Pusat Pengajian Sains Pergigian - Tesis

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The effects of sirna-targeting IL-17a receptor in regulating the osteogenic differentiation in stem cells from human exfoliated deciduous teeth
(2024-05)
Aduni, Wan Khairunnisaa Wan Nor
Interleukin-17-A holds significant roles in osteogenic differentiation and bone remodelling mechanism. To date, limited studies describe the effects of small interfering RNA (siRNA) on the expression of IL-17A receptor (IL-17RA) and how the modulation influences the process of osteogenic differentiation. Thus, the present study was to evaluate the effects of siRNA-targeting-IL-17RA on the osteogenic differentiation and the expression levels of osteogenic markers in stem cells from human exfoliated deciduous teeth (SHED). SHED were cultured in complete Minimum Essential Medium α supplemented with osteogenic medium which consists of 50 µg/mL L-ascorbic acid, 10 mM β-glycerophosphate, and 100 nM dexamethasone to induce osteogenic differentiation in SHED for 7 and 14 days. Differentiated SHED were cultured into two conditions: Group 1was treated with optimized concentration of IL- 17A (50 ng/mL) and Group 2 was treated with IL-17A and transfected with optimized concentration of siRNA-targeting-IL-17RA (50 nM) for 48 hours. Mineralisation activity by Alizarin red staining was performed on day 14 and day 21. The effects of siRNA were evaluated by measuring the expression levels of osteogenic markers such as ALP, OPG, RANKL, COL1A1, and RUNX2 by qPCR after 7 and 14 days. Untreated SHED were characterised by positively stained for stem cell markers such as CD90, CD73, and CD105 and were negatively stained for hematopoietic cell marker CD14. Differentiated-SHED showed significant expressions of ALP, COL1A1, and RUNX2 on day 7 and day 14 of differentiation. Staining of IL-17A-treated-SHED by Alizarin red demonstrated an increased calcium deposition compared to untreated SHED. Similarly, the expressions of ALP, OPG, COL1A1, and RUNX2 were significantly upregulated in IL-17A-treated SHED. However, RANKL expression was downregulated. Interestingly, siRNA- transfected SHED showed significant downregulation of ALP, OPG, COL1A1, and RUNX2 while RANKL was upregulated. These findings demonstrate that IL-17A enhances osteogenesis by promoting osteogenic differentiation and that siRNA- targeting-IL-17RA had interfered with the functions of IL-17A/IL-17RA, thus suggesting the importance of IL-17A in mediating the physiological mechanism of bone metabolism.
Radiographic analyses of skeletal and dental parameters for age estimation in Malaysian population
(2024-04)
Sigali, Waleed Mohammed Petro
To formulate a new prediction model for the age estimation range between 17-30 years old for both genders in the Malaysian population using oral parameters (root pulp visibility, periodontal ligament visibility, mental foramen and mandibular canal location) and stages of ossification of the medial clavicular epiphyseal cartilage. The study was a cross-sectional comparative study among the Malaysian population attending the clinic in the hospital set up at the Universiti Kebangsaan Malaysia and Universiti Sains Malaysia. Root pulp and periodontal ligament visibility showed a significant mean difference of age, mainly for stage 0 in the ethnic groups involved in the study between males and females. Measurements between right and left mental foramina and mental foramen to the inferior border of the mandible found a significant difference in mean between the ethnic groups after being adjusted for age and sex. There was also a significant difference in mean when measuring the distance from the midline to the right mental foramen between males and females after being adjusted for age and ethnic groups. Measurements from the right and left mandibular canal to the inferior border of the mandible found that there was a significant difference of mean between the ethnic groups after adjusted for age and sex, p-value < 0.001. The age prediction model using a combination of mandible variables, pulp, periodontal ligament visibility, mental foramen, and mandibular canal location showed R2 = 0.561. Hence, the model is considered to have a medium fit. Chest radiograph samples (390) showed a significant mean age difference between males and females, p-value = 0.017, using an independent t-test. Furthermore, there was a significant mean age difference between the ethnic groups, p-value < 0.001, by using a one-way ANOVA test. As for the age prediction model using right medial clavicle union, the ANOVA showed R2 = 0.767. This indicates that the final model explains 76.7% of the total variance in age. Hence, the model is considered to have an excellent fit. Using multi-factorial radiological methods showed good results while consuming less time and effort. Digital chest radiographs were a useful tool for predicting age.
Investigation of chemicomechanical properties of polyamide 12 composite reinforced with fillers from agriculture biowaste as a potential dental post
(2024-04)
Babu, Nurul Syafika Atikah
Nanofillers and short fibres were added to polymer composites as the reinforcements to improve their mechanical properties. The synthetic E-glass fibres used in fibre- reinforced composite of commercial dental post was reported to be hazardous. Oil palm fibres and rice husk silica are cheaper and generally safer for workers than glass fibres in composite production. The aim of this research is to produce dental post and core which incorporated natural oil palm fibre (OPF) and rice husk (RH) silica from agricultural waste into the matrix and also to investigate the chemicomechanical properties of the produced post compared to the commercial post. Preparation of OPF/RH Silica/PA12 reinforced nanocomposite post was done by incorporating treated silica from rice husk and oil palm fibre crystallized nanocellulose (OPF CNC) into Polyamide 12 (PA12) matrix. Six samples with a size of 1.5mm x 2.0mm x 25.0mm were prepared for 7 groups (n=6, N=42) and six samples with the size 4mm diameter x 6mm height, were also prepared for 7 groups (n=6, N=42); Group 1 100% PA12, Group 2 PA12 (99%) + OPF CNC (1%), Group 3 PA12 (98%) + OPF CNC (2%), Group 4 PA12 (80%) + (20%) RH silica, Group 5 PA12 (80%) +(19%) RH silica + (1%) OPF CNC, Group 6 PA12 (80%) +(18%) RH silica + (2%) OPF CNC, Group 7 everStick post (flexure test)/ everX FlowTM (compressive test). The flexure and compressive tests were carried out using Instron Universal Testing Machine (Shimadzu, Japan) and the data were analysed using IBM SPSS version 26.0 (SPSS Inc, Chicago, IL, USA). Fourier- transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and Thermogravimetric analysis (TGA) were used to examine the fractured flexural strength samples. Flexural test showed that there was a statistically significant difference in flexural strength between different groups (χ2 (df) = 38.65 (6), whereby the PA12 with CNC fillers showed an increased in flexure strength value compared to unfilled PA12 and has no significant difference with commercial post. The incorporation of OPF CNC in the PA12 composite however did not increase the compressive value compared to unfilled PA12 and showed a significantly reduction in compressive strength compared to commercial composite. SEM analysis confirmed the presence of both fillers in the composite and showed smoother surface with presence of lesser voids and gaps with increment of filler wt% which suggested enhanced interfacial bonding. TGA analysis showed that OPF CNC lowered the thermostability of the composite while RH silica improved the thermostability of the composite. Incorporation of OPF CNC into PA12 matrix increased flexure strength of the composite. Incorporation of silica on the other hand reduced the flexure strength of PA12. However, the incorporation of OPF CNC or RH silica did not give any impact to the compressive strength of PA12.
Fracture Resistance Of Weakened Root Structure Reinforced With Two Types Of Composite Resin And Endodontic Sealer
(2009-02)
Ahmad Mahmood Ahmad
The aim of this study was to compare the fracture resistance of weakened roots obturated with a new nano HA endodontic sealer or an epoxy resin endodontic sealer and reinforced by either auto-cured or light-cured composite resin.
The Intrinsic Role Of Endoplasmic Reticulum Stress Sensors In The Mechanism Underlying The Depressive Symptoms And Kratom Dependence In Chronic Kratom Users
(2023-07)
Muhamad Fauzi, Nurul Atiqah Binti
Background: This study aimed to determine the differences in the mRNA and protein expression of ER stress sensors (such as BiP, XBP1, ATF4 and CHOP) in the peripheral blood mononuclear cells (PBMCs) between non-drug using healthy controls and regular kratom users, evaluate how alterations of ER stress sensors expression was associated with the kratom use patterns (such as first age of using kratom, kratom use duration, kratom use average daily frequency, kratom use average daily quantity, and time of last kratom use prior to blood collection) and assess the correlations between the mRNA and protein expression of ER stress sensors in the peripheral blood mononuclear cells (PBMCs) among regular kratom users and the severity of depressive symptoms on kratom abstinence and kratom dependence severity. Methods: Data on socio-demographic characteristics were collected from kratom users and healthy controls. While data on kratom use patterns, kratom dependence severity and depressive symptoms on kratom abstinence were collected from kratom users. The expression of mRNA and protein of selected ER stress sensors (such as BiP, XBP1, ATF4 and CHOP) in the PBMCs of kratom users and healthy controls were measured with qRT-PCR and western blot, respectively. Results: A total of 20 kratom users and 20 healthy controls completed the study. The levels of expression of mRNA and protein of BiP were significantly elevated in kratom users compared with healthy controls regardless of the kratom use patterns.

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