SACM - United Kingdom
Permanent URI for this collectionhttps://drepo.sdl.edu.sa/handle/20.500.14154/9667
Browse
2 results
Search Results
Item Restricted Mechanical Properties of Custom-Made Post and Core Made of CAD/CAM Dental Ceramics(Queen Mary University of London, 2025) Almadi, Hussam; Karpukhina, Natalia; Cattell, Mike; Hill, Robert; Rashwan, MaherObjective: This study aimed to evaluate and compare the fracture resistance, failure modes, surface morphology, and crystallographic properties of three CAD/CAM fabricated post and core materials zirconia, resin nano ceramic, and experimental barium-based mica glass ceramic against a 3D-printed resin post and core used as a control. Materials and Methods: Sixty custom-designed post and core specimens (n = 15 per group) were fabricated and cemented into standardised resin tooth analogues. Four groups were tested: Group one - zirconia posts (CAD/CAM milled), Group two - resin nano ceramic posts (CAD/CAM milled), Group three - glass mica ceramic posts (CAD/CAM milled), and Group four - 3D-printed resin posts (control). All samples underwent static compressive loading until failure. Fracture resistance values were recorded and analysed using one-way ANOVA with post hoc Holm-Sidak comparisons (α = 0.05; power = 1.000). Failure modes were categorised under stereomicroscopy. Scanning electron microscopy (SEM) was performed to assess surface morphology and fracture patterns, and X-ray diffraction (XRD) was used to characterise the crystallographic structure of each material. Results: Zirconia exhibited the highest mean fracture resistance (1031.48 ± 150.40 N), but failed in a catastrophic, non-restorable manner. Resin nano ceramic (344.31 ± 71.21 N) and barium-based mica glass ceramic (377.29 ± 82.42 N) showed moderate strength and favourable, restorable failure modes, with SEM indicating energy dissipation through microcracking and crack deflection. The 3D-printed resin group showed the lowest fracture resistance (222.81 ± 10.87 N). SEM revealed distinct microstructural features for each material, while XRD confirmed the presence of densely packed polycrystalline zirconia and lamellar mica crystallites in the novel ceramic group. Conclusion: Material selection for post and core restorations should be based not only on fracture resistance but also on failure mode, microstructural behaviour, and retrievability. While zirconia offers superior strength, resin nano ceramic and the experimental mica-based ceramic demonstrate more favourable and restorable failure characteristics. Further research is recommended to investigate long-term fatigue resistance, modulus of elasticity via flexural testing, and performance in simulated clinical environments.10 0Item Restricted Key Physico-Mechanical Properties of Zirconia-reinforced Lithium Silicate Glass-ceramics(The University of Manchester, 2024) Al-Johani, Hanan; Nikolaos, Silikas; Satterthwaite, JulianSince lithium-silicate glass-ceramics (LSCs) were introduced to dentistry, their formulations have been modified significantly to meet the multifaceted aesthetic and mechanical requirements of dental restorations. Therefore, the focus of this thesis was to investigate various spectrophotometric, topographic, and mechanical aspects of novel zirconia-reinforced lithium silicate glass-ceramics (ZLSs) as a function of different intaglio and external surface treatments. The first part of this research applied intaglio treatments of acid etching and/or acid neutralising combinations to CAD/CAM LSCs (e.max CAD, VITA Suprinity, Celtra Duo and CEREC Tessera). Ceramic-related properties (light transmission, absorbance, roughness, wettability, and flexural strength) and light curing unit-related properties (transmitted irradiance, power, and radiant exposure) were assessed. Post-etching neutralisation did not detrimentally alter the micro-retentive intaglio features, and, neutralised LSCs demonstrated relatively adequate aesthetic and mechanical stability. The second part of this thesis assessed external treatments of varying firing/glazing protocols applied to fully crystallised CAD/CAM LSCs (Initial LiSi Block, Celtra Duo and CEREC Tessera). Thereafter, light transmission, roughness, gloss, hardness, flexural strength and crystalline phases were evaluated. Overall, single and duplicate firing treatments yielded favourable strength results, whereas glazing led to the strength deterioration of fully crystallised LSCs. The third part analysed the stain susceptibility and topography of pressable and machinable ZLSs (VITA AMBRIA, Celtra Press, VITA Suprinity, and Celtra Duo). Stain susceptibility of ZLSs concluded to be dependent on their fabrication methods as well as translucency and thickness levels.14 0