Dentistry Commons^™

Oral Health Inequalities In Adolescents And Young Adults In Ontario, Maria Rahman

Electronic Thesis and Dissertation Repository

Oral health is consistently linked to physiological, psychological, and social aspects of well-being in adolescents and young adults. In this thesis, I aimed to examine the social determinants of oral health and dental care utilization. First, I conducted a scoping review of the literature, demonstrated the multifaceted nature of oral health and its connections to broader social and economic factors. Then, I conducted a cross-sectional analysis of the Canadian Community Health Survey which showed a social gradient in oral health and dental care utilization among adolescents and young adults in Ontario. When stratified by age, there was a protective association …

The Impact Of Access To Oral Health Care On Inadequate Oral Health And Multimorbidity, Luis Limo

Electronic Thesis and Dissertation Repository

The connection between oral health and other non-communicable chronic conditions—commonly referred in the dental literature as the oral-systemic health connection—emphasizes the role of oral health care on both oral diseases and chronic conditions, particularly in vulnerable populations like the elderly. This thesis comprises 2 studies: the first is a systematic review on the impact of oral health care interventions, as an indicator of access to oral health care, on chronic conditions of which their co-existence would result in multimorbidity; the second study is a cross-sectional investigation of the associations between oral health, access to oral health care, and multimorbidity among …

Validation Study On The Differentiation Of Human Periodontal Ligament Cells In The Presence Of Cementum Protein 1 And Periostin, Deborah A. O'Reilly

Electronic Thesis and Dissertation Repository

Existing research alludes to the fact that human periodontal ligament cells differentiate into an ossifying phenotype in response to differential gene expression during orthodontic tooth movement. The purpose of this research was to validate the differentiation of human periodontal ligament cells of young individuals in the presence of specific proteins and stimuli (cementum protein, periostin and osteogenic media), which mimic the environment of the periodontal ligament. Another objective was to assess the differential gene expression within these cells under the same conditions. A protocol was developed to provide a collagen-protein scaffold on which human periodontal ligament cells were maintained for …

Characterizing Human Papillomavirus Associated Oral Epithelial Dysplasia, Damir Rosic

Electronic Thesis and Dissertation Repository

The role of high-risk human papillomavirus (HR-HPV) is well documented in oropharyngeal squamous cell carcinoma and cervical cancer. Although a subset of oral dysplastic lesions have been associated to HPV infection as well, there is currently limited data characterizing these lesions. We identified HPV-associated oral epithelial dysplasia (HPV-OED) through screening for histopathological features of HPV and p16INK4a immunoreactivity. Transcriptionally active infections were confirmed by performing RT-qPCR to identify E6 mRNA expression. We identified 82 cases of confirmed HPV-OED that showed a strong predilection for male patients and anatomical sites such as floor of mouth and ventral tongue. This group had …

Secretion Of Salivary Proteins And Their Interactions, Karla Tonelli Bicalho Crosara

Electronic Thesis and Dissertation Repository

Saliva’s clinical application for disease diagnosis and monitoring is limited by incomplete knowledge of salivary protein interactions, the effect of stimulation on the salivary proteome, and if these factors impact protein identification. This thesis expands knowledge of the salivary interactome and effects of stimulation intensity and duration on parotid saliva’s proteome. First, previous in vitro studies identified 43 proteins in the histatin 1-protein network and demonstrated histatin 1’s increased stability in whole saliva when interacting with amylase. We hypothesized that protein-protein-interaction databases could enlarge the histatin 1-protein network. A comprehensive histatin 1-protein network was created using STRING database, merging previous …

Extrinsic And Intrinsic Factors Influencing Homeostasis And Repair In Oral Tissues, Georgia Nikoloudaki

Electronic Thesis and Dissertation Repository

The oral tissues, including gingiva and buccal mucosa, heal rapidly with minimal scar formation. Although in the oral cavity, the palatal mucosa is associated with excessive scarring in response to injury. In this thesis, first, I investigated the complex relationship between cells and their microenvironment using wound healing models in which extracellular matrix composition and mechanical stiffness affect cellular responses during acute wound repair. I also determined how intrinsic differences of cells recruited during healing contribute to wound resolution.

In Chapter 2, I first investigated cell-extrinsic factors, specifically the influence of the pro-fibrotic matricellular protein periostin on palatal healing. Using …

The Effect Of Modifications To Intermaxillary Orthodontic Elastics On Force Levels And Degradation Over Time, Steven Dent

Electronic Thesis and Dissertation Repository

Introduction: Orthodontic elastics are frequently used in orthodontic treatment but there is little research into how to modify their prescription to improve their performance. The aim of this study was to evaluate potential wear modifications to a standard Class II intermaxillary elastic prescription on force levels and force degradation over time.

Methods: For this in vitro study, Ormco (OR) and American Orthodontic (AO) latex elastics had five modifications made to a standard 1/4”/4.5oz control elastic (Group 1). These included an increase of force level by one unit to 6 or 6.5oz (Group 2); a decrease in lumen size to 3/16” …

Torque Expression Of Active And Passive Self-Ligating Orthodontic Brackets With Different Stainless Steel Wire Sizes, Jennifer L. Boogaards

Electronic Thesis and Dissertation Repository

This investigation aimed to compare engagement angles and torquing moments generated by stainless steel (SS) wires in three active self-ligating (ASL), one passive self-ligating (PSL), and a conventional twin orthodontic bracket system control. Brackets were tested in simulations of buccal and palatal root torque using four sizes of SS wires (16x22, 17x25, 19x25, 20x20 mil). A custom 3D printed testing apparatus was developed to measure torque. After initial engagement within bracket slots, torquing moments increased with progressive rotation of brackets around wires. In general, the PSL and conventionally ligated systems generated significantly larger torquing moments than ASL systems, especially with …

Validation Of The Flexcell®Fx-5000 Tension System To Evaluate The Expression Of Cementum Protein-1 In Human Periodontal Ligament Cells While Under Cyclical Orthodontic Tensile Force, Allison Nicholls

Electronic Thesis and Dissertation Repository

The pressure-tension theory of orthodontic tooth movement (OTM) states that there are differences in microenvironment between the tension and compressions side within the periodontal ligament, leading to differential gene expression within those zones. Cementum protein 1 (CEMP-1) is a human-specific protein localized to the root of a tooth and may play a role in OTM. The first objective was to develop a protocol to apply tensile force to human PDL cells similar to that within the tension zone during OTM. For this, the FlexCell®FX-5000 Tension system was used and fluorescent microscopy was used to confirm validity of the protocol. The …

Catechol-Containing Copolymers As An Active Ingredient For Denture Adhesives, Vincent Ying Wun Kong

Electronic Thesis and Dissertation Repository

Moisture inside the mouth adds challenge to making denture adhesives formulations. Some formulations have zinc to enhance adhesion on wet skin despite knowing the health hazards. Inspired by mussel foot proteins’ catechol unit’s strong underwater adhesion, nine catechol-containing copolymers (P1A-P3C) were synthesized by free radical polymerization of 3,4-dimethoxystyrene (3,4- DMS) with different styrene derivatives followed by deprotection. P1A-P3C were used to make Fn(P)-C-PBS denture adhesive formulations which had suitable shear stresses around ≥ 5 kPa satisfying ISO 10873. In-situ NMR studies of free radical polymerization of 3,4 - DMS and styrene derivatives allowed computation of their reactivity ratios showing all …

A Critical Review And Finite Element Study Of Structural Relaxation In Veneered 3y-Tzp Dental Structures, Prashant S. Shelar

Electronic Thesis and Dissertation Repository

Yttria stabilized Tetragonal Zirconia Polycrystal (3Y-TZP) materials veneered with porcelain are preferred for clinical practice due to their bio-functionality, biocompatibility, and affordability. However, these materials are often subjected to premature clinical failures due to combination of subsurface flaws and tensile stresses within porcelains. This work focuses on performing a critical literature review and evaluating veneer characteristics, i.e. structural relaxation, to form a suitable explanation for the development of subsurface stresses. User material subroutines, UEXPAN and UTRS are developed, validated and integrated in ABAQUS finite element solver. With the use of validated models, it is shown that faster cooling rates and …

Debt And Stress Amongst Orthodontic Residents, Timothy Renison

Electronic Thesis and Dissertation Repository

Background: The cost of education to become an orthodontist has increased significantly over recent years which has led to an increase in debt of graduating orthodontists.

Aim: This paper aims to assess whether debt amongst orthodontic residents in North America is associated with their stress levels, attitudes towards debt, financial literacy and mathematics anxiety.

Materials and Methods: Web-based software was used to fabricate a questionnaire, based on previously validated scales, in which respondents were asked questions regarding their debt levels, stress levels, attitudes towards debt, financial literacy and math anxiety.

Results: A total of 101 orthodontic residents completed the online …

The Role Of Gsk3 Alpha And Beta In Embryonic Craniofacial Development, Harman Jassar

Electronic Thesis and Dissertation Repository

Background: The GSK-3 genes (Gsk3a and Gsk3b) have been known to affect many cellular processes and signaling pathways some of which are implicated in the growth and development of the craniofacial skeleton.

Aim: The purpose of this study was to assess the effect of chondrocyte-specific deletion of Gsk3a and Gsk3b on the size of the mandible and craniofacial skeleton in embryonic mice.

Materials & Methods: Mice were bred to generate cartilage-specific Gsk3a and Gsk3b KO mice. On embryonic day 18.5 (E18.5) the offspring were gathered by caesarian section. Whole mount skeletal staining was completed on the specimens using …

The Effect Of Pigmentation On Latex And Non-Latex Orthodontic Elastics, Dustin Wilson

Electronic Thesis and Dissertation Repository

Background: Intraoral Elastics have been widely used in Orthodontics for well over 100 years. Changes in material composition, manufacturing and addition of color to elastics has shown to effect force levels over time.

Aim: The purpose of the study was to determine the effect of pigmentation on force levels and their degradation over time in both Latex and Non-Latex orthodontic intraoral elastics.

Materials & Methods: Groups consisted of elastics in Latex from American Orthodontics in both natural and four different colors, American Orthodontics Non-Latex in natural, Ormco Latex in both natural and four different colors, Auradonics Latex in both natural …

Evidence Of An Antigen Presenting Cell Phenotype In Granular Cell Tumours, Benjamin J W A Rogala

Electronic Thesis and Dissertation Repository

Granular Cell Tumours (GCTs) are rare subepithelial lesions that are believed to develop from Schwann cells and are characterized by large polygonal cells with abundant lysosomes. Pilot studies from our laboratory showing unexpected HLA-DR immunoreactivity in GCTs lead us to hypothesize that GCTs have an antigen presenting cell (APC) phenotype.

To test our hypothesis, we assessed immunoreactivity of GCT lesions to APC phenotype markers, including CD68, HLA-DR, CD163, CD40 and CD11c. In addition, we assessed markers of neural crest cell (NCC) origin S100, SOX10, NSE and GAP43. Samples subjected to these studies included 23 cases of GCTs and 10 cases …

Metal Additive Manufacturing For Fixed Dental Prostheses, Mai El Najjar

Electronic Thesis and Dissertation Repository

The use of additive manufacturing (AM) in dentistry has gained momentum in recent years. However, high initial costs and uncertainty surrounding the quality of AM products are considered barriers to their use. This research compared dental substructures fabricated by AM versus conventional casting and milling.

Cobalt-chromium alloy rectangular bars and three-unit bridge substructures were fabricated by AM, casting or milling. Bars manufactured by AM exhibited superior flexural strength, shear bond strength of porcelain coating, and Vickers hardness. Bridge substructures fabricated by AM showed similar flexural stiffness to cast, similar flexural loads at failure to milled and cast, and overall accuracy …

Survey Of Canadian Orthodontists Regarding Orthodontic Miniscrew Usage, Leah A. Van Sant

Electronic Thesis and Dissertation Repository

Purpose: To obtain information on the clinical utilization of orthodontic miniscrews (OMSs) among orthodontists in Canada

Methods: Web-based software was used to fabricate a questionnaire in which respondents were asked questions regarding their usage of OMSs in their clinical practice. The survey consisted of between 11 and 39 questions, depending on the respondents’ answers. The survey was distributed via email to the 353 active Canadian members of the American Association of Orthodontists (AAO).

Results: A total of 82 Canadian orthodontists responded to the survey, for a response rate of 23.2%. Among them, 65.8% currently used miniscrews in their clinical practice. …

Evaluating The Utility Of Protein Biomarker, S100a7, And Diagnostic Test, Straticyte, In Predicting The Progression Of Oral Dysplasia, Lachlan Mclean

Electronic Thesis and Dissertation Repository

Five-year survival of oral cancer has remained relatively unchanged despite advancements in treatment, mostly because diagnosis is often made at an advanced stage of disease. The progression of dysplasia to oral cancer often follows a stepwise progression. Histopathology is considered the ‘gold standard’ for diagnosing dysplasia and lesions at a high risk of progression to oral cancer, but lends itself to subjectivity. The protein biomarker, S100A7, in oral dysplasia and squamous cell carcinoma has shown some predictive value for the transformation of dysplasia to cancer. Straticyte, a diagnostic test utilizing S100A7 to predict the probability of progression of oral dysplasia …

The Effect Of Pigmentation On Thermoplastic And Thermoset Elastomeric Power Chain, William Taylor

Electronic Thesis and Dissertation Repository

Aim: The purpose of the study was to determine the effect of pigmentation on force levels and their degradation over time in orthodontic power chain of different chain types and manufactures.

Materials & Methods: Groups consisted of closed power chain from American Orthodontic (AO) thermoplastic (TP) in 5 colors, AO thermoset (TS) in 2 colors, Ormco TP in 4 colors, Ormco TS in 2 colors, and Rocky Mountain Orthodontics (RMO) TS in 5 colors (18 groups total, 10 chain samples in each group). Testing was performed over a period of 6 weeks at intervals of initial (T0), 1 hour (T1), …

Mass Spectrometry-Based Proteomics Analysis Of Bioactive Proteins In Emd That Modulate Adhesion Of Gingival Fibroblast To Improve Bio-Integration Of Dental Implants, David Zuanazzi Machado Jr

Electronic Thesis and Dissertation Repository

Titanium implants are used in dental practice to replace damaged or lost teeth. The implant needs to integrate with the surrounding gingiva to protect it against bacterial invasion that leads to implant loss. The biointegration is dependent on the implant surface that interacts with proteins from biological fluids to modulate tissues response. Tailoring the surface with specific proteins from the enamel matrix derivative (EMD) would be beneficial to improve the implant-gingiva interface since EMD can affect various cells including gingival fibroblasts. A surface-affinity approach using three different titanium surfaces and saliva was utilized as a model in combination with tandem …

Acquired Bracket Pellicle Modulation Via Exposure To Histatin 3, Niklas W. Neilson

Electronic Thesis and Dissertation Repository

Objectives: To investigate the effect of histatin 3 on the protein pellicle formation on the orthodontic bracket surface.

Methods: Our study consisted of 4 sample groups. A sample of human parotid saliva without histatin functioned as a control group. Other groups were immersed with or without histatin 3 and human parotid saliva. Each group was incubated for 2 hours in their respective substrate at 37°C. The acquired pellicle from each group was harvested, then analyzed with SDS-PAGE and LC-ESI-MS/MS.

Results: Thirty-nine proteins were identified in the control group, 18 were identified in group 2, and 21 were identified in group …

Diagnostic Ultrasound In The Measurement Of Cortical Bone Thickness In Porcine Mandibular Specimens, Diego Diaz Guerrero

Electronic Thesis and Dissertation Repository

Introduction: Ultrasound (US) is a safe, non-invasive diagnostic method that has been used in various capacities in medicine and dentistry. Periodontal bone loss, bony dehiscence, and gingival recession have been reported as potential risks of orthodontic treatment in patients who have decreased buccal/labial bone thickness. US has the potential to aid in the diagnosis of patients at risk for these possible complications of orthodontic treatment. Purpose: To validate the use of a novel US device in the measurement of buccal cortical bone (BCB) thickness over roots in porcine mandibles. Materials and Methods: Jaw and cortical bone models were constructed and …

Effect Of Clear Aligner Therapy On Masticatory Muscle Tenderness And Orthodontic Pain, Johnny Tran

Electronic Thesis and Dissertation Repository

Introduction: Patients undergoing orthodontic clear aligner therapy (CAT) may experience discomfort in their teeth and jaws, and often present with visible wear on their aligners. This multi-site prospective clinical study aimed to analyze tooth pain and masticatory muscle tenderness in patients subjected to CAT with Invisalign©.

Methods: Twenty-seven healthy adults undergoing treatment with Invisalign© were recruited from three university-based orthodontic clinics. Tooth pain and muscle tenderness were reported on visual analog scales in pain diaries prior to, and after starting CAT. Pressure pain thresholds (PPT) measured using pressure algometers were used to assess somatosensory changes in trigeminal and extra-trigeminal locations. …

Kallikrein-Related Peptidases Are Dysregulated In Pleomorphic Adenoma, Matthew D. Morrison

Electronic Thesis and Dissertation Repository

Objectives: Pleomorphic adenoma (PA) is the most common benign salivary gland tumor. Kallikrein-related peptidases (KLKs) have been identified as biomarkers in many human tumors and may influence tumor behavior. We investigated KLK1-15 messenger ribonucleic acid (mRNA) and proteins in PA specimens to determine a KLK expression profile for this tumor.

Methods: Fresh frozen PA tissue specimens (n = 26) and matched controls were subjected to RT-qPCR to detect KLK1-15 mRNA. Expression of KLK1, KLK12, KLK13 and KLK8 proteins were then evaluated via immunostaining techniques. Statistical analyses were performed with the level of significance set at P < .05.

Results: We observed downregulation …

Aesthetic Outcome Of Maxillomandibular Advancement Surgery For The Treatment Of Obstructive Sleep Apnea, Jennifer Curran

Electronic Thesis and Dissertation Repository

Introduction:

Obstructive sleep apnea (OSA) is a common sleep disorder in which complete or partial airway obstruction causes disruptive sleep and excessive daytime sleepiness. Highly successful treatment outcomes for OSA utilizing maxillomandibular advancement (MMA) surgery have been reported. However, due to the large degree of surgical advancement that is performed, concerns may exist regarding the final aesthetic result.

Objectives:

To evaluate facial profile changes in patients treated for OSA with MMA surgery utilizing panels of oral and maxillofacial surgeons (OMFS), orthodontists (ORTHO) and laypeople (LAY).

Methods:

This was a retrospective cohort analysis. Pre- and post-treatment silhouettes of patients who underwent …

Friction Testing Of Contemporary Self-Ligating Appliance Systems, Michael Greene

Electronic Thesis and Dissertation Repository

Background: Resistance to tooth movement is multifactorial, with friction (FR) one of many important components. There is limited data comparing contemporary Passive and Active self-ligating bracket (SLB) systems in terms of FR created by archwire engagement. Aim: To compare classical FR in contemporary SLB systems and traditional twin brackets in vitro, and to identify the point of initiation of bracket-archwire engagement. Materials & Methods: Nine bracket systems of .022-in slot size were FR tested: Victory Series (3M Unitek) with elastic ligature (control); Passive SLB systems Damon Q (Ormco), Carriere SLX (Henry Schein), H4 (Ortho Classic), Altitude …

Binding Of Salivary Proteins To Orthodontic Brackets, Maria Pia Canales

Electronic Thesis and Dissertation Repository

Objectives: The aim of this study was to investigate the effect of different orthodontic materials on the formation of the protein pellicle on the bracket surface.

Materials and Methods: We used X-ray Photoelectron Spectroscopy (XPS) to analyze the atomic composition of orthodontic metallic and ceramic brackets. Following XPS, the brackets were immersed in human whole saliva supernatant for 2-hour incubation at 37°C. Hydroxyapatite (HA) discs were used as control. Acquired pellicle was harvested with sonication for each group, and liquid chromatography electrospray ionisation mass spectrometry was used for protein identification.

Results: Differences reported by XPS and mass spectrometry were noted …

Expression Of Human Tissue Kallikreins (Klks) In Polymorphous Low Grade Adenocarcinoma (Plga), Jacqueline M. Cox

Electronic Thesis and Dissertation Repository

Polymorphous low grade adenocarcinoma (PLGA) is the second most common malignant salivary gland tumour of the minor salivary glands. Human tissue kallikreins (KLKs) are a family of highly conserved serine proteases expressed by various tissues throughout the body. KLKs have become powerful tumour markers for the diagnosis of the cancer patient (e.g. PSA (KLK3)). The literature demonstrates a link between KLKs and salivary gland neoplasms. The purpose of this study is to determine levels of KLK mRNA in tissue samples of formalin fixed paraffin embedded polymorphous low grade adenocarcinoma (PLGA). Secondly, we wish to determine if KLK expression is limited …

Comparison Of Treatment Effects Of The Forsus Fatigue Resistance Device In Class Ii Patients With Different Underlying Vertical Skeletal Patterns, Michelle C. Watroba

Electronic Thesis and Dissertation Repository

The purpose of this study was to evaluate the differences in dental and skeletal changes induced by the Forsus^TM Class II dentoalveolar corrector in Class II patients with varying vertical skeletal growth patterns. The sample consisted of 26 (mean age 12.9 ± 1.3 years) Brachyfacial (BF) (SN-MP < 30^o) consecutively treated Forsus subjects, 16 (mean age 13.1 ± 0.8 years) BF untreated Class II subjects (control subjects), 12 (mean age 12.3 ± 1.2 years) Nonbrachyfacial (NBF) (SN-MP ≥ 30^o) consecutively treated Forsus subjects, and 8 (mean age 13.2 ± 0.9 years) NBF untreated Class II subjects (control). …

Role Of Lipid Mediators In P2x7 Signaling In Osteoblasts, Erin Eyer

Electronic Thesis and Dissertation Repository

P2X7 is a cell-surface nucleotide receptor that plays a critical role in skeletal mechanotransduction; however, the signaling pathways mediating these effects are poorly understood. Previous studies showed that the nucleotide analog benzoylbenzoyl-ATP induces anabolic gene expression in osteoblastic cells. Our first objective was to determine whether this effect was mediated by P2X7. Inhibition of anabolic gene expression by a P2X7-specific antagonist established involvement of this receptor. Our second objective was to investigate the role of lipid mediators, lysophosphatidic acid (LPA) and prostaglandin (PG), both of which are produced in response to P2X7 activation. The effect of P2X7 on expression of …