Date: April 26, 2013 (Friday)
Time: 12:45 p.m. to 1:30 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Miss Sununliganon Laddawun, PhD Candidate

Title: Stem cell approach for maxillary sinus grafting in atrophic maxilla

Abstract:

Maxillary sinus grafting is required in atrophic maxilla to facilitate dental implant placement.  Autogenous bone is a standard grafting material but bone harvesting procedure is traumatic to patients.  Bone substitute is used as an alternative but bone formation is limited.  Mesenchymal stem/stomal cells (MSC) supplement to promote bone regeneration was introduced to provide a cellular-based tissue engineering method.

This study aimed to evaluate the bone regeneration capacity of bone marrow aspirate concentrate (BMAC) in maxillary sinus grafting.  Quantitative and qualitative analysis of bone marrow aspirate was performed before and after concentration. Animal study in rabbits’ maxillary sinus was carried out to compare 4 grafting materials.   A pilot human study was also conducted.  The results showed that bone marrow aspirate can be concentrated by a one-step centrifuge method with confirmation of the presence of MSCs having differentiation capabilities.  In addition, BMAC transplantation is a worthy therapeutic option for bone grafting.

Date: March 26, 2013 (Tuesday)
Time: 1:15 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Mr. Huo Yongbiao, PhD Candidate

Title: Diversity, distributions and virulence factors of established and emerging periodontal pathogens

Abstract: Periodontal disease has a complex and highly variable bacterial etiology. A number of recent studies have noted that complex and diverse communities of oral treponemes, as well as a recently described group of bacteria called Synergistetes, are present within diseased periodontal sites. In this talk, the review of what is currently known about the distributions and etiological roles of Synergistetes and oral treponemes in periodontal disease processes will be given as well as the research plans, which are largely focused on investigating the clinical distributions of these two sets of putative periodontopathogens, with the aim of better-defining their etiological roles in disease processes. Specifically, this study is to investigate the differences in component species, species-levels ‘phylogroups’ and various other taxa, which are present within periodontal-diseased sites, versus disease-free sites. To achieve this, the reliable genetic and other methods that can be used to discriminate different Synergistetes and oral treponeme strains (taxa) will be developed, and to establish their genetic ancestry. In addition, this research is aiming to study on the form and function of one or more bacterial cell surface proteins, which have been suggested to play a role in periodontal pathogenesis and/or virulence.

Date: February 22, 2013 (Friday)
Time: 12:45 p.m. to 1:30 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Ms Xin Weini, PhD Candidate

Title: A randomized controlled trial on the efficacy of fluoride varnish in preventing dental caries of Sjögren’s syndrome patients

Abstract:
OBJECTIVES: The primary objective of this study was to evaluate the efficacy of fluoride varnish in preventing new caries on coronal and root surfaces of teeth over a 24-month period in Chinese Sjögren’s syndrome (SS) patients. Secondary objective was to investigate the effect of fluoride varnish on oral microorganism (Candida and lactobacilli).

METHODS: A total of 85 SS patients participated in this study. They were randomly assigned to two groups to receive either fluoride varnish or placebo gel quarterly. Dental examination, and assessment of the sicca symptoms, oral hygiene, salivary flow / pH / buffering capacity and oral microbiological profiles were carried out at the baseline, 12-month and 24-month visits.

RESULTS: Seventy-eight patients (92%) completed the 24-month assessment. At the 24-month visit, no statistically significant differences (Mann-Whitney test, P > 0.05) were found between the fluoride and the placebo groups regarding their mean numbers of coronal surfaces with new enamel caries lesions (fluoride: 1.6; placebo: 1.6), arrested caries lesions (fluoride: 0.6; placebo: 0.7), and also root surface caries lesions (fluoride: 0.3; placebo: 0.1). The SS patients who had received application of fluoride varnish were significantly less likely to develop active dentin caries in coronal surfaces over the 24-month study period (P = 0.035). The caries prevented fraction of fluoride varnish for coronal dentin caries was 33.3%.

No significant differences in the mean counts of Candida and lactobacilli between fluoride and placebo groups were detected (Mann-Whitney test, P > 0.05).

CONCLUSIONS: Fluoride varnish may be efficacious in preventing coronal active dentin caries in Chinese patients with SS. However, it may not be efficacious in preventing root caries and has no effect on oral microorganism.

Date: January 31, 2013 (Thursday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

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

Title: Aspects of bonding between resin luting cements and glass ceramic materials

Abstract: Glass ceramics are widely used in dental restorations because of their excellent esthetic performance. Nowadays, there are increasing cases where the retention of restorations is reliant on bonding. Hence, the quality of bonding is of increasing importance, and is a dominant factor required for the long-term success of glass ceramic restorations. It is accepted that adhesion between ceramics and resin cements is provided by two major mechanisms: micromechanical attachment and chemical bonding. However, no wide agreement has been reached for optimal bonding. Furthermore, the ceramic and resin cement bond is subjected to a complex environment in the oral cavity being influenced by several extrinsic factors. Consequently, laboratory testing should simulate these variables to enable the development of superior materials and surface preparation methods that provide long-term durable bond strengths in the oral environment.

The aim of this study is to analyze laboratory studies investigating the resin cement bond to glass ceramics, to compare two bonding models using a microtensile bond strength test and to evaluate the effect of surface treatments on resin ceramic bonding as well as to evaluate the influence of different storage media on the ceramic/resin bond.

 
Presenter: Mr. Liu Quan, PhD Candidate (1:15 p.m. to 1:45 p.m.)

Title: Studies on bone minerals: micro/nano-structural and compositional investigations, assessments and simulations

Abstract: Skeleton is of great importance to vertebrates since bones are responsible for the supporting and moving of animal body, mineral storage as well as hematopoiesis. Biological apatite is the main inorganic component of biological hard tissue, including human bones and teeth. Because of such a similarity, animal bone-derived grafting materials have been used for bone reconstruction in dentistry and medicine. Given the clinical value of biological apatite, numerous studies about its basic knowledge and clinical performance have been done. However, some gaps, limitations and problems about the morphology, crystal size, solubility and biodegradation of biological apatite still remain. Hence, this study is to investigate the micro/nano-structure and chemical compositions of series of vertebrate bones; to assess the physiochemical properties of biological apatite; and to examine the effect of various ions to the solubility of biological apatite by taking hydroxyapatite as a simulative model, aiming at obtaining a comprehensive understanding of the physiochemical properties of bone minerals.

Date: January 29, 2013 (Tuesday)
Time: 12:45 p.m. to 1:30 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

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

Title: Genetic risks for chronic periodontitis: A genome-wide association study

Abstract: A case-control study of 900 Southern Chinese (35 to 88 years) will be carried out to investigate the association between chronic periodontitis and genetic polymorphisms. Clinical periodontal status will be recorded and all subjects’ DNA will be genotyped. Specific alleles will be selected after the genome-wide screening of samples for polymorphisms associated with chronic periodontitis. The findings will be validated by a replication study targeting a cohort of 350 periodontitis and 350 periodontitis-free subjects.

 
Presenter: Miss Yan Haiping, PhD Candidate (1:15 p.m. to 1:30 p.m.)

Title: The mechanism and inhibition study of secreted aspartic protease in the interaction between C.albicans and oral epithelial cells

Abstract: In this seminar, firstly, a thorough literature review will be given to introduce the previous research about the mechanism and inhibition study of Saps in the interaction between C. albicans and oral epithelial cells. Secondly, three null hypothesizes on the aforementioned interaction will be discussed. Materials and methodology will also be discussed. Results of pilot studies and expected outcomes and interpretation of expected outcomes will be presented in the end.

Date: January 3, 2013 (Thursday)

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

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

Presenter: Dr. Khaing War War, MPhil Candidate

Title: Dental pulp stem cells isolation from Inflamed dental pulp tissues and comparisons of cytotoxic effcets of endodontic irrigants on dental pulp stem cells

Abstract: The dental pulp is regarded as most accessible source of mesenchymal stem cells that can be obtained at any age of an individual’s life. Many authors have been proposed that stem cells can be recruited from dental pulp tissues that are extirpated and discarded during invasive pulp treatments. Dental stem cells may be found from various sources situated inside or around the tooth. Inflamed pulp can be one such source and it has been demonstrated that functional putative stem cells exist in clinically inflamed pulps.

Regenerative approach for pulp canal therapy depends on the proliferation of seeded dental pulp stem cells within the root canal space that has been cleaned and disinfected by chemical irrigation agents. These chemicals may influence the attachment and survival of stem cells on the root canal dentine with direct impact on the regeneration of tissues. The aims of this in vitro study are to isolate stem cells from inflamed dental pulp tissues and to investigate the ability of stem cells to attach to root canal dentine that has been treated by various endodontic irrigants. This would be an indirect measure of the cyototoxic effects of these irrigants on the vitality of dental pulp stem cells.

Date: November 5, 2012 (Monday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

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

Title: Regeneration of tooth microstructure by a biomimetic mineralization method

Abstract: Dental erosion is tooth surface loss caused by chemical processes without bacterial involvement. Studies reported that the prevalence of dental erosion in children and adults were up to 82% and 54%, respectively. Dental erosion is also an important cause for dentine hypersensitivity. Restorative treatment is necessary when the loss of dental tissue is substantial. Conventional treatments of tooth defect focus on repair by dental materials such as silver amalgam and composite resin. However, this invasive approach has its limitations mainly because of its damage to the remaining sound dental tissue. Researchers therefore aim to pursue non-invasive therapeutic strategies to manage this challenging problem through remineralisation of dentine and enamel. This in vitro study aims to induce enamel and dentine regeneration to manage tooth defects by using biomimetic remineralization technology.

Presenter: Miss Ito Leticia, MPhil Candidate (1:15 p.m. to 1:45 p.m.)

Title: Arresting and preventive effects of silver diamine fluoride application and Er:YAG laser irradiation against dental caries

Abstract: Clinical trials found silver diamine fluoride (SDF) is effective on preventing and arresting coronal (enamel) caries. Another clinical trial demonstrated that SDF is effective in root (dentine) caries. SDF can also inhibit mono species biofilm formation, increase the fluoride content and reduce loss of calcium and phosphates. Studies also suggest laser irritation after topical sodium fluoride application increase fluoride uptake on dental hard tissues. Current literature however found no study reporting the effect of Er:YAG laser irradiation and SDF on caries lesions. Therefore, this in vitro study aims to investigate the caries preventive and arresting effect of SDF and Er:YAG laser irradiation with cariogenic biofilm. This study investigates the caries preventive and arresting effects on human enamel and dentine.

Date: October 16, 2012 (Tuesday)

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

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

Presenter: Mr. Ushida Keisuke PhD Candidate 

Title: Analysis of Oral Cancer Development in Hong Kong and Guangzhou

Abstract:

Oral cancer is the eleventh most common cancer worldwide (2008) and represents 2-4% of all diagnosed cancers. The morbidity and mortality associated with oral cancer can be reduced by primary prevention and early detection. After the Second World War, lifestyle in Hong Kong has been strongly influenced by other cultures, because of political reasons and geographical location. On the other hand, after “the reform and door- opening policies”, especially coastal cities of the PRC, made great economical strides. 95% of the population in Hong Kong are of Chinese ethnicity, mainly immigrated from southeast Chinese provinces.This represents a unique situation to investigate individuals of the same ethnicity living with different systems and different lifestyles.

The aim of this study is to figure out adaptive oral cancer risks, socio-historical imprint on cancer development, and current epidemiological differences in these two areas with very similar ethnicities. Because of the ethnic and cultural homogeneity, the result of this study might lead to more adequate health promotions, and to a prediction of public health condition changes in the near future in both areas.

Date: April 30, 2012 (Monday)
Time: 12:45 p.m. to 1:15 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Dr. Du Yanlin Rennan PhD Candidate

Title: Oral Health Promotion among Children with Autism Spectrum Disorder

Abstract:
Autism Spectrum Disorders (ASD) comprises a heterogeneous spectrum of neuro-developmental disorders that includes Autistic disorder, Asperger’s syndrome and pervasive development disorder not otherwise specified (PDD-NOS). It is behaviourally defined and characterized by impairments in communication and social interaction, along with repetitive, stereotypical patterns of behaviour, interests, or activity (APA 2000).

A systematic review has estimated that ASD affects approximately 20 per 10,000 children globally (Williams et al. 2006). In Hong Kong SAR, the prevalence of ASD among children under the age of 15 is 16.1 per 10,000, and the male to female ratio is ~6:1 (Wong and Hui 2008).

Several studies have reported a higher prevalence of dental caries experience (DMFT>0) among children with autism, when compared to unaffected children (Marshall et al. 2010; Lowe and Lindemann 1985). Studies among children with ASD have reported the prevalence of gingivitis to be between 50-60% (Klein and Nowak 1999, DeMattei et al. 2007). Past research has shown that children with autism and their families have compromised quality of life (QOL) in several domains. (Kuhlthau et al. 2010, Kamp-Becker et al. 2010, Allik et al. 2006, Shu 2009).

The objectives of our study is 1) to compare the clinical oral health and the subjective oral health among preschool children with and without ASD; 2) to evaluate the effectiveness of a visual pedagogy intervention in the performance of the task of tooth-brushing and improvement in oral hygiene status and gingival health among preschool children with ASD; 3) to evaluate the effectiveness of a visual pedagogy intervention in the performance of oral examination among children with ASD.

Date: April 18, 2012 (Wednesday)
Time: 12:45 p.m. to 1:45 p.m.
Venue: Lecture Theatre II, G/F, The Prince Philip Dental Hospital

Presenter: Ms. Yan Fung, PhD Candidate (12:45 p.m. to 1:15 p.m.)

Title: Resin-zirconia bonding

Abstract:
Objectives. The aim is to develop and evaluate surface treatments of zirconium dioxide (zirconia) to enhance the bond strength between zirconia and resin. Materials and methods. Laser irradiation and chemical coatings of the zirconia surface will be tested to evaluate their respective effects of resin-zirconia bonding. Four groups of sintered zirconia specimens will be subjected to different surface treatments: sandblasting, Er;Cr:YSGG laser irradiation, combined using of glass infiltration etching and silanization, and non-treated control. Composite resin stubs will be bonded to surface-treated specimens using acidic adhesive cement. Specimens will be aged in dry, water storage and thermocycling conditions before microtensile bond strength (MTBS) tests are carried out by a universal testing machine. Failure modes of zirconia interfaces will be analyzed.

Results. Based on the literature review, sandblasting can enhance the resin-zirconia bonding but microcracks might occur. Laser, silanes and glass coating could be alternative methods but no comparative studies have been presented. Optimization of each technique by changing different parameters is not yet established.

Conclusion. Different surface treatments might enhance the resin-zirconia bonding in vitro. The optimization of various parameters is needed to maintain the long-term stability of resin-zirconia bonding.

Presenter: Ms. Chan Kit Ping Cordelia, MPhil Candidate (1:15 p.m. to 1:45 p.m.)

Title: Comparing the effectiveness of a new innovative desensitizing paste to a home-used desensitizing toothpaste in reducing dentine hypersensitivity among Chinese adult

Abstract: Dentine hypersensitivity is a common oral problem.  Professional application of high concentration (2.26% F) fluoride topically has been used to treat dentine hypersensitivity for many years however the post-operative care can be a nuisance for some patients.

The purpose of the study is to compare the effectiveness of using 8% arginine and calcium carbonate desensitizing paste in dental office and 8% arginine, calcium carbonate and 1450ppm fluoride desensitizing toothpaste at home in reducing dentine hypersensitivity.  This 12 weeks study will involve 56 subjects who are students or staffs of The University of Hong Kong.  Clinical assessment of dentinal hypersensitivity to both cold and tactile stimuli will be performed at baseline, week 4 and week 12.