dentistry.

No responses yet| 113 views

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