SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
Browse
2 results
Search Results
Item Restricted Effect of Degradation on Long-term Stability of 3D-printed Dental Crowns(Saudi Digital Library, 2025-07-04) Tayeb, Hunaida Khaled; Silikas, Nick3D printing technology in digital dentistry has led to innovative approaches for fabricating indirect dental restorations. However, a comprehensive assessment of the properties and long-term performance of these materials is essential. Therefore, this thesis aimed to evaluate the durability of mechanical, optical and surface properties of novel 3D-printed ceramic-filled resin composite materials indicated for definitive crown restorations. The first experimental chapter assessed the mechanical properties (flexural strength, flexural modulus, Martens hardness, indentation modulus and Vickers hardness) of three 3D-printed resin composites (Permanent Crown Resin, VarseoSmile Crown Plus, and Crowntec) and three milled resin composite blocks (BRILLIANT Crios, SHOFU Block HC and Grandio Blocs). The findings revealed that the 3D-printed definitive resin composites showed clinically acceptable mechanical properties, however, the milled resin composites showed significantly superior mechanical properties. The second experimental chapter explored the impact of immersion in food-simulating solvents on flexural strength, flexural modulus, Martens hardness, and indentation modulus of the same three 3D-printed resin composites and milled Grandio Blocs. Results indicated that exposure to solvents adversely affected the mechanical properties of all materials. Nevertheless, all tested materials showed acceptable mechanical properties after ageing. The third experimental chapter investigated the influence of artificial toothbrushing on surface roughness and gloss of the 3D-printed resin composites and the milled Grandio Blocs. Following 20,000 brushing cycles, both 3D-printed and milled resin composites exhibited increased surface roughness and reduced gloss, with 3D-printed materials exhibited comparatively lower wear resistance. Despite these changes, all tested materials maintained clinically acceptable gloss and roughness levels. The last experimental chapter examined the effects of immersion in various beverages on the colour stability (ΔE00), translucency, gloss and Martens hardness of the 3D-printed resin composites and milled Grandio Blocs. The results highlighted that both material type and beverage had a significant influence on the investigated properties, though ΔE00 of all materials remained within the clinically acceptable threshold of colour change across all beverages and measurement points.48 0Item Restricted Understanding the Structural and the Mechanical Properties of Bone(Saudi Digital Library, 2023-12-12) Almoshawah, Yasser Ali H; Rehman, Ihtesham Ur; Dall’Ara, EnricoOsteoarthritis (OA) is one of the most common chronic diseases characterised by a disorder in the subchondral bone (SB), cartilage damage, and osteophyte formation. Due to an inadequate understanding of the mechanism of disease pathology, no treatment is currently available to effectively prevent the initiation or progression of OA, and severe treatment modalities, such as hip joint replacement, are currently available. A better understanding of the chemical and mechanical properties of bone will also help improve OA’s diagnosis. This study aims to investigate the chemical properties of SB from the femoral head (FH) of patients with OA through an invasive and label-free approach. Vibrational spectroscopy has shown the potential to provide diagnostic information. A combination of Raman, Fourier-Transform Infrared (FTIR) spectroscopic, and Photoacoustic Fourier Transform Infrared Spectroscopy (FTIR-PAS) methods were used for the chemical analysis of samples. Principal Component Analysis (PCA) was used to identify variations within different tissue of OA bone. Linear Discriminant Analysis (LDA) was used to predict pathogenic markers with high sensitivity (Sn) and specificity (Sp). The combination of Infrared and Raman spectroscopy with chemometrics were very helpful in identifying new spectral markers to differentiate OA bone samples. Initially, preliminary studies were conducted on bovine bones, which are almost comparable to human bones. They were applied on Raman and FTIR to study the chemical composition concerning the different cutting directions to prevent mistakes and enhance the primary study. For Raman, the PCA bovine result showed a perfect clustering, with PC-1 and PC-2 accounting for 92% of the variation, resulting in excellent Sn and Sp of 100%. The results for FTIR also exhibited perfect clustering, with PC-1 and PC-4 accounting for 80% of the variance, resulting in 100% Sn and Sp. Raman, FTIR and FTIR-PAS have identified structural and compositional changes in OA compared to tissue-specific (subregion). Significant statistical differences were detected among the bone types, including organic and inorganic composites. The results of the PCA in all vibrational spectroscopy showed that the PCA had good clustering, accounting for 74, 75, and 86% of the variation for Raman, FTIR and FTIR-PAS, respectively, leading to excellent Sn and Sp of 100%, representing the whole spectrum. Furthermore, as the aetiology and pathogenesis of OA are not fully understood, measuring the mechanical properties of bone by applying nanoindentation to FH to extract the mechanical properties is essential in order to understand the disease profile. The mechanical results show that the reduced modulus (𝐸𝑟) and the hardness (H) averaged out to be (16.07±3.05 GPa) and (0.56±0.107 GPa), respectively. The average elastic modulus (𝐸𝑏) of bone was measured to be (14.84±2.85 GPa), whereas the indentation modulus (E_ind) was (16.31±3.14 GPa). Compared to the other bone types, the osteophyte (Osteo) bone has the lowest value, while the cortical bone (Cort) has the highest value. The parameters in RS and FTIR confirm that increasing mineralisation ratios in bone types were correlated with a decreased 𝐸𝑏 and vice versa. In conclusion, vibrational spectroscopy is a highly effective method for identifying chemical changes associated with different subtypes of bone tissue disease. This study confirms its significance in evaluating both chemical and mechanical changes in cases of severe OA affecting the human FH helping to understand the reasons for the disease process and enable an improved treatment modality. Furthermore, these findings will assist the research community in identifying regions of the skeleton where the local physical and chemical properties of bone, in addition to the mechanical properties, should be characterised during the preclinical optimisation process of treatments for skeletal diseases.31 0