FoD Research Day 2018 1 | Page Handout_for website.pdf · FoD Research Day 2018 4 | Page SESSION 1...

FoD Research Day 2018 1 | P a g e


Contents SESSION 1, 8.05AM – 1.05pM: POST GRADUATE STUDENTS PRESENTATION ........................... 4

PG01 Bioprinting of Functional Salivary "Mini-Glands" from Human Oral Stem Cells ...................... 6

PG02 Dental Plaque pH In Predicting Caries Relapse After General Anesthesia .............................. 7

PG03: Ethnic Differences In Caries Susceptibility In A Multi-ethnic Asian Cohort ............................ 8

PG04: Neural Differentiation of Dental Pulp Stem Cells on Advanced 2D Materials ...................... 10

PG05: Use Of Haploid Candida Albicans Model In Drug Discovery................................................. 11

PG06: MSC Exosomes Alleviate Pain and Tissue Degeneration In TMJ-OA ................................... 12

PG07: Effects Of Hyperglycemia On Immune Modulatory Effects Of Porphyromonas Gingivalis .. 13

PG08: Therapeutic Potential of MSC Exosomes For Periodontal Regeneration ............................. 14

PG09: Bacterial Species Associated with Persistent Apical Periodontitis Exert Differential Effects on Osteogenic Differentiation ....................................................................................................... 16

PG10: Retrospective Study On Aesthetic Outcomes of Anterior Dental Implants...........................17

PG11: Surface Topographies Modulate The Differentiation Of Dental Pulp Stem Cells In Vitro ..... 18

PG12: Masticatory Efficiency And Food Preferences After Dental Rehabilitation In Children with Severe Early Childhood Caries ....................................................................................................... 20

PG13: Validation Of Early Childhood Oral Health Impact Scale (ECOHIS) Among Preschoolers with Autism ........................................................................................................................................... 21

PG14: The Effect Of Parenting Styles On Enforcement Of Oral Health Behaviours In Children ..... 22

PG15: Associations between TMD symptoms, Quality of Life and Psychological States in Asian Military Personnel ......................................................................................................................... 23

PG16: Effect of Periodontal Therapy on Patients Treated with Calcium Channel Blockers ............ 25

PG17: Spectrophotometric and Visual Evaluation of Maxillary Anterior Single Implant Restorations ...................................................................................................................................................... 26

PG18: Clinicians’ Decision Making In Borderline Class III Orthodontic–Orthognathic Surgery Cases ...................................................................................................................................................... 27

PG19: Quality Of Life (QOL) In Patients with Dentofacial Deformities Undergoing Orthodontic-Orthognathic Management ........................................................................................................... 29

PG20: Prevalence of Dental Anomalies in Various Antero-Posterior and Vertical Skeletal Types in a Chinese Orthodontic Population ................................................................................................... 30

SESSION 2, 2.10pm – 3.30pm: STAFF PRESENTATIONS ........................................................... 32

STF01:Modelling An In Vitro Organotypic Model of Human Atopic Dermatitis .............................. 33

STF02:The Role of Oral Microbiota in the Severity of Chemotherapy-Induced Oral Mucositis ...... 34

STF03:Distribution And Chondroprotective Effect Of Pericellular Matrix Molecules In TMJ .......... 34

STF04:The Multi-faceted Mechanism of MSC Exosomes in Cartilage Repair ................................. 35


SESSION 3, 3.50pm – 5.10pm: STAFF PRESENTATIONS ........................................................... 37

STF05:Effects Of Probiotics On Fusobacterium Nucleatum-mediated Inflammatory Response In Colonic Cells .................................................................................................................................. 38

STF06:pH-Responsive Protein Corona for Caries Risk Assessment ................................................ 38

STF07: One-atom-thick Graphene Coating Enhances Orthotopic Bone Formation on Titanium Implants ........................................................................................................................................ 39

STF08: Accuracy Of Digital And Conventional Implant Impressions In Edentulous Arches ............ 40


SESSION 1, 8.05AM – 1.05pM: POST GRADUATE STUDENTS PRESENTATION

PG01: Bioprinting of Functional Salivary "Mini-Glands" from Human Oral Stem Cells Ms Christabella Adine, PhD PG02: Dental Plaque pH In Predicting Caries Relapse After General Anesthesia Dr Ashish Chetan Kalhan, PhD PG03: Ethnic Differences In Caries Susceptibility In A Multi-ethnic Asian Cohort Dr Tosha Ashish Kalhan, PhD PG04: Neural Differentiation of Dental pulp Stem Cells on Advanced 2D Materials Ms Thulasi Thiruvallur Madanagopal, PhD PG05: Use Of Haploid Candida Albicans Model In Drug Discovery Ms Truong Nhat Quynh Thuyen, PhD PG06: MSC Exosomes Alleviate Pain and Tissue Degeneration In TMJ-OA Dr Zhang Shipin, PhD PG07: Effects Of Hyperglycemia On Immune Modulatory Effects Of Porphyromonas Gingivalis Ms Ong Zoei, MSc PG08: Therapeutic Potential of MSC Exosomes For Periodontal Regeneration

Dr Chew Ren Jie Jacob, MDS

PG09: Bacterial Species Associated with Persistent Apical Periodontitis Exert Differential Effects on Osteogenic Differentiation

Dr Chow Ai Tee, MDS

PG10: Retrospective Study On Aesthetic Outcomes of Anterior Dental Implants

Dr Alethea Foong Li Yen, MDS

PG11: Surface Topographies Modulate The Differentiation Of Dental Pulp Stem Cells In Vitro

Dr Heng Pei Fang, MDS


PG12: Masticatory Efficiency And Food Preferences After Dental Rehabilitation In Children with Severe Early Childhood Caries

Dr Jessica Khong Sok Yin, MDS

PG13: Validation Of Early Childhood Oral Health Impact Scale (ECOHIS) Among Preschoolers with Autism

Dr Lim Wei Ying Justine, MDS

PG14: The Effect Of Parenting Styles On Enforcement Of Oral Health Behaviours In Children

Dr Quek Shumin Judith, MDS

PG15: Associations between TMD symptoms, Quality of Life and Psychological States in Asian Military Personnel

Dr Tay Koong Jiunn, MDS

PG16: Effect of Periodontal Therapy on Patients Treated with Calcium Channel Blockers

Dr Ho Wen Nee, MDS

PG17: Spectrophotometric and Visual Evaluation of Maxillary Anterior Single Implant Restorations

Dr Wong Jin Lin, MDS

PG18: Clinicians’ Decision Making In Borderline Class III Orthodontic–Orthognathic Surgery Cases

Dr Karen Kai Rou Voon, MDS

PG19: Quality Of Life (QOL) In Patients with Dentofacial Deformities Undergoing Orthodontic-Orthognathic Management

Dr Joyce Ong Li TIng, MDS

PG20: Prevalence of Dental Anomalies in Various Antero-Posterior and Vertical Skeletal Types in a Chinese Orthodontic Population

Dr Chan Xiu Ling, Grace, MDS


PG01 Bioprinting of Functional Salivary "Mini-Glands" from Human Oral Stem Cells Christabella Adine1, Adeline Koh1, Phoebe Grace Castillo1, Kiaw Kiaw Ng1, Glauco R. Souza2

Joao N. A. R Ferreira1 1National University of Singapore 2University of Texas Health Sciences Center

Objectives

Radiotherapy, the preferred therapy for head and neck cancers, can irreversibly damage the saliva-secreting cells from salivary glands (SG) in about 40-60% of patients [1]. This damage results in dry mouth, which increases the susceptibility to oral infections, decreasing the quality of life of patients. Current options for dry mouth therapies are heavily dependent on the limited number of residual SG secretory cells. Hence, cell-based approaches to replace and/or regenerate the damaged SG epithelia are paramount [2], together with the use of mesenchymal-derived stem cells, like human dental pulp stem cells (hDPSC). Thus, our aim was to generate saliva-secreting epithelial cells arranged in 3D organoids using a novel culture system [3], the magnetic 3D bioprinting (M3DB) from hDPSC.

Methods

hDPSCs were expanded as 3D spheroids followed by an epithelial differentiation step using two systems, the novel M3DB and 3DFA (a conventional 3D system similar to M3DB but without magnetic nanoparticles). Cleaved Caspase 3 and intracellular ATP was assessed in spheroids to determine cell viability and survival. These spheroids were evaluated for functional secretion, trans-epithelial resistance, TEM and characterized genotypically and phenotypically by qPCR and whole-mount immunofluorescence, respectively.

Results

3D spheroids using M3DB system exhibited similar proliferation to conventional 3DFA after 3 days in vitro. The differentiated 3D organoids showed increase expression of α-amylase at gene and protein levels compared to undifferentiated spheroids. Furthermore, these differentiated 3D spheroids express diverse SG cellular markers including acinar epithelial secretory (AQP5, Amy1, Chrm3), ductal epithelial (KRT14, KRT5), pan-neuronal (B3-tubulin). This was dependant on Fibroblast Growth Factor-10 (FGF-10), a key signalling cue in SG development [4]. Upon parasympathetic and sympathetic neuro-stimulation, salivary α-amylase was increased as well as calcium influx, and trans-epithelial electrical resistance, when compared to conditions when FGF-10 was absent. Electron microscopy further confirmed the presence of tight junctions between secretory cells as well as secretory granules in differentiated 3D spheroids.

Conclusion

Overall, this tissue construct indicates the presence of a functionally innervated SG-like secretory epithelia organoid, comparable to a “mini-SG”. This project offers a promising 3D bio-printing therapeutic solution to alleviate dry mouth in irradiated cancer patients.


References

1. Jensen, S.B., et al., A systematic review of salivary gland hypofunction and xerostomia induced by cancer therapies: prevalence, severity and impact on quality of life. Supportive Care in Cancer, 2010. 18(8): p. 1039-1060.

2. Lombaert, I., et al., Concise Review: Salivary Gland Regeneration: Therapeutic Approaches from Stem Cells to Tissue Organoids. Stem Cells, 2017. 35(1): p. 97-105.

3. Souza, G.R., et al., Three-dimensional Tissue Culture Based on Magnetic Cell Levitation. Nature nanotechnology, 2010. 5(4): p. 291-296.

4. Teshima, T. H. N., Lourenco, S. V., & Tucker, A. S. (2016). Multiple Cranial Organ Defects after Conditionally Knocking Out Fgf10 in the Neural Crest. Frontiers in Physiology, 7, 488. http://doi.org/10.3389/fphys.2016.00488

Keywords

salivary gland, radiation-induced xerostomia, oral stem cell, magnetic bioprinting

PG02 Dental Plaque pH In Predicting Caries Relapse After General Anesthesia Kalhan AC1, Lin YT2, Kalhan TA1, Lin YTJ2, Chou CC2, Hsu CY1

1Faculty of Dentistry, National University of Singapore, Singapore 2Kaohsiung Chang Gung Memorial Hospital, Taiwan Objectives Numerous caries risk assessment (CRA) tools have been proposed in literature, with few validated in preschool children1. Past caries experience, the best predictor thus far in literature2, may not be a reliable indicator after clinical intervention. This longitudinal study was aimed to investigate the role of plaque pH in predicting future caries incidence after oral rehabilitation under general anesthesia (GA) among preschool children. Methods Ethical approval was obtained from the Institutional Review Board of Kaohsiung Chang Gung Memorial Hospital, Taiwan (IRB no: 102-3921A32). Caries detection, plaque pH measurements, questionnaire survey and CRA, using Cariogram, were performed, among pre-schoolers indicated for GA, by two trained examiners, at baseline (n=92), and at 6-month (6M; n=83), 12-month (12M; n=79), and 24-month (24M; n=66) recall visits after GA. “Plaque pH”, the main independent variable, was recoded as a categorical variable at 6M and 12M recall into “low-pH” and “control” groups. Caries increment (Δdmft) at recall visits was the main study outcome. Univariable and multivariable logistic regression analysis were performed to investigate the association of plaque pH and caries increment at different recall visits. For each model, receiver-operating characteristic (ROC) curve was plotted to evaluate its prediction accuracy.


Results High post-GA caries recurrence rates were observed, with 54.2% (6M), 79.7% (12M) and 90.9% (24M) of children developing new caries lesions at follow-up visits, despite routine preventive and educational measures. Individuals with low resting plaque pH at 6M and 12M recall visits, were shown to be at higher risk of 1-year caries incidence at 12M and 24M visits, respectively, compared to control group (both p<0.05). Moreover, plaque pH demonstrated superior prediction accuracy, compared to past caries experience and Cariogram. Conclusion Resting plaque pH may be a useful risk predictor for future caries development in high-risk children undergoing oral rehabilitation under general anesthesia.

References 1. Gao X, Di Wu I, Lo EC, Chu CH, Hsu CY, Wong MC (2013) Validity of caries risk assessment programmes in preschool children. J Dent 41:787-795.

2. Divaris K (2016) Predicting Dental Caries Outcomes in Children: A "Risky" Concept. J Dent Res 95:248-254.

Keywords

plaque pH, dental caries, caries relapse, general anesthesia

PG03: Ethnic Differences In Caries Susceptibility In A Multi-ethnic Asian Cohort Kalhan TA1, Kalhan AC1, Xu Y2, Un Lam C1, Khin LW3, Chong Y4, Shek L5, Lee Y4, Kwek K6, Saw S7, Godfrey K8, Hsu CY1

1Faculty of Dentistry, National University of Singapore 2Fudan University, Shanghai, China 3Singapore Institute for Clinical Sciences, A*STAR, Singapore, Singapore. 4Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore 5National University Hospital, Singapore, Singapore. 6KK Women’s and Children’s Hospital, Singapore, Singapore. 7Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore 8University of Southampton and Southampton General Hospital NHS Foundation Trust, Southampton, United Kingdom


Objectives Tooth decay in young children (early childhood caries, ECC) is a highly prevalent diet-related, infectious multifactorial oral disease. However, published comparative information on ethnic differences in caries experience among Asian populations is nearly non-existent. Hence, this study was aimed to investigate the role of ethnicity in variations in caries development among preschool children. Methods Data was collected from a mother-offspring cohort, Growing Up in Singapore Towards Healthy Outcomes (GUSTO), which recruited healthy pregnant mothers and followed them through pregnancy and their offspring into childhood. Detailed interviewer-administered questionnaires were periodically conducted to collect general and health-related information of mothers and their infants/toddlers, including child’s feeding patterns, oral hygiene practices and parental oral health-related knowledge-attitude-practices. At 3 years of age, oral examinations were performed in 721children by dentists trained using a standardized approach to determine the children’s oral hygiene (Silness-Loe Plaque index) and ECC status (modified ICDAS II criteria). Univariable and multivariable regression analysis was used to assess the ethnicity-ECC relationship. Results ECC lesions were observed in 42.9% (309/721) of children at 3 years of age. After adjusting for potential confounders, a two-fold higher ECC risk was observed in Chinese and Malay children, compared to Indian children. Ethnic differences in pre-, peri-, and post-natal factors were noted. Conclusion Indian children are at lower risk of caries development, compared to Chinese and Malay children, possibly due to variations in the pathogenic pathways leading to ECC.

References - Keywords

caries susceptibility, early childhood caries, ethnicity


PG04: Neural Differentiation of Dental Pulp Stem Cells on Advanced 2D Materials Thulasi Thiruvallur Madanagopal & Vinicius Rosa Faculty of Dentistry, National University of Singapore

Objectives To evaluate the neural differentiation efficiency of dental pulp stem cells (DPSC) on 2D graphene (2DG) and hexagonal boron nitride (hBN) substrates. Methods Both 2DG and hBN substrates coated on glass coverslip were characterized using Raman spectroscopy and Atomic force microscopy (AFM). DPSC were seeded on both substrates and cultured in growth media (Control; DMEM+10% FBS) and neural induction media with 40ng/ml bFGF and 20ng/ml EGF for 21 days (treated). Cytocompatability was tested using MTS assay at days 1, 3 and 5. Expression of neural gene namely Nestin, beta III tubulin (TUB-3), and neurofilament-heavy (NF-H) were evaluated by RT-PCR at days 1, 7, 14 and 21. Protein expression for nestin, TUB-3 and NF-H was evaluated after 21 days using flow cytometry. All assays were performed in triplicates and statistical analysis was performed with one way ANOVA and t test (α=0.05). Results Raman spectroscopy and AFM showed that the glass surface was completely covered with 2DG. Both the substrates were cytocompatible and supported proliferation of DPSC (p<0.05; 2DG and hBN vs glass). The neural genes expression was higher for cells on 2DG-treated group than glass and hBN treated groups. Moreover cells on 2DG expressed mature neural gene NF-H by day 14, while cells on hBN did not show higher expression than glass treated group even after 21 days. Similarly, the neural proteins expression was higher for cell on 2DG-treated group than glass and hBN treated groups. Conclusion The results suggest that both 2DG and hBN were cytocompatible; 2DG substrate supports neural differentiation while hBN does not yield mature neurons by 21 days which is evident by neural genes and proteins expression.

References -

Keywords

dental pulp stem cells; neural differentiation; graphene; boron nitrite


PG05: Use Of Haploid Candida Albicans Model In Drug Discovery Thuyen Truong1, Guisheng Zeng2, Teck Kwang Lim3, Cao Tong1, Qingsong Lin3, Yue Wang2, Chaminda Jayampath Seneviratne1 1Faculty of Dentistry, National University of Singapore 2Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, Proteos, Singapore 3Department of Biological Sciences, Faculty of Science, National University of Singapore Objectives

Recent study has discovered a new molecule designated as SM21 with promising activity against Candida albicans. Nevertheless, the mechanism of action of SM21 remains elusive. In present study, we explored the advantages of the new C. albicans haploid model to understand the mechanism of action of SM21.

Methods

Reference haploid strain GZY803 was selected for study. Firstly, antifungal susceptibility of GZY803 relative to the diploid standard SC5314 strain was examined. Next, GZY803 cells were treated with 2 ug/ml of SM21 for 1 h and 4 h, and RNA was extracted for analyzing using RNA sequencing approach. Untreated samples were also included as control. Subsequently, differential expression analysis and functional annotation were applied to identify the list of differently expressed genes and altered pathways in GZY803 under SM21 stimulant. Biochemical experiments were also performed on the haploid GZY803 and diploid SC5314 strains to validate and confirm the hypothesis from RNA sequencing data.

Results

GZY803 cultures showed significant altered gene expressions related to ATP generation, transmembrane transport, and cytochrome assembly when exposed to SM21. Following analyses on mitochondrial structure, ATP production, reactive oxygen species release, and total antioxidant potentials, confirmed the inhibitory effect of SM21 at mitochondrial activity in C. albicans haploid and diploid cells.

Conclusion

In conclusion, we have demonstrated the use of C. albicans haploid model in drug discovery research and identified mitochondrial activity inhibition as a fungicidal effect of SM21. This study has brought new information to the development of SM21 as novel antifungal molecule, which could bring benefits to patients suffering from oral and systemic candidiasis.

References 1. Wong, S.S., Kao, R.Y., Yuen, K.Y., Wang, Y., Yang, D., Samaranayake, L.P., and Seneviratne, C.J. (2014). In vitro and in vivo activity of a novel antifungal small molecule against Candida infections. PLoS One 9, e8583 2. Seneviratne, C.J., Zeng, G., Truong, T., Sze, S., Wong, W., Samaranayake, L., Chan, F.Y., Wang, Y.M., Wang, H., Gao, J., and Wang, Y. (2015). New "haploid biofilm model" unravels IRA2 as a novel regulator of Candida albicans biofilm formation. Sci Rep 5, 12433.


3. Truong, T., Zeng, G., Qingsong, L., Kwang, L.T., Tong, C., Chan, F.Y., Wang, Y., and Seneviratne, C.J. (2016). Comparative Ploidy Proteomics of Candida albicans Biofilms Unraveled the Role of the AHP1 Gene in the Biofilm Persistence Against Amphotericin B. Mol Cell Proteomics 15, 3488-3500. Keywords

Candida albicans, SM21, mitochondria

PG06: MSC Exosomes Alleviate Pain and Tissue Degeneration In TMJ-OA

Zhang Shipin, Toh Wei Seong Faculty of Dentistry, National University of Singapore Objectives

The efficacy of mesenchymal stem cell (MSC) therapies is increasingly attributed to paracrine secretion, particularly exosomes [1]. Here, we investigate the effects of MSC exosomes on pain severity and degeneration of temporomandibular joint (TMJ) in an experimental model of TMJ osteoarthritis (TMJ-OA).

Methods

OA of bilateral TMJs was induced in rats by intra-articular injection of monosodium iodoacetate [2]. Thereafter, weekly intra-articular injections of either 100 µg exosomes in 50 µl of phosphate buffered saline (PBS) or 50 µl PBS were given over 8 weeks. The animals were assessed for pain and disease severity by head withdrawal threshold (HWT) measurement, micro-computed tomography, histology and immunohistochemistry, and Mankin scoring.

Results

MSC exosomes attenuated the nociceptive response, and reversed cartilage degradation and subchondral bone loss in rats with TMJ-OA. Exosome-treated lesions showed improved restoration of cartilage structure and subchondral bone integrity as measured by Mankin scores than the PBS-treated lesions. Greater suppression of inflammation and oxidative damage in conjunction with enhanced cellular proliferation were also observed. By 8 weeks, HWT in exosome-treated rats improved to that in the sham control rats. The cartilage and subchondral bone in the exosome-treated rats as measured by condylar height, cartilage thickness, cellularity, matrix deposition, and subchondral bone architecture were also similar to the sham control and closely resembled that of the native rats.

Conclusion

This study demonstrates for the first time that MSC exosomes can attenuate pain, reduce degeneration and promote cartilage and bone repair in an animal model of TMJ-OA.


References 1. Toh WS, Foldager CB, Pei M, Hui JH. Advances in Mesenchymal Stem Cell-based Strategies for Cartilage Repair and Regeneration. Stem Cell Reviews and Reports 2014; 10: 686-696.

2. Wang X-D, Kou X-X, He D-Q, Zeng M-M, Meng Z, Bi R-Y, et al. Progression of Cartilage Degradation, Bone Resorption and Pain in Rat Temporomandibular Joint Osteoarthritis Induced by Injection of Iodoacetate. PLoS ONE 2012; 7: e45036.

Keywords

Mesenchymal stem cells; Exosomes; Cartilage; Bone; Temporomandibular joint; Regeneration

PG07: Effects Of Hyperglycemia On Immune Modulatory Effects Of Porphyromonas Gingivalis Zoei Ong and Kai Soo Tan Faculty of Dentistry, National University of Singapore Objectives

Periodontitis is characterized by infections of structures surrounding our teeth i.e. gum, periodontal ligament and alveolar bone. Studies have investigated the link between periodontitis and diabetes, which occurs when glucose level in the bloodstream is abnormally high. Using the major periodontal pathogen P. gingivalis as the bacteria model, this study aims to determine effects of hyperglycemia on P. gingivalis-mediated innate immune response.

Methods

Primary periodontal fibroblasts were exposed to culture media with 5.5mM or 25mM glucose which approximates glucose found in normal and diabetic blood individuals, for 48 and 72 hours. Subsequently, cells were infected with P. gingivalis and the amount of IL-8 and TNF-α produced were determined by ELISA. The ability of P. gingivalis to modulate Fusobacterium nucleatum, toll-like receptor (TLR) and TNF-α-mediated immune response under normal and hyperglycemic conditions were also evaluated. Viability of periodontal fibroblasts under these conditions were determined by MTS assay.

Results

Viability of uninfected and P. gingivalis-infected fibroblasts did not vary significantly under both normal and hyperglycemic conditions. Fibroblasts infected with live P. gingivalis did not produce significant amounts of IL-8 and TNF-α under both normal and hyperglycemic conditions. In contrast, heat-attenuated P. gingivalis induced 76 and 5 folds more IL-8 production under normal and hyperglycemic conditions, respectively. Interestingly, live P. gingivalis significantly reduced both TLR, TNF-α and F. nucleatum-mediated IL-8 production, suggesting that suppression is independent of the MyD88 signaling pathway. Live P. gingivalis inhibited IL-8 production to a more significant extent (4 folds more) in cells exposed to hyperglycemia.


Conclusion

Live P. gingivalis inhibits IL-8 production independent of MyD88 signaling. Immune suppression was more significant under hyperglycemia suggesting that defective innate immune response may contribute to persistence of P. gingivalis in diabetic patients.

References 1. Polak, D., & Shapira, L. (2018). An update on the evidence for pathogenic mechanisms that may link

periodontitis and diabetes. Journal of Clinical Periodontology, 45(2), 150-166. 10.1111/jcpe.12803

2. MIRANDA, T. S., FERES, M., RETAMAL-VALDÉS, B., PEREZ-CHAPARRO, P. J., MACIEL, S. S., & DUARTE, P. M. (2017). Influence of glycemic control on the levels of subgingival periodontal pathogens in patients with generalized chronic periodontitis and type 2 diabetes. Journal of Applied Oral Science, 25(1), 82-89. 10.1590/1678-77572016-0302

3. Takeuchi, H., Hirano, T., Whitmore, S. E., Morisaki, I., Amano, A., & Lamont, R. J. (2013). The serine phosphatase SerB of porphyromonas gingivalis suppresses IL-8 production by dephosphorylation of NF-κB RelA/p65. PLoS Pathogens, 9(4), e1003326. 10.1371/journal.ppat.1003326

4. Kashiwagi, Y., Takedachi, M., Mori, K., Kubota, M., Yamada, S., Kitamura, M., & Murakami, S. (2016). High glucose-induced oxidative stress increases IL-8 production in human gingival epithelial cells. Oral Diseases, 22(6), 578-584. 10.1111/odi.12502

Keywords

Porphyromonas gingivalis, Fusobacterium nucleatum, interleukin-8, immune modulation, MyD88

PG08: Therapeutic Potential of MSC Exosomes For Periodontal Regeneration Jacob Chew Ren Jie, Fu Jia Hui, Toh Wei Seong Faculty of Dentistry, National University of Singapore Objectives Mesenchymal stem cells (MSC) have been found to promote periodontal regeneration through secretion of paracrine factors [1]. The objectives of this study were 1) to evaluate the effects of MSC exosomes on periodontal ligament (PDL) cell behavior in vitro, and to develop a rat periodontal defect model for evaluating the efficacy of MSC exosome as cell-free therapeutic for periodontal regeneration. Methods Rat PDL cells were treated with varying doses (1, 5 and 10µg/ml) of exosomes in cellular migration, proliferation and osteogenic differentiation assays. Gene expression analysis of ALP, OCN and Runx2 and Alizarin red staining were performed to assess osteogenic differentiation of PDL cells. To develop the rat periodontal defect model, bilateral periodontal defects (2x2x1.5mm) mesial to the first molars


were surgically created [3]. At 2 and 4 weeks post-surgery, animals were euthanized and validation of the critical size periodontal defects was performed by micro-CT and histology. Results MSC exosomes showed dose-dependent effects on PDL cell migration and proliferation. Compared to control, PDL cells treated with 10µg/ml exosomes demonstrated more than 2-fold increase (P<0.05) in cell proliferation and in migratory activity (P<0.001). Interestingly, MSC exosomes enhanced osteogenic mineralization of PDL cells at 1µg/ml, but this effect diminished at increasing concentrations. Currently, we have established the animal model. At both 2 and 4 weeks, the surgically-created defects presented with apically limited, minimal regeneration. The distance from the cementoenamel junction (CEJ) to bone crest was 55-57% of the tooth length and long junctional epithelium (LJE) was also consistently observed. Conclusion Our results demonstrated potent effects of MSC exosomes on cellular functions of PDL cells in migration, proliferation and osteogenic differentiation, that are critical events in periodontal regeneration. With the validation of the rat periodontal defect model, studies are ongoing to evaluate the therapeutic efficacy of MSC exosomes in periodontal regeneration in vivo. References 1. Nagata, M., et al., Conditioned medium from periodontal ligament stem cells enhances periodontal regeneration. Tissue Eng Part A, 2016 2. Shirakata, Y., et al., Periodontal healing after application of enamel matrix derivative in surgical supra/infrabony periodontal defects in rats with streptozotocin-induced diabetes. J Periodontal Res, 2014. 49(1): p. 93-101 3. Yu, N., et al., Enhanced periodontal tissue regeneration by periodontal cell implantation. J Clin Periodontol, 2013. 40(7): p. 698-706 Keywords

Mesenchymal stem cells; Exosomes; Periodontal; Regeneration


PG09: Bacterial Species Associated with Persistent Apical Periodontitis Exert Differential Effects on Osteogenic Differentiation Chow Ai Tee, Tan Kai Soo, Victoria Yu Soo Hoon & Lim Kian Chong Faculty of Dentistry, National University of Singapore Objectives Persistent apical periodontitis (AP) has a bacterial profile dominated by a few bacterial species. Using bacterial culture, gram-positive bacteria predominate. However, using molecular techniques, fastidious gram-negative anaerobes were reported. Interestingly, periapical lesions of larger size appear to be associated with higher incidence of gram-negative bacteria. We hypothesized that different bacterial species may induce differential immune responses in macrophages eliciting species-specific microenvironments which impact periapical healing. We aimed to (i) compare the production of pro-inflammatory cytokines induced by macrophages in response to gram-positive and gram-negative bacteria associated with persistent AP, and (ii) determine the effects of this microenvironment on osteogenic differentiation. Methods Macrophages were exposed to Enterococcus faecalis, Streptococcus oralis, S. mitis, Fusobacterium nucleatum, Treponema denticola or Tannerella forsythia. The levels of TNF-α and IL-1β were determined by immunoassay. Following treatment of MG-63 pre-osteoblasts with conditioned media from bacteria-exposed macrophages, osteogenic differentiation and viability of osteoblasts were analyzed by Alizarin Red Staining and MTS assay, respectively. Results Macrophages exposed to gram-positive bacteria did not produce significant amounts of cytokines. F. nucleatum-challenged macrophages produced up to 4-fold more TNF-α and IL-1β compared to T. denticola- or T. forsythia. Only the conditioned media from macrophages treated with gram-negative bacteria decreased the degree of mineralization and viability of osteoblasts. Conclusions Gram-negative bacteria, in particular F. nucleatum elicited an enhanced pro-inflammatory response in macrophages, inhibited osteogenic differentiation and reduced cell viability. Findings suggest that their presence could potentially increase the severity of persistent AP, whereas the observations did not support a significant effect of gram-positive bacteria. References 1. Nanes MS. Tumor necrosis factor-α: molecular and cellular mechanisms in skeletal pathology. Gene 2003;321:1-15 2. Martinho FC, de Rabello DGD, Ferreira LL, Nascimento GG. 2017. Participation of endotoxin in root canal infections: A systematic review and meta-analysis. European journal of dentistry. 11(3):398


Keywords

Persistent Apical Periodontitis, Osteogenic differentiation

PG10: Retrospective Study On Aesthetic Outcomes of Anterior Dental Implants Alethea Foong Li Yen*#, Tan Beng Choon, Keson#, Teoh Khim Hean*, Tan Ken*, Tey Hwee Shinn Valerie* *National Dental Centre Singapore # Faculty of Dentistry, National University of Singapore Objectives

To compare the aesthetic outcomes of anterior implant-supported crowns as evaluated by patients and clinicians of different specialties.

Methods

133 patients restored with 138 implant-supported anterior crowns were invited to rate their satisfaction with aesthetic outcomes using a 100-mm VAS questionnaire with seven questions. Three prosthodontically-trained clinicians (PTCs) rated each implant with the modified PES/WES index, using photographs and models. Two periodontists, two orthodontists, and two general dentists each rated a randomized sample (n=40) of the implants with PES/WES as well. Scores were compared using Intraclass correlation coefficient (ICC), Kappa coefficient, and Spearman’s rho. Results Mean PES, WES and PES/WES of the implants were 5.0, 5.3, and 10.0, respectively. 27 (19.6%) of 138 implants were deemed clinically acceptable (PES/WES ≥ 12) according to PES/WES criteria. Mean patient satisfaction scores ranged from 79.3 – 84.4 for 7 VAS questions. Weak correlation was found between patient VAS scores and PES/WES scores. PTCs had the lowest mean scores for PES, WES and PES/WES (4.7, 5.0, 9.7) compared to other specialties, who scored similarly. ICC for PES, WES and PES/WES was highest for PTCs (r = 0.74, 0.76, 0.86), followed by periodontists (r = 0.69, 0.70, 0.73), and lowest for orthodontists (r = 0.41, 0.60, 0.50). ICC for PES of orthodontists was significantly lower than PTCs (p < 0.05). Kappa for PES and WES variables for all specialties ranged from poor to moderate (κ = 0.01 – 0.59). When orthodontists were excluded, the highest agreement was for papilla scores. Conclusion Although most implants did not meet the threshold of clinical acceptability based on PES/WES criteria, patients were generally satisfied with their implants. PTCs were the strictest in scoring. There was moderate to good correlation for PES, WES and PES/WES within each specialty but lower Kappa agreement for each individual variable. Orthodontists had significantly lower ICC than PTCs for PES.


References 1. Belser, U. C., Grütter, L., Vailati, F., Bornstein, M. M., Weber, H., & Buser, D. (2009). Outcome evaluation of early placed maxillary anterior single-tooth implants using objective esthetic criteria: A cross-sectional, retrospective study in 45 patients with a 2- to 4-year follow-up using pink and white esthetic scores. Journal of Periodontology, 80(1), 140-151. 2. Chang, M., Odman, P. A., Wennström, J. L., & Andersson, B. (1999). Esthetic outcome of implant-supported single-tooth replacements assessed by the patient and by prosthodontists.The International Journal of Prosthodontics, 12(4), 335. 3. Fava, J., Lin, M., Zahran, M., & Jokstad, A. (2015). Single implant-supported crowns in the aesthetic zone: Patient satisfaction with aesthetic appearance compared with appraisals by laypeople and dentists. Clinical Oral Implants Research, 26(10), 1113-1120. 4. Vaidya, S., Ho, Y. L. E., Hao, J., Lang, N. P., & Mattheos, N. (2015). Evaluation of the influence exerted by different dental specialty backgrounds and measuring instrument reproducibility on esthetic aspects of maxillary implant-supported single crown. Clinical Oral Implants Research, 26(3), 250-256. Keywords

dental implant, implant aesthetics, patient satisfaction, pink esthetic score/white esthetic score

PG11: Surface Topographies Modulate The Differentiation Of Dental Pulp Stem Cells In Vitro Heng Pei Fang1, Aliz Kunstar2, Apoorva Shivankar2, Mohammad Adnan3, Lui Jeen Nee2, Victoria Soo Hoon Yu1, Hemant Vijaykumar Unadkat2

1Faculty of Dentistry, National University of Singapore 2National Dental Centre Singapore 3Indian Institute of Technology, Guwahati, India Objectives Recently, it has been discovered that material surface topographies uniquely modulate cell behaviour. However, the determination of functionally architectured surfaces is constrained by experimental limitations in design and testing. Micro-fabrication techniques coupled with high throughput screening of biomaterials enable us to overcome these barriers. The aim of this study was to fabricate a screening platform to identify surface topographies that favour multi-lineage differentiation of dental pulp stem cells (DPSCs) in vitro. The null hypothesis was that surface topographies do not modulate differentiation of DPSCs.


Methods DPSCs were seeded on micro-fabricated Poly (e-caprolactone) "Cellompic chips". Each "Cellompic chip" consists of 160 algorithmically designed and distinct surface topographies. Fluorescent images of the nuclei, cytoskeleton and 4 antibodies (dentin sialophosphoprotein, nerve growth factor, collagen II and CD31) were acquired for all the chips using an automated microscope. The images were quantitatively analyzed on CellProfiler. Results Specific topographical and discrete Fourier transformation parameters were identified to favour cellular and nuclei eccentricity, odontoblastic, neuronal, connective tissue and lastly endothelial differentiation. Heatmaps generated provided a quick method to identify "hit" topographies. Receiver operating curves (ROC) generated gave an estimate of the predictive power of the parameters identified. Our observations confirm that biomaterial design modulates DPSC differentiation. The null hypothesis was rejected. Conclusion We were able to demonstrate the use of the "Cellompic chip" as a screening platform to identify surface topographies that encourage multi-lineage differentiation. This provides valuable information for development of a potential scaffold that may be utilized in regenerative endodontics in the future.

References 1. Unadkat H, Gauvin R, Blitterswijk C, Khademhosseini A, Boer J, Truckenmüller R (2013). Microfabrication techniques in materiomics. Materiomics: High-Throughput Screening of Biomaterial Properties:51. 2. Unadkat HV, Hulsman M, Cornelissen K, Papenburg BJ, Truckenmüller RK, Carpenter AE et al. (2011). An algorithm-based topographical biomaterials library to instruct cell fate. Proceedings of the National Academy of Sciences 108(40):16565-16570. 3. Carpenter AE, Jones TR, Lamprecht MR, Clarke C, Kang IH, Friman O et al. (2006). CellProfiler: image analysis software for identifying and quantifying cell phenotypes. Genome biology 7(10):R100. 4. Hulsman M, Hulshof F, Unadkat H, Papenburg BJ, Stamatialis DF, Truckenmüller R et al. (2015). Analysis of high-throughput screening reveals the effect of surface topographies on cellular morphology. Acta biomaterialia 15(29-38. 5. Cornelissen K, Unadkat H, Truckenmüller R, van Blitterswijk C, Post G, de Boer J et al. ALGORITHMIC FEATURE GENERATION FOR MICROSCALE TOPOGRAPHIES. Keywords

Surface topographies, Dental pulp stem cells, Multi-lineage differentiation, In vitro


PG12: Masticatory Efficiency And Food Preferences After Dental Rehabilitation In Children with Severe Early Childhood Caries Jessica Khong3, Ciarán G Forde2, Ai Ting Goh2, Bien Lai1, Betty YY Mok3, Yu Fan Sim3, Catherine HL Hong3

1 National Dental Centre Singapore 2Singapore Institute for Clinical Sciences (A*STAR) 3Faculty of Dentistry, National University of Singapore Objectives To analyse objective changes in masticatory efficiency and food preferences before and after dental rehabilitation in children with severe early childhood caries (SECC) Methods This was a prospective cohort study of children (48 to 71 months old) with SECC requiring dental rehabilitation under general anaesthesia. Participants attended 3 visits in total: before dental rehabilitation, 2 weeks and 3 months after dental rehabilitation. At all 3 visits, the parent completed 2 questionnaires: (1) child eating behaviour questionnaire and (2) food frequency questionnaire. In addition to an oral examination, the child completed a food preference questionnaire at all 3 visits and underwent 2 masticatory efficiency tests (1) chewing a duo-coloured chewing gum to show degree of mixing and (2) observation of the child’s chewing while he/she eats 6 foods with different textures at the first and third visits. Results 35 children were recruited. Data from 24 children (14 girls, 10 boys) were analysed. The mean age of the child participants was 58.7±6.3 months old. The mean baseline dmft was 10.9±5.1. The mean number of restorations/child and extractions/child were 5.1±2.7 and 6.2±5.1 respectively. Children reported a significantly lower pain score (p=0.03) at 2-weeks post-dental rehabilitation compared to before rehabilitation. Preliminary analysis using Wilcoxon signed-rank test found no statistically significant change (p=0.191) in the degree of mixing of gum before and after dental rehabilitation. Using Pearson correlation, there was low negative correlation (r=-0.338) between number of posterior extractions and change in degree of mixing of gum. Using a scatter plot, subjects with more posterior extractions took more chews and time for peanuts and Froot Loops. This trend was not observed for apple, chiffon cake, chewy sweet and popcorn. Conclusion Dental rehabilitation reduced pain and did not affect the childrens’ ability to mix chewing gum. However, there was a trend showing that children with more posterior extractions experienced more difficulty eating harder foods. References 1. Subramaniam, P. and K.G. Babu, Effect of Restoring Carious Teeth on Occlusal Bite Force in Children, Journal of Clinical Pediatric Dentistry, 2016. 40(4): p. 297-300.


2. Alhowaish, L., Bite force evaluation in children following dental treatment. 2012, University of Leeds. 3. Schimmel, M., et al., A two-colour chewing gum test for masticatory efficiency: development of different assessment methods. J Oral Rehabil, 2007. 34(9): p. 671-8. Keyword

Masticatory efficiency, food preferences, dental rehabilitation, childhood caries

PG13: Validation Of Early Childhood Oral Health Impact Scale (ECOHIS) Among Preschoolers with Autism Justine Lim, Rahul Nair, Violeta Lopez, Tong Huei Jinn, Monty Duggal Faculty of Dentistry, National University of Singapore Objectives To test that the Early Childhood Oral Health Impact Scale (ECOHIS) is face and content valid among parents of 3 to 5 years old children with autism spectrum disorder (ASD) in Singapore. Methods We recruited parents of 3 to 5 years old children with ASD from paediatric dental clinics at National University Hospital, Singapore and National University of Singapore. ECOHIS questionnaire was administered to the parents. This was followed by a semi-structured interview an investigator. Results 10 parent-child dyads were recruited. Recruitment ended once data saturation was reached. Mean age of diagnosis of ASD was 2.9 years old (±SD 0.55). 70% (N=7/10) and 80% (N=8/10) were unable to answer questions on their child’s intellectual and adaptive functioning respectively. Parents were able to answer all 13 questions in ECOHIS, except for 10-30% of parents who chose “Don’t Know” options for certain questions. 6 out of 10 children were caries free. 4 out of 10 children had a dmft of 4 and above. 1 out of 10 children had history of toothache and signs of infection. All the parents interviewed found the ECOHIS questionnaire to be relevant in assessing their child’s oral health-related quality of life. They found the questions to be comprehensive and covered all domains of oral health-related quality of life. Parents did not have any difficulty understanding the questions. Conclusion The results suggest that ECOHIS is face and content valid for parents of 3 to 5 years old children with ASD in Singapore.


References 1. Pahel, B. T., Rozier, R. G., & Slade, G. D. (2007). Parental perceptions of children's oral health: the Early Childhood Oral Health Impact Scale (ECOHIS). Health Qual Life Outcomes, 5, 6. doi:10.1186/1477-7525-5-6 2. Tavernor, L., Barron, E., Rodgers, J., & McConachie, H. (2013). Finding out what matters: validity of quality of life measurement in young people with ASD. Child Care Health Dev, 39(4), 592-601. doi:10.1111/j.1365-2214.2012.01377.x Keywords

Oral health-related quality of life, Autism spectrum Disorder, Preschoolers, ECOHIS

PG14: The Effect Of Parenting Styles On Enforcement Of Oral Health Behaviours In Children Quek Shumin Judith1, Mok Yuen Yue, Betty1, Lai Wen Pui Bien2, Eu Oy Chu3, Lim Wanyi3, Khong Sok Yin, Jessica1, Lim Wei Ying Justine1, Sim Yu Fan1, Hong Catherine1 1Faculty of Dentistry, National University of Singapore 2National Dental Centre Singapore 3Health Promotion Board Singapore Objectives To examine the relationship between parenting styles and enforcement of preventive oral health behaviours in children in Singapore. Methods This is a cross-sectional study involving parents of children aged 4-6 years presenting for the first time to 4 public dental clinics in Singapore. Parents were asked to complete the Parenting Styles Dimensions Questionnaire and a questionnaire on demographics, child diet and oral hygiene practices. The child was examined by a calibrated examiner at the same dental visit before prophylaxis. Plaque Index and dmf-Index were used to evaluate oral health status. Results Three hundred and eighty-nine parent/child dyads participated in the study. The mean age of the children was 62.3 (±9.8) months. Majority of children were caries active (n=285, 73.3%) with a mean dmft and plaque score of 5.4 (± 5.0) and 1.5 (±0.6) respectively. An authoritative style was observed in 95.1% of parents, permissive in 3.9%, and authoritarian in 1.0%. When compared to permissive parents, authoritative parents were more likely to monitor sweets/snacks intake (n=248, 67.2%) (P=0.004) and less inclined to offer sweets/snacks in exchange for good behaviour (n=117, 31.7%) (P=0.045). Permissive


parenting was associated with omitting bedtime tooth brushing (P=0.006), while authoritative parents tend to ensure thorough brushing of their child’s teeth (P=0.034). No correlation was found between parenting styles and caries or plaque score. Conclusion Authoritative parenting was associated with good oral hygiene practices and preventive dietary behaviours such as monitoring sweets/snacks intake and withholding sweets/snacks from the child. However, the association between parenting styles and caries development could not be established. References 1. Howenstein, J., Kumar, A., Casamassimo, P. S., McTigue, D., Coury, D., & Yin, H. (2015). Correlating Parenting Styles with Child Behavior and Caries. Pediatric dentistry, 37(1), 59-64. 2. Park, H., & Walton-Moss, B. (2012). Parenting style, parenting stress, and children's health-related behaviors. Journal of Developmental & Behavioral Pediatrics, 33(6), 495-503. Keywords

parenting styles, child, diet habits, oral hygiene practices, caries

PG15: Associations between TMD symptoms, Quality of Life and Psychological States in Asian Military Personnel

Tay Koong Jiunn1 2, Yap Adrian U-Jin1 3, Wong Johnny Chiew Meng3, Tan Keson Beng Choon1, Allen Patrick Finbarr1

1Faculty of Dentistry, National University of Singapore 2Singapore Armed Forces Medical Corps, Singapore 3Department of Dentistry, Ng Teng Fong General Hospital Objectives This study determined the prevalence of TMD symptoms, and the impact of type and number of TMD symptoms on oral-health related quality of life (OHRQoL) and psychological states among Asian military personnel. Methods The cross-sectional study, involving personnel aged 18-65 years, was conducted across 12 military dental centres using a self-administered questionnaire comprising demographical data, the DC/TMD symptom questionnaire, OHIP-14 and DASS-21. A total of 3028 personnel were invited to participate with an


acceptance rate 90.5% (n=2739). Incomplete questionnaires (n=696) were duly discarded. Data analysis was done using non-parametric tests, regression analysis and Spearman correlation. Results Out of 2043 subjects (1998 males; 45 females, mean age 24.18±7.18 years), 36.32% reported at least one self-reported TMD symptom. Significant differences in global OHIP-14, depression, anxiety and stress scores were observed between subjects with and without TMD symptoms. Significant differences in OHRQoL and psychological states were observed between dissimilar type and number of TMD symptoms in the TMD group. Those with headaches, and 2-3 symptoms have substantially poorer OHRQoL and greater psychological distress. Associations between number of TMD symptoms, OHRQoL, depression, anxiety and stress were significant but weak. (r=0.19-0.40). Conclusion TMD symptoms were prevalent in the Asian military population. Significant differences in OHRQoL and psychological states were observed between subjects with and without TMD symptoms. Specific type and number of TMD symptoms impacted OHRQoL and psychological states differently. Associations between number of TMD symptoms and OHRQoL, depression, anxiety and stress were significant but weak. References 1. Lovibond, P. F., & Lovibond, S. H. (1995). The structure of negative emotional states: comparison of the Depression Anxiety Stress Scales (DASS) with the Beck Depression and Anxiety Inventories. Behav Res Ther, 33(3), 335-343. 2. Schiffman, E., Ohrbach, R., Truelove, E., Look, J., Anderson, G., Goulet, J. P., . . . Orofacial Pain Special Interest Group, International Association for the Study of Pain. (2014). Diagnostic Criteria for Temporomandibular Disorders (DC/TMD) for Clinical and Research Applications: recommendations of the International RDC/TMD Consortium Network* and Orofacial Pain Special Interest Groupdagger. J Oral Facial Pain Headache, 28(1), 6-27. doi: 10.11607/jop.1151 3. Slade, G. D. (1997). Derivation and validation of a short-form oral health impact profile. Community Dent Oral Epidemiol, 25(4), 284-290. 4. Yap, A. U., Dworkin, S. F., Chua, E. K., List, T., Tan, K. B., & Tan, H. H. (2003). Prevalence of temporomandibular disorder subtypes, psychologic distress, and psychosocial dysfunction in Asian patients. J Orofac Pain, 17(1), 21-28. Keywords

TMD symptoms, Quality of life, Depression, Anxiety, Stress


PG16: Effect of Periodontal Therapy on Patients Treated with Calcium Channel Blockers Wen Nee Ho , Tan Kai Soo , Lim Lum Peng Faculty of Dentistry, National University of Singapore Objectives This study aims to find out the effect of periodontal therapy on the clinical parameters and biomarker levels in medicated hypertensive patients with and without gingival overgrowth (GO). At the start of the study (T1), patient background information, saliva samples and clinical parameters were recorded, including periodontal probing depth (PPD), gingival recession (REC), bleeding on probing (BOP), plaque (PLAQ), calculus (CALC), mobility (MOB) and degree of gingival overgrowth according to the Ingles criteria (INGLES). The subjects were divided into a nonGO and GO group. Subjects then received oral hygiene advice and periodontal therapy. At 3 months (T2), subjects were recalled for review of clinical parameters and saliva resampling. Saliva samples were processed with sandwich ELISA for the detection of epidermal growth factor (EGF) and transforming growth factor beta (TGF-b)1. Methods At the start of the study (T1), patient background information, saliva samples and clinical parameters were recorded, including periodontal probing depth (PPD), gingival recession (REC), bleeding on probing (BOP), plaque (PLAQ), calculus (CALC), mobility (MOB) and degree of gingival overgrowth according to the Ingles criteria (INGLES). The subjects were divided into a non-GO and GO group. Subjects then received oral hygiene advice and periodontal therapy. At 3 months (T2), subjects were recalled for review of clinical parameters and saliva resampling. Saliva samples were processed with sandwich ELISA for the detection of epidermal growth factor (EGF) and transforming growth factor beta (TGF-b)1. Results At 3 months, 12 non-GO patients and 18 GO patients were reviewed. There was significant clinical improvements were in both groups. The percentage of sites in which pocket depth reduced by more than 2mm was 16% in the GO group and 10.5% in the non-GO group. The percentage of sites in which there was CAL gain more than 2mm was 10.9% in the GO group compared to 2.7% in the non-GO group. Whist there was a general decrease in biomarkers at T2, some subjects had no change or an increase. This change was not associated with improvements in clinical parameters. Conclusion Periodontal treatment resulted in significant clinical improvements in both groups. Changes in EGF and total TGF-b1 levels did not correspond well to changes in the clinical parameters.

References -


Keywords

Periodontal Therapy; Non-surgical; Gingival Overgrowth; Calcium Channel Blockers

PG17: Spectrophotometric and Visual Evaluation of Maxillary Anterior Single Implant Restorations Wong JL1, Sim C1, Teoh KH1, Tan K2 1National Dental Centre Singapore 2Faculty of Dentistry, National University of Singapore Objectives To determine spectrophotometrically and visually the differences in the color of implant-supported restorations and peri-implant mucosa with their natural controls. Methods Forty-four patients restored with a single anterior maxillary implant supported restoration were assessed after at least six months in function. Images of the implant crowns, peri-implant mucosa and the control teeth and gingivae were captured using a spectrophotometer. The soft tissue color data were obtained in five incremental areas of 1mm x 2mm from the mid labial aspect of the gingival margin towards the apical direction. The color data of the crown portion were obtained from the incisal, mid and cervical third areas. Visual assessment of the color differences between the implant crown and peri-implant mucosa and their respective controls were performed by the patients and four dental professionals (prosthodontist, prosthodontic resident, periodontist and dental surgery assistant) using the Visual Analog Scale (VAS). Correlation between spectrophotometric and visual assessment was also determined. Results The mean color differences (∆E) between peri-implant mucosa, implant crown and their respective controls were 6.64±2.77 and 4.84±2.62 respectively. A significant difference (p=0.03) in mean ∆E value was observed only at the cervical third of the implant crown. The patient group showed the highest mean VAS scores for shade matching of the peri-implant mucosa (7.8±1.6) and implant crown (8.4±1.2) with their respective controls. A significant difference in visual assessment between the patient group and the dental professional group was observed (p=0.0108). A mild to moderate correlation between the spectrophotometric and visual evaluation of peri-implant mucosa, implant crown and their respective controls were demonstrated by all four dental professionals. Conclusion Spectrophotometric analysis showed significant color differences at the cervical third of the anterior implant crowns. The patient group is the most satisfied with the color match of their implant restorations.


References 1) Benic G.I., Scherrer D., Sancho-Puchades M, Thoma D.S. & Hammerle C.H.F. (2017) Spectrophotometric and visual evaluation of periimplant soft tissue color. Clinical Oral Implants Research 28: 192-200. 2) Paniz G., Bressan E., Stellini E., Romeo E. & Lops D. Correlation between subjective and objective evaluation of peri-implant soft tissue color. Clinical Oral Implants Research 25: 992-996. 3) Park, S.E., Da Silva, J.D., Weber, H.P. & Ishikawa-Nagai, S. (2007) Optical phenomenon of peri-implant soft tissue. Part I. Spectrophotometric assessment of natural tooth gingiva and peri-implant mucosa. Clinical Oral Implants Research 18: 569–574. Keywords

dental implants, color, peri-implant mucosa, spectrophotometer, visual analog scale

PG18: Clinicians’ Decision Making In Borderline Class III Orthodontic–Orthognathic Surgery Cases 1Voon KKR, 1Lim AAT, 2Wong HC, 1Foong KWC 1Faculty of Dentistry, National University of Singapore 2Yong Loo Lin School of Medicine, National University of Singapore

Objectives

To determine the decision making pattern and level of agreement among expert orthodontists, expert oral surgeons, novice orthodontists and novice oral surgeons in the management of these cases. The clinician and patient related factors influencing decision making were also investigated. Methods A cross-sectional questionnaire survey involving 55 clinician participants stratified into the four groups was conducted. Experts had ten or more years of clinical experience while novices were in practice for fewer than ten years. The subjects assessed six borderline cases and responded on whether each case required orthognathic surgery and whether the case can be managed alone by the orthodontic camouflage approach. The patient parameters used to assess the limits of orthodontic camouflage were also recorded. Results Variable decision making patterns were observed among the clinicians with poor inter-observer agreement (Kappa values range from 0.023 to 0.323) on both decisions among the four groups. Intra-observer agreement over time was also moderate to poor with only one out of 20 subjects who managed


to respond the same answer during the first and the second assessment for all the six cases on both decisions. Clinical experience did not seem to influence clinicians’ clinical decisions as there were no statistical significance in the comparisons between experts and novices in their clinical decisions. Similarly, the study did not find any statistical significance in the comparisons between orthodontists and oral surgeons in their clinical decisions. However, there seemed to be a trend that oral surgeons were more inclined to indicating surgery compared with orthodontists. It was found that the percentages of oral surgeons indicating surgery were substantially higher than the percentages of orthodontists. On the other hand, there seemed to be a trend that orthodontists were more inclined to indicating camouflage than oral surgeons with the percentages of orthodontists indicating camouflage substantially higher than the percentages of oral surgeons. The study identified nine patient parameters most commonly used to assess whether a Class III malocclusion can be managed by orthodontic camouflage. These parameters include ANB angle, degree of dentoalveolar compensation, overjet, overbite, lower incisors to mandibular plane angle, upper incisors to maxillary plane angle, incisor relationship, facial profile and lip profile. Of all the parameters studied, molar relationship, gingival biotype and alveolar ridge thickness were more frequently used by the orthodontists but not the oral surgeons to make the assessment (p<0.05). ANB angle, Wits appraisal, maxillary-mandibular length ratio, molar relationship and soft tissue pogonion to zero meridian line were the important parameters that influenced clinicians’ decision in deciding the limits of orthodontic camouflage (p<0.05) in at least one of the Class III cases. Conclusion

There were variable clinical decisions and generally little inter-observer and intra-observer agreement among the clinicians in managing borderline Class III orthodontic-orthognathic surgery cases. A distinct trend was observed in the orthodontists’ and the oral surgeons’ clinical decisions. However, clinical experience did not influence their decision making. The patient parameters identified above could potentially serve as important parameters for the assessment of limits of orthodontic camouflage. This study may be a step in the direction to develop a practical framework for identifying diagnostic and treatment planning parameters across institutions and clinicians who manage borderline Class III malocclusions.

References 1. Bell R, Kiyak HA, Joondeph DR, MchNeill RW, Wallen TR. Perceptions of facial profile and their influence on the decision to undergo orthognathic surgery. Am J Orthod Dentofacial Orthop 1985;88:323-332 2. Cassidy DW, Jr., Herbosa EG, Rotskoff KS, Johnston LE, Jr. A comparison of surgery and orthodontics in "borderline" adults with Class II, Division 1 malocclusions. Am J Orthod Dentofacial Orthop 1993;104:455-470 3. Rabie A-B M, Wong RWK, Min GU. Treatment in borderline Class III malocclusion: orthodontic camouflage (extraction) versus orthognathic surgery. The Open Dentistry Journal 2008;2:38-48 4. Stellzig-Eisenhauer A, Lux CJ, Schuster G. Treatment decision in adult patients with Class III malocclusion: orthodontic therapy or orthognathic surgery? Am J Orthod Dentofacial Orthop 2002;122:27-37


5. Tseng YC, Pan CY, Chou ST, Liao CY, Lai ST, Chen CM, Chang HP, Yang YH. Treatment of adult Class III malocclusions with orthodontic therapy or orthognathic surgery: receiver operating characteristic analysis. Am J Orthod Dentofacial Orthop 2011;139 (5):e485-e493 Keywords

Decision making, clinical decision, borderline Class III, orthodontic camouflage, orthognathic surgery

PG19: Quality Of Life (QOL) In Patients with Dentofacial Deformities Undergoing Orthodontic-Orthognathic Management 1Ong LT, 1Yow M, 2Wong HC, 3Foong KWC 1Department of Orthodontics, National Dental Centre Singapore 2Yong Loo Lin School of Medicine, National University of Singapore 3Faculty of Dentistry, National University of Singapore Objectives

1. To evaluate the effects orthodontic-orthognathic treatment have on QOL in patients with dentofacial deformities.

2. To investigate for any gender differences in QOL at various time points of treatment.

Methods

A total of 100 patients planned for combined orthodontic-orthognathic management were recruited consecutively. QOL measures include: World Health Organisation Quality of Life – BREF (WHOQOL-BREF), 14-item short form Oral Health Impact Profile (OHIP-14), and Orthognathic Quality of Life Questionnaire (OQLQ). Questionnaires were administered at pre-treatment (T1), on completion of pre-surgical orthodontic decompensation (T2), 1-week (T3) and 6-months (T4) post-treatment. Repeated measurement method was used with statistical significance set at p < 0.05.

Results

1. T1 versus T2: Orthodontic decompensation led to increases in OHIP-14 physical pain score (p = 0.034) and OQLQ oral function score of borderline significance (p = 0.0561).

2. Baseline versus post-treatment i. After treatment (T3, T4), overall scores of OHIP-14 and OQLQ were lower (p < 0.0001) and

overall WHOQOL-BREF score was higher (p < 0.05) than T1. ii. Short-term evaluation showed significantly lower OHIP-14 and OQLQ domain scores at T3

than T1, with the exception of OHIP-14 functional limitation, OHIP-14 handicap (p = 0.0511, borderline statistical significance) and OQLQ awareness of facial deformity. All WHOQOL-BREF scores were significantly higher at T3 than T1, except the physical health domain.


iii. Longer-term evaluation showed significantly lower OHIP-14 and OQLQ domain scores at T4 than T1, with the exception of OHIP-14 functional limitation. WHOQOL-BREF psychological score remained higher at T4 than T1 (p < 0.0001).

3. At T2, females had lower WHOQOL-BREF physical scores (p = 0.0006) and higher OQLQ social aspects of deformity scores (p = 0.0170).

Conclusion

Orthodontic-orthognathic management improved overall QOL in patients with dentofacial deformities. Some gender differences were found at completion of pre-surgical decompensation.


Quality of life; Orthognathic patients; Orthognathic surgery; Orthodontic-orthognathic treatment; dentofacial deformities

PG20: Prevalence of Dental Anomalies in Various Antero-Posterior and Vertical Skeletal Types in a Chinese Orthodontic Population 1Chan XLG, 1Tan ELY, 1Yow M, 1Chew MT, 2Wong HC, 3Foong KWC 1Department of Orthodontics, National Dental Centre Singapore 2Yong Loo Lin School of Medicine, National University of Singapore 3Faculty of Dentistry, National University of Singapore Objectives To investigate the difference in the prevalence of dental anomalies in the various antero-posterior (AP) and vertical skeletal types in the Singapore Chinese orthodontic population. Methods This study was conducted using radiographs, photographs, and clinical records of patients who attended the National Dental Centre Singapore Department of Orthodontics. In this study, the records of 2,508 Chinese orthodontic patients aged 14 – 25 years were enrolled. They were classified into AP skeletal types of Class I (n = 1241), Class II (n = 580) and Class III (n = 687) based on the ANB angle measured from the lateral cephalogram. They were also divided into vertical skeletal types of average (n = 1496), low (n = 232) and high angle (n = 780) based on the maxillary-mandibular plane angle measured from the lateral cephalogram. Their records were examined for the prevalence of various dental anomalies in the permanent dentition, excluding third molars.


Statistical analyses were performed using SAS® 9.4. Logistic regression was used to determine if there was any association between AP skeletal class (Class I, II, and III) and the prevalence of the various dental anomalies. Class I group was used as the control group. Logistic regression was used to determine if there was any association between vertical skeletal type (average, low, and high angle) and the prevalence of the various dental anomalies. Average angle group was used as the control group. Bland-Altman method was used to test for intra-examiner reproducibility for the measurement of ANB and MMPA. Kappa coefficients were calculated to test for intra-examiner reproducibility for the assessment of the presence of each dental anomaly. Statistical significance was set at p < 0.05. Results The prevalence of dental anomalies found in this sample is: 5.7% hyperdontia, 11.7% hypodontia, 5.5% peg-shaped upper lateral incisors, 21.9% impacted teeth, 1.3% transposition, and 0.4% double teeth (fusion and gemination). There was no significant gender difference in the prevalence of the various anomalies except for hyperdontia, with male orthodontic patients having significantly higher odds of developing hyperdontia compared to females (p = 0.021). Skeletal Class III patients had significantly lower odds of having at least one dental anomaly compared to Class I (p = 0.022). Skeletal Class III patients also had lower odds of having impacted teeth compared with Class I type (p = 0.0001). Conclusion There are significant differences in the prevalence of dental anomalies between genders and AP skeletal types in the permanent dentition of a sample of Chinese orthodontic patients.

References 1. Qian L, Chew MT, Yow M, Wong HC, Foong KWC (2017). Anomalies of permanent tooth number in three Asian ethnicities. Australasian Orthodontic Journal 33(2):22-29. 2. Uslu O, Akcam MO, Evirgen S, Cebeci I (2009). Prevalence of Dental Anomalies in Various Malocclusions. American Journal of Orthodontics and Dentofacial Orthopedics 135(3):328-335. 3. Vahid-Dastjerdi E, Borzabadi-Farahani A, Mahdian M, Amini N (2010). Non-syndromic Hypodontia in an Iranian Orthodontic Population. Journal of Oral Science 52(3):455-461. 4. Vahid-Dastjerdi E, Borzabadi-Farahani A, Mahdian M, Amini N (2011). Supernumerary Teeth Amongst Iranian Orthodontic Patients. A Retrospective Radiographic and Clinical Survey. Acta Odontologica Scandinavica 69(2):125-128. Keywords

dental, anomalies, orthodontic, prevalence


SESSION 2, 2.10pm – 3.30pm: STAFF PRESENTATIONS STF01:Modelling An In Vitro Organotypic Model of Human Atopic Dermatitis

Dr Gopu Sriram

STF02:The Role of Oral Microbiota in the Severity of Chemotherapy-Induced Oral

Mucositis

AP Catherine Hong Hsu Ling

STF03:Distribution And Chondroprotective Effect Of Pericellular Matrix Molecules In

TMJ

Mr Chuah Shang Jiunn, Research Assistant

STF04:The Multi-faceted Mechanism of MSC Exosomes in Cartilage Repair

Ms Kristeen Teo Ye Wen, Research Assistant


STF01:Modelling An In Vitro Organotypic Model of Human Atopic Dermatitis Sriram G1, Sudhaharan T2, Wright GD2

1 Faculty of Dentistry, National University of Singapore 2 Institute of Medical Biology, A*STAR, Singapore Objectives

Atopic dermatitis (AD) is a chronic skin disease characterized by epidermal thickening (hyperplasia), impaired differentiation and disruption of the skin’s barrier function. This study aims to develop and characterize a novel in vitro three-dimensional (3D) organotypic model of human atopic dermatitis.

Methods

Human full-thickness skin equivalents were fabricated by seeding human keratinocytes over a fibroblast-populated dermal matrix, followed by culture at air-liquid interface. To induce AD-like phenotype, the skin cultures were treated with Th2 cytokine (IL4: Interleukin-4, primary cytokine involved in the pathogenesis of AD) during air-liquid interface culture. The normal and IL4 treated skin cultures were characterized by histology and immunohistology and 2-photon microscopy based non-invasive imaging.

Results

Histologically, the IL4-treated skin cultures exhibited epidermal hyperplasia. Immunohistological analysis revealed (1) downregulation of keratinocyte differentiation markers keratin-10 and involucrin, and (2) expansion of the basal proliferative compartment demonstrated by increased Ki67 proliferation index and multiple layers of Integrin-β1 positive basal cells. Non-invasive imaging using two-photon microscopy revealed the presence of epidermal hyperplasia and significantly smaller keratinocytes in the suprabasal compartments of the epidermis of IL4-treated skin cultures, indicative of the immaturity or the impairment in the keratinocyte differentiation.

Conclusion

The epidermal hyperplasia and impaired differentiation observed in IL4-treated skin cultures are suggestive of AD-like phenotype. The model provides a physiologically relevant in vitro platform to investigate the cellular mechanisms of AD and evaluate novel therapeutics.


Atopic Dermatitis, Keratinocytes, Organotypic Cultures, Tissue Engineering, Organoids, Skin Equivalents


STF02:The Role of Oral Microbiota in the Severity of Chemotherapy-Induced Oral Mucositis Catherine Hsu Ling Hong; Nitasha Gupta; Samantha Quah; Jin Fei Yeo; Joao Ferreira; Kai Soo Tan Faculty of Dentistry, National University of Singapore

Abstract unavailable as it contains confidential information

STF03:Distribution And Chondroprotective Effect Of Pericellular Matrix Molecules In TMJ Chuah Shang Jiunn, Toh Wei Seong Faculty of Dentistry, National University of Singapore Objectives The objectives of this study were to (1) determine the distribution and synthesis of pericellular matrix (PCM) molecules (collagen VI, collagen IV and laminin) in rat temporomandibular joint (TMJ) and (2) investigate the effects of PCM molecules on chondrocytes against inflammation in osteoarthritis. Methods Four zones (fibrous, proliferating, mature and hypertrophic) of condylar cartilage and three bands (anterior, intermediate and posterior) of disc were analysed by immunohistochemistry for the presence of PCM molecules in rat TMJs. Isolated chondrocytes were pre-treated with PCM molecules before being subjected to interleukin (IL)-1β treatment to stimulate inflammation. The responses of the chondrocytes were analysed using gene expression, nitric oxide release and matrix metalloproteinase (MMP)-13 production measures. Results Histomorphometric analyses revealed that the highest areal deposition of collagen VI (67.4%), collagen IV (45.7%) and laminin (52.4%) was in the proliferating zone of TMJ condylar cartilage. No significant difference in the distribution of PCM molecules was noted among the three bands of the TMJ disc. All three PCM molecules were expressed intracellularly by chondrocytes cultured in the monolayer. Among the PCM molecules, pre-treatment with collagen VI enhanced cellular proliferation, ameliorated IL-1β-induced MMP-3, MMP-9, MMP-13 and inducible nitric oxide synthase gene expression, and attenuated the downregulation of cartilage matrix genes, including collagen I, aggrecan and cartilage oligomeric matrix protein (COMP). Concurrently, collagen VI pretreatment inhibited nitric oxide and MMP-13 production.


Conclusion In conclusion, this study shows the presence an distribution of PCM molecules, including collagen VI, Collagen IV and laminin, in TMJ condylar cartilage and disc. Among the PCM molecules, collagen VI demonstrates proliferative and protective effect on TMJ chondrocytes against IL-1β-induced inflammation. References Chu WC, Zhang S, Sng TJ, Ong YJ, Tan WL, Ang VY, Foldager CB, Toh WS. Distribution of pericellular matrix molecules in the temporomandibular joint and their chondroprotective effects against inflammation. International Journal of Oral Science 2017; 9: 43-52.

Keywords

Cartilage; Chondrocytes; Collagen IV; Collagen VI; Laminin; Temporomandibular joint

STF04:The Multi-faceted Mechanism of MSC Exosomes in Cartilage Repair Kristeen Teo Ye-Wen, Toh Wei Seong Faculty of Dentistry, National University of Singapore Objectives Mesenchymal stem cell (MSC) exosome was previously shown to be effective in repairing critical size osteochondral defects in an immunocompetent rat model [1]. Here we investigate the cellular processes modulated by MSC exosomes and the mechanism of action underlying the exosome-mediated responses in cartilage repair. Methods We investigated the therapeutic efficacy of MSC exosomes in a rat critical-sized osteochondral defect model. Weekly injections of either 100μg exosomes in 100μl of phosphate buffered saline (PBS) or 100μl PBS were given over 12 weeks. At 2, 6 and 12 weeks, animals were euthanized for histology, immunohistochemistry, histomorphometry and cytokine analysis. To elucidate the exosome-mediated processes in cartilage repair, chondrocyte survival, migration, proliferation and matrix synthesis were evaluated. Additionally, chondrocytes were treated with exosomes in the presence and absence of different inhibitors to investigate the involvement of adenosine and activation of AKT and ERK pathways. Results We observed that exosome-mediated repair of osteochondral defects was characterised by increased cellular proliferation and infiltration, enhanced matrix synthesis and a regenerative immune phenotype. Using chondrocyte cultures, we could attribute the rapid cellular proliferation and infiltration during exosome-mediated cartilage repair to exosomal CD73-mediated adenosine activation of AKT and ERK signalling. Inhibitors of AKT or ERK phosphorylation suppressed exosome-mediated increase in cell


proliferation and migration but not matrix synthesis. The role of exosomal CD73 was confirmed by the attenuation of AKT and ERK signalling by AMPCP, a CD73 inhibitor and theophylline, an adenosine receptor antagonist. Exosome-treated defects also displayed a regenerative immune phenotype characterised by a higher infiltration of CD163+ regenerative M2 macrophages over CD86+ M1 macrophages, with a concomitant reduction in pro-inflammatory synovial cytokines IL-1β and TNF-α. Conclusion Together, these observations demonstrated that the efficient osteochondral regeneration by MSC exosomes was effected through a coordinated mobilisation of multiple cell types and activation of several cellular processes.

References 1. S. Zhang, W.C. Chu, R.C. Lai, S.K. Lim, J.H. Hui, W.S. Toh, Exosomes derived from human embryonic mesenchymal stem cells promote osteochondral regeneration, Osteoarthritis and Cartilage 24(12) (2016) 2135-2140. 2. S. Zhang, S.J. Chuah, R.C. Lai, J.H. Hui, S.K. Lim, W.S Toh, MSC exosomes mediate cartilage repair by enhancing proliferation, attenuating apoptosis and modulating immune reactivity, Biomaterials 156 (2018) 16-17. Keywords

Mesenchymal stem cells; Exosomes; Cartilage; Regeneration; Chondrocytes


SESSION 3, 3.50pm – 5.10pm: STAFF PRESENTATIONS STF05:Effects Of Probiotics On Fusobacterium Nucleatum-mediated Inflammatory

Response In Colonic Cells

AP Tan Kai Soo

STF06:pH-Responsive Protein Corona for Caries Risk Assessment

Mr Tan Guang Rong, Research Associate

STF07: One-atom-thick Graphene Coating Enhances Orthotopic Bone Formation on

Titanium Implants

Dr Vinicius Rosa

STF08: Accuracy Of Digital And Conventional Implant Impressions In Edentulous

Arches

Dr Tan Ming Yi


STF05:Effects Of Probiotics On Fusobacterium Nucleatum-mediated Inflammatory Response In Colonic Cells Kai Soo Tan*, Yue Xuen Lan¶, Samantha Yiling Quah¶ and Tiow Suan Sim¶

*Faculty of Dentistry, National University of Singapore ¶Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore

Abstract unavailable as it contains confidential information

STF06:pH-Responsive Protein Corona for Caries Risk Assessment Guang-Rong TAN1, Chin-Ying HSU1, and Yong ZHANG2

1Faculty of Dentistry, National University of Singapore 2Biomedical Engineering, National University of Singapore Objectives Plaque pH is a critical biophysical driver of dental caries. A pH sensor to map Stephan Curve and identify high caries-risk individuals for targeted caries prevention is clinically needed, but effective options are limited. Here, we report on a fluorescent, pH-responsive, protein corona candidate sensor that is highly-sensitive, broad-ranged and reliable in detecting real-time biofilm-pH for caries-risk assessment. Methods Protein corona was synthesized by coating silica nanoparticles (SiO2-NPs) with fetal bovine serum that has been pre-loaded with Oregon Green (OG) and Methylene Blue (MB). Corona formation and stability were characterized by transmission electron microscopy and bicinchoninic acid protein assay. Ratiometric emissions of OG (522nm) and MB (699nm) were plotted as a function of pH. Sensor specificity was tested in multiple biofilm ions (NaF, CaCl2, MgCl2 and NaCl) and human saliva. The method was validated against a conventional pH-electrode. Stephan Curve of differential concentrations (0, 0.05, 0.2 and 0.5 OD) of planktonic Streptococcus Mutans (SM), in 1% glucose, was measured, and the area under the curve (AUC, below pH 5.5) was computed. Results Spherical monodispersed SiO2-NPs with average diameter of 25nm had uniform protein corona layer of about 15nm. Protein loading was 328.7±5.1μg protein/mg NP. 85 – 91% of protein corona remained adsorbed after dispersion in pH 4.0 – 8.0 for 30mins at 37°C, indicating good corona stability. Sensor response was highly-sensitive with 13.4 fold-increase in ratio-change over a broad pH range of 3.0 – 8.0, enabling precise measurement of Stephan Curve. Sensor specificity was accurate within 0.18 pH units. Measurement was comparable with conventional pH electrode to within 5.3% deviation. Notably,


medium (0.2 OD) and high (0.5 OD) bacterial concentrations could only be distinguished by AUC (p<0.05), but not by minimum pH, demonstrating greater diagnostic utility compared to endpoint measurement. Conclusion The pH-responsive protein corona offers new prospects for clinical caries-risk assessment by enabling high-quality biofilm-pH detection. References -

Keywords

protein corona; hydrogen-ion concentration; fluorescence; sensitivity and specificity; biomarkers; investigative techniques

STF07: One-atom-thick Graphene Coating Enhances Orthotopic Bone Formation on Titanium Implants Vinicius ROSA, Nileshkumar DUBEY Faculty of Dentistry, National University of Singapore Objectives To characterize the extracellular matrix (ECM) deposited by pre-osteoblast MG-63 on graphene coated titanium in vitro and to evaluate the potential of the coating to promote bone formation in vivo. Methods Graphene was produced by chemical vapour deposition and deposited on titanium discs (8 mm diameter, 0.5 mm thickness) by a wet (WGp) and hot-pressing transfer (DGp). For the in vitro characterization of ECM, MG-63 were seeded on graphene-coated and uncoated titanium (Control) for up to 120 h. The matrix was characterized by the Sircol Collagen Assay, Raman and XRD. The expression of Col1A1, Col2A1, Col3A1, Integrin β1, Vinculin, Talin, FAK were assessed by qPCR. Statistical analysis was performed with One-way ANOVA (α=0.05). For the in vivo, implants were placed in critical-size calvarial defects and analysed after 4 and 8 weeks by micro-CT imaging and histology. Results DGp and WGp increased the expression of adhesion supporting and extracellular matrix genes compared to CpTi. The collagen production was higher on graphene than CpTi (>52%, Table 1). The graphene coating did not change the peak heights of combined phosphates (24 h) but decreased the amorphous calcium phosphate and increased octacalcium phosphate peak (120 h). XRD indicated that the mineral phase deposited on WGp and DGp had similar crystal structure to the observed on the CpTi. Both


graphene coating increase bone formation on the implants in vivo as shown by H&E and Von Kossa. The bone volume/total volume (BV/TV) ratio of CpTi group was significantly lower compared with WGp and DGp at weeks 4 and 8 indicating graphene allow faster bone regeneration. Conclusion Graphene-coated titanium showed enhanced secretion of the collagenous matrix and faster mineralization. Both WGp and DGp increased bone formation on implants in vivo. References - Keywords

Ostebolast, Bone, Carbon, Regenration, Mineralization

STF08: Accuracy Of Digital And Conventional Implant Impressions In Edentulous Arches Ming Yi Tana; Sophia Hui Xin Yeeb; Keng Mun Wonga; Ying Han Tana; Keson Beng Choon Tana a Faculty of Dentistry, National University of Singapore b Khoo Teck Puat Hospital, Singapore Objectives This study compares the 3D-accuracy of implant positions from a conventional impression system versus digital impression systems (intra-oral scanner [IOS], dental laboratory scanner [DLS]) at various inter-implant distances in an edentulous arch. Methods Six systems were tested in vitro on edentulous maxillary master models (A/B) with six/eight bone-level implants: (1)CV–polyether conventional impression; (2)TS–3Shape TRIOS IOS; (3)TD–3MTM True Definition IOS; (4)AG–Ceramill Map400 DLS; (5)SR–inEos X5 DLS; (6)TSL–3Shape D900 DLS. Centroid positions at the platform level were derived through CMM functions. Comparison of centroid positions between master and test models (n=5) allowed for calculation of linear displacements (dx, dy, dz), global linear displacement (dR), and 3D reference distance distortions between implants (ÄR). 2D-angles between the central axis of each implant to the x- or y-axis were compared to derive absolute angular distortions (d x, d y). Results Model A mean dR ranged from 8.7±8.3μm to 731.7±62.3μm. Model B mean dR ranged from 16.3±9μm to 620.2±63.2μm. Model A mean d x ranged from 0.021±0.2047º to -2.3488±0.1656º; mean d y ranged from


-0.0016±0.1595º to -0.9322±0.2899º. Model B mean d x ranged from -0.0066±0.0761º to -0.6877±0.5738º; mean d y ranged from -0.0179±0.0477º to -1.0519±0.2972º. One-way ANOVA revealed differences among systems for dR and ÄR in both models for all implant locations except the origin, with TD exhibiting the poorest accuracy. Independent samples t-tests for dR, between homologous implant location pairs in Model A versus B, revealed two or three significant pairings out of six possible pairings for IOS systems (TS, TD), for which dR was larger in Model A by 110-150μm. Conclusion TD exhibited the poorest accuracy for dx, dy, dz, dR and ÄR in both models, but not for d x and d y. The impression systems could not be consistently ranked for angular distortions. dR of IOS systems may decrease with reduced inter-implant distance.

References 1. Papaspyridakos P, Gallucci GO, Chen CJ, Hanssen S, Naert I, Vandenberghe B. Digital versus conventional implant impressions for edentulous patients: accuracy outcomes. Clin Oral Implants Res. 2016;27:465-72 2. Vandeweghe S, Vervack V, Dierens M, De Bruyn H. Accuracy of digital impressions of multiple dental implants: an in vitro study. Clin Oral Implants Res. 2017;28:648-53 3. Gherlone E, Capparé P, Vinci R, Ferrini F, Gastaldi G, Crespi R. Conventional versus digital impressions for “all-on-four” restorations. Int J Oral Maxillofac Implants. 2016;31:324-30 Keywords

3D accuracy, Implant, CMM, Digital impression, IOS, DLS

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