Poster Presentations

Faculty, Graduate Students, Residents and International Scholars

Presentations

1. Shear Bond Strength of Cements to Dentin with Varying Moisture Conditions, Sorensen JA, Chen YW

1. Yen-Wei Chen

Shear Bond Strength of Cements to Dentin with Varying Moisture Conditions
Sorensen JA, Chen YW
Restorative Dentistry

Objectives:  New adhesives/adhesive cements purported as more tolerant of dentin moisture conditions are available. This study evaluated 4 levels of dentin surface moisture conditions, non-conditioned smear layer (NC), enamel and self-etch (SE) on shearbond strength (SBS) of dentin adhesives (DA) used with dual cure cements (DCC), self-etch adhesives (SEA), self-adhesive cements (SAC).

Presenter with Poster at Research Day 2017Methods:  Human molars were decoronated, sectioned, embedded in resin. Tooth surfaces were wet ground to 240- grit, then 600-grit. Experimental substrate groups(n=10) created were: EN=Enamel; D1=Dentin, 5uL water layer; D2=Dentin,”Moist”; D3=Dentin, Air Dried (AD) 3 seconds; D4= Dentin, AD 10 seconds; ESE=Enamel Self-Etch; DSE=Dentin Self-Etch. SEA/DCC resin cements (RC) groups tested: Adhese Universal (AU)/Variolink Esthetic(VE), Scotchbond Universal (SBU)/Ultimate(U), Prime&Bond Elect (PBE)/Calibra(C), OptiBond XTR (OBX)/Nexus 3(N3) applied with both etch-and-rinse (EAR) and SE techniques to tooth substrates. SACs tested: SpeedCem(SC), UniCem2(UC), PanaviaF(PF) on NC dentin. Lithium disilicate (e.Max) buttons (Ø=2.38 mm) were etched, silanated (MonoBondS). Manufacturers’ instructions followed for specimen fabrication in 37oC@90%RH chamber. To produce a C-factor consistent with cementation, a 133gram loading pin secured ceramic onto tooth as excess cement wiped away, lightcured when indicated. Specimens stored in 37oC water, 24 hours. Shear testing with semicircular edge (Ultradent). SBS (MPa), summary statistics, One-way ANOVA, Post hoc tests performed.

Results:  The SBS(MPa): EN-SEA/DCC (EAR/SE treatments) were: AU/VE (39.2±6.7/28.0±5.5); SBU/U (35.3±7.9/26.0±6.7); PBE/C (32.2±10.5/22.4±7.5); OBX/N3 (27.2±6.7/23.5±6.4). The highest and lowest SBS (MPa) on dentin of SEA/DRC were: AU/VE- D2(38.9±7.1), D4 (31.8±5.5); SBU/U- D2 (35.0±6.3), D1 (26.8±9.3); PBE/C- D4 (30.8±4.3), D1 (11.0±5.2); OBX/N3- D2 (26.7±7.4), D1 (16.3±8.1). Dentin to SAC: SC (11.8±5.8); UC (11.8±7.5); PF (1.9±2.4).

Conclusions:  Several adhesives/cements were highly tolerant of varying dentin moisture conditions. SBS of SEA on Enamel ranged from 64.3% to 86.3% of Etched Enamel. SBS of SEA on Dentin ranged from 64.3% to 87% of EAR Dentin. The SBSs of SAC on Dentin were approximately half of SEA/Cements.

Supported in part by Ivoclar Vivadent.

2. Influence of Desensitizers on Bond Strength of Adhesives to Dentin, Zeola LF, Moura GF, Silva MB, Soares PV, Cunha-Cruz J

2. Livia Fávaro Zeola

Influence of Desensitizers on Bond Strength of Adhesives to Dentin
Zeola LF, Moura GF, Silva MB, Soares PV, Cunha-Cruz J
Oral Health Sciences

Presenter with Poster at Research Day 2017The aim of this study was to evaluate the influence of desensitizing agents on bond strength of self-etch adhesives to dentin submitted to acid-abrasive challenge, using the microtensile bond strength (μTBS) test and analysis of the failure mode. Sixty human molars were selected. The teeth were sectioned at the crown and roots and then in the proximal aspects, to expose the area of dentine. Each sample was submitted to acid (immersion in Coca-Cola-10s) and abrasive (brushing – 300g /20s) challenges cycles performed 2x/day for 5 days. The samples were divided into six groups (n=10): Clearfil SE Bond Universal (C); Teethmate Desensitizer + Clearfil SE Bond (TC); Gluma Desensitizer + Clearfil SE Bond (GC); Single Bond Universal (U); Teethmate Desensitizer + (TU); Gluma Desensitizer + Single Bond Universal (GU). Restorations were made using the conventional composite resin Z350, in two increments of 2.0mm. Rectangular sticks were obtained for each tooth, and each one was used for μTBS testing at 1.0mm/min. The data were analyzed statistically using a one-way analysis of variance (ANOVA) test and Tukey post hoc. The failure mode distribution was analyzed using a chi-square test (α=0.05). The U group had the highest bond strength value (26.8±4.9 MPa). The presence of Teethmate Desensitizer (groups TU and TC) promoted reduction in bond strength values. However, there was a statistically significant difference for group TU (p <0.05), presenting the lowest bond strength value (16.5±5.7 MPa). No significant differences were found when the Clearfil SE bond adhesive was used. Adhesive and mixed failures were prevalent for all tested groups. The use of the Teethmate Desensitizing agent in association with Single Bond Universal adhesive affected the bond strength. Regardless of the desensitizing agent type used, Clearfil SE Bond had no influence on bond strength to dentin.

Supported by:  Brazilian Federal Agency for Support and Evaluation of Graduate Education – CAPES

3. Degradation in the Strength of Dentin Following Endodontic Treatment, Yan W, Øilo M, Chen HA, Zhang H, Arola D

3. Weishi Yan

Degradation in the Strength of Dentin Following Endodontic Treatment
Yan W, Øilo M, Chen HA, Zhang H, Arola D
Materials Science & Engineering, Restorative Dentistry

Objectives:  Teeth receiving endodontic treatment are more susceptible to vertical root fracture (VRF), especially in senior patients. However, no studies have identified if the higher risk of VRF is attributed to the loss of tooth structure, a consequence of aging, or degradation of dentin resulting specifically from the treatment. In this study, we evaluated the effects of endodontic treatment on the strength, microstructure and chemical composition of radicular dentin.

Methods:  Multiple teeth were obtained from the arches of selected dental patients according to an approved protocol.  A total of 48 teeth were examined from five patients that included 15 teeth that were endodontically restored. The strength was determined using beams of radicular dentin sectioned from the bucco-lingual quadrants of the roots and subjected to 4-pt flexure to failure. Scanning electron microscopy was performed on longitudinal sections of each tooth to distinguish the number of lumens filled with mineral (i.e. occlusion ratio) and Raman spectroscopy was performed to quantify the mineral to collagen ratio (PO4/Amide I) and the collagen cross-link ratio (1668 cm-1/1689 cm-1).

Results:  According to an unpaired student t-test, the average strength of dentin from the endodontically treated teeth (136±24 MPa) was significantly (p = 0.0075) lower than that of the untreated teeth (159±25 MPa). Endodontic treatment resulted in up to 15% reduction in strength with regards to untreated teeth. Although the occlusion ratio and mineral-to-collagen ratio of the endodontic treated and untreated teeth were not significantly different, the collagen cross-linking ratio was significantly larger in those that received treatment (p≤0.05).

Conclusion:  Results showed that there are significant decreases in the strength of radicular dentin as a result of endodontic treatment, and that it appears to result from an increase in collagen cross-linking.

Supported by:  University of Washington Seed Grant

4. Cryopreservation of Teeth: Consequences on Microstructure and Mechanical Properties, Tenwalde M, Yan W, Zhang H, Arola D

4. Mathea G Tenwalde

Cryopreservation of Teeth: Consequences on Microstructure and Mechanical Properties
Tenwalde M, Yan W, Zhang H, Arola D
Materials Science & Engineering, Restorative Dentistry

Presenter with Poster at Research Day 2017Objectives:  Autogenous transplantation has become increasingly viable for tooth replacement, and provides motivation for storage of healthy, routinely extracted teeth. Cryopreservation followed by autotransplantation of teeth is reported to be successful, as indicated by the high level of periodontal ligament survival achieved. A critical issue not yet investigated is the potential for dentinal damage as a result of the crystallization of dentinal fluid. Expansion of intra- and extra-fibrillar bound fluid may lead to microcracks that reduce durability. The objective of this study is to determine whether cryopreservation degrades the microstructure of dentin causing reduction in resistance to mechanical failures.

Methods:  Healthy third molars were collected from young donors (age≤ 30 years) within 24 hrs of extraction according to an approved protocol. Teeth were randomly assigned to either ‘frozen’ or ‘control’ groups. Frozen teeth underwent a slow-cool cryopreservation protocol to -196°C and were stored an average of 10 days before thawing.  Control teeth were stored at 4°C for ≤1 week prior to testing. Rectangular beams were obtained from the mid-coronal dentin and the strength and resistance to fatigue failure were evaluated in 4-pt flexure under quasi-static and cyclic loading, respectively. Optical microscopy, scanning electron microscopy and Raman spectroscopy were used to evaluate microstructure and collagen conformation.

Results:  The monotonic flexural response showed there was no difference in average strength or energy to fracture between the cryopreserved and control dentin. The fatigue strength decreased with cyclic stress amplitude for both groups. There was no significant difference in number of cycles to failure at all stress amplitudes. In evaluation of the microstructure, it was found that there was no apparent difference in the collagen as a result of cryopreservation.

Conclusions:  Within the limitations of this study, cryopreservation does not cause degradation to the integrity and durability of dentin.

Supported by:  Arola Start Up Grant

5. Amelogenin-Derived Peptide Guided Biomimetic Tooth Repair, Yucesoy DT, Fong H, Saadat S, Dogan S, Sarikaya M

5. Deniz T. Yucesoy

Amelogenin-Derived Peptide Guided Biomimetic Tooth Repair
Yucesoy DT, Fong H, Saadat S, Dogan S, Sarikaya M
Materials Science & Engineering, Oral Health Sciences, Restorative Dentistry

Presenter with Poster at Research Day 2017Caries is a global health issue that affects a large percentage of the population despite the widespread use of fluoride and other preventive treatments. Early stage carious lesions are associated with a variety of clinical conditions, including white spot lesions, incipient caries, and hypersensitivity.  If left untreated, caries can lead to tooth loss or require complex restorative procedures. The aim of this study is to develop a peptide-based biomimetic remineralization treatment to restore the demineralized dental hard tissues. For this purpose, we have identified a set of remineralization-directing peptides derived from amelogenin. This is achieved through a design algorithm which includes biocombinatorial selection using peptide libraries, similarity analysis using bioinformatics tools, molecular dynamics simulations, and iterative binding and mineralization assays. The remineralization was performed both under simulated physiological conditions in vitro and in vivo by delivering the peptide and ionic calcium and phosphate, either in aqueous solutions or in a gel formulation. Following the treatment, the structure and morphology of the remineralized tissues were characterized in detail using scanning electron microscopy and energy dispersive X-ray spectroscopy. Local mechanical properties, including elastic modulus and hardness, were determined using nanoindentation tests. In both aqueous solution-based and gel formulation-based treatment modalities, the peptide treated test groups resulted in the formation of continuous hydroxyapatite mineral layer on both enamel and dentin, at a rate of approximately 5-10 µm/hr. More significantly, cross-sectional SEM imaging revealed that the mineralized layer formed a transition region by completely integrating with the underlying dentin, similar to dentin-enamel junction (DEJ). The resulting mineral layers had mechanical properties that are comparable to that of dentin. The treatment procedure developed here has the potential for clinical implementation in a variety of formulations as well as for developing over-the-counter products in novel dental health care.

Supported by:  Washington State Life Sciences Discovery Fund, Dean and Margaret Spencer Endowed Clinical Research Fund and Amazon-UW/CoMotion Catalyst Program

6. TLR2 and TLR4 Responses Regulate Neutrophil Infiltration into the Junctional Epithelium, Chang AM, Liu Q, Hajjar AM, Greer A, McLean JS, Darveau RP

6. Ana M. Chang

TLR2 and TLR4 Responses Regulate Neutrophil Infiltration into the Junctional Epithelium
Chang AM, Liu Q, Hajjar AM, Greer A, McLean JS, Darveau RP
Oral Health Sciences, Periodontics

Presenter with Poster at Research Day 2017Oral gingival tissue, especially the junctional epithelium (JE), is constantly exposed to sub-gingival plaque and plays an important role in maintaining gingival health.  A key component of healthy gingival homeostasis is the continuous migration of neutrophils out of the vasculature and into the gingival crevice.  In this report, Toll-like receptor 2 (TLR2), TLR4, and TLR2/4 double knockout (KO) mice were used to determine the contribution of these innate defense components in the maintenance of oral health.  Using immunohistochemistry, neutrophils were targeted in the junctional epithelium and quantitated.  In comparison to wild-type (WT) mice, all TLR KO mice displayed significantly increased numbers of neutrophils in the JE, which did not correlate with oral bacterial load.  Comparative compositional analyses of the oral microbiome from each KO strain revealed significant differences (PCoA of unweighted unifrac distances) between each KO strain and to WT.  This demonstrates that TLRs are not required for neutrophil migration into the JE, but may instead play a modulatory role.  Finally, this study provides evidence that TLR2 and TLR4 significantly contribute to shaping the composition of normal oral microbiota.  New insights demonstrating alterations of both, neutrophil infiltration and oral microbial composition in TLR2 and TLR4-deficient mice, preclude previous conclusions concerning their relative roles in disease and need to be re-evaluated.

Supported by: NIH/NIDCR Grant No. DE023453 to R. Darveau

7. Peri-Implant Debridement May Lead To Accelerated Titanium Dissolution, Black R, Costa I, Berbel L, To T, Daubert D, Kotsakis G

7. Rachel Black

Peri-Implant Debridement May Lead To Accelerated Titanium Dissolution  
Black R, Costa I, Berbel L, To T, Daubert D, Kotsakis G
Periodontics

Objectives:  Peri-implantitis is a prevalent inflammatory disease, but with limited information on an effective treatment of this disease. The aim of this study was to assess the effect of clinically-relevant peri-implantitis treatment methods on: 1) bacterial removal from titanium-bound biofilms; and 2) titanium elution as a result of these interventions. The long-term goal of this project is to identify peri-implantitis treatments that effectively remove biofilms while maintaining the electrochemical properties of titanium to avoid accelerated corrosion.

Methods:  Subgingival plaque in peri-implantitis sites was collected and expanded in SHI media under anaerobic conditions. Titanium discs were then inoculated for two days until a mature microcosm biofilm was formed. Five antimicrobial interventions were then completed for 30 seconds each: 0.12% Chlorhexidine, Rotary nylon brush, Titanium brush, Waterpik on high, and low setting and compared against sterile and untreated controls. Subsequently, N=2 discs per group were utilized for CFU counts, N=2 for bacteria viability assay, N=4 for titanium elution assays, and N=2 for electrochemical impedance spectroscopy (EIS).

Results:  Waterpik high and waterpik low were most effective in reducing CFU counts; results of LIVE/DEAD bacterial staining were confirmatory. Titanium brushes reduced CFUs more than controls, but led to increased titanium elution as compared to waterpik, nylon brushes and controls. EIS confirmed loss of passivity of titanium following use of mechanical cleaning aids.

Conclusion:  While certain strategies for bacterial removal from titanium biofilms may yield favorable microbiological results, they may have a hazardous effect on titanium electrochemical properties. The biological ramifications of loss of titanium passivity warrant further investigation and should be considered in the selection of peri-implantitis treatment aids.

Supported by:  Elam M. and Georgina E. Hack Memorial Research Fund, Department of Periodontics

8. Comorbid Migraine/Severe Headache and Facial Pain in Adolescents, Werfalli S, LeResche L, Mancl L, Truelove E

8. Sumeia Werfalli

Comorbid Migraine/Severe Headache and Facial Pain in Adolescents
Werfalli S, LeResche L, Mancl L, Truelove E
Oral Health Sciences, Oral Medicine

Objectives:  Our study aims to assess cumulative incidence and risk factors for migraine and for comorbid severe headache and facial pain among adolescents.

Methods:  This is a secondary analysis of data from a population-based study. Data about pain complaints and risk factors was collected. Facial pain and severe headache were assessed through self-report and a TMD diagnosis was based on the RDC/TMD examination. Migraine diagnosis was based on the International Headache Society classification.

Presenter with Poster at Research Day 2017Results:  A total of 3,100 adolescents aged 11-17 from the cross-sectional survey and a cohort of 1,817 adolescents who were followed for 3 years beginning at age 11 were included in the analyses.  Migraine prevalence decreased from 11% at baseline to 6.3% at follow-up.  At baseline, cumulative incidence of severe headache among those reporting a history of facial pain was 55.7% versus 30.5% among those reporting no history of facial pain (OR, 2.86; 95% CI, 2.21-3.70); at follow up, cumulative incidence of severe headache among those reporting a history of facial pain was 41.9% versus 24.5% among those reporting no history of facial pain (OR,2.00; 95% CI,1.54-2.59). At baseline, other pain complaints (OR,3.2), physical activity (OR,1.86), depression (OR,1.96) and somatization (OR,4.4) were associated with migraine; and other pain complaints (OR,4.42), depression (OR,2.79) and somatization (OR,2.56), were associated with facial pain-severe headache comorbidity.  At follow up, female gender (OR,1.83), physical activity (OR,2.52), other pain complaints (OR,1.18), depression (OR,3.06) and somatization (OR,2.18) were associated with migraine; other pain complaints (OR,8.39) and somatization (OR ,3.33) were associated with comorbid severe headache and facial pain.

Conclusion:  Severe headache and facial pain are comorbid in adolescents. Several risk factors were associated with both migraine and comorbid severe headache and facial pain. Better diagnosis and prognostic outcomes may be achieved by addressing such risk factors and by managing both conditions.

Supported by:  NIH/NIDCR Grant No. P01 DE 08773

9. The Causes and Consequences of Midfacial Hypoplasia in the Yucatan Minipig, Baldwin M, Liu Z-J, Herring S

9. Michael Baldwin

The Causes and Consequences of Midfacial Hypoplasia in the Yucatan Minipig
Baldwin M, Liu Z-J, Herring S
Oral Health Sciences, Orthodontics

Background: Midfacial hypoplasia (MFH), or underdevelopment of the upper jaw, nose, and cheek bones, can lead to severe deformity with impairment of breathing. A lack of understanding about the cause of MFH and how it impairs breathing has limited current treatments to invasive surgeries that are not always successful. Understanding the primary cause of MFH and how it affects the airway is a critical step in better treating and even preventing this disease. Using the Yucatan minipig as a novel model for MFH, the objective of this project is to determine if the cartilages of the cranial base are the primary cause of MFH, and whether the airway of the nasal and pharyngeal airway is compromised, or compensation, either structural or functional, occurs.

Methods: Sections from the synchondroses and nasal septum, including its anterior and posterior junctions, will be harvested, immunostained, and labeled with bone and cell replication markers in order to analyze their morphology, cellularity, and mineralization. Computed tomography (CT) scans will be used to measure the dimensions of the pharyngeal airway to measure the dimensions of the nasal passages. Air temperature and humidity will be measured with sensors inserted into the nasopharynx.

Preliminary observations: Yucatan minipigs appear to be missing the posterior cartilage tail of the nasal septum, possibly due to early ossification. This finding suggests that a defect in the nasal septal cartilage is a primary cause of MFH. The Yucatans also tend to have enlarged lymphoid tissue and increased fat deposition in the posterolateral pharynx, suggesting a soft tissue etiology to airway compromise in these animals. Finally, Yucatan minipigs have a short snout, which also appears to be taller and wider than in normal farm pigs, possibly due to compensatory growth. These dimensional changes may decrease the surface to volume ratio of the nasal cavity and hinder proper regulation of air temperature and humidity.

Supported by: NIH/NIDCR Grants Nos. R21 DE23988, R21 DE24814, T90 DE21984

SURF and 4th Year Dental Student Research Track

10. Airflow Dynamics in Obese Minipigs with Obstructive Sleep Apnea, Do T, Liu Z, Fong H

10. Tiffany Do

Airflow Dynamics in Obese Minipigs with Obstructive Sleep Apnea
Do T, Liu Z, Fong H
Orthodontics, Materials Science & Engineering

Presenter with Poster at Research Day 2017Objectives: The dimensions of the upper airway (nasopharynx and oropharynx) and airflow dynamics are key determinants of respiratory function. Although obstructive sleep apnea (OSA) correlates to the restriction of these spaces, the mechanism of airflow dynamics in OSA is largely unknown. This project aims to build 3D configurations of the upper airway to utilize a model of computational flow dynamics (CFD). The CFD will test the hypothesis that the restricted upper airway in OSA-obese minipigs will produce higher resistance, which will create turbulence that induces temporary block-out of upper airway patency.

Methods: Three non-obese control (BMI<35) and two obese (BMI>50) 9-11 month-old Yucatan minipigs were monitored to verify OSA episodes by using wireless BioRadio systems. Afterwards, MRI images and airflow parameters were collected during drug-induced sleep. The MRI images were processed to create 3D configurations of the upper airway. These 3D configurations were used to obtain the dimensions of these spaces and meshed to create finite element models (FEM). The obtained airflow parameters were input into the models to identify turbulent airflow production and location.

Results: Whereas OSA was not present in the non-obese minipigs, OSA was present in the obese minipigs with apnea/hypopnea index (AHI) of 15-20. Compared to non-OSA minipigs, OSA minipigs showed significantly lower inspiratory and expiratory tidal volumes, and inspiratory airflow speed. With the use of model simulation, it was found that turbulence was not present in the upper airway of OSA minipigs.

Conclusion: The absence of turbulence is presumed to be a result of the overall lower airflow speed found in OSA minipigs relative to the control minipigs. Turbulence production requires both an abrupt dimensional change and high flow velocity. Considering that the overall airflow speed was low in OSA minipigs, turbulence was not produced.

Supported by:  NIH/NIDCR Grant No. R21 DE023988, University of Washington Dr. Douglass L. Morell Dentistry Research Fund

11. Genotype-Dependent T2R38 Regulation of Epigenetic Markers and Antimicrobial Peptides, Wilkins T, Coldwell S, Chung WO

11. Taylor Wilkins

Genotype-Dependent T2R38 Regulation of Epigenetic Markers and Antimicrobial Peptides
Wilkins T, Coldwell S, Chung WO
Oral Health Sciences

Objectives: The bitter taste receptor T2R38 is known to play a genotype-dependent role in regulating factors of the innate immune system in the upper airway epithelium as well as in gingival epithelial cells. Individuals with the PAV/PAV genotype who are sensitive to the taste of 6-n-propylthiouracil (PROP) may have an increased resistance against the cariogenic bacteria in the oral cavity over the AVI/PAV (intermediate) and AVI/AVI (non-taster) genotypes. This study aims to quantify the expression of epigenetic markers and antimicrobial peptides (AMPs) in patient saliva samples and compare it to the genotypes to determine the protective effect of the PAV/PAV genotype in vivo.

Methods: Saliva samples from pediatric patients with caries (n=20) and caries-free (n=20) were previously collected. Norgen Biotek DNA extraction kit was used to extract human DNA from salivary samples. Levels of epigenetic markers DNMT and HDAC2 were quantified and compared to the standard housekeeping control GAPDH with QRT-PCR along with levels of S. mutans. ELISA was previously performed to measure levels of AMPs HNP-1-3 and hBD-2. SNP analysis was performed at Monell Chemical Senses Center.

Results: While the PAV/AVI genotype has higher proportions of caries-free patients and patients without S. mutans than the other genotypes, the results were not significantly different (p > .05). There was no significant difference between the levels of AMPs or of fold expression change of the epigenetic markers by genotype or caries status (p > .05).

Conclusions: The data neither support nor refute the theory that T2R38 genotype confers resistance to cariogenic bacteria through increased expression of AMPs in the PAV/PAV SNP. Further studies with larger samples sizes are needed to determine the role that epigenetics plays in the T2R38 bitter taste receptor expression.

Supported by: University of Washington Dr. Douglass L. Morell Dentistry Research Fund

12. Titanate-Metal Complex as a Novel Antimicrobial in Dentistry, Theda L, Kim P, Hobbs D, Chan D, Chung WO

12. Lindsey Nicole Theda

Titanate-Metal Complex as a Novel Antimicrobial in Dentistry
Theda L, Kim P, Hobbs D, Chan D, Chung WO
Oral Health Sciences, Restorative Dentistry

Presenter with Poster at Research Day 2017Objectives:  Metal-titanates possess promising antimicrobial properties because of their ability to bypass systemic toxicity. Previous studies show that metal-titanates could be particularly beneficial in dental materials and treatments. Here, we investigate the mechanism of the antibiotic effect of Au(III)-monosodium titanate complex on known cariogenic bacteria, Streptococcus mutans and Lactobacillus casei.

Methods:  Bacteria were passed to fresh media after exponential growth phase and exposed sequentially to 10, 25, 50, 100, 200, and 400 mg/L of Au(III)-titanate in order to determine their ability to develop resistance.  Bacterial counts were determined using OD reading. Changes in adhesion gene expression were assessed by quantitative real-time PCR using the Pffafl method. Cells were grown for 4 and 18 hours following exposure or no exposure (controls) before RNA extraction.  Assessment of adhesion of bacteria was carried out using Syto 13 dye and polystyrene plates. Bacterial adhesion was determined using OD reading.

Results:  The expression of genes srtA and fbpA in L. casei was initially decreased after 4 hours of exposure. The expression of the Pac gene in the S. mutans culture was increased after 18 hours. In the resistance study, the growth of L. casei in the presence of the metal complex was decreased compared to the control.  We also found that for S. mutans, the growth of bacteria in the presence of Au(III)-titanate was not significantly impaired until the concentration of 400 mg/L.

Conclusions:  L. casei is not able to confer resistance to the Au(III)-titanate complex, while S. mutans is able develop resistance up to a concentration of 400 mg/L. The mechanism behind the resistance of S. mutans against Au(III)-MST is through increased expression of the Pac gene over time. The mechanism behind the impairment of the growth and attachment of L. casei involves the initial downregulation of srtA1 and fbpA.

Supported by: University of Washington Dental Alumni Association, Washington Dental Service

13. Mucosal Immunity and NF-κB Activation in Peri-implantitis, Chi D, Coats S, Darveau R, Kotsakis G

13. David Chi

Mucosal Immunity and NF-κB Activation in Peri-implantitis
Chi D, Coats S, Darveau R, Kotsakis G
Periodontics

Objectives: Each year, 3 million Americans have dental implants placed to offset tooth loss. This number is growing, by half a million annually. While dental implants are considered the optimal solution to replace lost teeth, 1 out of every 4 implants are compromised by peri-implantitis; a destructive inflammatory disease that leads to rampant jaw bone loss. The objective of this exploratory study was to assess toll-like-receptor (TLR)4 mediated inflammatory responses to patient plaque samples in order to determine if Gram negative bacterial dysbiosis plays a role in peri-implantitis.

Methods: 8 peri-implant and 4 healthy submucosal peri-implant plaque samples were collected from 12 participants using sterile paper points.  A luciferase reporter assay was conducted on each sample in human embryonic kidney (HEK) cells to assess TLR4-dependent NF-κB activation in response to Gram negative bacteria in the plaque samples. Veillonella parvula, Escherichia coli, and Fusobacterium nucleatum served as positive controls. Limulus amebocyte litmus (LAL) assays were performed concordantly to measure each sample’s LPS endotoxin concentration.

Results: The peri-implant samples exhibited higher mean levels of TLR4-dpendent NF-κB activation than their healthy implant counterparts, while endotoxin levels were also higher in the diseased samples. LAL assay results correlated strongly with the outputs from the corresponding luciferase reporter assays (rho: p<0.05).  TLR4 inflammatory activation was elevated in peri-implant samples, similar to the Veillonella, E. coli, and F. nucleatum bacterial standards. Peak inflammatory response in peri-implant plaque samples was at 10-8 g/ml.

Conclusion: Our data suggests peri-implant communities may be associated with potent activation of TLR4. This finding is corroborated by LAL assays indicating that Gram negative species expressing pro-inflammatory LPS structure may participate in peri-implantitis communities. Further studies on the structure and function of peri-implant communities are warranted to develop targeted therapeutic approaches for peri-implantitis.

Supported by:  Elam M. and Georgina E. Hack Memorial Research Fund, University of Washington Dr. Douglass L. Morell Dentistry Research Fund

14. Effect of Silver Diamine Fluoride and Potassium Iodide on Bonding to
Caries-affected Dentin, Van Duker M, Chan D, Sadr A

14. Mark Van Duker

Effect of Silver Diamine Fluoride and Potassium Iodide on Bonding to
Caries-affected Dentin
Van Duker M, Chan D, Sadr A
Restorative Dentistry

Objectives: Silver diamine fluoride (SDF) has anti-cariogenic properties that may help in arresting caries when applied as a pretreatment on caries-affected dentin underneath restorations. Application of a saturated potassium iodide (KI) solution following SDF has shown potential in decreasing dark staining of the tooth by SDF. We previously showed that SDF had a negative effect on bonding to sound dentin. This study aimed to evaluate the micro-tensile bond strength (MTBS) of resin composite to caries-affected dentin treated with either SDF or SDF-KI.

Methods: Occlusal enamel of 30 caries-free extracted human molars was removed to expose flat dentin surface. The specimens were immersed in demineralizing solution (pH 4.5) for 7d. A standard smear layer was created using 600-grit silicon carbide paper on the artificial caries-affected dentin, and the specimens were distributed into three groups (n=10). Control: Dentin rinsed with deionized (DI) water. SDF: Dentin treated with 38% SDF (Advantage Arrest) and rinsed off. SDF-KI: Dentin treated with SDF, then KI and finally rinsed off. Composite was bonded using Scotchbond Universal (3M ESPE) in total-etch mode over dentin. MTBS beams were cut from each specimen using a diamond saw after 24h and tested. Data was analyzed by one-way ANOVA with Tukey HSD post-hoc.

Results: MTBS test results ranged from 0 to 40 MPa. The highest values were obtained in the Control and the lowest in SDF-KI, where pre-test failures were frequently observed. One-way ANOVA showed a significant difference among groups (p<0.005); post-hoc analysis suggested that while there was no statistical difference between Control and SDF, both groups were significantly different from SDF-KI.

Conclusion: Application of SDF followed by rinsing and phosphoric acid etching did not significantly change MTBS values when caries-affected dentin was the substrate. However, SDF-KI had a dramatic weakening effect on MTBS, compromising bonding to caries-affected dentin.

Supported by: University of Washington Dental Alumni Association

15. MicroCT Assessment of Dentin Demineralization Prevention by SDF and SDF-KI, Zander V, Sadr A

15. Vernon Zander

MicroCT Assessment of Dentin Demineralization Prevention by SDF and SDF-KI
Zander V, Sadr A
Restorative Dentistry

Objectives: Silver Diamine Fluoride (SDF) has been used to treat caries. However, SDF treated anterior teeth are contraindicated by discoloration; specifically as it affects aesthetics by staining carious areas black. An additive, potassium iodide (KI), has been shown to reduce this effect but has not been tested with regard to its anti-carious properties. The goal of this study is to determine the demineralization-resistance of SDF and KI treated teeth.

Methods: Dentin blocks (n=40) were prepared from bovine incisor roots. The blocks were covered with nail polish, leaving a window (2x3mm) exposed and split into groups; positive (sodium fluoride)/negative control (deionized water), SDF, and SDF+KI. After the application of solution the specimens are subjected to 3 cycles of demineralization solution (3hr immersion) followed by artificial saliva immersion. Following this, specimens are subjected to micro-computed X-ray Tomography (micro-CT) and mineral density profiles are plotted.

Results: SDF treated teeth showed the highest demineralization resistance, especially when compared to the control groups. SDF+KI has the second highest demineralization resistance after the SDF treated teeth. Both groups were significantly different than the controls, and each other.

Conclusion: The application of SDF alone had increased performance when compared to dentin with SDF+KI. While the color of SDF+KI was more aesthetically pleasing, the dentin will not be as viable as dentin that is are treated with SDF alone. Clinically this may limit the application of this additive.

Funded by: University of Washington Dr. Douglass L. Morell Dentistry Research Fund

16. Which Factors Affect Citation Rates in Oral and Maxillofacial Surgery? Cheng KL, Dodson TB, Egbert MA, Susarla SM

16. Kristie L. Cheng

Which Factors Affect Citation Rates in Oral and Maxillofacial Surgery?  
Cheng KL, Dodson TB, Egbert MA, Susarla SM
Oral and Maxillofacial Surgery

Presenter with Poster at Research Day 2017Objectives: Citation rate is one of several tools to measure academic productivity. The purposes of this study were to estimate and identify factors associated with citation rates in the oral and maxillofacial surgery (OMS) literature.

Methods: This was a retrospective longitudinal study of publications in the Journal of Oral and Maxillofacial Surgery (JOMS), International Journal of Oral and Maxillofacial Surgery (IJOMS), and Oral Surgery, Oral Medicine, Oral Pathology, and Oral Radiology (OOOO) from January through December 2012. The predictor variables were author- and article-specific factors. The outcome variable was the citation rate, defined as the total number of citations for each article over a 4-year period.  Descriptive, bivariate, and multiple regression statistics were computed.

Results: The authors identified 993 articles published during 2012. The mean number of citations at 4 years after publication was 5.6 ±5.3 (median, 4). In bivariate analyses, several author- and article-specific factors were associated with citation rates. In a multiple regression model adjusting for potential confounders and effect modifiers, first author H-index, number of authors, journal, OMS focus area, and Oxford level of evidence were significantly associated with citation rate (P ≤.002).

Conclusion: The authors identified 5 factors associated with citation rates in the OMS literature. These factors should be considered in context when evaluating citation-based metrics for OMS. Studies that focus on core OMS procedures (eg, dentoalveolar surgery, dental implant surgery), are published in specialty-specific journals (eg, JOMS or IJOMS), and have higher levels of evidence are more likely to be cited.

Supported by:   University of Washington Dr. Douglass L. Morell Dentistry Research Fund

17. Patient Satisfaction with the Postoperative Results of Genioplasty: A Systematic Review, McMartin S, Hujoel P, Khosravi R

17. Sarah McMartin

Patient Satisfaction with the Postoperative Results of Genioplasty: A Systematic Review      
McMartin S, Hujoel P, Khosravi R
Orthodontics, Oral Health Sciences

Objectives:  The primary aim of this systematic review is to evaluate patient satisfaction with the postoperative results of genioplasty. Secondary objectives looked at comparing patient satisfaction across different modalities of chin augmentation as well as the potential impact on patient satisfaction when genioplasty is done alone or in conjunction with additional surgical procedures.

Presenter with Poster at Research Day 2017Methods:  Six electronic databases were searched without language restriction to identify studies pertinent to the research question. Identified articles were screened first by title and abstract. The full-text of relevant studies was then assessed based on pre-established criteria to objectively include or exclude these studies. The quality of included studies was assessed according to the Cochrane Collaboration’s risk of bias tool and ROBINS-I tool. A summary table of both quantitative and qualitative measures was then created to systematically assess the included studies.

Results:  Of 133 records, 21 publications met the selection criteria. Included studies were: 9 retrospective studies, 8 case-series, 3 prospective studies, and 1 RCT. Methods to report patient satisfaction were inconsistent across the studies. Nine studies used a qualitative scale to measure patient satisfaction and 12 studies used a numerical scale. Only 3 studies used a validated scale. Overall, patient satisfaction regarding postoperative outcomes was reported high. Only 7 patients out of all 1,893 patients involved in the included studies were dissatisfied.

Conclusions:  Patient satisfaction with the postoperative outcome of a genioplasty procedure appears to be high. However, standardized methods to measure patient satisfaction and increased anonymity in patient satisfaction surveys is necessary to achieve more reliable and unbiased results.

Supported by:   University of Washington Dr. Douglass L. Morell Dentistry Research Fund

18. Targets in the Treatment of HPV+ Oral Cancer, Gem HY, Diab AR, Mendez E

18. Hakan Gem

Targets in the Treatment of HPV+ Oral Cancer          
Gem HY, Diab AR, Mendez E
Fred Hutchinson Cancer Research Center

Presenter with Poster at Research Day 2017Objectives: Specific strains of human papilloma virus (HPV) are capable of inducing oral squamous cell carcinoma (OSCC) by abrogating the P53 and PRb tumor suppressors with their own E6 and E7 oncoproteins. Targeting other tumor suppressors, such as WEE1, in HPV+ OSCC has shown therapeutic success in vitro and in vivo. In this study, we examined the apparent drug synergy between two targeted therapies: AZD1775 and vorinostat. We hypothesize that AZD1775 induces significantly greater HDAC expression in HPV+ OSCC, and its synergy with vorinostat is a result of cell damage by way of single and/or double strand DNA breaks.

Methods: To detect HDAC expression, HPV+ OSCC cell lines UMSCC47(n=2) and UPCISCC152(n=3) were cultured and treated with AZD1775. After harvesting mRNA, polymerase chain reactions were conducted to evaluate the expression levels of HDAC1-3. Cultured cells were separately treated with combinations of AZD1775 and vorinostat to observe drug synergy. These cells were then prepared for single-cell gel electrophoresis (comet assays) to detect single and/or double strand DNA breaks.

Results: Our data revealed no significant difference in HDAC expression between control and experimental groups treated with AZD1775. Moreover, comet assay analysis did not show an increase in single and/or double strand DNA breaks for cells treated with AZD1775 and vorinostat compared to their control groups. This finding held true even as concentrations of vorinostat were increased across experiments.

Conclusion: We established that HDAC expression is not upregulated in HPV+ OSCC in response to AZD1775. Furthermore, our comet assays demonstrated that the reported synergism between AZD1775 and vorinostat is not a result of DNA strand breaks, leaving the underlying mechanism a mystery. Broader examination of HDAC interaction with other cell cycle regulators, such as E2F, or deregulators, such as E7, may determine the validity of AZD1775 and vorinostat synergism in HPV+ OSCC.”

Supported by: The Seattle Translational Tumor Research (STTR) Transformative Research Grant, departmental resources at the Fred Hutchinson Cancer Research Center, University of Washington Dr. Douglass L. Morell Dentistry Research Fund, NIH/NIDCR Grant No. T90 DE21984

19. The Combination of Pre-emptive Acetaminophen and Ibuprofen for the Management of Orthodontic Pain Compared to Monotherapy, Keith AJ, Bollen AM

19. Andrew Jacob Keith

The Combination of Pre-emptive Acetaminophen and Ibuprofen for the Management of Orthodontic Pain Compared to Monotherapy    
Keith AJ, Bollen AM
Orthodontics

Objectives: Pre-emptive analgesics have been shown to decrease the onset and magnitude of pain associated with orthodontic treatment, but the additive relationship of a combination of pre-emptive analgesics has not been tested for the management of orthodontic pain.  This double-blinded study is designed to determine if the pre-emptive use of the combination of acetaminophen and ibuprofen is more effective in reducing pain following orthodontic tooth movement when compared to the use of acetaminophen or ibuprofen alone.

Methods: One hour before the orthodontic appointment, 22 participants aged 8-52 years were randomly administered acetaminophen (650mg), ibuprofen (400mg), or acetaminophen (650mg) + ibuprofen (400mg).  Participants recorded their pain intensity using an 11-point [0-10] numeric rating scale during rest, light biting, and while chewing paraffin wax during the following time intervals: immediately, 6-hours, 1-day, and 2-days after drug administration.

Results: There were generally no statistically significant differences between any of the time points among the different groups or conditions, supporting previous findings that ibuprofen and acetaminophen are equally efficacious as pre-emptive analgesics for the management of orthodontic pain.  There were significant increases in pain over time (baseline to 6h) for the ibuprofen and acetaminophen groups and no significant increases for the combined analgesics group.  Pain scores returned to baseline levels by day 2 for the combined analgesic group for all three conditions.

Conclusion: The pre-emptive use of a combination of 400mg ibuprofen and 650mg acetaminophen may reduce the overall magnitude and duration of pain for the orthodontic patient.

Supported by:  University of Washington Dr. Douglass L. Morell Dentistry Research Fund

20. Evaluating PA and CBCT Accuracy for Diagnosing Cysts and Granulomas, Estrada D, Rawal Y, Paranjpe A

20. Daniel A. Estrada

Evaluating PA and CBCT Accuracy for Diagnosing Cysts and Granulomas      
Estrada D, Rawal Y, Paranjpe A
Endodontics, Oral and Maxillofacial Surgery

Presenter with Poster at Research Day 2017Objectives: Periapical granulomas and cysts are common pathoses treated by endodontists. Initial treatment of these lesions is completed through non-surgical root canal therapy (NSRCT).  When NSRCT fails, surgical removal of the lesion is required, and cysts are the least likely to respond to NSRCT.  Both PA and CBCT radiographs exhibit the standard of care in radiographic diagnosis of these lesions. The aim of this study is to assess the diagnostic accuracy of PAs and CBCTs in differentiating periapical cysts from granulomas.

Methods: A chart review was performed to identify cases who have had root-end surgery with a histopathological report. Two surveys were constructed, one consisting of CBCT images and another of PAs, and three evaluators were asked to diagnose lesions based on set criteria. The data obtained will be compared to the histological diagnosis. Univariate logistic regression models will be performed, from which receiver-operating characteristic curves will be derived to determine sensitivity, specificity, and accuracy of each criteria. Inter- and intra-observer reliability will also be assessed.

Results: All surveys have been distributed and we are awaiting the first round of results. After completion, the surveys will be re-administered after 3 months. Answers from both rounds of surveys will be assessed according to the methods above.

Conclusion: Because endodontic treatment planning relies on radiographic findings, it is necessary to determine the discriminatory ability of the images.  Our goal is to determine the specificity by which CBCT and PA radiographs are able to distinguish these lesions.  We believe that by establishing the diagnostic reliability of these radiographs, clinicians will be better able to a) devise an appropriate treatment plan and b) better inform the patient about their condition. This will help determine whether the established criteria are useful in determining accuracy of PA radiographs and CBCTs to differentiate periapical cysts from granulomas.

Supported by: University of Washington Dr. Douglass L. Morell Dentistry Research Fund

21. Monocytic Responses to Titanium and Susceptibility to Peri-Implantitis, La V, Daubert DM, Kotsakis GA

21. Van-Anh La

Monocytic Responses to Titanium and Susceptibility to Peri-Implantitis         
La V, Daubert DM, Kotsakis GA
Periodontics

Presenter with Poster at Research Day 2017Objectives:  Peri-Implantitis is a destructive inflammatory process that leads to bone loss around an osseointegrated implant. Emerging data on the prevalence of peri-implantitis raises concerns about susceptibility to peri-implant inflammation. Monocytes are key mediators of early host response to foreign agents in inflammation and prevail among innate immune defenders in peri-implant lesions. In fact TNF-α, a pro-inflammatory cytokine secreted by monocytes increases in peri-implantitis versus health. The objective of this preliminary study was to assess differential TNF-α release from primary monocytes in response to titanium in persons with peri-implantitis versus healthy controls.

Methods:  Whole blood from subjects with peri-implantitis (N=5) and healthy implants (N=5) was collected for experimental stimulation. Peripheral blood mononuclear cells (PBMCs) were isolated via gradient separation and monocytes were then selected via cell adhesion, which was confirmed by flow cytometry. Monocytes were stimulated with varying concentrations of LPS and titanium particles to elicit pro-inflammatory cytokine production. Subsequently TNF-α production was measured using a sandwich ELISA assay for each sample.

Results:  In peri-implantitis cases, monocytes produced six-fold greater TNF-α levels than as compared to cells from healthy subjects when stimulated with titanium particles in FBS supplemented media. Inflammatory response was higher in the group stimulated with protein-coated titanium particles versus stimulation with LPS or titanium particles in PBS. Healthy patients showed little to no difference in their TNF-α level production when introduced to titanium particles in the presence of proteins.

Conclusion: Within the limitations of this pilot study, monocytes from persons with peri-implantitis may be hypersensitive to titanium particles. As we have previously demonstrated, titanium particles are generated via biocorrosion from implant surfaces in peri-implantitis and are released into the surrounding environment. This lends to the hypothesis that the excess presence of titanium in disease may lead to monocyte priming.

Supported by:  Elam M. and Georgina E. Hack Memorial Research Fund, University of Washington Dr. Douglass L. Morell Dentistry Research Fund

Other Dental Students

22. Alterations in Alveolar Bone Structure Caused by Type 2 Diabetes, Roll K, Sattler D, Zhang H, Wolff L, Kotsakis G

22. Dylan Sattler

Alterations in Alveolar Bone Structure Caused by Type 2 Diabetes         
Roll K, Sattler D, Zhang H, Wolff L, Kotsakis G
Periodontics, Restorative Dentistry

Presenter with Poster at Research Day 2017Objectives: Type 2 Diabetes Mellitus accounts for 90-95% of diabetes cases totaling roughly 17.7 million people in the United States alone. DM can not only lead to tooth loss, but also make implant placement difficult due to decreased blood supply to the bone and overall decreased bone density. Although there is a need to better understand how to treat these patients, there is little research on how. The goal of this study was to clinically assess mandibular alveolar bone structure, vascularity, and bone density in well controlled versus poorly controlled Type 2 diabetic patients, as well as researching the known and possible alternative biochemical mechanisms responsible for these in the current literature.

Methods: Alveolar bone density was compared between well-controlled and non-well-controlled diabetic patients. Clinical bone density was measured by resonance frequency analysis and charted as an implant stability quotient. Implant stability was measured using maximum insertion torque during implant placement. OHIP-5 (oral health impact profile) was used to follow oral health quality of life following implant placement. Preliminary background research showed the possible implication of Runx2 and PPARу which were then stained for in histological preparations.

Results: Minimal change was seen between primary and secondary implant stability. Maximum insertion torque was slightly higher in the uncontrolled diabetic group at the time of implant placement. OHIP-5 steadily decreased after implant placement in both groups. Runx2 signaling was amplified in well-controlled diabetics while PPARу was amplified in poorly-controlled diabetics.

Conclusion: Dental implants with hydrophilic surface characteristics may be a better alternative for poorly controlled diabetic patients, but implants in diabetics as a whole have been shown to increase oral-health related quality of life. Based off of other existing studies and biochemical pathway research, PPARу may be an alternative target in diabetic patients due to their role in osteogenesis and adipogenesis.

Supported by:  ABCD Collaborators

23. Micro-shear Bond Strength of RMGI to Silver Diamine Fluoride-treated Dentin, Lutgen PJ, Chan DC, Sadr A

23. Paul J. Lutgen

Micro-shear Bond Strength of RMGI to Silver Diamine Fluoride-treated Dentin         
Lutgen PJ, Chan DC, Sadr A
Restorative Dentistry

Objectives: We previously demonstrated that silver diamine fluoride (SDF) may affect composite bonding to sound dentin depending on the protocol and adhesive used. This study evaluated micro-shear bond strength (MSBS) of resin-modified glass ionomer (RMGI) to SDF-treated dentin using polyacrylic acid conditioning or phosphoric acid etching.

Methods: Coronal discs (2.0±0.2mm thick) prepared from 40 extracted caries-free human teeth were distributed into 4 groups (n=10). Uniform smear layers were created using #600-grit SiC paper. Dentin was pre-treated with either deionized water (DIW) or SDF 38% (Advantage Arrest) via micro-brush for 10s and rinsed after 1min for control and experimental groups respectively. After air-drying for 5s, the surfaces were treated with either polyacrylic acid (Ketac Conditioner, 3M ESPE) conditioning for 10s or phosphoric acid (Universal Etchant; 3M ESPE) etching for 15s. A layer of RMGI (Fuji II LC, GC) approximately 0.5mm in thickness was placed and light-cured. Composite cylinders (0.79mm D, 1mm H) were bonded to RMGI using Scotchbond Universal (3M ESPE) adhesive. Specimens were stored in DIW at 37°C for 24h prior to MSBS testing using the wire-loop technique. Three cylinders were tested per disc and averaged. Data were subjected to two-way ANOVA (α=0.05).

Results: ANOVA suggested that none of the factors (DIW vs. SDF and conditioning vs. etching) were significant (p>0.05). Out of total 120 cylinders tested, 65 mixed failures (complex fracture involving RMGI and dentin) and 55 adhesive failures (fracture at RMGI/dentin interface) were observed under 5x magnification.

Conclusions: Bond strength of RMGI to dentin was not affected by SDF application, regardless of polyacrylic acid conditioning or phosphoric acid etching. Given that adhesive resin bonding to SDF-treated dentin is compromised, placement of RMGI may be a reliable way to improve bond strength while ensuring therapeutic effects of SDF as a caries arresting agent are achieved.

Supported by: University of Washington Dental Alumni Association

24. Characterization of a Human Apical Papilla Stem Cell Line, Blanchard L, Chrepa V

24. Lauren Hagel Blanchard

Characterization of a Human Apical Papilla Stem Cell Line         
Blanchard L, Chrepa V
Endodontics

Presenter with Poster at Research Day 2017Objectives:  Mesenchymal stems cells (MSC) of the apical papilla (SCAP) have been identified as an important cell population for the regeneration of the pulp-dentin complex. Their strategic location and successful clinical delivery into the root canal systems by lacerating the apical papilla makes them an easily accessible source for postnatal stem cells. Preclinical studies that evaluate the various aspects of the regenerative process must use fully characterized MSCs using standardized criteria for MSC definition that include MSC marker expression and multi-lineage differentiation potential. The objective of this study was to isolate, culture and characterize a human SCAP population.

Methods: Cells were isolated from an apical papilla tissue collected from an extracted third molar. The expression of MSC-related molecular markers CD73, CD90 and CD105 was analyzed by flow cytometry and the percentage of each marker expression and co-expression was recorded. Osteogenic and adipogenic differentiation were assessed qualitatively using Alizarin red stain and Oil red O stain under light microscopy.

Results: More than 98% of cells co-expressed the MSC markers CD73, CD90 and CD105 while being negative for the endothelial marker CD45. The induced differentiation groups demonstrated a more robust presence of mineralized nodules and lipid droplets compared to controls.

Conclusion: Isolated cells from a human apical papilla highly expressed MSC markers and showed differentiation potential into osteogenic and adipogenic lineages.

25. “Case-Control” Studies are Frequently Mislabeled in Dental Journals:
Systematic Review, UW-SOD Student Research Group (SRG), Chrepa V, Kapos F, Nguyen S, Kotsakis G

25. UW-SOD Student Research Group

“Case-Control” Studies are Frequently Mislabeled in Dental Journals: Systematic Review            
UW-SOD Student Research Group (SRG), Chrepa V, Kapos F, Nguyen S, Kotsakis G
Endodontics, Periodontics, Epidemiology

Objectives:  In clinical research, study design guides recruitment strategies and analytical techniques to be used. However, there is evidence of mislabeling across health fields implying threats for study validity. The objective of this study was to estimate the proportion of studies in dental journals mislabeled as “case-control.”

Methods:  An electronic search of MEDLINE from January 2015 to December 2016 was conducted using the search terms case-control, dental health services, dental health, dental, craniofacial and oral. Utilizing a two-phase search strategy, reviewers screened the titles and abstracts of the identified articles and studies labeled as “”case-control”” were assessed in the second phase of the search. Each study that met inclusion criteria then had a full-text review for verification of study design by two independent reviewers. Case-control studies were defined as having study groups defined by outcome and prior exposure status ascertained by the investigators. Studies not meeting these criteria were considered mislabeled and had their study design re-classified by calibrated reviewers. Subsequently, the proportion of falsely labelled (i.e. false positive) “case-control” studies to the total number of studies labelled as “case-control” (i.e. false positive and true positive) was calculated.

Results:  The search yielded 1973 titles and abstracts; after initial screening, 300 “case-control” studies were scrutinized during the second phase of the review. Finally, 109 articles were classified as mislabeled (36% mislabeled studies). Examples of mislabeled studies included “prospective case-control study” and “randomized case-control trial”. Mislabeled studies were reclassified as cross-sectional (61%), cohort (28%) and clinical trials (11%).

Conclusion:  36% of the studies published in dental journals in 2015 and 2016 as “case-control” were mislabeled, which raises concerns regarding quality of reporting and has unknown ramifications to study validity. It further raises concerns regarding the rigor of peer review in dental journals.