Pusat Pengajian Sains Pergigian - Tesis

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Bacterial leakage and marginal adaptation of three bioceramics pulp dressing material
(2023-04)
Siddiqua, Snigdha Niher Tabassum
This study aims to evaluate the sealing ability and marginal adaptation of three different bioceramics pulp dressing materials using a bacterial leakage test and scanning electron microscope (SEM). Fifty-five recently extracted lower first premolars were randomly divided into five groups, with three experimental groups (n=15), a positive control group (n=5) and a negative control group (n=5). The samples were instrumented with a modified coronal pulpotomy procedure except for the negative control group (n=5). Different types of bioceramics dressing material were placed in the cavity 3mm thickness in group 1 (Biodentine), group 2 (MTA) and group 3 (ProRoot MTA). There was no dressing material placed in the positive control group. Samples were placed in an incubator at 37℃, 100% humidity, for 24 hours to allow the material to be set, after the placement of the composite restoration. Two layers of nail varnish were applied, and the 3mm root tip was removed. The bacterial leakage test was performed using Enterococcus faecalis, and one sample from each experimental group was sliced and examined under SEM for marginal adaptation. Data analysis was conducted under the One-way ANOVA test, completed by Tukey’s post hoc test. The groups observed a significant difference in sealing ability and marginal adaptation (p<0.05), wherein Biodentine showed bacterial leakage on day 6 (7%), and on day 14 (80%), MTA showed on day 9 (14%) and on day 14 (40%), ProRoot showed on day 11 (7%) and on day 14 (33%). From SEM, ProRoot MTA demonstrated the least gap between the dressing material and significantly higher penetration in dentinal tubules. ProRoot MTA demonstrated better sealing ability and marginal adaptation compared to other groups. The finding indicates that ProRoot MTA would be the best pulp dressing material for the clinical setting. Keywords: Bacterial leakage test, bioceramics, Biodentine, MTA, ProRoot MTA, Pulpotomy, SEM.
The development and validation of digital medical education environment (digimee) instrument in measuring online learning environment for undergraduate medical students
(2024-08)
Haris, Noor-I-Kiran
Given the acknowledged role of technology-enhanced learning in medical education, there is a need for a focused evaluation approach for online learning environments specific to this field. The current lack of dedicated evaluation methods underscores the necessity for identifying key components in online learning environments for medical education. In response to this pressing need, this study seeks to develop and validate the Digital Medical Education Environment (Digi-MEE) Instrument, recognizing its pivotal role in addressing the existing gap and enhancing the quality of online learning experiences in medical education. The study was designed as a multi-phase mixed- methods research project conducted in online settings involving a diverse group of experts, teachers, and instructional designers and multiple medical colleges in Pakistan ( Phase 2 and 3), spanning 18 months. In Phase 1, experts in medical education and technology-enhanced learning identified and validated components of online learning environments through a scoping review and a modified e-Delphi study. Phase 2 involved undergraduate medical students and faculty members for content validation, response process validation, and refinement of Digi-MEE instrument versions v.1.0 and v.2.0. Content validity of the questionnaire items as assessed through expert reviews (S-CVI/Ave: 0.98), and response process validity through participant feedback, (S-FVI/Ave: 0.87). EFA of Digi-MEE v.3.0 revealed 9 components with 46 items, explaining 57.18% of the variance, with high internal consistency. The number of items per component were as follows: Cognitive Enhancement (5 items), Content Curation (6 items), Cybergogical Practices (6 items), Learner Characteristics (7 items), Digital Capability (4 items), Platform Usability (4 items), Facilitation Dynamics (5 items), Social Interactions (4 items), and Institutional Support (5 items). The internal consistency for these components was high, with a Cronbach’s alpha of 0.952. Factor loadings ranged from 0.404 to 0.721 for each component, indicating strong associations within each factor.CFA of the final 28-item Digi-MEE instrument showed good model fit indices, excellent internal consistency (Cronbach’s alpha: 0.952), and acceptable composite reliability (0.7). Key indices include a chi-square/df ratio of 2.4, RMR of 0.03, and GFI of 0.902. CFI and TLI are strong at 0.926 and 0.91, respectively, while RMSEA is 0.057, indicating a close fit. In Phase 3, a usability study involving a cross-sectional survey and phenomenology study validated the practical utility of the Digi-MEE instrument. In Phase 3 of the study, the usability of the Digi-MEE instrument was evaluated using a cross-sectional survey and phenomenological study, validating its practical utility. In Phase 3, the usability of the Digi-MEE instrument was validated through a survey and phenomenology study, with participants rating their online learning environment at 2.95 ± 0.84 out of 4. Findings highlighted issues with content quality, engagement, and interactivity. Recommendations included improving digital skills training, personalized feedback, and platform communication, alongside better self-regulation support and more effective applications.These insights led to a list of recommendations for the university. The findings confirmed that the Digi-MEE instrument is a useful and straightforward tool for evaluating online learning environments in medical education, guiding improvements in various components based on the results.
Development and characterisation of kenafnanohybrid dental composites
(2024-02)
Rasid, Noorasyikin Ab
Natural fibres such as kenaf fibres have enormous potential in replacing synthetic fibre used for composite reinforcement. This study aimed to optimize the bonding mechanism between kenaf and nanohybrid dental composite from rice husk and investigate mechanical properties of this composite. Kenaf fibres was processed to obtain cellulose nanocrystals (CNC) and silane treated with hybridization of tetraethyl orthosilicate (TEOS) sol gel and γ-Methacryloxypropyltrimethoxysilane (γ- MPS). The treated CNC was investigated through Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). Six specimens from each group with different ratio of γ-MPS and TEOS were prepared for compressive and flexural investigation. The experimental composites were compared with commercial nanohybrid composite and fibre reinforced composite (Ever-X posterior, Filtek Z350 and Neofil). Data was statistically analysed using one-way ANOVA test and the fracture surfaces of the samples were subjected to scanning electron microscope (SEM) assessment. FTIR results showed formation of chemical bonds between kenaf CNC with γ-MPS and TEOS sol gel. TGA showed highest decomposition temperature in non-silane treated kenaf fibre compared to silane treated kenaf fibre. Mean flexural and compressive strength between all groups showed statistically significant results (p=0.000). Experimental composite group with fibre reinforced showing higher flexural strength by 31 % while compressive strength increases by 38% compared to non- fibre reinforced composite, however the strength was lower as compared to commercial composites. The compressive strength of all the experimental composites were significantly lower than that of commercial composites. Silane treatment showing evidence of modification and improved bonding between the kenaf fibres and the resin matrix, even though the strength was lower than the commercial composite.
A study of temporomandibular joint morphology and positions among class i, class ii, class iii malocclusion and the effect of petit facemask in class iii malocclusion subjects
(2022)
Azhar, Mohammed Irfan
The temporomandibular joint (TMJ) is the most complex synovial joint in the body. TMJ morphology can be affected due to various reasons such as age, sex, increased or decreased muscle activity, the growth pattern of the face, pathological changes, occlusal forces, and changes in the dental occlusion. The effect of these changes can result in remodelling and reconfiguration of the TMJ surfaces. Therefore, careful diagnosis and treatment planning is very essential before the initiation of any orthodontic procedure. The purpose of our study was to evaluate and compare the TMJ morphology of 120 subjects with 40 subjects each in Class I, Class II and Class III malocclusion using pre-treatment lateral cephalometric radiographs (LCRs) and to evaluate and compare the TMJ morphology of 28 subjects with Class III malocclusion treated with petit-FM (Facemask) using pre-and post-treatment LCRs. TMJ evaluation included the measurements of porion location (PL), glenoid fossa, condyle position, condylar height (CH), joint spaces, maxillary base position (MX) and mandibular base position (MD). This was a retrospective cross-sectional study. LCRs were obtained using Planmeca Promax 3D machine (Planmeca Oy, Helsinki, Finland). TMJ morphology measurements were accomplished using the WinCeph cephalometric software version.11 (Rise corporation, Sendai, Japan) for both objectives. Data analysis was performed using SPSS ver.26 software (IBM, SPSS Statistics, Armonk, NY-USA). A one-way ANOVA and Bonferroni post hoc test was done for objective 1, while paired t-test was carried out for objective 2. The comparison of TMJ morphology between Class I, II and III malocclusions showed a significant difference for superior joint space (SJS), posterior joint space (PJS), and MD with (p = 0.00). Correspondingly, the comparison of TMJ morphology between pre-and post-treatment subjects of Class III malocclusion in response to petit-FM therapy revealed significant difference for horizontal positions of the glenoid fossa with (p = 0.00) and (p = 0.03) respectively. Significant difference was observed in hinge axis with (p = 0.00) and (p = 0.04) and all variables of condyle position with (p = 0.00). Lastly, all the joint spaces, MX, and MD showed statistically significant differences with (p = 0.00). In conclusion, the first objective revealed highest SJS and PJS for Class III malocclusion and lowest for Class II malocclusion respectively. There was increase in the length of mandibular base (MD) in Class III subjects which indicate forwardly placed mandible and decrease in Class II subjects which represent backwardly placed mandible. Correspondingly, the second objective demonstrated significant alterations in horizontal position of the glenoid fossa indicating posterior displacement after FM therapy. The hinge axis and condylar head (both superior and posterior condyle) were placed postero-superiorly, while the anterior condyle was placed postero-inferiorly suggesting clockwise rotation of the mandible post treatment. There was an increase in the length of maxillary base which indicate forwardly placed maxilla and decrease in the length of mandibular base which exhibit backwardly placed mandible. Among joint spaces, the anterior joint space (AJS) was found to be larger, and smaller for SJS and PJS post treatment suggesting upward and backward movement of the mandible.
Inhibition of endoplasmic reticulum stress using 4-phenyl butyrate mitigates osteoporosis in a mouse model of hindlimb suspension
(2024-08)
Al-Daghestani, Hiba Saad Subhi
Osteoporosis (OP) characterized by micro-architectural deterioration of bone tissue is a common skeletal disease in the elderly and may lead to fragility fractures. It may also negatively affect implant rehabilitation and prosthesis fixation in the older people. Mouse hindlimb suspension (HLS) is an established model to study disuse- induced OP and its molecular pathology. The disruption of protein folding by endoplasmic reticulum (ER), called ER stress may be a prime driver of OP during disuse. 4- phenylbutyrate (4-PBA) is short chain fatty acid that functions as a chemical chaperone to reduce ER stress. We aimed to investigate the impact of ER stress on OP, and the effect of 4-PBA, as an ER stress inhibitor in the HLS mouse with OP. 21 male C57BL/6J mice were randomly divided into three groups namely: ground-based controls, untreated HLS group, and HLS treated with 4-PBA via intra-peritoneal injections at 100mg/kg/d for 21 days. HLS duration was for 21 days, thereafter, mice were euthanized by cervical dislocation. Humeri, femora, and tibiae bones were collected and cleaned from soft tissues for measurements of reactive oxygen species (ROS) levels, histomorphometry, micro-CT, Raman spectroscopy, and gene expression studies. The results obtained were analysed using GraphPad Prism version 8. High levels of ROS were generated in the hindlimbs (HLs) and forelimbs (FLs) of the untreated HLS group compared to controls. The tibiae bones of the untreated HLS group demonstrated lower osteocyte density, numerous multinucleated osteoclast-like cells, and adipocyte infiltration within the marrow, while micro-CT revealed lower bone volume fraction, reduced trabecular thickness, along with fewer trabeculae striations with increased trabecular separation. Cortical thickness and total cross-section of cortical area were also reduced. Raman spectrophotometric analysis of the femur in the untreated HLS group revealed elevated ER stress with an increase in levels of hydroxyproline, non-collagenous proteins, phenylalanine, tyrosine, and CH2Wag, and a reduction in proteoglycans and adenine. Alkaline phosphatase (ALP) and osteocalcin (OC) expressions were downregulated, while cathepsin K (Cat K), Tartrate resistant Acid Phosphatase (TRAP), and sclerostin were upregulated. Taken together, these characteristics of bone reflect poorer mineralization, less collagen crosslinking, and a pro-inflammatory effect. Treatment with 4-PBA mitigated ER stress levels, restored the normal bone histomorphometry and microarchitecture, increased collagen crosslinking and mineralization, and promoted anti-inflammatory and downregulated bone resorption markers. This study shed light on characterizing the potential contribution of ER stress to OP during bone disuse and the potential effect of 4-PBA as an innovative pharmacological approach to OP treatment.

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