SACM - United States of America
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9668
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Item Restricted Bond Strength of Denture Teeth to Conventional, Milled and 3D-Printed Denture Bases(Saudi Digital Library, 2025) Abumansour, Malik; Ontiveros, Joe C; Gonzalez, Maria D; Belles, Donald M; amnuay, Sudarat Kiat; amnua, Chun-YenOBJECTIVE: This in vitro study assessed the shear bond strength and failure modes between denture teeth and denture bases fabricated using conventional, two-part milled, monolithic milled, or 3D-printed complete denture techniques. MATERIALS AND METHODS:A total of 40 denture base substrates (30 mm diameter x 10 mm height) were processed according to the following material treatment groups, n=10 for all groups: (1) Conventional complete denture processed using heat-polymerized resin (Lucitone 199, Dentsply Sirona) as a control; (2) 3D-printed denture resins (Lucitone Digital IPN 3D Premium, shade A1, and Lucitone Digital Print 3D Denture Resin, Original); (3) Two-part milled dentures from pre-polymerized polymethylmethacrylate pucks (Lucitone Digital Fit Denture Base Disc, Dentsply Sirona; Multilayer PMMA Discs, Dentsply Sirona), and (4) Monolithic milling denture (AvaDent, Extreme cross-linked PMMA). For all groups, prefabricated denture teeth or bases were embedded in autopolymerizing acrylic resin, except for Group four, in which the base and teeth were fabricated as a single unit. After embedding, specimens were polished using 400-grit sandpaper to achieve uniform surface exposure. The bonding of the two parts, base and teeth, was performed according to each manufacturer’s protocol. All specimens were tested within 24 hours of bonding. Shear bond strength was measured using a universal testing machine at a crosshead speed of 1 mm/min. The mode of failure was observed and recorded. Data were analyzed using one-way ANOVA followed by Tukey post hoc test at a significance level of α = 0.05. RESULTS: The monolithic milling group demonstrated the highest bond strength among all groups, with statistically significant differences compared to the others (p < 0.01), with 100% cohesive failure. The 3D printed group exhibited a significantly higher mean bond strength than both the conventional and milled groups (p = 0.001), with 70% of mixed failure. There was no significant difference between the conventional and milled groups (p = 0.98), which represent 90% and 100% of adhesive failure, respectively. CONCLUSIONS: Among all groups, the monolithic milled dentures (AvaDent) demonstrated the highest bond strength at the base-to-tooth interface. The 3D-printed denture specimens showed greater base-to-tooth bond strengths compared to both the conventionally processed and the two-part milled dentures, which showed no significant difference from each other.17 0Item Restricted COMPARING EFFECTIVENESS OF INTRAORAL SCANNER IN CARIES DETECTION(Saudi Digital Library, 2025-05-20) Alruwaili, Mohand; Weinstein, GeraldineThis study investigates the diagnostic performance of the TRIOS 5 intraoral scanner in detecting dental caries compared to traditional methods such as visual-tactile examination and radiographic imaging. With 21 adult participants, the study used a comparative diagnostic accuracy design to evaluate the scanner’s sensitivity, specificity, and agreement with the gold-standard radiographic findings. Results showed that while the TRIOS 5 demonstrated high sensitivity (89.4%) and a strong negative predictive value (87.0%), its specificity was low (26.4%), indicating a high rate of false positives. Cohen’s Kappa analysis revealed poor agreement between scanner and radiograph findings (κ = 0.100), and McNemar’s test confirmed statistically significant discrepancies (p = 4.648). These findings suggest that although the TRIOS 5 is effective in early caries detection, its diagnostic output should be interpreted alongside conventional methods to avoid overtreatment. The study highlights the scanner’s potential as an adjunct diagnostic tool and calls for further research on AI-driven enhancements and standardized calibration protocols to improve clinical accuracy and reliability.33 0Item Restricted VOCABULARY LEARNING STRATEGIES AMONG SAUDI EFL MILITARY CADETS: PATTERNS AND PREFERENCES(Saudi Digital Library, 2025-07-29) Aldosari, Fahad Ammar; Leiva, Carlos LopezThis study investigates the vocabulary learning strategies (VLSs) of 126 Saudi military EFL cadets, an underexplored group in second language acquisition research. Using an explanatory sequential mixed-methods design, a questionnaire identified the most and least used strategies, followed by interviews with 10 participants for deeper insights. Findings show cadets frequently use bilingual dictionaries, vocabulary lists, and group work, while cognitive strategies like written repetition and note-taking are underutilized. No significant differences in VLS use were found between Level 1 and Level 2 cadets, suggesting stable strategy preferences. Additionally, emerging strategies such as gamified learning and collaborative storytelling indicate a shift toward technology-assisted and social learning approaches. These results highlight the unique challenges of vocabulary acquisition in a regimented military setting and emphasize the need for interactive, context-specific instructional methods to improve vocabulary retention and language proficiency. The study’s findings provide valuable insights for curriculum designers and military language instructors, offering practical recommendations to enhance vocabulary teaching strategies in structured EFL environments.4 0Item Restricted From Raw Data to Insightful Decisions: A Framework for Environmental Data Management, Analytics, and Visualization for Smarter Cities(Saudi Digital Library, 2025-06-05) Alsalehy, Ali; Bailey, MikeSmart cities depend on continuous streams of environmental data to monitor air quality, detect emerging risks, and guide effective responses. Yet these data are frequently incomplete, noisy, and inconsistent, limiting their reliability for decision-making. Overcoming this challenge requires more than isolated algorithms. It demands an integrated framework that addresses data quality, predictive insight, and human-centered interpretation. This thesis introduces a unified solution for environmental data analytics, demonstrated using five years of gas and weather data from Jubail Industrial City. The first contribution presents a dual-phase cleaning framework for multivariate time series. Statistical and machine learning techniques are used to detect anomalies, followed by context-aware interpolation to reconstruct missing values. This method preserves temporal structure and produces a high-resolution, analysis-ready dataset. The second contribution applies advanced forecasting using representative models such as XGBoost to predict carbon monoxide concentrations with high accuracy. These predictions are enriched by descriptive and spatiotemporal analysis, revealing spatial patterns and seasonal trends that support a shift from reactive mitigation to proactive air quality management. The third contribution translates analytical output into an interactive visual analytics platform. Designed for performance and usability, the system enables decision-makers to explore sensor data and forecasts through maps, heatmaps, and time series visualizations. Its human-in-the-loop design integrates expert judgment into the interpretation process, promoting transparency, trust, and context-aware decision-making. Together, these contributions form a cohesive framework that transforms raw environmental data into actionable intelligence. By combining rigorous data preparation, predictive modeling, and intuitive visual tools, this research enhances the capacity of smart cities to make faster, more informed, and more effective decisions.43 0Item Restricted Essays on Blockchain Technology(Saudi Digital Library, 2025-05-15) Alkhars, Kazem Abdulkarim; Radhakrishnan, AbiramiThis dissertation consists of two essays on blockchain technology adoption and application. The first essay empirically examines the factors affecting the adoption of cryptocurrency at the individual level using the theoretical lenses of the Theory of Technological, Personal, and Environmental factors and Diffusion of Innovation Theory. The existing literature emphasizes the need for broader adoption by individuals. Therefore, in this large-scale, theory-driven study, I investigate the factors influencing the intention to adopt cryptocurrencies at an individual level. The findings show that the main technological factors impacting the intention to adopt cryptocurrency are complexity, perceived benefits, and trialability. The main personal factors are compatibility, individual risk propensity, and trust. Finally, it reveals the role of positive market sentiments as the main environmental factor. The second essay uses the Dynamic Capabilities View as a theoretical lens to empirically investigate the impact of blockchain technology usage on a firm’s resilience to supply chain disruptions and operational performance. Witnessing the negative impacts of disruptions such as COVID-19 on supply chain performance, this research addresses this gap. While prior studies present blockchain chain technology as a potential solution a firm can use to enhance resilience, not one study has shed light on how blockchain usage can impact firms' resilience and operational performance. The findings provide empirical evidence of the relationship between blockchain technology usage and supply chain capabilities. Second, it also provides empirical evidence of the indirect relationship between blockchain technology usage and a firm's resilience and operational performance in the face of environmental uncertainty.9 0Item Restricted MODIFIED CORE-LINE TECHNIQUES FOR VORTEX IDENTIFICATION USING LIUTEX(Saudi Digital Library, 2025-05-07) Albalawi, Bassam Zaki; Chaoqun, LiuVortex dynamics govern critical processes in turbulent flows, yet conventional identification methods struggle to resolve individual structures’ morphology and evo- lutionary pathways. Detecting and extracting vortex structures by objective algo- rithms may lead to a better understanding of turbulence regeneration dynamics through the automated and quantitative assessment of the structures. Although there are many vortex-identification criteria available, they pinpoint only the spatial regions belonging to vortices, with no information on the specific identity, topology, and shape of individual vortices. In this dissertation, we develop a new scheme based on Vortex axis tracking by iterative propagation (VATIP), called modified VATIP al- gorithm, for three-dimensional vortex axis-line tracking and analysis in wall-bounded turbulent flows. This new algorithm employs the Liutex magnitude R, a rigorous rotation strength metric, to guide axis-line propagation through three-dimensional velocity fields. This alternative method makes a significant improvement over some of the weaknesses of the original method, thus resulting in a better physical and accurate representation of vortex structures. Moreover, we introduce an advanced version of the predictor-corrector vortex identification method, called the modified PCM. The idea revolves around replacing pressure and vorticity variables by Liutex magnitude R and the real eigenvector ⃗r, respectively. Our approach enables enhanced isolation of the rigid rotational components of the flow field in complex geometries. This methodological advancement allows for more accurate characterization of vortex core dynamics, along with numerically inherent artifacts, which will be proven further in theory and computatio.17 0Item Restricted STOCHASTIC ANALYSIS WITH OPERATIONAL CALCULUS IN RELIABILITY(Saudi Digital Library, 2025-05-05) Aljahani , Hend; Jewgeni DshalalowOur dissertation models several reliability systems subject to occasional random shocks of random magnitudes W1,W2,..occurring at times tau0, tau2,..In Model 1, the underlying system becomes inoperational if it wears out due to aging specified by a monotone increasing continuous function Delta identifying system's wear at any time t>=0 . The system is deemed inoperational if delta crosses a sustainability threshold at some moment T=(delta )^-1(D). The precise time T is difficult to identify making the realistic failure time randomly delayed and thus identified at some opportune observation epoch. The system can also fail due to damages by external shocks, some of which are harmless and some other - critical categorized through their magnitudes relative to a specified threshold H1 . The kth shock is harmless if Wk< =H1and critical if Wk >H1 . It takes a total of N critical shocks to knock the system down. In a nutshell, the system fails if it is worn out assessed at some random observation point or if it is hit by a total of N critical shocks whichever of the two events comes first. In Model 2, we introduce four types of shocks that land at the system: again harmless and critical (as in Model 1) and additionally extreme and delta-shocks. The kth shock is extreme if Wk>H2 where H1 In Model 3, we exclude harmless shocks from those we deemed delta . Namely, a shock can only be delta when it is critical or extreme and when the previous critical shock is not extreme and lags within an interval of delta-length. In this model we had to restructure the stream of shocks by dropping those defined as harmless and study the system on a conditional probability space. In all three models we obtain closed-form joint distributions of the time-to-failure shock count upon failure, delta-shock count, and cumulative damage to the system on failure, among other less significant characteristics. In particular, the reliability function (a quintessential merit in reliability modeling) directly followed from the marginal distribution of the failure time. We treated the systems as generalized random walk processes and use embellished variants of discrete operational calculus. We demonstrate analytical tractability of our formulas through various examples and special cases. The accuracy has also been validated through Monte Carlo simulation.7 0Item Restricted Effect of Brushing on Surface Properties of Subtractively and Additively Manufactured Resin-based Materials for Permanent Restorations.(Journal of Esthetic and Restorative Dentistry, 2025-02-17) Bataweel, Omar O; Delgado, Alex JThis in vitro study evaluates the impact of simulated toothbrushing on the surface roughness, gloss, and color stability of subtractively and additively manufactured resin-based materials intended for permanent dental restorations. Six materials were tested: two CAD/CAM pre-polymerized resin blocks, a ceramic material, a composite resin for direct and indirect use, and a newly FDA-cleared 3D-printed resin material designed for permanent crowns. To simulate clinical conditions, specimens were subjected to a controlled brushing protocol for up to 50,000 cycles, equivalent to approximately five years of brushing. Measurements of surface roughness (Ra), gloss (GU), and color stability (ΔE) were measured at baseline and after 10,000, 30,000, and 50,000 cycles. Surface roughness was assessed with a non-contact optical profilometer, gloss with a glossmeter, and color stability was with a spectrophotometer. Additionally, scanning electron microscopy (SEM) was used to analyze surface morphology post-brushing. The results showed significant differences in surface properties among the tested materials (p < .001). Ceramic materials, particularly the lithium disilicate glass-ceramic blocks, exhibited superior resistance to surface roughness and gloss loss, maintaining high aesthetic properties even after extensive brushing. In contrast, the 3D-printed resin material experienced a notable increase in surface roughness and significant gloss reduction, indicating higher susceptibility to wear. Resin composites varied in their performance, with direct-use resin composites performing worse in terms of gloss retention and color stability compared to their CAD/CAM counterparts. Color stability assessments indicated that ceramic materials remained within clinically acceptable color change thresholds, while resin-based materials generally exceeded these limits, suggesting potential long-term aesthetic challenges. Statistical analysis confirmed these findings, with ceramic materials showing minimal changes across all parameters, while the 3D-printed and direct-use resin materials demonstrated the most significant changes.10 0Item Restricted Towards Legal Reform of the Enforcement of Directors' Duties in the Context of Shareholders' Rights Protection.(Saudi Digital Library, 2025-05-16) Alotaibi, Ayman; STEVEN D ROSEN, ESQUIRECorporate Governance, Directors' Duties, and Shareholders' Rights Protection Legal Landscape of Directors’ Duties in Saudi Arabia Legal Landscape of Directors’ Duties in the USA7 0Item Restricted Exploring Al Balad(Saudi Digital Library, 2025-05-23) alqunfuzi, danah; Mitchell, JacobAl Balad is a well-known destination for Jeddah’s visitors. With its inclusion in UNESCO World Heritage, the site has been transforming to fit the standards and become a more tourist destination. The reason the site is included in UNESCO is due to its diversity and unique architecture and sense of place. Preservation of this type is problematic because it threatens to suppress the dynamics that gave rise to Al Balad, freezing it in time. This thesis asks: How can landscape representation capture agents of change, the present moment, and the past so that the forces that breathe life in historically preserved areas are identified and these sites don’t lose their sense of place?4 0