Kimia Imani
Faculty Mentors: Dr. Donald Chi
Department: Oral Health Sciences
Supported By: T90 DE021984, Dr. Douglass L. Morell Dentistry Research Fund
Title: A Mixed-Methods Study on Differential Decision-Making about Topical Fluoride by Caregivers with Multiple Children
Objectives: To identify correlates of and reasons for differential decision-making about topical fluoride by caregivers with multiple children.
Methods: This mixed-methods study employed an explanatory sequential mixed methods approach. For the quantitative component, survey data from 725 caregivers were analyzed to explore associations between caregiver sociodemographic characteristics and topical fluoride-related decision-making, using logistic regression to calculate odds ratios (OR) and 95% confidence intervals (CI). For the qualitative component, data from 13 interviews with caregivers who reported making different decisions about topical fluoride for each child were coded inductively and thematically analyzed with the goal to create a conceptual model.
Results: In the quantitative analysis, 165 (22.8%) caregivers made different decisions about topical fluoride for each child. Being a male caregiver (OR: 1.59, 95% CI 1.05, 2.40; p= .028), of Asian race (OR: 1.93, 95% CI 1.21, 3.06; p= .0052), and having a higher degree of concern (OR: 1.18 (1.12, 1.25, p<.001), and opposition top topical fluoride (OR: 1.17, 95% CI 1,11, 1.23; p<.001) significantly increased the odds of differential decision-making about topical fluoride, whereas having a very liberal political view (OR: 0.37, 95% CI 0.14, 0.96; p=.036) significantly decreased the odds of differential decision-making. In the qualitative analysis, the key elements of the conceptual model for caregiver differential decision-making were focused on four domains: perceived health risk of topical fluoride, perceived efficacy of topical fluoride, perceived need for topical fluoride, and the child’s preference with topical fluoride.
Conclusions: Caregivers’ decisions regarding topical fluoride for multiple children are complex and tailored to each child. The study’s findings provide healthcare providers with valuable insights into how to navigate and address the varying decision-making values that caregivers have for each child within a family.
Elissa Elmorr
Faculty Mentors: Dr. Jeffrey McLean, Dr. Kristopher Kerns
Department: Periodontics
Supported By: SURF
Title: Change in Plaque Microbial Composition in an Intervention to Reduce Sugar-Sweetened Fruit Drinks in Alaska Native Children
Objectives: Determine the change in supragingival plaque microbial composition during an intervention trial to reduce sugar-sweetened fruit drink consumption in Alaska Native children.
Methods: The change in the supragingival plaque composition of rural Native Alaska children from three communities participating in a longitudinal intervention trial to reduce sugar-sweetened fruit drink consumption was assessed. Communities A and B received the intervention while Community C served as a control group. Supragingival plaque was collected from labial incisors (N=180, aged 1 to 11 years) using dental micro-brushes at baseline and 6 months (post-intervention). DNA was extracted, the V3-V4 hypervariable region (~460 bp) of the 16S rRNA gene was amplified and sequenced on an Illumina MiSeq (600 cycles) with positive and negative controls. Raw paired-end sequences were imported to Qiime2, denoised using the DADA2 algorithm, for exact amplicon sequence variants (ASVs) and assigned taxonomy using the eHOMD. Alpha diversity and taxonomic changes within and between communities were assessed.
Results: When combining Community A and B, there was a statistically significant increase in alpha diversity between baseline and 6 months compared to Community C (p=0.0032). Between each group, Community A showed a statistically significant increase in alpha diversity between baseline and 6 months (p=0.003) and the mean diversity increased in Community B but was not statistically significant (p=0.2). Community C showed no statistical significance (p=0.76).
Conclusions: Overall, our results highlight that the intervention targeting added sugar-sweetened fruit drinks in rural Alaska Native communities was associated with community-specific increases in microbial alpha diversity within supragingival dental plaque, which has been shown to be an indication of a healthier microbial community composition. The results of this study will be critical when determining future interventions to reduce caries and address oral health inequities in Indigenous communities. Authors: Elissa Elmorr, University of Washington (UW), Kristopher Kerns, PhD, MPH, UW, Lloyd Mancl, PhD, UW, Allison Naumann, UW, Donald L. Chi, DDS, PhD, Jeffrey McLean, PhD, MS, UW.
Yung-Hsin Cheng
Faculty Mentors: Dr. Greg J. Huang, Dr. Jing-Sheng Li, Dr. Fritzie Arce-McShane, Dr. Douglas S. Ramsay
Department: Orthodontics, Oral Health Sciences
Supported By: SURF
Title: A Self-instructional Training Video to Perform 3D Mandibular Border Movements
Objectives: Assessing mandibular movements is a fundamental aspect of clinical dentistry, yet there is a lack of self-instructional resources for teaching these movements to patients. This study’s goal was to create and evaluate a self-instructional training video for performing mandibular border movements.
Methods: Ten participants (4 males, 6 females; age range 19-22 years) without a history of temporomandibular joint (TMJ) discomfort were instructed to practice along with a self-instructional video until they believed they could successfully make the requested jaw movements. The video used dental/jaw animations accompanied by a verbal audio description to guide subjects to perform the requested movements. After self-training, subjects came to the clinic and performed the jaw movements while following the self-instructional video and being video recorded. Maximal opening (MO) was measured. Three evaluators independently scored each subject’s recorded movements based on how well a subject duplicated the movements in the video with respect to each movement’s direction and quality. Intraclass correlation coefficients confirmed the reliability of scoring between evaluators. Each of the 19 mandibular movements was categorized as being good, moderate, or poor based on its mean score.
Results: The mean MO for males (57.78mm, SD=6.6) and females (43.33mm, SD=4.84) differed significantly. A significant negative correlation was found (r=-0.71, p=0.02) between a subject’s MO and reported TMJ discomfort level during practice/clinical test sessions. Although there was no significant correlation between the amount of practice and how well the subjects performed the movements, two practice sessions prior to clinical assessment may be sufficient for training.
Conclusions: The results support the potential of training subjects with a self-instructional video. Most of the poorly rated movements asked subjects to maintain a specified amount of mouth opening throughout the movement. Placing a flat inter-occlusal guide plane of a thickness equal to the amount of the desired opening might make these movements more accurate.
Fionna Lee
Faculty Mentors: Dr. Philippe Hujoel
Department: Oral Health Sciences
Supported By: Dr. Douglass L. Morell Dentistry Research Fund, the University of Washington, R21 DE033319
Title: Facilitators and Barriers to Receiving Oral Health Care in Patients with Opioid Use Disorder: A Dentist Perspective
Objectives: The objective of this study was to understand the perspectives of dentists in improving oral health care among patients with Opioid Use Disorder (OUD).
Methods: This qualitative study used semi-structured interviews to inquire about dentists’ perceptions and experiences of their interactions with patients with OUD. Dentists were recruited and screened through recruitment emails and word-of-mouth. Seventeen dentists were enrolled and interviewed using an interview guide. Interviews were digitally recorded and transcribed using the Nvivo® software. Trained coders used a deductive thematic approach to thematically code interview content. Codes were analyzed to look for themes within and between dentists.
Results: Seventeen dentists participated. The mean years of experience in dentistry was 20 years. 47.1% were men and 52.9% were women. Multiple themes emerged as perceived barriers to care. This included patient inconsistency with attending appointments, complexity in pain management, patient resistance, and insufficient education and experience of dentists in treating individuals with OUD. Dentist and individual facilitators include increased interprofessional collaboration and co-location, and other patient care team members encouraging the patient to seek dental care. Dentists believe that ways to improve access to dental care for individuals with OUD include increased insurance reimbursement rates and increased public funds to support dentists treating individuals with OUD.
Conclusions: The results of this study may inform on resolving barriers of care for the treatment of oral diseases among individuals with OUD.
Shaili Rathod
Faculty Mentors: Dr. Cameron Randall
Department: Oral Health Sciences
Supported By: University of Washington Dr. Douglass L. Morell Dentistry Research Fund
Title: A Memory Restructuring Intervention to Prevent Dental Fear: Parent Perspectives
Objectives: Pediatric dental fear/anxiety is common and associated with numerous negative outcomes. Memory restructuring interventions have shown promise for preventing pediatric dental fear/anxiety. Parent-delivered memory restructuring interventions may be particularly good for widespread implementation and public health impact; these have been used effectively in pediatric medicine but not yet in dentistry. The aim of this pilot study was to understand parent perspectives on a parent-delivered post-procedure memory restructuring intervention.
Methods: Parents of children receiving dental treatment were recruited for this cross-sectional, mixed-methods study. Participants were presented with a hypothetical memory restructuring intervention before completing: (1) validated measures of intervention acceptability, appropriateness, and feasibility; and (2) an in-depth qualitative interview probing perceived intervention utility and implementation preferences. Quantitative data were analyzed using descriptive statistics. Interviews were recorded, transcribed, verified, and coded using inductive content analysis.
Results: Fifteen parents participated (80% mothers, child age M=10.2, SD=3.65). Participants rated the memory restructuring intervention as highly acceptable (M=4.7, SD=0.72), appropriate (M=4.7, SD=.68), and feasible (M=4.8, SD=.33). Qualitative interview data indicated a high degree of interest in and expected comfort using the intervention. Participants believed the intervention would be helpful for reinforcing positive/balanced memories and preventing fear. Regarding implementation, participants suggested the intervention be presented to them by a dentist or dental assistant briefly before or immediately after the procedure, with opportunity for questions.
Conclusions: There is potential for successful application of a parent-delivered post-procedure memory restructuring intervention for fear prevention in pediatric dentistry. Results will inform refinement of the memory restructuring intervention for a future randomized controlled trial.
Sydney Kim
Faculty Mentors: Dr. Hannele Ruohola-Baker
Department: Oral Health Sciences
Supported By: T90 DE021984, SURF
Title: Dental Regeneration: An Engineered Plasmid For Live Cell RNA Monitoring
Objectives: The goal of regenerative dentistry is growth of a tooth, including the organizational complexity of its dentin and enamel hard tissues. Current investigation of differentiation of induced pluripotent stem cells (iPSCs) into secretory odontoblasts and ameloblasts is limited by validation methods that sacrifice cells. On the basis of recent papers that introduce an RNA-based gene marker for live cells leveraging endogenous adenosine deaminases acting on RNA (ADARs), this experiment engineered plasmids targeting relevant genes for human cells. The goal of this research is to characterize gene expression in live cells undergoing differentiation to streamline protocols.
Methods: Plasmids were obtained from Addgene. A plasmid targeting the housekeeping gene GAPDH was created via molecular cloning using PCR amplification. As a pilot experiment, HEK293 cells were grown in a 12-well plate to 70-90% confluency and transfected using Lipofectamine 3000 and observed for fluorescence after 72 hours. Images were obtained by the Live-Cell Widefield System system at 10x microscopy. Cells expressing the fluorescent markers blue fluorescence protein (BFP) and green fluorescence protein (GFP) were counted using ImageJ.
Results: Positive BFP indicating successful transfection and GFP indicating successful targeting of GAPDH were present in all wells transfected with the plasmid. BFP-GFP coincidence ranged from 2.8% to 59.2%, and cells with added 0.5 μg/μL doxycycline had a larger BFP count and BFP-GFP coincidence compared to non-doxycycline cells.
Conclusions: BFP-GFP coincidence in this experiment indicates that the engineered plasmid successfully reflects target gene expression. However, low coincidence rates suggest that the ADAR mechanism may have low sensitivity for the target gene expression. The addition of doxycycline may improve coincidence in future experiments. These results are encouraging for further experiments in creating transcripts targeted to genes relevant to differentiation for odontoblasts and ameloblasts, which will be incorporated at the genome level into iPSCs due to their low transfection efficiency. Creating these novel cell lines will allow identification of differentiation progression without sacrificing cells to streamline protocols for creating regenerative dental cells.
Nelson Wong
Faculty Mentors: Dr. Jonathan An
Department: Oral Health Sciences
Supported By: Dr. Douglass L. Morell Dentistry Research Fund, VitaDAO Longevity Fund.
Title: Evaluation of Periodontal Bone Through High-Resolution microCT After Inhibition of the PI3K-pathway during Aging.
Objectives: This project aims to evaluate the clinical phenotype in the aged mice treated with PI3K inhibitors by analyzing the linear and volumetric alveolar bone in the maxillary using high resolution micro-computed tomography (microCT)
Methods: A medical imaging software called Analyze 14.0(Analyze Direct) was used to quantify the volume of the alveolar bone. Linear bone loss was calculated using a landmarking technique on aged mice and volumetric bone quantification will be completed using Drishti.
Results: The 3D volumetric and linear analysis performed on the maxillary dentition, specifically segmenting out the 1st molar, required substantial computational resources and processing time due to the complexity and high-resolution of the data. In addition to analyzing the alveolar bone, we expanded our efforts to comprehensively evaluate the periodontal complex by segmenting the enamel, dentin, and pulp spaces. Assessing the volumetric and structural changes across all the samples demands detailed examination to ensure accuracy and reproducibility.
Conclusions: Preliminary analyses indicate notable volumetric and linear differences in aged samples compared to young controls; however, further in-depth processing and validation are ongoing. Given the significant time required for these analyses, additional efforts are needed to characterize and interpret the final results fully. We anticipate presenting these findings at the 2025 Research Day.
Rebecca Lee
Faculty Mentors: Dr. Peggy Lee
Department: Oral Medicine, Oral Maxillofacial Radiology Residency
Supported By: SURF
Title: Exploring the Relationship Between Temporomandibular Disorders and Gonial Angle
Objectives: This study aimed to investigate the relationship between gonial angle and temporomandibular disorders (TMD), including myalgia, disc displacement (DD), and degenerative joint disease (DJD), using rigorous diagnostic criteria and CBCT imaging.
Methods: A total of 386 subjects from a multicenter TMD study were assessed, with gonial angle measurements obtained from CBCT images for 209 subjects. Previously determined TMD diagnoses include myalgia, DD, and DJD.1 Regression analyses, controlling for age and sex, were used to examine associations between gonial angle and TMD diagnoses.
Results: No statistically significant associations were found between gonial angle and the severity or presence of myalgia, DD, or DJD. The primary analysis and sensitivity analyses consistently showed no evidence of a statistically significant relationship. High inter- and intra- rater reliability of gonial angle measurements (CCC = 0.98) validated the precision of measurements.
Conclusions: This study found no evidence to support a relationship between gonial angle and TMD diagnoses.
Delbert Oxborrow
Faculty Mentors: Dr. Amy Kim
Department: Office of Educational Partnerships
Supported By: SURF 2024
Title: Free Dental Clinic Program Analysis: Union Gospel Mission
To determine the treatment volume, production value, and cost effectiveness at the Union Gospel Mission (UGM) dental clinic during fiscal year 2023.
Methods: A list of all completed dental procedures recorded as Current Dental Terminology (CDT) codes during fiscal year 2023 were exported from Eaglesoft. The number of times each code appeared was counted to determine each code’s volume. Codes were then assigned a value based on UGM’s master fee schedule. Each individual code’s production value was calculated by multiplying the volume of the code by the assigned value. Category production values were calculated for each of the 12 standard CDT categories as the sum of the included individual code production values. Total production value was calculated as the sum of all individual code production values. Cost effectiveness was evaluated as a direct comparison between the total production value and operational costs. Operational costs were assessed as the sum of all expenses from the monthly expense reports.
Results: During the examined period, 1146 CDT codes were completed for a total production value of $236,415. The total operational expenses were $211,583. The Diagnostic category had the highest volume of treatment with 521 CDT codes completed and D7140, extraction of an erupted tooth, had the greatest contribution to total production of $48,150.
Conclusions: The value of treatment provided at the UGM dental clinic during fiscal year 2023 was greater in comparison to the operation expenses making the program cost effective. These results allow for better comparison between the cost effectiveness of dental outreach modalities and can inform future dental interventions.
Kristi Trinh
Faculty Mentors: Dr. Tracy Popowics
Department: Oral Health Sciences
Supported By: SURF
Title: Mechanoreceptor Development in the Periodontal Ligament from Eruption to Occlusion
Objectives: This study aims to test the hypothesis that mechanoreceptors within the PDL are distributed throughout the root length during tooth eruption and undergo morphological reorganization upon the tooth’s transition into functional occlusion. The study aims to evaluate the development of the periodontal ligament mechanoreceptors of teeth erupting into occlusion using a pig model.
Methods: The project utilizes sagittal cross-sectioned histological slides obtained from 13-week-old (n=3) and 23-week-old (n=3) pigs. The samples included whole dissections of the mandible, thus the relationship between the tooth, PDL, and alveolar bone remain intact. Samples were prepared to assess the structural components of the PDL and were used to identify and characterize the presence of mechanoreceptors. The third premolars (P3) and mandibular first molars (M1) were decalcified, paraffin embedded, and serially sectioned. Each sample slide was deparaffinized and reacted with a general neuronal marker antibody (anti-pgp.9.5 antibody, Abcam), and counterstained with methyl green or a myelin sheath marker (Luxol Blue). The periodontium of P3 and M1 were imaged with a light microscope at low and high magnification (x10 and x40). These slides were compared with previously stained hematoxylin and Eosin (H & E) slides from corresponding tissue samples of the same age group to identify tissue structure.
Results: PGP9.5 immunohistochemical staining was employed to assess neuronal and mechanoreceptor activity within periodontal tissues. Representative images demonstrated varying staining intensities across dental structures, with the strong staining observed in odontoblasts within the root canal adjacent to the dentin layer. Notably, the darker blue stained areas are at the boundaries that are adjacent to the odontoblast and cementoblast. Conversely, lighter staining was noted in coronal odontoblasts, suggesting a gradient in staining intensity along the length of the tooth.. Marginal staining was also observed in other periodontal tissues, although it was relatively indiscriminate and lacked clear localization to mechanoreceptor-specific regions. The faint yet definitive staining of odontoblasts within the pulp, confirmed the efficacy of the PGP9.5 staining protocol.. This observation underscores the functional presence of PGP9.5-associated proteins within odontoblasts, providing evidence that the protocol was effective, but limited for mechanoreceptor structures. Luxol Blue staining was utilized to evaluate myelinated nerve bundles in relation to the developing tooth root. The staining highlighted nerve fibers predominantly in proximity to the apical region of the root, corresponding to areas of active neural innervation during tooth development. Nerve bundles appeared as distinct, dark blue structures against the surrounding lighter-stained periodontal ligament and pulp tissues. Notably, the staining revealed a greater density of nerve fibers near the root apex compared to the coronal portions of the developing tooth, consistent with the localization of mechanoreceptors and sensory input regions. Representative images illustrate the localization and density of stained nerve bundles, providing insight into the neural organization within developing dental tissues. These findings emphasize the utility of Luxol Blue staining in delineated myelinated structures within the tooth and its supporting tissues. Overall, the developmental pattern of mechanoreceptors was undetermined.
Conclusions: Determining the developmental patterns of periodontal ligament mechanoreceptors proved challenging due to sample limitations, including staining inconsistencies and potential tissue degradation. Despite these obstacles, this study underscores the critical importance of advancing research into the innervation of the PDL. Understanding the developmental patterns and roles of mechanoreceptors in the PDL has the potential to shift the predominantly restorative focus of modern dentistry toward a more regenerative-oriented approach. For instance, restoring mechanoreceptive function in implants could enhance proprioception, aiding in the regulation of occlusal forces and preventing overloading that often contributes to implant failure. Additionally, a deeper understanding of neural regeneration could inform therapies for conditions affecting periodontal tissues, such as periodontitis, by promoting reinnervation alongside tissue repair. Future studies should focus on improving sample preservation and optimizing staining protocols to enable more definitive identification of mechanoreceptor structures and their developmental patterns. Incorporating advanced imaging techniques, such as confocal or electron microscopy, could further elucidate the structural and functional properties of PDL innervation. By addressing these limitations and building upon the findings of this study, future research has the potential to bridge gaps in current knowledge of PDL mechanoreceptors.
These efforts could transform dental and periodontal care with innovative methods of regenerative medicine.
Sheeba Soni
Faculty Mentors: Dr. Yung-Ting Hsu
Department: Periodontics
Title: The Outcomes of Ridge Augmentation via Tunneling Technique: a Systematic Review and Meta-analysis
Objectives: Bone augmentation has been widely utilized in implant dentistry to enhance the alveolar ridge for further implant reconstruction. While conventional procedures vial flapped approaches have been associated with various complications, minimally invasive techniques via flapless approaches has been introduced in recent year aiming to reduce these complications and improve clinical outcomes. This systematic review aims to summarize English-language dental literature evaluating dimensional changes in the alveolar ridge following bone augmentation using tunnelling techniques.
Methods: An electronic search was conducted in PubMed, Embase, and Web of Science to identify randomized and non-randomized prospective or retrospective human case-control or cohort studies comparing the efficacy of ridge augmentation using tunneling techniques during 1st January 1980 to 31st August, 2024. Two calibrated independent reviewers assessed the selected studies. The main outcome measured was the horizontal bone gain (HBG) and vertical bone gain (VBG) evaluated from the initial baseline visit to the final follow-up. Meta-analysis was performed to analyze HBG and VBG and their differences between the test group (undergoing tunneling bone augmentation) and controls (ridge augmentation via flapped approaches). Meta-regression was performed to investigate the contributing factors of these outcomes.
Results: A total of 498 titles and abstracts were identified. After full-text analysis of 42 articles, only 10 studies met the inclusion criteria. The test group showed significant HBG or VBG in responses to the treatment compared to baseline. The pooled HBG and VBG were 5.03mm (CI [3.79,6.27], p<0.01) and 5.17mm (CI [3.89,6.46], p<0.01), respectively. Compared to the control group, the HBG was not significantly different between the two groups (0.33mm, CI [-0.26,0.91], p=0.27). However, the test group had significantly greater VBG than the control group (0.56mm, CI [0.14,0.98], p=0.01).
Conclusions: The tunneling bone augmentation techniques demonstrates significant potential for achieving horizontal and vertical bone gains, while minimizing commonly occurred complications in conventional GBR techniques. Further studies with bigger sample size are required to assess the long-term outcomes and predictability in different clinical scenarios.
Joshua Lim
Faculty Mentors: Dr. Donald Chi
Department: Oral Health Sciences
Title: Are Caregivers Hesitant about Topical Fluoride for Multiple Reasons?
Objectives: We examined whether caregivers are hesitant about topical fluoride for a single or multiple reasons and the philosophical and sociodemographic predictors of multi-reason hesitancy.
Methods: We administered an 85-item survey (11/2020-09/2021) to 1,135 caregivers that included the 20-item, 5-domain validated Fluoride Hesitancy Identification Tool. We estimated the extent of multi-reason hesitancy based on a 5-domain hesitancy model. We defined multi-reason hesitancy as parental endorsement of items measuring more than one hesitancy domain. We ran logistic regression models to evaluate associations of child-level demographic and caregiver-level sociodemographic and philosophical factors and multi-reason hesitancy.
Results: The analyses included 1,042 caregivers. Mean age was 42.0 years (SD:8.3), 78.7% were woman, and 58.3% were white. About 18% of caregivers were non-hesitant and 43.9% were hesitant for a single reason. About 39% of caregivers indicated multi-reason hesitancy, 9.3% endorsing two reasons, 6.8% three reasons, 7.7% four reasons, and 14.7% five reasons. The most common domain for multi-reason hesitancy was necessity, with 99.5% of multi-reason hesitant caregivers endorsing items in this domain. Of caregivers hesitant for two reasons 51.1% were hesitant on the necessity and chemicals domains. Of caregivers hesitant for three reasons, 39.7% were hesitant on the necessity, uncertainty, and chemicals domains. Of caregivers hesitant for four domains, 53.2% were hesitant on all domains but harm. In the regression model, a positive statistically significant association was observed between multi-reason hesitancy and the following: the child not having dental insurance, non-white caregiver race, and very conservative caregiver political views.
Conclusions: Multi-reason hesitancy is relatively common. Regardless of the number of domains endorsed, nearly all parents expressed concerns about topical fluoride. Additional work should identify tailored strategies to manage single and multi-reason hesitancy in clinic.
Priyanka Prajapati
Faculty Mentors: Dr. Ana Lucia Seminario
Department: Pediatric Dentistry, DeRouen Center for Global Oral Health
Supported By: Matthews Family Foundation
Title: Integrating Oral Health Among HIV Health Clinics in West Kenya
Objectives: To integrate oral health within medical care at HIV clinics in Kisumu County, Kenya.
Methods: Using the World Health Organization (WHO) training module (OpenWHO) on oral health education in primary healthcare settings, non-dental healthcare workers were recruited from three sub-county hospitals in Kisumu County (September 2024). The training program was divided into three sections: “Identifying Oral Diseases and Promoting Oral Hygiene in Primary Healthcare Settings”, “Use of fluoride varnish to prevent dental caries”, and “Oral health care of pregnant women and newborns”. Data from pre-and post-surveys were obtained. In addition to the WHO training data, demographics and work experience information were collected. Descriptive statistics and paired t-test were conducted to determine changes in knowledge towards oral health (p<0.05).
Results: Our study population consisted of 33 non-dental healthcare workers. The majority were female (67%) with an age range of 20-58 [IQR=14]. Participants were mainly clinicians (18%), nurses (15%), community health assistants (15%), and nutritionists (12%). Overall, there was a significant positive difference in the mean learning scores pre- and post-training (14.53 vs 20.25) (p< 0.05). Highest mean scores increase was observed among nursing officers 23.33 (SD:4.05), clinical officers (mid-level healthcare workers) 21.95 (SD:5.06), and clinicians 21.44 (SD:2.25). Modules with most learning was “Oral health care of pregnant women and newborns” (p< 0.05) with average change from 4.72 (SD:1.63) to 6.85 (SD:1.48). Qualitative feedback emphasized the training’s relevance, and direct applicability to participants’ daily clinical practice.
Conclusions: This study improved oral health knowledge among non-dental healthcare providers in Kisumu by implementing the OpenWHO module. Our findings emphasize the critical role of collaboration and oral health education for healthcare professionals in improving patient care of children living with HIV. Furthermore, the results provide valuable evidence to advocate for increased support and resources, particularly in underserved communities with limited access to dental care.
Megha Rao
Faculty Mentors: Dr Alireza Sadr
Department: Restorative Dentistry
Supported By: Partially funded by Dentsply
Title: Evaluation of Deep Class II Composite Placement Techniques Using OCT
Objectives: This study evaluated post-polymerization defects in MOD restorations using different composite placement strategies with optical coherence tomography (OCT).
Methods: Standard MOD cavities (5 mm depth) were prepared in human mandibular molars using a coarse-grit diamond bur (836 KR – Midwest) followed by fine-grit diamond burs (836, 247 – Midwest) to finish dentin surfaces and enamel cavosurface margins respectively. A clear circumferential matrix (Reel Matrix 6.3, Garrison) was placed prior to selective etching with 37% phosphoric acid followed by application of a universal multi-mode adhesive (Prime & Bond Active, Dentsply Sirona). Three composite placement techniques were compared: BULK–one 5mm increment of nanohybrid composite (TPH Spectra ST, Dentsply Sirona); LAYER – a flowable composite (SDR flow+, Dentsply Sirona) in a 3 mm increment followed by a 2 mm horizontal layer of TPH Spectra ST; ASCRPT – SDR flow+ in 3 mm increment, followed by a 2mm depth by 2 mm wide circumferential increment of TPH Spectra lining the interproximal and buccolingual walls leaving a space in the middle of the preparation; and a final occlusal increment to fill the space. Each increment in all techniques was photo-polymerized for 10 sec using a LED curing light (Smartlite®Pro – Dentsply-Sirona). Each specimen was scanned with the Dental OCT system (Yoshida). 3D images were analyzed for gaps at the dentin interface, internal voids, marginal deficiencies, and stress cracks. Data were analyzed using Kruskal–Wallis and Mann-Whitney tests with Bonferroni correction (p<0.05).
Results: Representative OCT images are presented in Figure. There were significant differences among the groups in dentin gaps, marginal deficiency and crack (p<0.01). LAYER and ASCRPT were significantly different from BULK in dentin gaps (p<0.05) and internal stress cracks (p<0.01). ASCRPT showed better proximal marginal adaptation, which was significantly different from BULK (p<0.05).
Conclusions: The BULK technique increased failures such as stress-induced cracks, deep dentin debonding and proximal marginal deficiencies. The techniques using a base increment of the flowable composite improved bonding to deep dentin and reduced cracks in the composite. The new circular layering technique (ASCRPT) improved marginal adaptation, suggesting a potential to reduce clinical failures.
Claire Mills
Faculty Mentors: Dr. Slobodan Beronja
Department: Human Biology, Fred Hutch
Supported By: R01AR070780-08; Human Biology Pilot Project Funding; TDS IRC New Collaboration Award; ACS RSG-19-074-01
Title: Single-cell Multiomics Reveals Field Cancerization’s Role in Oral Cancer Progression
Objectives: The high morbidity and mortality of oral squamous cell carcinoma (OSCC) is driven by rapid recurrence which occurs at an unappreciated rate, though the underlying mechanisms remain unknown. This work investigates OSCC field cancerization where a “field” of genetically altered but normal-appearing cells surrounding tumors, drive recurrence following primary tumor removal. I hypothesize that these cancer “field” cells possess unique molecular features that promote stem cell renewal, predisposing normal-appearing cells to malignant transformation.
Methods: 1: Identification of “field” cell molecular characteristics with multi-omic single-cell (scRNA-seq+scATAC-seq) and whole genome sequencing (WGS) analysis of 10 patient sample sets (tumor, normal-adjacent “field”, contralateral, and blood). 2: Functional testing of genetic alterations necessary to transform precancerous cells to cancer using orthotopic patient-derived xenograft models.
Results: Patient multiome analysis revealed “field” stem cells consistently display a distinct shift towards a tumor-specific transcriptional signature which prominently features regulators of the TGF-β pathway, a critical stem cell regulator. Consistent with this transcriptional predisposition, WGS uncovered normal “field” and tumor samples harbor a higher driver mutation burden than contralateral tissue. Underscoring the role of renewal in tumorigenesis, initial in vivo functional testing demonstrated that overexpression of stem cell regulator HRAS in precancerous cells was sufficient to induce tumor transformation. Leveraging findings from my genomic studies, ongoing work utilizes in vivo screening to identify genes responsible for cancer field cell transformation.
Conclusions: Stem cell renewal plays an integral role in OSCC progression where genetic and epigenetic changes promoting renewal in “field” cells likely predispose patients to higher rates of recurrence. Extending this work, I will identify field cancerization biomarkers and validate the role of stem cell regulation in OSCC progression using ex vivo cell fate tracing. Collectively, this research will identify mechanisms regulating transformation of the genetically primed “field” to identify novel therapeutics to prevent recurrence.
Lay Soon
Faculty Mentors: Dr. Jeffrey McLean
Department: Periodontics
Supported By: NIH
Title: Progress on Experimental Gingivitis Clinical Trial Investigating Inflammatory Responder Types
Objectives: A recent experimental gingivitis (EG) study conducted at the University of Washington identified three inflammatory responder types (IRTs) – High (H-IRT), Low (L-IRT), and Slow (S-IRT) based on variation of clinical inflammatory measures. The novel S-IRT exhibited a distinct delayed plaque growth rate and microbial community maturation. Significant differences in host inflammatory mediators across all IRTs were also uncovered. The objective of this current registered clinical trial (RCT) NCT05968742 is to use a multi-omic approach to determine mechanisms underlying observed variations in gingival inflammation among different IRTs.
Methods: Healthy adults aged 18-35 years old are enrolled in this split-mouth clinical trial. The intervention is to refrain oral hygiene on 4 test teeth with a stent for 21 days and includes a contralateral set of brushed control teeth. Clinical measures including plaque index (PI), gingival index (GI) and percentage of bleeding on probing (%BOP) and biospecimens were collected across 7 study visits during Hygiene phase (Day -14-0), Gingivitis Induction phase (Day 0-21) and Resolution phase (Day 21-35).
Results: Here we describe the clinical trial design, recruitment, biospecimen collection, processing methods, and planned data analysis pipelines for the ongoing study. Compliance of the intervention is high for the participants who completed the study to date (9M/18F, 45 screened, 27 enrolled and 22 completed; 33% targeted enrollment). Clinical study outcomes (GI and %BOP) show compliance with the intervention. Average PI scores at Day 21 are 0.11 (0-0.17; control) and 1.03 (0.33-1.625; test), GI scores are 0.07 (0-0.125; control) and 0.96 (0.54-1.5; test), and % BOP are 6% (0-12.5%; control) and 35% (17-58%; test), demonstrating evident variation in gingival inflammatory levels and rates.
Conclusions: Successful progress in recruitment and compliance for completed subjects for this EG RCT are expected to facilitate the understanding of microbial and host factors regulating differences across inflammatory responder types.
Celine Atkinson
Faculty Mentors: Dr. Jeffrey McLean
Department: Periodontics
Supported By: R21 DE032890
Title: Investigating synergistic virulence in periodontal pathogens using MicroSPLiT
Objectives: The study aims to understand how physical interactions between oral bacteria contribute to synergistic virulence and progression of periodontitis. By using microSPLiT, a high-resolution, single-cell, RNA sequencing technique, our goal is to assess gene expression in subpopulations of oral microbes and uncover the regulation of genes involved in synergistic interactions.
Methods: We are evaluating Porphyromonas gingivalis ATCC 33277 (PG) and Fusobacterium nucleatum ATCC 23726 (FN) monocultures and cocultures. Monocultures are grown to mid-exponential phase in high nutrient media and standardized before being added in a co-culture and passaged to optimal growth conditions. Standardized cultures are grown for an adherence incubation period (13h) before fixation in 4% (v/v) formaldehyde. StarSOLO v2.7.9a was used to map single-cell prokaryotic RNA reads to reference genomes and Scanpy v1.10.1 was used for cluster and differential gene expression analysis. All programs were run using Python v3.12.3 and optimized for bacteria and microSPLiT to assess scRNA-seq data.
Results: We are currently in the preliminary stages in the optimization and application of this technique for oral bacteria. Currently, with 938 cells from PG and FN monoculture and co-culture populations, microSPLiT generated an average of 29 reads per cell using a permeabilization method consisting of mild detergents (i.e. 10% Tween-20) and enzymatic permeabilizing agents (i.e. lysozyme) for optimal in-situ ligation barcoding. Using the current permeabilization method, microSPLiT generates an average of 25 gene calls for PG and FN populations per cell.
Conclusions: Optimization of cell permeabilization and incorporation of an rRNA depletion in the microSPLiT design will maximize mRNA signal and reads per cell. We expect to gain insights into the regulation of genes within functional microbial subpopulations relevant to periodontal disease progression and improve the accuracy of detecting microbial interactions that were previously missed using bulk RNA sequencing approaches. ”
Philip Walczak
Faculty Mentors: Dr. Cecilia Giachelli
Department: Bioengineering
Supported By: NIH
Title: Slc20a2 in Osteo-CARs and Potential Role in Osteogenic Differentiation
Objectives: The role of inorganic phosphate transporters at the bone surface remains unknown. Previous studies in our lab and others have shown that Slc20a2, encoding PiT-2, plays an anti-calcific role in vascular and brain tissues while essential in osteogenesis; loss of Slc20a2 in dynamic histomorphometry shows decreased osteoblast numbers and mineral apposition without changes in osteoclast values. Herein, we investigate the Slc20a2 expression in bone cells and their signaling effects leading to impaired osteogenesis.
Methods: Tibia samples were collected from C57Bl6/J animals carrying the EUCOMM tm1a knockout-first cassette. Whole-tissue X-Gal staining was performed, and samples were demineralized to verify Slc20a2 expression. Publicly available datasets were analyzed to confirm expression and cell signatures (Parse Trailmaker). Demineralized samples were utilized for spatial transcriptomic analysis (Nanostring GeoMx DSP and 10X Genomics Visium HD). Immunofluorescent studies were performed for vascular and cell markers on demineralized samples. SPiDER-βGal (Dojindo) was used to sort LacZ-expressing cells from heterozygous and knockout mice to confirm their identity utilizing mRNA-seq.
Results: Publicly available scRNA-seq datasets show that Slc20a2 expression is highest in CXCL12-abundant reticulocytes, specifically osteo-CARs. Limch1 and KCNK2 staining co-expressed with X-gal staining, confirming our analysis of publicly available data. Spatial transcriptomic technologies successfully recapitulate cell-specific markers in ROIs. RNA-seq of sorted cells confirms the identity of these cells.
Conclusions: Slc20a2 is highly expressed in osteo-CARs, which are hypothesized to either influence osteogenesis through signaling or directly serve as a reservoir of pre-osteoblasts. Our results are the first to implicate a bone lining cell as playing a role in phosphate sensing, illuminating possibilities for clinical applications of inorganic phosphate in bone disorders, such as hyperphosphatemia or osteoporosis.
Derrick Tang
Faculty Mentors: Dr. Fritzie Arce-McShane, Dr. Tracy Popowics
Department: Oral Health Sciences
Supported By: T90 DE021984
Title: Neural Encoding of Periodontal Ligament Strain Under Load
Objectives: The mechanoreceptors in the periodontal ligament (PDL) transmit tooth load information to the orofacial sensorimotor cortex to regulate motor tasks like chewing, biting, and occlusion. However, the exact relationship between forces applied to the tooth, strain in the PDL, and neural processing of that strain in vivo has not been explored. The goal of this research is to uncover these relationships and how they are affected by age-related changes.
Methods: Fiber Bragg Grating (FBG) sensors were inserted into the labial and lingual PDL spaces of an anesthetized, aged rhesus macaque’s incisor. Using an anesthesiometer (Electronic Von Frey), force was applied continuously and intermittently in two directions: vertical intrusion on the incisal edge and horizontal tipping on the labial face. We recorded force and FBG strain simultaneously with neuronal activity from 320-channel microelectrode arrays in primary motor and somatosensory areas of the orofacial cortex and prefrontal cortex.
Results: Vertical intrusive forces showed compressive microstrain in the labial and lingual PDL spaces. Horizontal tipping forces showed tensile microstrain on both sides of the tooth during continuous force application, but compression in the lingual and tension in the labial PDL spaces during intermittent force application. Stress-strain curves showed peaks of up to 20 με at 100 grams of loading. Neural data across all three regions show silencing during the application of force and bursting behavior in its absence.
Conclusions: During vertical intrusion, both PDL spaces experience compressive strain. 1. Tensile strain in the PDL during continuous horizontal tipping force and 2, mixed compressive and tensile strain in the PDL space during horizontal tapping shows the lower right incisor responds differently to the tempo and direction of force application.
Azeez Fashina
Faculty Mentors: Dr. Robert Cornell
Department: Oral Health Sciences
Supported By: R01 DE023575, R90 DE021984
Title: Exploring the roles of periderm and endoderm in formation of the primary mouth
Objectives: To identify the cells and signals regulating primary mouth formation, one of several examples during embryogenesis where a mesenchymal structure is cleaved by migrating epithelia.
Methods: Using the zebrafish as a model, we deployed transgenic lines and mutants that allowed us to kill the periderm or eliminate the endoderm and to monitor different cell types (endoderm, periderm) that involved in primary mouth formation. We used novel epifluorescence microscopy on transparent zebrafish embryos, and immunohistochemistry on tissue sections, to analyze the consequence of loss of periderm or endoderm on primary mouth formation.
Results: Contrary to our expectations, foregut endoderm is not necessary for invagination of the stomodeum. By contrast, loss of periderm prevents stomodeal invagination and primary mouth formation. We hypothesize that during primary mouth formation, as in separation of the forelimb mesenchyme into digits, basal epithelia of ectoderm (external) and endoderm (internal) meet and fuse, and subsequently migrating periderm peels apart the otherwise adhered faces of the basal epithelia cells in the newly formed oral cavity and pharynx.
Conclusions: Using a zebrafish model, we present data suggesting that the periderm is required for formation of mouth opening. Understanding the mechanisms may yield insight into the cause and prevention of craniofacial anomalies that result from disrupted fusion events during embryogenesis, including cleft lip and palate.
Ke’ale Louie
Faculty Mentors: Dr. Lisa Maves
Department: Pediatrics, SCRI Center for Developmental Biology and Regenerative Medicine
Supported By: T90 DE021984
Title: Testing epigenetic inhibitors for Duchenne muscular dystrophy therapy using zebrafish
Objectives: Duchenne muscular dystrophy (DMD) is a congenital disorder characterized by progressive weakness and skeletal muscle fibrosis. Specialized muscles (e.g., craniofacial and cardiac) become affected in advanced disease, despite the long-term administration of palliative therapeutics aimed at preventing further lesions and functional deficits. The resilience of specialized craniofacial muscles raises interest in identifying pharmacologic treatments targeting different muscle groups during development. Our objective in performing a large-scale screen of epigenetic compounds was to identify those affecting muscle biology prior to lesion development.
Methods: Using an established zebrafish model of DMD (i.e., sapje), embryos were exposed to either individual compounds or pools of 8-10 epigenetic compounds beginning at 24 hours post fertilization (hpf). Embryos at 96hpf were scored for trunk muscle lesion severity and rescue via birefringence microscopy. Phenotypic improvement, median survival, and changes in histone acetylation are reported relative to control DMSO-exposed DMD mutant siblings.
Results: We validated at 96hpf phenotypic rescue potential of trichostatin A (TSA), a histone deacetylase inhibitor known to improve the zebrafish DMD model, under both standard and shortened treatment conditions (24-96hpf vs. 24-48hpf, respectively). Other histone deacetylase inhibitors had varied effects upon rescue at 96hpf and median survival through 50 days post fertilization. Overall, increased pan-H4ac and H3K9-ac were associated with effective doses. Our ongoing investigations into these, and other, epigenetic small molecules seek to improve muscle function by targeting specific mechanisms and variation across muscle groups.
Conclusions: These results create a promising platform for discovery regarding the early development, regulation, and management of this incurable childhood disease.
Cameron Renteria
Faculty Mentors: Dr. Dwayne Arola
Department: Materials Science & Engineering
Supported By: T90 DE021984
Title: The 3D Structure of Dental Enamel: Synchrotron CT Insights and Property Relationships
Objectives: To explore the feasibility of leveraging machine learning (ML) and artificial intelligence (AI) techniques combined with bioinspired design from native enamel systems to create novel microstructural restoratives and to guide future efforts in tissue regeneration. Specifically, we use various mammalian sources of enamel with different predation requirements and mechanical properties to serve as inspiration for synthetic restorative material systems with improved damage tolerance. Moreover, these efforts can serve as a guide to tissue engineering efforts who seek to regrow enamel. Further reaching, this research will advance our understanding of structure-property relationships in enamel with the goal of manufacturing synthetic enamel-inspired systems for engineering applications.
Methods: We utilize various advanced characterization techniques including: Raman Spectroscopy, Scanning Electron Microscopy (SEM), Nanoindentation, Indentation Fracture Resistance, and Synchrotron micro- and nano-computed tomography (CT) to reveal structure property relationships in various mammalian enamel sources in order to guide bioinspired design as it relates to oral health sciences. Moreover, we identify key design parameters in order to begin building digital 3D enamel-inspired models that could be realized through additive manufacturing.
Results: A combination of synchrotron scanning modalities and SEM, complemented by Raman spectroscopy and indentation fracture techniques, was used to evaluate the structure-property relationships of enamel obtained from mammalian molars. These efforts aim to serve as bioinspiration for damage-tolerant restoratives and to guide tissue regeneration strategies. The microstructures were analyzed at both the nano- and micro-scales, and the results revealed differences in mechanical properties, potentially reflective of function-specific structural adaptations. Moreover, structural differences were identified at the nanoscale enamel rod-interrod interfaces and in the micro-scale decussation patterns. These features are key to understanding the 3D structure-property relationships that endow enamel with extreme damage tolerance. To develop fracture-resistant restorative prostheses and guide tissue engineering efforts, machine vision and AI can be applied to synchrotron CT datasets to auto-segment decussation patterns. This will be a critical step in developing next-generation damage-tolerant materials.
Conclusions: This research pursues a unique paradigm in which enamel is treated as a universal material that undergoes “processing” by nature to achieve its function-specific properties. The study employed a variety of experimental modalities to characterize the chemical, structural, and mechanical properties of enamel from a wide range of mammals, which serve as bioinspiration for damage-tolerant systems. It is imperative that the 3D structure of enamel decussation patterns and nanoscale interfaces be better understood. To develop fracture-resistant restorative prostheses and guide tissue engineering efforts, machine vision and AI can be applied to 3D synchrotron CT datasets to auto-segment decussation patterns. This will be a critical step in developing next-generation damage-tolerant materials.
Allison Naumann
Faculty Mentors: Dr. Jeffrey McLean
Department: Periodontics
Supported By: R01 DE023810, R01 DE031470
Title: Dynamics of Ultrasmall Patescibacteria During Induced Gingival Inflammation: Insights from Experimental Gingivitis Clinical Trials
Objectives: To examine the characteristics and variation of ultrasmall epibiont Patescibacteria in subgingival plaque from multiple experimental gingivitis clinical trials across inflammatory responder types (IRTs).
Methods: Patescibacteria, also known as the Candidate Phyla Radiation (CPR), is a large, monophyletic group that accounts for over 25% of global bacterial diversity. Three members of this group, Saccharibacteria (TM7), Absconditabacteria (SR1), and Gracilibacteria (GN02), are common members of the human oral microbiome. These phyla are ultra-small in size, only 200-300 nm, and have a reduced genome with limited de novo biosynthetic capabilities. As a result, these epibionts live a parasitic lifestyle and are dependent on a physical association with their host. In order to better understand their growth dynamics in vivo as well as the host-epibiont relationship, we examined the presence of CPR in the controlled setting of experimental gingivitis clinical trials. These trials were composed of healthy adults (ages 18-35) with the following phases: preinduction/hygiene phase (day -14 to day 0), gingivitis induction phase (day 0 to day 21) and resolution phase for two weeks (day 21 to day 35). During these trials, subjects either did not brush their teeth or brushed with a custom oral stent protecting test teeth. Clinical measurements of gingivitis (plaque index, gingival index, and bleeding on probing) were measured at each visit, and subgingival plaque samples were collected from test and control teeth via sterile paper points, then frozen until further processing. Inflammatory responder types (IRTs) were assigned based on measured clinical data after subjects completed the trial. DNA was extracted and 16S rRNA libraries were created. Analysis of merged reads was performed using Quantitative Insights into Microbial Ecology (Qiime2) following the Divisive Amplicon Denoising Algorithm 2 (DADA2) pipeline workflow to generate ASVs. Taxonomic assignment to classify ASVs was performed using the Human Oral Microbiome Database (HOMD 16S rRNA RefSeq). Data were integrated into a single object using the “phyloseq” R package and further analyzed. The abundance of Saccharibacteria (formerly TM7), Gracilibacteria (GN02), and Absconditabacteria (SR1) were examined according to both study visit and inflammatory responder type.
Results: Absconditabacteria, Gracilibacteria, and Saccharibacteria all show increase during plaque growth and maturation and gingival inflammation with variation across inflammatory responder type. Analysis shows that there are six diverse families with 20 unique species identified. The abundance of Saccharibacteria is greater than that of Absconditabacteria and Gracilibacteria. Saccharibacteria selectively increased during the induction phase among high and low responders, but not in the slow response group. The low responder groups display a low abundance of Absconditabacteria and Gracilibacteria, while there is a relatively high abundance of all three groups in the high responders. Slow responders display a delayed increased abundance of all three groups, with Saccharibacteria being the most delayed.
Conclusions: This study highlights the significant role of Patescibacteria, specifically Saccharibacteria, Gracilibacteria, and Absconditabacteria, in the context of experimental gingivitis and inflammation. These findings demonstrate that these bacteria increase in abundance during gingivitis, with notable variations across different inflammatory responder types (IRTs). For instance, Saccharibacteria shows a selective increase during the induction phase among high and low responders, but not in slow responders. This suggests that the abundance and response patterns of these bacteria could potentially serve as biomarkers for different inflammatory responses in gingivitis. Understanding these variations can provide more robust insights into the microbial dynamics of gingival inflammation and aid in the development of targeted therapeutic strategies.
Nino Geradze
Faculty Mentors: Dr. Zi-Jun Liu
Department: Orthodontics
Supported By: R01 DE028864
Title: Oropharyngeal Spatial Dynamics in Enlarged and Reduced Volume of the Tongue Base during Respiration
Objectives: To examine respiratory adaptations of the oropharyngeal structures to volumetric alterations of the tongue base in a minipig model.
Methods: Six same-sex sibling pairs of 8-9-month-old Yucatan minipigs were selected. Of each pair, one was fed to be obese with a BMI > 50 (enlargement group), while the other maintained a normal weight and underwent a partial surgical tongue base ablation (reduction group). Live x-ray videofluoroscopy (30 frames/s) was recorded under sedation, at baseline (before surgery) and 5 weeks after the surgery. The selected landmarks of the last molar (zero point), soft palate, epiglottis, tongue base, and pharyngeal wall were digitally traced frame by frame for 25-30 respiratory cycles, and the paths of motion of these anatomical structures were defined in the coordinates using the video-analysis software Tracker 6.2.0. Exceedingly large values likely related to sporadic spontaneous salivary swallowing were excluded. The directional and distance changes of these structures were calculated and tested for group differences using the Mann-Whitney U test.
Results: For both inspiratory and expiratory phases, the moving distances (distances from the structure markers to the zero point) of all structures increased at week 5 compared to the baseline only in the enlargement group (p < 0.05). Distances between the soft palate and tongue base were larger in the reduction group compared to the enlargement group during expiration over time (baseline: 15.64 ± 6.75 mm vs 11.94 ± 3.84 mm; week 5: 23.34 ± 8.83 mm vs 19.39 ± 9.30 mm) (p < 0.05). The soft palate-pharyngeal wall distance change was greater at week 5 compared to baseline in the reduction group (15.54 ± 9.90 mm vs 13.34 ± 7.45 mm) during inspiration and (14.97 ± 8.99 mm vs 11.71 ± 9.09 mm) during expiration, as well as in the enlargement group (13.07 ± 6.64 mm vs 10.41 ± 8.41 mm) during inspiration and (12.22 ± 6.45 mm vs 10.24 ± 8.51 mm) during expiration. During expiration, rostral-ventral movement of the pharyngeal wall in the enlargement group was directed more ventrally (leaning further along the Y-axis) compared to the reduction group (p < 0.05).
Conclusions: These results suggest that oropharyngeal spatial dynamics during respiration in minipigs with reduced tongue base volume are characterized by significantly increased soft palate-tongue base distances and altered pharyngeal wall directional movements compared to the volume-enlarged minipigs.
Keywords: Oropharynx, Tongue Base, Videofluoroscopy, Respiration, Minipig.
Alexander Simnhoung
Faculty Mentors: Dr. Zi-Jun Liu, Dr. Doris H. Rosero Salazar, Dr. Daniel F. Leotta
Department: Orthodontics, Center for Industrial and Medical Ultrasound/Applied Physics Laboratory
Supported By: R01 DE028864
Title: Tissue Stiffness in Volume-Enlarged/Reduced Tongue Base in Minipigs
Objectives: Ultrasound elastography (USE) is an emerging technique used to measure in vivo tissue stiffness. This study applied USE to examine in vivo stiffness of volume enlarged (via obese) and reduced (via surgery) tongue bases in minipigs.
Methods: Six same-sex sibling pairs of 8-9-month-old Yucatan minipigs were used. Of each pair, one was fed to reach a BMI>50 (obese group), while the other was normal weight and underwent a surgical volumetric reduction of the tongue base. USE scans were taken from the submandibular region with sagittal orientation using the hyoid bone as a location reference. Data were collected before (baseline) and 5-weeks after reduction surgery (terminal). From each USE video clip, image frames were extracted and then analyzed with custom-developed software converting image pixel colors to stiffness values. Stiffness values within the region of interest (ROI) were averaged over 20-50 frames to produce an average elastography ROI. These values were used to quantify the tissue stiffness of the tongue base and their regional differences in relation to the hyoid bone.
Results: At baseline, the tongue base for the normal-weighted minipigs had an average stiffness of 10.79 kPa (7.05-15.31 kPa), higher than that of the obese group, which measured 8.44 kPa (4.98-17.46 kPa). Five out of six minipigs in the normal-weighted group presented a stiffer tongue base as compared with obese ones. At terminal, stiffness increased in four of the five obese minipigs. No significant differences were found over time for the reduction group. Within the normal-weighted minipigs, there was a correlation coefficient of 0.40 when comparing tongue stiffness in relation to the distance from the hyoid bone, with values being stiffer for more anterior locations. No such correlation in regional differences was found in the obese minipigs.
Conclusions: These results provide insight into how fat tissue infiltration and wound healing may alter the stiffness of the tongue base, thus leading to a better understanding of the mechanisms and treatment strategies for various breathing and swallowing disorders.
Keywords: Ultrasound elastography, Tongue-base, Tissue stiffness, Obesity, Minipigs.
Amylia Liu
Faculty Mentors: Dr. Doris H. Rosero Salazar, Dr. Zi-Jun Liu
Department: Orthodontics
Supported By: R01 DE028864
Title: Effects of Volumetric Alterations of the Tongue Base on Craniofacial Skeletal Growth
Objectives: This study aimed to evaluate the effects of alterations of the tongue base volume (both increases and decreases) on craniofacial skeletal growth.
Methods: Nineteen 7-9-month-old Yucatan minipigs (half each sex) were randomly assigned to three groups: control (n = 7), reduction (n = 6) involving surgical tongue base volume reduction by ablation, and enlargement (n = 6) involving obesity with BMI > 50. Their skulls were cleaned with forceps and scalpel after dermestid beetles cleaning. Using a compass and a measuring tool, 52 individual skeletal measurements were recorded for each skull. Each whole tongue and their tongue bases were measured for volume, length, and width via the same instruments. Data was organized in excel spread sheets, and comparative analyses were performed to identify significant differences in skeletal dimensions among the 3 groups, and correlations between the tongue base/whole tongue and skeletal measurements were assessed. Because the minipigs in the control group were younger at terminal, all measurements were standardized by the age of each animal.
Results: Mandibular width showed a significant decrease between the control (113.23 +/- 7.72mm) and reduction groups (108.99+/-7.45mm) (p = 0.037). A marginal decrease was observed between the control (113.23 +/- 3.70mm) and enlargement groups (109.13+/-3.47mm) (p = 0.064). A significant reduction in oropharyngeal width was also noted between the control (27.61+/-1.05mm and reduction (24.47+/-2.26mm) (p = 0.00065), but not significant between the reduction and enlargement groups (p = 0.098). Strong correlations were found as follows: Oropharyngeal length vs. Tongue base length; r=0.85 (p < 0.05) in the control, and r = 0.86 (p < 0.05) in the reduction groups. Mandibular Width vs. Whole Tongue Volume: r=0.83 (p < 0.05) in the control and r = 0.63 (p < 0.05) in the reduction groups.
Conclusions: Volume-reduced tongue base resulted in measurable decreases in mandibular length and width compared to the control group, indicating structural adaptations in the mandible. The oropharyngeal bone width also decreased significantly in the reduction group relative to controls. Positive correlations between oropharyngeal and tongue base dimensions were found across all groups. Additionally, moderate correlations between mandibular width and whole tongue volume were noted.
Key words: Tongue Base, Growth, Craniofacial skeletons, Biometrics, Minipig
Christina Hahn
Faculty Mentors: Dr. Fritzie Arce-McShane
Department: Oral Health Sciences
Supported By: R01AG069227, R01DE027236
Title: Impact of Nerve Block on Cortical Decoding of Tongue Movement Across Axes of Motion and Marker Regions
Objectives: The orofacial sensorimotor cortex plays an important role in controlling tongue and jaw movements in complex behaviors such as speaking and eating. Being able to reliably perform these movements has critical implications for people suffering from neurological diseases such as stroke, Alzheimer’s disease, or Parkinson’s disease, which are known to affect orofacial functions. Which features of the complex lingual function drive motor cortical activity is still poorly understood. Here we investigate how information in the orofacial primary motor cortex (MIo) varies based on factors such as absence of tactile sensation, axis of motion, and specific regions of the tongue.
Methods: To answer this question, we tracked marker-based movements of the tongue and jaw while recording neural activity from implanted microelectrode arrays in MIo of two rhesus macaques (Macaca mulatta) engaged in feeding. We tested various machine learning models to predict tongue and jaw positions and found that long short-term memory neural networks had the best performance. Decoding accuracies of models based on (i) axis of motion, i.e., antero-posterior (x-axis), supero-inferior (y-axis), and medio-lateral (z-axis), (ii) tongue marker region (superficial or deep, anterior vs. intermediate vs. posterior), and (iii) local anesthesia applied to sensory branches of the trigeminal nerve, were then compared to evaluate the ability to predict MIo activity.
Results: Generally, decoding performance was best when using the supero-inferior tongue position and worst with medio-lateral position (Kruskal Wallis, p<0.05). The effect of tongue marker region was also apparent, as using tongue markers located in the posterior region for movements in the x-axis led to superior model performance (Kruskal Wallis, p<0.05). Model performance did not differ based on the depth of the tongue marker location (Mann-Whitney, p>0.10). Lastly, we found significant differences in model performance between control and nerve block conditions across all motion axes (Mann-Whitney, p<0.05), with the antero-posterior tongue movements showing the largest decrease in performance post-nerve block (p<0.0001).
Conclusions: Overall, these findings indicate that information carried by MIo neurons differ as a function of the tongue’s motion axis, region, available tactile information, and varying combinations of these factors. These have important implications for the development of evaluation tools, rehabilitation strategies, and neural prosthesis to restore orolingual function in particular and limb sensorimotor function in general.