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(2024-12-16) Diggory, Mark R
Comparison of surgical techniques to accelerate orthodontic tooth movement: a review
(2024) Lemoine, Jesse Abreu; Kernitsky, Jeremy; Price, Albert
BACKGROUND: Accelerating orthodontic treatment is a priority for clinicians and patients aiming to reduce treatment duration and associated discomforts. This systematic literature review assesses the current evidence regarding the efficacy of surgically assisted acceleration techniques in orthodontics.
MATERIALS AND METHODS: In November 2021, an extensive search was conducted across EMBASE, Cochrane, and PubMed databases, yielding a total of 2,022 articles. After application of selection criteria and full text analysis the articles for review, were narrowed down to a total of 26 entries. These studies included Piezocision, Propel, Micro-osteoperforations (MOP), Periodontally Assisted Osteogenic Orthodontics (PAOO), and laser-assisted techniques as interventions.
RESULTS: The scrutinized literature revealed that 75% of articles on Piezocision reported a favorable impact on treatment time, whereas MOP was found effective in half of the related articles. The Propel system was deemed beneficial in only 25% of the studies examined. In contrast, both articles evaluating PAOO unanimously found it to be an effective method for accelerating orthodontic tooth movement.
CONCLUSION: Our review indicates a significant variance in the success rates of surgically assisted orthodontic acceleration methods, with Piezocision and PAOO displaying the highest efficacy, 1.5-2x faster than control groups. Risk of bias assessment revealed moderate to high risk across our selected studies, with the most common issues including lack of blinding of participants and assessors as well as inconsistent reporting of outcomes.
Shear bond strength of different cements to printed resins and zirconia
(2024) Allanqawi, Rawan Taleb; Giordano, Russell
OBJECTIVES: This in-vitro study aimed to measure bonding of multi and single step cements to printed resins and Layzir zirconia. Evaluate the effect of different material combinations on shear bond strength, and to evaluate the effect of thermocycling on shear bond strength of different materials combinations.
MATERIALS AND METHODS:
Rectangular specimens (N= 384) were prepared from PacDent Rodin Sculpture 2.0 (RS), SprintRay Ceramic Crown (SCC), Rodin Titan (RT), and Layzir Zirconia (LZ), and were divided into 16 groups according to material combinations, static or thermal aging process. Stainless-steel rods (Shofu Dental Corporation) of 4 mm diameter were used for this in-vitro study. Shear bond strength (SBS) test was performed on all static and thermocycled groups. The final dimension of each plate was about 15 mm in length, 2mm thick, and 15 mm in width. 3D printing of resins was done using the Asiga 3D printer. Layzir Zirconia specimens were prepared by sectioning the zirconia disc using the Isomet 5000 sectioning machine. Zirconia specimens were dried in the oven and sintered using a high temperature furnace (Zircar). All materials were surface treated based on material recommendations. All stainless-steel rods and Layzir Zirconia were sandblasted, PacDent Rodin Sculpture 2.0 and Rodin Titan were etched with hydrofluoric acid 5%, and SprintRay Ceramic Crown was sandblasted and etched using 5% Hydrofluoric acid. In the last stage of specimen preparation, the framework plate was placed on a flat surface, then the adhesive resin cement was injected to fill the bonding area. Excess cement was removed around the rod border with a plastic instrument and a micro brush, and the bonded plate/rod was kept under a static load of 1.4 kg for 10 minutes. Half of the specimens were tested in a control/static condition, and another half were thermal aged for 5000 cycles before shear bond testing was done. A shear bond test was performed on all static and thermocycled specimens by using the universal testing machine (Instron Model 5566A). The crown material was secured into a jig and a flat shear blade was used to shear the pins. The blade had a perpendicular contact at the interface between the rod and the plate. A load was applied at the adhesive interface between the plate/rod during the testing. The shear bond strength was calculated in MPa by load of failure over the area of the bond. The maximum shear load was recorded at debonding. Specimens were examined to determine failure location, load to failures values were also analyzed as well as the mode of failures.
RESULTS: This study showed a significant difference in shear bond strength between the printed resin groups compared to Layzir Zirconia group (P<.0002). Layzir Zirconia group showed the lowest SBS mean values among the tested groups (16.18 MPa). SprintRay bonded with Panavia SA materials produced the highest shear bond strength mean values (32.07MPa), followed by Rodin Titan bonded with Panavia V5 and Clearfil (30.91MPa) and Panavia SA (29.50 MPa), and PacDent Rodin Sculpture 2.0 Bonded with Panavia SA (25.51 MPa). The lowest shear bond strength mean values were recorded in SprintRay bonded with Clearfil and Panavia V5 (17.26 MPa), Layzir Zirconia bonded with Rodin bond and Panavia V5 (15.06 MPa), and Pacdent Sculpture 2 bonded with Clearfil and Panavia V5 (13.62 MPa). There was a significant difference in SBS between control and treated (thermal cycle) groups (decrease in treated group than control group) (P<.0001). There’s a significant difference between SBS values for specimens bonded with Panavia SA compared to other resin cements used (P<.0001).
CONCLUSION: Significant differences were found between 3D printed resins compared to Layzir Zirconia groups. Layzir Zirconia groups showed the lowest SBS among all tested groups. Thermal aging significantly decreased SBS values of thermocycled groups. Adhesive failure was the primary mode of failure among all SBS tested groups. Material surface topography, filler content, surface pretreatment and adhesive techniques, as well as thermal aging impact the bonding and as a result SBS values of specimens.
Investigations of novel endodontic sealers and modifications of existing bioceramic sealers
(2024) Gunarajasingam, Ayinkeran; Giordano, Russell
The advent of modern bioactive sealers have introduced the ease of obturation with sealers that possess bioactive properties when used to obturate an endodontically treated canal. With increase use comes increased questions about the efficacy that these sealers have in obturating canals (1). From unpredictable setting time to questions about their ability to obturate and occlude dentinal tubules many questions and criticisms have arisen with their increased popularity. In light of these concerns this study sought to find if there alternative materials with bioactive properties that might adequately obturate an endodontically treated canal. The second part of this project sought to determine if the particle size of an existing bioceramic sealer and determine if the particles of the premixed bioceramic sealer could be reduced to size small enough to potentially obturate dentinal tubules (25).
Objective 1. : The first objective of this study was to determine if commercially available pulpal liners and crown and bridge cements could be used to seal endodontically treated canals.
Objective 2: the second objective of this project was to determine if reduction in particle size could improve the properties of an existing sealer.
Materials and Methods: One pulpal liner, Activa (Pulpadent), one crown and bridge cement Ceramir (Doxa), and EndoSequence BC sealer (Brasseler) were evaluated to determine if the repurposed materials could seal an endodontically treated canal with Endosequence as the control. The second part of this study modified a commercially available powder and liquid sealer, BioRoot (Septodont) BC sealer, to decrease its particle size and evaluated if this modification had any affect on its physical properties. 45 single-rooted teeth were decoronated, endodontically treated, and obturated using one of the commercially available products (n=3) Activa, Ceramir, Endosequence. The modified sealers were separated into groups by the time the powdered sealer was milled using a Speedmixer: 0 seconds (control), 40 seconds, 60 seconds, 120 seconds, and 240 seconds. Data was analyzed using a one-way ANOVA and all pairs comparison using a post-hoc Tukey-Kramer HSD test. Results: Of the repurposed materials Activa showed the most promising results with a setting time of 2.5 ± 0.9 hours as well as the best performance in terms of flow, film thickness, bond strength, and leakage resistance.
For the modified sealers the mechanical properties increased as the milling times were increased for all except shear bond, where bond strength peaked at 7.9 ± 6.9 MPa for 120 seconds of milling time. Conclusion: we were able to determine that Activa a pulpal liner demonstrates superior performance in terms of shear bond strength, dye-leakage prevention, setting time, film thickness, flow compared to EndoSequence bioceramic sealer. We were also able to successfully decrease the particle size of an existing bioceramic sealer and were able to show that this improved the setting time, film thickness, flow, and dye-leakage prevention, we were not able to show that it appreciably increased the bond strength of BioRoot bioceramic sealer to dentine in the root canal space.
Evaluation of the mechanical and the physical properties for resin 3D printed material and machinable composite
(2024) Alhussain, Musstafa Musa; Giordano II, Russell; Fan, Yuwei
OBJECTIVES: This in vitro study assessed the mechanical and physical properties of various 3D-printed resin materials and a machinable hybrid resin.
MATERIALS AND METHODS: Eight 3D printing resin materials were selected for evaluation: Pac-Dent Rodin Sculpture 2.0 (RS), Pac-Dent Rodin Titan (RT), BEGO VarseoSmile Crown Plus (BVS), Desktop Health Flexcera Smile Ultra Plus (DHF), SprintRay OnX tough 2 (SROnX), SprintRay Ceramic Crown (SCC), Saremco Crowntec (SC), GC Dental Cerasmart Universal 270 (CS). These materials were tested to evaluate their flexural strength, flexural modulus, biaxial flexural strength, thermocycling, fatigue, fracture toughness, and wear resistance. The specimens still intact after thermocycling and fatigue were subjected to a biaxial flexural strength test. A DLP 3D printer, Asiga Max, was used to print 12 specimens from each printable material to determine three-point flexural strength, biaxial flexural strength, and fracture toughness using a single-edge V-notched beam. and wear resistance was measured using a pin on plate two-body system. The pins acted as test material, and VitaMKII was used as the tooth analog plate material. For the machinable block, bar specimens were prepared by sectioning with an Isomet 5000 diamond saw. A core drill press was also used to prepare pins of the specimens for wear resistance testing and discs for biaxial flexural strength, thermocycling, and fatigue tests. The filler weight percentage of each material was determined using the ash-burning method. The microstructure of a wear rod from each material was examined under a scanning electron microscope (SEM), and the elemental composition was investigated by Energy Dispersive Spectroscopy (EDS).
To compare means, a one-way ANOVA (α=0.05) with Tukey's HSD posthoc tests was performed using Excel 365 and JMP Pro 17.
RESULTS: Utilizing the three-point method, the flexural strength test results reveal significant differences among the materials tested. The flexural modulus also exhibited significant differences, with the highest to the lowest average observed in CS, RS, SCC, SC, RT, BVS, SROnX and DHF, measuring 8.23, 8.20, 7.33, 6.70, 6.63, 5.65, 4.84 and 4.47 GPa, respectively. The resin materials with the highest biaxial flexural strength were DHF, which demonstrated the highest mean value of 236.89 MPa, followed by CS 229.13 MPa and SROnX 216.85 MPa, with no significant distinction. CS exhibited the highest biaxial flexural strength at 205.52 MPa, while BVS demonstrated the lowest at 117.29 MPa. The thermocycling test presented no significant differences in strength between SROnX, DHF, CS, SC, and SCC. In contrast, BVS displayed the statistically lowest biaxial flexural strength. The fracture toughness test presented no significant differences between CS, RT, and SCC, with values of 3.18, 2.74, and 2.63 MPa·m^0.5, respectively, exceeding the remaining materials. In the wear test, SC showed the least weight loss of 0.0025 g, and SC exhibited the smallest height reduction of 0.040 mm after undergoing the same number of cycles. In contrast, SROnX experienced the highest weight loss of 0.0051 g and height reduction of 0.091mm after 200k cycles.
CONCLUSION: The study results demonstrate significant differences in the mechanical properties of 3D-printed resin materials compared to machined hybrid resin materials. These properties included flexural strength, flexural modulus fracture toughness, wear resistance, biaxial flexural strength before and after thermocycling, and cyclic fatigue.
Oral health among children with failure to thrive
(2024) Milaeh, Rua Sameer A.; Discepolo, Keri; Chiao, Christine
This study investigated the relationship between Failure to Thrive (FTT) and oral health in children, focusing on the influence of medical, dietary, and environmental factors on Early Childhood Caries (ECC) and Severe Early Childhood Caries (S-ECC). A significant gap in U.S. studies concerning the relationship between nutritional status and dental caries, particularly in children aged 0-5 years, highlights the need for more focused and diverse research.
A retrospective evaluation of medical records from Boston Medical Center's Growth Clinic examined children diagnosed with FTT from January 2018 to December 2022 and investigated the prevalence of dental caries in these children. The control group consisted of typically developing children matched by age, gender, and insurance status. Data analysis included descriptive statistics and Chi-Square tests to explore differences in demographics, dietary factors, and oral health outcomes between the groups.
Results indicated similar gender ratios and predominant public insurance usage in both groups. The FTT group showed a higher incidence of environmental factors contributing to their condition, a greater dependency on bottle feeding and soft diets, and poorer oral hygiene. These factors also correlated with a significantly higher prevalence of ECC and S-ECC compared to the control group.
The study uncovered significant environmental and dietary influences on the oral health of children with FTT. It underscored the importance of integrating oral health evaluations and treatments into care strategies for children with FTT given the strong association between FTT and adverse dental outcomes. Limitations of the retrospective approach and sample size are discussed, with recommendations for future prospective studies and larger sample sizes. Applications for clinical practice focused on enhancing healthcare accessibility and integrating updated training for providers to ensure effective management of FTT in children.
Fabrication of polymer infused multiphase glass ceramic block
(2024) Kantikosum, Kirana; Giordano, Russell A.
OBJECTIVES: This study aims to fabricate polymer infused multiphase glass ceramic block and explore mechanical properties, optical properties and physical properties of the ceramic block.
MATERIALS AND METHODS: Polymer Infused Multiphase glass ceramic specimens were prepared with the slip-casting technique. The specimens were divided into 3 groups based on different sintering temperatures: Group 1) 850 °C, 2) 880 °C, and 3) 900 °C. After sintering, density before resin infiltration of specimens was measured and calculated. All specimens were immersed in silane solution and infused with resin solution then cured under Hydraulic press. Specimens were examined for physical optical and mechanical properties including microstructure, crystal characterization, biaxial flexural strength, translucency parameter and contrast ratio. All data underwent one-way of variance (ANOVA) and Tukey HSD test for comparisons with a significance threshold set at a p-value of <0.05.
RESULTS: A slip casting technique was effectively employed to fabricate a multiphase glass ceramic material, followed by resin infusion and curing under isostatic pressure. Biaxial flexural strength variations were observed among specimens subjected to different sintering temperatures, as evidenced by testing with a universal testing machine. Additionally, spectrophotometer analysis revealed no statistically significant differences in translucency parameter and contrast ratio among groups of specimens sintered at varying temperatures before polymer infiltration. However, there is a statistically significant difference among groups after polymer infiltration. Scanning Electron Microscope images confirmed the presence of resin interpenetrating networks within the specimens. Notably, the properties of the specimens were significantly influenced by the sintering temperature.
CONCLUSION:
1. Polymer Infused Multiphase glass ceramic material can be fabricated from the combination of resin infused ceramic and feldspathic porcelain.
2. Different sintering temperatures show no influence on the density of polymer infused multiphase glass ceramic materials, both before and after resin infiltration.
3. Different sintering temperatures show no influence on translucency parameter, contrast ratio of polymer infused multiphase glass ceramic materials before resin infiltration.
4. Resin infiltrated networks sintered at 900°C exhibit lower biaxial flexural strength and translucency parameter compared to polymer infused multiphase glass ceramic material sintered at 850°C and 880°C.
5. Resin infiltrated networks sintered at 900°C exhibit superior contrast ratio compared to polymer infused multiphase glass ceramic material sintered at 850°C and 880°C.
6. Scanning Electron Microscope images reveals interpenetrating networks in the polymer infused multiphase glass ceramic material.
Econometric analysis of heterogeneity in financial markets using quantile regressions
(2018) Tian, Yuan; Qu, Zhongjun
This dissertation studies heterogeneity in financial markets using quantile regressions.
The first chapter develops uniform confidence bands for the linear quantile regression estimator in a time series setting. The confidence bands are important for estimating the precision at different quantiles of the conditional distribution. The inference procedure is carried out through bootstrapping and allows for serially correlated error terms. An empirical application to the relationship between stock returns and investor sentiments suggests the method can be informative.
The second chapter analyzes the heterogeneity of firm characteristics on returns to capital. It develops a theoretical model under a utility maximization framework with imperfect insurance and credit markets constraints. From the model, the returns to capital are derived as a function of the parameters, which affects the production function of the firm and the entrepreneur utility form. Quantile regression is applied to analyze the field experiment data from the Sri Lanka Micro Enterprises Project (2005-2010). Empirical evidence shows that returns vary across different quantiles of firm profits. Further, the ability/risk aversion of entrepreneurs affect the returns differently at different quantiles.
The third chapter examines capital account liberalization and its effect on price volatility in the Chinese housing market. The chapter assesses the extent to which: a) short-term capital flows and foreign direct investment may have impacted prices and volatility in the Chinese housing market; and b) whether 2006 Capital Account Regulations on foreign purchases of Chinese real estate were effective in reducing the level and volatility of prices in the housing market. The results show that hot money magnified the impacts of capital flows on housing prices during upward surges in housing prices. Quantile regression provides quantitative evidence that the more volatile the housing market was, the larger the impact short-term capital flows had on accentuating such volatility. Furthermore, the 2006 CAR continued to have a strong impact on reducing volatility in the Chinese housing market during the period under study.
Economic imperialism on the global frontier: William Henry Jackson’s photographs for the World’s Transportation Commission, 1894-1897
(2023) Monroe, Casey Cameron; Sichel, Kim
This dissertation investigates William Henry Jackson’s photographs for an international scouting and fact-finding mission, the World’s Transportation Commission, and the multivalent meaning the images possessed for period patrons and audiences in four contexts. I argue that Jackson visually constructed a homogenous global frontier of economic imperialism that channeled and advanced burgeoning expansionist ideologies in American cultural and political realms during the 1890s.
Organized under the auspices of the Field Columbian Museum, the World’s Transportation Commission consisted of five members, including Jackson, who traveled the world between October 1894 and March 1896 seeking information and artifacts regarding railroad history for display at the museum. The Commission also received funding from five major American railroad tycoons, as well as from Harper’s Weekly, which published forty-five articles between February 1895 and August 1897 that featured 372 Jackson photographs. After returning, Jackson presented these pictures as colored lantern slides in a stereopticon lecture series in Colorado throughout spring 1897. Each chapter of this dissertation focuses on one of the four patrons and contexts for which Jackson intended his images and in which they were seen.
Chapter One investigates the intended function of these images as didactic objects within a public context for the Field Columbian Museum. The second chapter positions Jackson’s work for five industrialist patrons as an imperial scouting report that studied existing colonial railway systems as models for possible future deployment of corporate interventions throughout Latin America. Chapter Three analyzes the popular cultural dissemination of Jackson’s photographs in Harpers Weekly and the complicated intersections between photographer and editors working to captivate armchair tourists while forwarding notions of ostensible American moral superiority and global hegemony. Chapter Four examines Jackson’s stereopticon lecture tour and his presentation of a hand-colored spectacle within the context of personal entrepreneurial gain. In this final, unmediated venue, Jackson shifted his photographic focus towards a seemingly candid, snapshot approach.
My analysis of these four contexts and applications demonstrate how Jackson pictorially destroyed existing worlds of indigenous customs and perspectives, and replaced them with a new, unified vision of an international commercial frontier ripe for exploitation.
Louis Douglas and Jonny spielt auf: performing Blackness in interwar Germany
(2018) Edwards, Paul Johnson; Mizruchi, Susan; Zatlin, Jonathan
This dissertation, “Louis Douglas and Jonny spielt auf: Performing Blackness in Interwar Germany,” traces the reception of traveling and expatriate Black American performers in Germany during the interwar period and the cultural productions made by Germans in response to this interaction with the New Negro Renaissance. The performances of Black Americans challenged German views of the European colonizer and the colonized Other. Blackness played an important role in altering conceptions of race and culture during one of the greatest transitions in modern Germany, framed by the extraordinarily open and heterogeneous aesthetic of the Weimar era on one end and the harsh racial stratification of the Nazi regime on the other. Black arts provided a deeply decentering experience, forcing Germans to reassess their conceptions of Black people.
Chapter One offers a theory of Black performance that explores how blackface minstrelsy became the referent for Black performance in the twentieth century. Chapter Two examines satirical magazines which introduced working and middle class Germans to Black people in the period between the German Empire and the Weimar Republic. Chapter Three reveals how the first Black American traveling revue, The Chocolate Kiddies, altered German conceptions of Black identity through performances that highlighted the importance of the Great Migration and the performance culture of Harlem. Chapter Four introduces Louis Douglas, a Black American performer who helped to bring Josephine Baker to Europe, and created a revue designed to present Black Americans to French and German audiences. Chapter Five explores how Louis Douglas developed a persona of the modern Black dancer in Germany following Baker’s return to France. Chapter Six examines Ernst Krenek’s blackface “jazz opera” Jonny spielt auf as an exemplary German appropriation of the Black American male body showing how Krenek’s opera created a transnational discourse on the modern Black American man.