School of Dentistry: Recent submissions
Now showing items 1-20 of 686
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A Cadaver-based Comparison of Sleeve-guided Implant-drill and Dynamic Navigation Osteotomy and Root-end ResectionsThe purpose of this study was to compare the accuracy and efficiency of fully guided static and dynamic computer-assisted surgical navigation methods for osteotomy and root-end resection (RER). Fifty root specimens from cadaver heads were divided into two groups: fully guided static computer-assisted endodontic microsurgery (FG sCAEMS) and dynamic computer-assisted endodontic microsurgery (dCAEMS) (n=25). Cone-beam computed tomography (CBCT) scans were conducted before and after the surgery. Osteotomy and RER were virtually planned in the preoperative CBCT scan. Endodontic microsurgery was executed with the guidance of 3D-printed surgical guides in FG sCAEMS and a 3D-dynamic navigation system in dCAEMS. Analysis involved calculating 2D and 3D deviations as well as angular deflection. Additionally, osteotomy volume, resected root length, and recording osteotomy and RER time were measured. The number of procedural errors were recorded. FG sCAEMS demonstrated comparable accuracy to dCAEMS, with no significant difference in 2D and 3D deviation values or angular deflection (P > .05). FG sCAEMS led to reduced osteotomy and RER times (P < .05). However, FG sCAEMS exhibited a higher incidence of incomplete RERs compared to dCAEMS. Osteotomy volume, RER angle, and resected root length were similar in both groups (P > .05). Overall, both FG sCAEMS and dCAEMS proved to be viable options for performing osteotomy and RER. Within the constraints of this study based on cadaver samples, FG sCAEMS demonstrated comparable accuracy to dCAEMS and both methods were efficient for performing osteotomy and RER.
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Clinical Investigation of the Impact of Endodontic Disinfection on the Bacteriome of Root Canal Infection Using Next-Generation Sequencing on the Illumina MiSeq PlatformThe primary cause of root canal infection is bacteria and their by-products, making disinfection of the root canal system a key goal in endodontic therapy. However, the complex anatomy of root canal systems, particularly the isthmus and its ramifications, poses challenges for effective disinfection. Currently, no disinfection protocol can eliminate all bacterial contents from root canal infections, driving the ongoing search for an optimal disinfection approach. Recently, next-generation sequencing (NGS), particularly the Illumina MiSeq platform, has been widely explored in endodontic infections due to its low sequencing error rates, cost-effectiveness, and high-quality reads. Leveraging advanced sequencing techniques to reveal the bacteriome of root canal infections and assess the impact of current disinfection methods could enable the development of more targeted and effective disinfection protocols. This dissertation presents an interventional clinical study aiming to investigate the diversity and composition of the bacteriome in primary endodontic infection (PEI) with apical periodontitis (AP) and evaluate the impact of root canal disinfection on the endodontic bacteriome using NGS on the Illumina MiSeq Platform. First, we characterized the bacteriome in PEI with AP, identified core and rare bacteriome species, and analyzed community diversity metrics using the Illumina MiSeq platform. Our results showed that Bacteroidetes, Firmicutes, Synergistetes, Fusobacteria, and Actinobacteria were the most abundant bacterial phyla. We identified 113 genera and 215 species. Analysis revealed differences in abundant taxa among distinct age, gender, symptomatology, and lesion size groups. These findings suggest that the bacteriome in PEI with AP is complex and has high microbial heterogeneity among patients. Moreover, age, gender, symptomatology, and lesion size might play a role in the abundant taxa present in PEI with AP. Second, we determined quantitatively and qualitatively the impact of chemomechanical preparation (CMP) using 2.5% sodium hypochlorite (NaOCl) on the bacteriome found in PEI with AP using the Illumina MiSeq platform. Our findings demonstrated a distinct community composition and increased alpha diversity after CMP using 2.5% NaOCl, despite a significant decrease in bacterial abundance. We observed differential enrichment of specific taxa, including Stenotrophomonas_unclassified, Enterococcus_unclassified, and Actinomyces_unclassified, suggesting lower effectiveness of CMP using 2.5% NaOCl against these taxa. Findings from this dissertation highlight the complexity and heterogeneity of the bacteriome in PEI with AP, emphasizing the influence of patient-related factors on microbial diversity. The research highlighted the limited effectiveness of current endodontic disinfection protocols, specifically the use of 2.5% NaOCl, in reducing bacterial abundance while revealing limitations against certain taxa. These insights provide a foundation for developing more targeted and effective disinfection strategies, potentially leading to improved outcomes in endodontic therapy.
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Impact of SARS-CoV-2 Salivary Gland Infection on the Production of the Antifungal Peptide Histatin-5, Candida Colonization, and the oral Microbiota.Despite the myriad oral manifestations during COVID-19 and presence of SARS-CoV-2 in saliva, the oral cavity remains an underappreciated site. However recent findings have shown that SARS-CoV-2 can replicate in salivary gland cells, leading to inflammation and tissue destruction. Saliva contains antimicrobial peptides considered integral components of innate immunity crucial for oral health, with the most notable being histatin-5. This peptide is exclusively produced in salivary glands and exhibits unique potent antifungal activity against Candida albicans. In this dissertation, we discovered that destruction of salivary gland by SARS-CoV-2 can compromise histatin-5 production, predisposing patients to oral candidiasis and dysbiosis in the oral microbiome. First, we utilized our novel customized immunoassay to measure salivary histatin-5 levels in a prospective study involving stratified COVID-19 cohorts. Our data indicates a trend showing a decrease in salivary histatin-5 and increase in Candida during COVID-19, persisting post-COVID-19 recovery, potentially contributing to the long COVID-19 syndrome. To provide lacking mechanistic insights into the pathophysiology of salivary gland dysfunction during COVID-19, we performed in situ hybridization coupled with immunofluorescence to co-localize SARS-C0V-2 and histatin-5, respectively, in salivary gland tissue from deceased COVID-19 patients. Our findings indicated diminished or absent histatin presence in salivary gland acini with proliferating SARS-CoV-2 providing the first direct evidence associating SARS-CoV-2 with histatin-5 production. Next, we conducted a comprehensive metagenomic analysis on clinical oral samples and identified potential COVID-19 associated pathologic dysbiotic shifts in the oral microbiome. Lastly, we conducted in-vitro experiments coupled with scanning electron microscopy and confocal imaging to identify the effect of histatin-5 on candida cells and biofilm concluding the antifungal effect of histatin-5 on candida albicans. This clinical study clearly shows the effect of SARS-CoV-2 on oral microbiota, highlighting the importance of understanding and managing the complex dynamics within the oral cavity of COVID-19 patients.
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Enhancing Cervical Composite Restorations ManagementThe management of cervical composite restorations, also known as Class V restorations, represents a challenge in contemporary dentistry. This difficulty arises from the complex nature of cervical lesions and unfavorable location, close to soft tissues prone biofilm accumulation. Additionally, cervical composite restorations have significant failure rates, further complicating their management and longevity. The etiological factors contributing to cervical cavitation are diverse, ranging from mechanical trauma, abrasion, and erosion leading to non-carious cervical lesions (NCCLs), to cariogenic biofilms responsible for root caries. The combination of these factors, high failure rates, varied etiology, and the technical difficulty of restoring dentin-margin cavities underscores the need for advanced understanding of proper management and techniques in treating cervical composite restorations. This master thesis is presented in chapters with the following aims: 1) perform a scoping review as a preliminary assessment to identify how restorative protocols (surface pre-treatment, such as etching with different agents and techniques, like bevel) influence the longevity outcome of non-carious cervical lesions (NCCLs) restorations, and, 2) to comprehensively analyze and compare the biofilm composition grown over healthy and cavitated root caries lesions in two distinct age groups: patients younger than 65 years old (healthy and cavitated) and those older than 65 years old (healthy and cavitated). As the methodology approached, the scooping review and clinical studies were performed according to the cited objectives. For the results, a collective of the literature showed that the most frequently dentin pretreatment method studied was 'Application mode - Etching', with over 35% of studies focusing on this area, followed by 'Application mode - Adhesive' in 34% of the studies. 'Pre-treatment of surface with substance' was the focus of around 14% 'Pre-treatment of surface with lasers' accounted for approximately 11% of studies (Chapter 1.) In our clinical study the analysis of predominant bacteria in control and cavitated root caries lesions across two age groups (<65 years old and >65 years old) reveals notable variations in microbial composition. Cavitated lesions exhibit higher bacterial diversity compared to control ones, as indicated by the Shannon diversity index, suggesting a more complex microbial ecosystem within these lesions. Furthermore, the Simpson's dominance index suggests that control lesions are characterized by a few dominating species, contrasting with the more evenly distributed bacterial community in cavitated lesions. Age-related differences further modify these patterns, with older individuals displaying distinct bacterial profiles. These findings underscore the impact of lesion type and patient age on the oral microbiota's diversity and dominance, highlighting the complexity of microbial ecosystems in root caries lesions. (chapter 2)
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Comparison of Virtual Treatment Setup among Clear Aligner CompaniesOver the past two decades, clear aligner therapy grew as an alternative to traditional brackets for orthodontic treatment. Recently, several orthodontic companies introduced their clear aligner brands, each with unique features such as material type and thickness, gingival trim design, specific auxiliary tools, and different strategies for guiding orthodontic movement. However, little is known about how these features impact their virtual treatment setup. This study aimed to compare the virtual treatment setups among five clear aligner companies to assess their differences. The initial records of 10 patients, including extra and intraoral photos and scans, were submitted to Invisalign®, ClearCorrect®, 3M™ Clarity™, Spark™, and Reveal® clear aligner systems. Each case prescription was standardized to ensure comparable treatment plans across the companies. The comparison focused on the number of aligners, number of attachments, amount of interproximal reduction per arch, planned extrusive or intrusive movement of maxillary central incisors, final canine and molar relationships, final intercanine and intermolar widths, and planned expansion or constriction of the intercanine and intermolar widths. Results indicated significant differences in the virtual treatment setups for the same patient among clear aligner companies in the number of aligners (p-value = 0.003), number of attachments (p-value < 0.001), and predicted final canine relationship (p-value = 0.013). However, no statistical differences were observed in the other variables evaluated. ClearCorrect® stands out by prescribing the fewest number of aligners and attachments, whereas 3M™ Clarity™ tends to prescribe the highest number of aligners and attachments. There is a notable deficiency across companies, particularly with ClearCorrect® and Spark™, in planning for a final bilateral canine Class I relationship. These findings suggest that the unique characteristics of each aligner company lead to distinct approaches in treating the same patient, highlighting both areas of discrepancy and consistency in the virtual treatment setups.
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Comparing Accuracy of Commonly used Final Impression Techniques in Recording Excessively Movable Tissues in Completely Edentulous Patients.Purpose Traditionally several impression materials and techniques utilizing custom tray with a window have been proposed to record excessively movable tissues. These procedures are meant to produce very minimal if not no compression of the tissues during the process of impression to avoid any tissue distortion. Although studies have shown compression on tissues can be minimized, a technique that can completely eliminate the pressure is not proven. This study focuses on comparing accuracy of impression techniques that use common impression materials which produce minimal tissue displacement using digital intra oral scan as a reference. Materials and methods This is an in vivo clinical study on a cohort of 14 edentulous patients that presented with excessively movable tissues. An intra oral scan of the edentulous ridge was obtained using Medit i700 scanner (Medit Corp, Seoul Korea). Final impressions were made in light body vinyl polysiloxane (Dentsply Sirona Milford, Delaware) after the tissues were border molded with Type 1 modelling plastic compound (Kerr Corporation, Orange, CA) in a conventional custom tray and a custom tray with a window (Zahn, Melville NY). The impressions were scanned using 3Shape D2000 (3M Shape Copenhagen, Denmark) desktop scanner. These files were imported into Geomagic Control X software (Geomagic Control X; 3D Systems, Rock Hill, SC). The STL (standard tessellation language) files of final impression with conventional tray and tray with a window were aligned to the intra oral STL scan file using best fit alignment. The areas of interest (anterior region, palate and tuberosity) were delineated for three-dimensional comparison. Root mean square (RMS) values describing deviations in impression techniques were obtained and compared using Two-Way ANOVA followed by Tukey HSD posthoc analysis. Each subject served as their own control as the study compared tissues recorded with 3D surface scans to impressions using vinyl polysiloxane. A p<0.05 was considered significant. Results There was no significant difference in the RMS values between the two impression techniques that used conventional tray and tray with a window studied in terms of their deviation from the intra oral scan (p=0.56). However, there was significant difference between the areas tested in terms of deviation from the intra oral scan (p=0.0049). The tuberosity area in the open tray impression showed deviation with a mean difference of -0.12 RMS value when compared to the anterior area in the closed tray impression (p=0.002). The anterior area in the closed tray impression showed deviation with a mean difference of +0.1012 RMS value when compared to the palatal area in the closed tray impression (p=0.013) Finally, the anterior area in the closed tray impression showed deviation with a mean difference of 0.106 RMS value when compared to the tuberosity area in the closed tray impression (p=0.01). The Tukey HSD posthoc analysis demonstrated that there was no significant difference between all other groups (p>0.05). There was also no significant interaction between impression technique and area (p=0.46). Conclusion There were no significant differences in the tissue displacement when final impressions made with conventional closed tray and tray with a window were compared to intra oral scan. However, there were significant differences in tissue displacement between areas compared in a conventional closed tray, where anterior area consistently showed more displacement compared to palate and tuberosity. Lastly there was no significant interaction between the two variables impression technique and areas. Therefore, final impression in a custom tray with window can minimize displacement of excessively movable tissues in comparison to a conventional closed tray.
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Assessing language use patterns for terminology to describe bimaxillary protrusive phenotypesObjective: This study aimed to evaluate orthodontists’ terminology use for characterizing dentoalveolar segments and jaws that are prominently positioned relative to the cranium. Methods: An 11-item survey was distributed to orthodontists worldwide. Participants were asked to rate their preference for the terms “bimaxillary protrusion,” “bimaxillary dentoalveolar protrusion,” “bidental protrusion,” “bialveolar protrusion,” and “bidentoalveolar protrusion” in general, as well as in reference to lateral cephalograms that depicted various combinations of dentoalveolar and jaw protrusion. Results: Respondents most preferred “bimaxillary protrusion,” followed by “bimaxillary dentoalveolar protrusion,” to describe lateral cephalograms with dentoalveolar protrusion, with or without jaw protrusion. They did not consider a phenotype with only protrusion of apical jaw bases as bimaxillary protrusive. Moderation analyses found that older respondents were more likely to use “bidentoalveolar protrusion” for a phenotype with both jaw prognathism and protrusive teeth and “bidental protrusion” for a phenotype with normally positioned jaws with dentoalveolar protrusion. Non-native English speakers were overall more likely to prefer the term “bimaxillary dentoalveolar protrusion.” Conclusions: Respondents generally showed a strong preference for “bimaxillary protrusion” over other terms to describe dentoalveolar protrusion and did not consider bimaxillary prognathism in the absence of dentoalveolar protrusion as bimaxillary protrusive.
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Saliva Levels of IL-18 in Healthy and Peri-implantitis PatientsTitle of Thesis: Saliva Levels of IL-18 in healthy and peri-implantitis patients Purpose: Peri-implantitis is a common problem that occurs in 9.25% in functioning implants and approximately 20% of patients. Our understanding of the etiology of Peri-implantitis is limited. Understanding molecular mechanisms associated with peri-implantitis may help in developing and improving treatments for peri-implantitis. The purpose of this study was to assess the levels of IL-18 in saliva of healthy patients and patients diagnosed with peri-implantitis. Materials and Methods: Institutional Review Board approval was obtained. Unstimulated saliva was collected from a total of 24 subjects (peri-implantitis n=14, healthy n=10). Saliva was collected from subjects using 15 ml tubes every minute for 5 minutes. Collected saliva were then centrifuged for 5 minutes at 10,000 x g. The aliquot layer was collected and immediately stored at -80°C until analysis. The concentration level of IL-18 was measured using high-sensitivity enzyme-linked immunoabsorbent assays (ELISA). All statistical analyses were performed using Microsoft® Excel®. Statistical comparisons were tested for normality followed by the Mann Whitney U test. Results: Twenty-four subjects with 33 implants were analyzed. Twenty-two implants were diagnosed with peri-implantitis, while the remaining 11 were healthy controls. The Median values of IL-18 analytes were 1.92 pg/ml for peri-implantitis and 2.23 pg/ml for healthy control. The range was 8.58 pg/ml for peri-implantitis (min 0.079 pg/ml – max 8.66 pg/ml). The range was 21.26 pg/ml for healthy control (min 1.13 pg/ml – max 22.39 pg/ml). The mean was 5.47 pg/ml for healthy control and 2.61 pg/ml for peri-implantitis. The standard deviation was 6.80 pg/ml for healthy control and 2.04 pg/ml for peri-implantitis. Conclusions: In non-smoking patients not suffering from diabetes or other inflammatory disease, it appears that the levels of IL-18 are comparable to those of healthy patients.
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Extra! Extra! Read All About It: A National Dental Survey of the Emergency Room PhysicianIntroduction: Physicians are the first point of contact for patients who present to the ED with dental pain, infection, and trauma. This study determined the Physician's knowledge gap when assessing and rendering care to the ED dental patient. Methods: 81 American College of Emergency Physicians (ACEP) ED physician members were surveyed online using Qualtrics.TM The sample group was questioned about their comfort level when assessed and rendered care for dental pain, infection, and trauma. If satisfied with support when assessed and rendered, Chi-square and Fisher’s exact test analysis was undertaken using contingency tables. Results: The survey associated assessment and rendered care for dental trauma and severe local odontogenic infection. This is influenced by satisfaction with dental education (10x odds more comfortable), years in practice, and ACEP affiliation. Conclusions: This survey presented an opportunity for advancement in physician management of trauma and infection. Continuing medical education courses for ED physicians with dental emergencies could include instruction and guidelines on assessing and rendering care for dental trauma and severe dental disease.
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Impact of Clear Aligners on the Risk of Biofilm-Induced Oral DiseasesThe increasing demand for clear aligners in orthodontics over the past decade reflects patients' preferences for simplicity and more comfortable treatment options. As clear aligners become more prevalent, there is a growing interest in understanding the physiological and microbial alterations accompanying their use. In light of these findings, it is crucial to guide orthodontists and general dentists in managing clear aligner cases regarding the impact on the risk of biofilm- induced oral diseases. Here, this master thesis is presented in chapters with the following aims: 1) perform a scoping review as a preliminary assessment of whether clear aligners are associated with a higher, lower, or similar risk of biofilm-related oral health issues such as dental caries and periodontal disease, and, 2) to investigate the microbiome change of clear aligners users as a relevant factor for caries development or periodontal diseases. As the methodology approached, the scooping review and cohort studies were performed according to the cited objectives. For the results, a collective of the literature showed a 58% similar risk of biofilm-inducing diseases for users of clear aligners and fixed appliances. For 17% of studies, clear aligners have shown reduced risk (chapter 1). 59% of these studies, considering clear aligner users, investigated periodontal diseases and the main biofilm-induced disease. In our clinical study, no significant differences were detected over time . At the genus level, after 30 days demonstrated significantly increased Bacillus abundance and decreased Prevotella abundance. Our results suggested that the general biodiversity and salivary microbial community structure did not change significantly and that patients had increased beneficial oral hygiene habits and awareness during the first six months of Invisalign treatment. (chapter 2). Key words: Orthodontics, Oral biofilms, Clear Aligners, Biofilm-related diseases.
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Comparison of Feldspathic Veneer Surface Treatments on Color Stability after Debonding of Orthodontic Brackets: An In Vitro StudyObjectives: To analyze the color stability of feldspathic porcelain veneers treated with different surface preparation methods after bonding/debonding orthodontic brackets. Materials and methods: 25 feldspathic porcelain veneers samples were divided into groups according to surface treatment procedures: (S) glaze-layer retained; (SHF) hydrofluoric acid etch; (SOXA) sandblasting; (SB) diamond burs; and control (C). Specimens were primed using silane and brackets were bonded. After removal of brackets, Color stability (NBS score) was determined following coffee staining for 21 days. Results: No significant interclass difference was identified between overall color stability for the four test groups (S, SHF, SOXA and SB). All test groups showed a statistical significant increase in color change compared to the control. Conclusions: Surface treatment resulted in a significant decrease in color stability with no statistical difference between treatments. Regardless of surface preparation method, bonding and debonding of orthodontic bracket results in decreased color stability of feldspathic porcelain veneers.
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Post-traumatic Hyperalgesia and Degeneration of Temporomandibular joints in mice: the role of nociceptive afferentsTrauma to the temporomandibular joint (TMJ) can increase the incidence of developing temporomandibular disorder (TMD), and there is some controversy regarding the relationship between TMJ pain and degeneration. Considering the clinical implications of pain management, it is important to recognize whether it can affect the prognosis of TMJ degeneration. Recent studies have demonstrated that nociceptive afferents participate in bone remodeling via several pathways, suggesting that these afferents may be involved in both the perception of pain and the structural modulation of the TMJ. The specific impact of nociceptive afferents on TMJ pain and degeneration, however, remains ambiguous. We utilized the forced mouth opening (FMO) model on mice to address this issue. The FMO model resulted in increased mechanical hyperalgesia, as measured by the Von Frey (VF) test, spontaneous pain-like behaviors observed through the mouse grimace scale (MGS), and anxiety-like behaviors ascertained by the open-field test (OFT). These symptoms align with clinically relevant pain conditions such as spontaneous, mechanical, and function-evoked pain. Most TMJ afferents in the TG were small peptidergic neurons expressing calcitonin gene-related peptides, whereas non-peptidergic TMJ afferents were comparatively scarce. Additionally, the FMO induced thinning of the condylar cartilage and degeneration of the subchondral bone, corroborating the model's ability to replicate post-traumatic hyperalgesia and TMJ condylar degeneration. Chemogenetic silencing of TRPV1-lineage afferents, using an inhibitory designer receptor exclusively activated by designer drugs (DREADD), lessened spontaneous pain-like behaviors but did not affect mechanical hyperalgesia in the skin overlying the TMJ. This silencing also modestly reduced FMO-induced subchondral bone degeneration without impacting cartilage degeneration. Our findings imply that TRPV1-lineage afferent fibers may not be the main factor in condylar degeneration following TMJ injury. Conclusively, our study results endorse the FMO model as a clinically relevant and translational approach for investigating post-traumatic, pain-like behaviors. Moreover, manipulating the TMJ nociceptive terminals may be effective in treating pain without aggravating degeneration after injury.
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A multimodal system for lipid A structural analysis from a single colonyipid A, the hydrophobic anchor of lipopolysaccharide (LPS) is a potent sepsis-inducing molecule that stimulates human immune responses. The structural diversity of lipid A is correlated both with pathogenic capability and adaptation to the unique bacterial growth environments. Thus, understanding the structure of lipid A is important in fundamental microbiology and host-pathogen interactions. Previously, our group developed Fast Lipid Analysis Technique (FLAT) which employs an on-surface extraction combined with conventional Matrix-Assisted Laser Desorption/Ionization Mass Spectrometer (MALDI-MS), allowing for rapid structural characterization of lipid A directly from raw biomass of bacterial cells. Here, we employ tandem MS in both polarities, negative-ion (FLATn) and positive-ion (FLATn+) modes, to elucidate the structure of lipid A of various Gram-negative bacteria form single colonies.
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A PHENOMENOLOGICAL STUDY OF PREDOCTORAL DENTAL STUDENTS’ EXPERIENCES WITH SERVICE-LEARNINGThe purpose of this qualitative phenomenological study is to understand predoctoral dental students’ lived experiences with service-learning (SL) in general dentistry and explore how these experiences influence their perceptions of community service and future professional practice. Purposive sampling will be used to identify predoctoral students from dental schools with SL rotations that satisfy the study criteria. A SL rotation in this study is defined as an experiential learning approach that aims to encourage civic awareness and participation. The sample for this study is senior predoctoral dental students enrolled in an accredited dental school program in the United States that participate in a SL clinical rotation during their dental education training. Data will be collected by performing virtual semi-structured interviews. Data analysis includes an iterative process and inductive approach where a thematic framework is developed to create an initial list of codes and analyze data to develop themes and descriptions of the participants’ experiences and report the essence of the phenomenon. SL experiences in dental schools vary in their organization, structure, type of assessments used, length of the experience, and type of learning site. It is not clear whether students get comparable SL experiences that might impact their perspectives on community service and future professional practice. In addition, this study will expand the understanding of Mezirow’s (2000) transformative learning theory and add to the base of the theoretical literature. Particularly, dental students SL clinical experiences might present a disorienting dilemma which is connected to the initiation of the transformative learning process.