Student Guest Speaker Student Presenters - Faculty of Dentistry ...

1Student Guest SpeakerGrace LeeFifth year dental student Grace Lee won first prize in the Hatton competition (JuniorCategory) at the 89th General Session of the International Association for DentalResearch (IADR) in San Diego, USA in March 2011.Grace undertook a research project to investigate how drugs are pumped out ofdrug-resistant fungal cells. She developed a way of measuring pump function and usedthis to identify a pump inhibitor that could overcome fungal drug resistance.Her research was selected by the New Zealand branch of the IADR to compete inthe Australasian IADR poster competition in Kiama, Australia in 2010. She won thatcompetition and received a travel grant from Unilever to enable her to compete inthe Hatton Competition in San Diego. Here she was up against top dental studentsselected from North America, Latin America, Europe, Asia, Africa and the Middle East.Her research was supported by a University of Otago Division of Health SciencesSummer Studentship, and funding from the NIH, USA, and the Foundation forResearch Science and Technology.Student PresentersHaizal HussainiAlthea BlakeyDr Rami FarahSobia ZafarGuy FarlandPraveen ParachuruMichael SmithAnuj BatraAla Al-damehT cell anergy and immune tolerance patterns in formalin-fixedparaffin-embedded oral squamous cell carcinoma and metastaticlymph nodesExperiences of critical thinking, critical action and critical being inhealth science tutorialsMolar-Incisor Hypomineralisation: five years of researchEffects of bisphosphonate on the mevalonate pathway in humangingival fibroblastsUnder pressure: are we the same?Tregs and IL17 + cells infiltrate periodontal disease tissuesTwo bovine xenograft compared in the sheep maxillary sinus modelEffect of sodium hypochlorite and CPP-ACP on hypomineralisedenamel in Molar Incisor Hypomineralisation (MIH)Root canal preparation with two different rotary systems:comparative study assessed by micro-computed tomography

2Faculty of Dentistry – Sir John Walsh Research InstituteRESEARCH DAY PROGRAMMEHutton Theatre, Otago Museum, Dunedin, 11 August 20118.45 Registration: Hutton Theatre, Otago Museum9.00 Opening Address: Professor Peter Crampton, Pro-Vice-Chancellor,Division of Health Sciences, University of Otago9.15 Dean’s Address: Professor Gregory Seymour, Dean, Faculty ofDentistry, University of OtagoSession 1 9.30 – 10.45 Chair: Associate Professor Alison Rich9.30 Keynote Speaker: Professor E. Dianne Rekow, Senior Vice Provostfor Engineering and Technology, New York UniversityWhat compromises performance of all-ceramic crowns?10.00 Keynote Speaker: Professor Van P. Thompson, Professor and Chair,Biomaterials and Biomimetrics, NYU College of DentistryPEARL Practice Based Research Network Results: posterior compositerestoration and dentin caries activity, noncarious cervical lesion treatmentand endodontic treatment patient centered outcomes10.30 Student Guest Speaker: Grace LeeInhibiting drug efflux pumps relevant to fungal infections and cancer:developing fluorescence assays of efflux10.45-11.30 Morning Tea: Refreshments in the 1877 Gallery with our sponsor 3M’srepresentative & displaySession 2 11.30 – 1.00 Chair: Associate Professor Anita Nolan11.30 3M Presentation from Helen Gerrard, 3M Sales Specialist12.00 Keynote Speaker: Professor Shinya Murakami, Professor andChairman, Department of Periodontology, Osaka University GraduateSchool of DentistryFGF-2 stimulates periodontal regeneration12.30 Haizal HussainiT cell anergy and immune tolerance patterns in formalin-fixed paraffinembeddedoral squamous cell carcinoma and metastatic lymph nodes

312.45 Althea BlakeyExperiences of critical thinking, critical action and critical being in healthscience tutorials1.00-2.00 Lunch: To be held in the 1877 Gallery with our sponsor 3M’srepresentative & displaySession 3 2.00 – 4.00 Chair: Alison Meldrum2.00 Dr Rami FarahMolar-Incisor Hypomineralisation: five years of research2.30 Sobia ZafarEffects of bisphosphonate on the mevalonate pathway in human gingivalfibroblasts2.45 Guy FarlandUnder pressure: are we the same?3.00 Praveen ParachuruTregs and IL17 + cells infiltrate periodontal disease tissues3.15 Michael SmithTwo bovine xenograft compared in the sheep maxillary sinus model3.30 Anuj BatraEffect of sodium hypochlorite and CPP-ACP on hypomineralised enamel inMolar Incisor Hypomineralisation (MIH)3.45 Ala Al-damehRoot canal preparation with two different rotary systems: comparative studyassessed by micro-computed tomography4.00-5.00 Closing remarks from Professor Jules Kieser, Director, Sir JohnWalsh Research InstituteAnnouncement of the winner of the Best Student PresenterDrinks in the 1877 Gallery

4What compromises performance of all-ceramic crowns?E D RekowSenior Vice Provost for Engineering and Technology, New York University,United States of AmericaThis address will describe initiation and propagation of competing damage mechanismsin all-ceramic crowns. Interestingly, the first crack to develop is rarely the first topropagate to failure. The initiation sites of cracks and the ultimate mechanism offailure depend not only on the materials used to fabricate the restoration but alsoon the damage introduced during both the fabrication and clinical operations andfunctional loading by the patient. The influence of these factors on clinical performancewill be summarized. The value of different laboratory testing regimens as predictors ofclinical performance will be discussed.PEARL Practice Based Research Network Results: posterior compositerestoration and dentin caries activity, noncarious cervical lesiontreatment and endodontic treatment patient centered outcomesV P ThompsonProfessor and Chair, Biomaterials and Biomimetrics, NYU College of Dentistry, United Statesof AmericaThe address will describe practice based research and present the results of thepatient centered “effectiveness” studies in the PEARL PBRN on; Class I resinbasedcomposite restoration postoperative hypersensitivity, dentin caries activity inthese lesions, comparison of treatments for noncarious cervical lesions, as well asretrospective endodontic treatment and restorative outcomes in general practice.

5Inhibiting drug efflux pumps relevant to fungal infections and cancer:developing fluorescence assays of effluxG Lee, A Holmes, K NiimiSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandBackground: The development of multidrug resistance following upregulation of ATPbindingcassette (ABC) and major facilitator superfamily (MFS) transporters poses asignificant problem in antimicrobial and anticancer drug therapy. If inhibitors of thesetransporters can be found, combination treatments may overcome efflux-mediateddrug resistance, thus enhancing cell sensitivity to drug therapy.Aim: To develop and optimise a reproducible fluorescence-based assay of pump activitywhich mimics high throughput screening conditions.Methods: We used the fluorescent dye Nile Red, an intracellular lipid-soluble pumpsubstrate which is only fluorescent when cell-associated. This study was conductedusing a previously validated expression system involving recombinant strains of themodel non-pathogenic yeast S. cerevisiae, in which individual efflux pumps had beencloned. Yeast cells were pre-loaded with Nile Red before distribution into microtitreplate wells. Nile Red efflux from whole cells in the absence and presence of glucosewas determined by measurement of loss of fluorescence using a Synergy 2 microplatereader (Biotek, USA) with excitation and emission wavelengths at 485 and 520 nm,respectively.Results: A Nile Red concentration of 5 µM and a cell density of 7x10 7 cells/mL wereselected for an optimal efflux response. Following addition of glucose, there was a cleardose response to glucose in all recombinant strains tested. Efflux kinetics were slowerat 25 °C than at 30 °C. Effective inhibition of efflux from Mdr1p pumps by a novelcompound was observed.Conclusion: We have optimised a fluorescence-based assay to measure the activity offungal and human membrane efflux pumps. Using this optimised assay, further researchcan be undertaken to screen for clinically safe inhibitors.

6FGF-2 stimulates periodontal regenerationS MurakamiProfessor and Chairman, Department of Periodontology, Osaka University Graduate Schoolof Dentistry, JapanProfessor Murakami’s presentation will cover the following topics: molecular andcellular bases of periodontal tissue regeneration; introduction of periodontalregeneration by signaling molecules; background information on biological activitiesof FGF-2; information of medical uses of FGF-2; in vivo analyses of effects of FGF-2on periodontal regeneration (beagle dog and non-human primate models); in vitroanalyses of effects of FGF-2 on periodontal ligament cells (proliferation, migration andextracellular matrix production); clinical trial of FGF-2 for periodontal regeneration(Randomized controlled Phase II clinical trial in Japan); and the future outlook for FGF-2 therapy.

7T cell anergy and immune tolerance patterns in formalin-fixed paraffinembeddedoral squamous cell carcinoma and metastatic lymph nodesH Hussaini*, A Rich, N Firth, G SeymourSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandBackground: Oral squamous cell carcinoma (OSCC) develops in an immune cell-richenvironment, where inflammatory cells in the tumour microenvironment establishan anti-tumour response by secreting pro-inflammatory cytokines. The cancer cellsalso can induce various mechanisms suppressing the anti-tumour response such asregulating network of suppressive cytokines and recruitment of suppressive regulatoryT cells (Tregs). These escape mechanisms are seen at the local tumour site and similarmechanisms may also occur in regional lymph nodes (LN).Aim: To investigate T cell anergy and immune tolerance patterns usingimmunohistochemistry, immunofluorescence and gene expression analysis in formalinfixed paraffin embedded (FFPE) tissue from primary OSCC tissues and metastatic LN.Methods: 25 archival cases of OSCC were stained via single and/or doubleimmunostaining with T cell receptor markers including Fas and CD25/FoxP3antibodies. For investigation of gene expression a further 38 FFPE archival cases ofOSCC were divided into three groups:- 1) primary OSCC without metastasis 2)OSCC with associated metastatic LN and 3) control tissues. The expression of humanT cell anergy and immune tolerance genes was determined using focused arraytechnology via RT-PCR.Results: A higher frequency of CD25 + FoxP3 + Tregs and T cell anergy markers includingFas were observed on the lymphocytes of OSCC compared to controls. FFPE samplesprovided adequate material for RNA expression analysis. Preliminary data showed thatincreased expression of FoxP3 genes can be observed in primary OSCC tissue and LN.Conclusion: OSCC tissue and metastatic lymph nodes showed strong T cell anergy.This may contribute to the molecular ability of OSCC to metastasise to secondarylymphoid organs.This work was supported in part by grants from the New Zealand Dental AssociationResearch Foundation and the Otago Medical Research Foundation.

8Experiences of critical thinking, critical action and critical being in healthscience tutorialsA Blakey*, T Harland 1 , J Kieser 2*Faculty of Medicine, Early Learning in Medicine, University of Otago, Dunedin,New Zealand1Higher Education Development Centre, University of Otago, Dunedin, New Zealand2Sir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: Educating for critical thinking is a fundamental purpose of higher education yetparadoxically, critical thinking concepts are diffuse and difficult for some to understandand use in practice. Ronald Barnett proposes that such concepts are also self-limitingand fail to realize the emancipatory potential that higher education offers. In response,Barnett developed concepts of critical thinking, critical action and critical being. Thisthesis examines these concepts for utility in the very place that higher educationupholds for critical thinking development.Methods: Four case studies of small teaching groups were investigated; teachingsessions were videotaped, tapes replayed to teachers and students, and responsestaped using Interpersonal Process Recall (IPR). Responses were transcribed alongsideinterviews with group teachers. Data were analysed and themes developed in termsof teachers’ and students’ perceptions of their own thinking processes, the nature ofcritical thought, critical action and critical being in teaching and learning, what studentsand teachers do to enhance these critical processes. In particular, data were examinedfor meaning in terms of Barnett’s concepts.Results: Results supported Barnett’s concepts in that critical thinking is purposeful andindividualistic but also that critical thinking can result in suboptimal student outcomes,that true critical actions occur in social contexts and that critical being begins with therealization of ones values and has potential to develop in undergraduate education.Conclusion: This thesis offers many ways for teachers to inform their practice and offersadvice to students who wish to develop such critical processes. Students need towork hard, take risks, choose actions depending on what is going on around them anddevelop the ability to apply critical thinking and action to all life experiences. Studentsalso need to realize their own values but in doing so also face the possibility theyappear a little different to others in professional life.

9Molar-Incisor Hypomineralisation: five years of researchR Farah*, B Drummond, B Monk, M SwainSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: To assess the biochemistry, biomechanics and structure of Molar-IncisorHypomineralisation (MIH) enamel.Methods: Several methods were employed to address the aims of the study. Clinicalpresentation and laser fluorescence were used for assessment of the severity of MIHand they were linked to the mineral density of the enamel (as measured by X-raymicrotomography) and its mechanical properties (as measured by nanoindentation).Polymerase chain reaction (PCR) was used for detection of bacterial penetration intoMIH enamel. Proteomic assays quantified and qualitatively assessed the proteinouscontent of MIH and sound enamel. Immunohistological examination of the enamelmatrix was also used to trace the distribution of certain protein markers.Results: MIH enamel showed significant reduction in its mineral density and itsmechanical properties, which showed strong correlation with the clinical appearanceand the laser fluorescence of the enamel. No bacterial penetration into MIH enamelwas detected with the PCR assessment. MIH enamel had 20-fold higher proteincontent than sound enamel. A substantial amount of serum and blood proteinsappeared to gain access into MIH enamel during its formation, and prevent it fromachieving full maturation.Conclusion: MIH enamel is unlike any other hypomineralised enamel. A possible modelfor its aetiology is described in this study.

10Effects of bisphosphonate on the mevalonate pathway in human gingivalfibroblastsS Zafar*, D Coates, G Seymour, B Drummond, M CullinanSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandBackground: Bisphosphonates (BPs) are prescribed for the treatment of bone diseasesthat involve excessive bone resorption. Bisphosphonate related osteonecrosis of thejaw (BRONJ) is now a widely recognized dental condition in which the key finding isexposed necrotic bone in the oral cavity. However the mechanisms underlying BRONJare poorly understood.Aim: The aim of the present study was to test the hypothesis that the effect of thenitrogen containing BP, zoledronic acid (ZA), on human gingival fibroblasts (HGFs) ismediated via the mevalonate pathway (MP) and that HGFs function could be restoredby the addition of exogenous isoprenoids, such as farnesol (FOH) and geranylgeraniol(GGOH) which replenish the cytosolic isoprenoid substrate of the MP.Methods: Primary cultures of HGFs were developed from gingival tissues excisedduring gingivectomy/crown-lengthening surgeries. HGFs were seeded in 96-wellplates, ZA (30µM) alone and in combination with farnesol (FOH) or geranylgerionyl(GGOH) was added to the cultures. Cell proliferation was measured at 72hrs using acell titer blue cell viability assay.Results: Cell proliferation was significantly inhibited by ZA but the simultaneousaddition of GGOH ameliorated the effect of ZA and completely restored the cells tothe control state. However, the simultaneous addition of FOH with ZA only partiallyrestored cellular proliferation.Conclusion: The results of the present study not only support the hypothesis andindicate that the effect of ZA on HGFs is mediated, at least in part, via the MP but alsosuggest possible therapeutic / preventive strategies for BRONJ.

11Under pressure: are we the same?G Farland*, J Kieser, M FarellaSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: To analyse patterns of pressure change across the hard palate within healthyvolunteers swallowing substances of differing viscosity.Methods: I used a custom made appliance with 7 miniature pressure transducerslocated along the mid-line and lateral palate to measure absolute pressures during10ml water and honey-thick liquid swallows. Data were obtained from 10 healthyvolunteers (5 males, 5 females; 22-42 years) with full permanent dentition. Followingaccommodation, subjects performed liquid swallows on command. Each subjectperformed swallows on 2 subsequent days yielding data from 12 swallows perindividual for each liquid.Results: When highly variable individual pressure patterns were aligned on the initialpeak of the mid-palatal channel, an underlying pattern common to all subjects wasfound. This was divided in to 4 stages: preparatory, primary propulsive, intermediateand terminal. Individuals could then be sub-classified within these stages to facilitatedescriptive analysis. Though there was an increase in the frequency of certain subclassificationswith increased viscosity, the response was highly individual and someindividuals showed no difference. Inter-individual variation of absolute pressures wastoo great to derive any significant change at the group level. Significant changes inpressure values were, however, found at the individual level. These were highly variablewith respect to region, polarity and the individual.Conclusion: Though there is an underlying pressure pattern common to all, responsesto increased viscosity vary markedly between individuals. As such effects of swallowinginterventions on pressure generation should be analysed at the individual rather thatthe population level.

12Tregs and IL17 + cells infiltrate periodontal disease tissuesP Praveen * , G Seymour, A Rich, T Milne, D Coates, M Cullinan, N HengSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandBackground: The role of two recently identified and closely related T-helper cellsubsets, regulatory T-cells (Tregs; FoxP3 + ) and Th17 cells (IL-17 + ), in periodontaldisease is yet to be determined. Tregs are essential in maintaining peripheral toleranceand regulating the immune response. Alternatively, Th17 cells play a critical role inseveral autoimmune diseases, inflammation and host defence. Hence, it is reasonableto assume that the balance between Th17 and Tregs may be critical in the chronicperiodontal disease process.Aim: The initial aim of this study was to determine the expression of FoxP3 andIL-17 in tissues with periodontal disease and to determine the nature of cell typesexpressing FoxP3 and IL-17, the topographical relationship between FoxP3 + and IL-17 +cells and the relative proportion of FoxP3 + and IL-17 + cells.Methods: Using immunohistochemistry and immunofluorescence techniques, twentyninearchival formalin-fixed paraffin-embedded hyperplastic/non-specific inflammatorygingival samples and twenty fresh gingival samples obtained during periodontalsurgical procedures were examined and the presence of FoxP3 + and IL-17 + cells wasdetermined and their relationship to each other and to other cells was established.Results: Both FoxP3+ and IL17+ cells were detected in all samples. More FoxP3 + cellsthan IL-17 + cells were observed in both T-cell and B-cell/plasma cell predominant tissues.FoxP3 was localized within CD4+ cells but not in CD8+ cells in periodontal diseasedtissues. The majority of IL-17 expression was localized within tryptase+ mast cells.Conclusion: These results suggest that FoxP3 + cells may have a more prominent role inperiodontal disease process when compared to IL-17 + cells and that the major sourceof IL-17 in periodontal tissues appears to be mast cells.

13Two bovine xenograft compared in the sheep maxillary sinus modelM Smith*, W Duncan, D Coates, A Tawse-Smith, J Leichter, A RichSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: To compare the healing of two xenograft materials in a sheep sinus model.Methods: Grafts of MB or BO were placed, via an external approach, in the maxillarysinuses of eight sheep. Contra-lateral sinuses were grafted with the alternate material.Two sheep / time period were sacrificed 4, 6, 8 and 12 weeks post-operatively.The harvested graft-sites were halved and processed into undemineralised resinembeddedand demineralised paraffin-embedded sections. The following parameterswere described: histologic healing, new bone formation, bone-to-graft contact, graftresorption and Tartrate Resistant Acid Phosphatase (TRAP) staining for osteoclasts.Results: Both materials were associated with osteoclasts at 4 and 6 weeks, howeveronly MB showed signs of resorption during the study period. Only BO was associatedwith significant new bone before 8 weeks. Both materials associated with new boneafter 12 weeks, however only MB showed signs of graft remodeling.Conclusion: BO did not resorb over the healing period studied in this animal model,whereas MB showed evidence of resorption. Both xenografts were associated withnew bone growth. The development of resorbable bone augmentation materialsis desirable in order to achieve peri-implant bone capable of natural modeling andremodeling.

14Effect of sodium hypochlorite and CPP-ACP on hypomineralised enamelin Molar Incisor Hypomineralisation (MIH)A Batra*, B Drummond, M Swain, J KieserSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: To evaluate the effect of (1) 5% sodium hypochlorite in removing proteins and onmechanical properties in MIH enamel (2) CPP-ACP on hypomineralised enamel withand without treatment with 5% sodium hypochlorite.Methods: Six samples were sectioned mesiodistally/buccolingually and mounted inclear acrylic resin with the aim of keeping only the external hypomineralised enamelexposed. Enamel was polished using a specific protocol following which the sampleswere divided into four study groups of three samples each: (a) Sodium hypochlorite(NaOCl) treatment (b) Sodium hypochlorite (NaOCl) and Tooth Mousse (TM)treatment (c) No treatment (d) Tooth Mousse treatment. All the samples weresubjected to nanoindentation, confocal microscopy (using FITC, a protein bindingmarker) and laser fluorescence (using DIAGNOdent) before and after treatment, andafter storage for 30 days in hank’s solution.Results: Application of sodium hypochlorite decreased the protein content andmechanical properties of MIH enamel and subsequent storage in Hank’s solution andTM TM did not improve the mechanical properties. A significant drop in DIAGNOdentreadings was observed after hypochlorite treatment. Storage in Hank’s solutionresulted in an increase in surface H and E while storage in Hank’s solution and TM TMalso improved the mechanical properties of MIH enamel.Conclusion: Single application of sodium hypochlorite removes protein from the surfaceof hypomineralised enamel and results in reduction of its mechanical properties.Application of CPP-ACP after sodium hypochlorite treatment does not improve themechanical properties of hypomineralised enamel whereas its application withouthypochlorite treatment improves the mechanical properties.

15Root canal preparation with two different rotary systems: comparativestudy assessed by micro-computed tomographyA Al-dameh*, R Love, R FarahSir John Walsh Research Institute, Faculty of Dentistry, University of Otago, Dunedin,New ZealandAim: To evaluate root canal transportation of BioRaCe and AlphaKite rotaryinstruments, and their efficiency in eradicating canal variations.Methods: Mesiobuccal roots of 20 maxillary first molars with similar angles of curvaturewere divided randomly into two groups and scanned using a micro-computedtomography scanner (SkyScan, Belgium). Root canals were then prepared withBioRaCe instruments (FKG Dentaire, Switzerland) or AlphaKite (Komet, Germany).The prepared roots were re-scanned and cross-sectional images of the pre- andpost- instrumentation scans were reconstructed using the appropriate software.Transportation was assessed by using a formula, where a value of zero indicates notransportation, a positive value indicates transportation toward the outside of thecurve, and a negative result indicates transportation toward the inside of the curve.Three dimensional images of the roots were then reconstructed to evaluate theefficiency of the two systems in removing canal variations.Results: Canal transportation using BioRaCe in the coronal, middle, and apical thirdswas (-0.12 ± 0.19 mm), (-0.01 ± 0.09 mm) and (0.06 ± 0.05 mm) respectively, with asignificant difference (P < 0.05) between the coronal and apical levels. Transportationusing AlphaKite in the coronal (-0.05 ± 0.22 mm), middle (-0.04 ± 0.10 mm) andapical thirds (0.03 ± 0.03 mm) showed no significant difference between the groups(P > 0.05). No statistically significant difference between the two systems was found atany levels (P > 0.05). Both systems were unable to completely remove canal variations.Conclusion: Within the limitations of this ex vivo study both systems produced minimalcanal transportation.

16The Faculty of DentistrySir John Walsh Research InstituteResearch Day 2011is proudly sponsored byUnitekESPE