Residual strain mapping through pair distribution function analysis of the porcelain veneer within a yttria partially stabilised zirconia dental prosthesis

Abstract

Objectives: Residually strained porcelain is influential in the early onset of failure in Yttria Partially Stabilised Zirconia (YPSZ)porcelain dental prosthesis. In order to improve current understanding it is necessary to increase the spatial resolution of residual strain analysis in these veneers. Methods: Few techniques exist which can resolve residual stress in amorphous materials at the microscale resolution required. For this reason, recent developments in Pair Distribution Function (PDF) analysis of X-ray diffraction data of dental porcelain have been exploited. This approach has facilitated high-resolution (70 µm) quantification of residual strain in a YPSZ-porcelain dental prosthesis. In order to cross-validate this technique, the sequential ring-core focused ion beam and digital image correlation approach was implemented at a step size of 50 µm. This semidestructive technique exploits microscale strain relief to provide quantitative estimates of the near-surface residual strain. Results: The two techniques were found to show highly comparable results. The residual strain within the veneer was found to be primarily tensile, with the highest magnitude stresses located at the YPSZ-porcelain interface where failure is known to originate. Oscillatory tensile and compressive stresses were also found in a direction parallel to the interface, likely to be induced by the multiple layering used during fabrication.

Investigations into the interface failure of yttria partially stabilised zirconia - porcelain dental prostheses through microscale residual stress and phase quantification

“…The variation of residual stress across the entire YPSZ-porcelain interface has been determined using FIST sequential ring core residual stress analysis and is shown in Figure 6a. These results include those presented in Figure 4, as well as those obtained from the re-evaluation of ring-core FIB milling data previously reported by Lunt et al [31,32]. Micro-scale mechanical testing of the YPSZ-porcelain interface has recently been performed to determine the spatial variation of fracture toughness through micropillar splitting [15], as well as the Young's modulus and yield strength from micropillar compression [14] ( Figure 6b).…”

“…The location of the sequential FIB milling was determined by placing the sample in the orientation shown in Figure 1, locating the apex of YPSZ free surface and then shifting the sample 3 mm. During this analysis sequential ring-core milling was also performed over the porcelain veneer, and the results of this analysis have been published elsewhere [31,32]. The parallel FIB milling approach was then implemented at an offset of 75 μm relative to the sequential analysis as shown in Figure 1.…”

“…As previously explained, a line array of sequential ring-core FIB milling markers (micropillars) was performed across both the YPSZ and porcelain veneer layers within this sample. The results of porcelain residual strain quantification in directions parallel and perpendicular to the YPSZ-porcelain interface have previously been published elsewhere [31,32]. However, for the analysis that follows, insight into the full in-plane strain tensor was necessary.…”

Carbon Fibre Lattice Strain Mapping Via Microfocus Synchrotron X-Ray Diffraction of a Reinforced Composite

“…It should be noted that these types of experiments have only recently become viable due to the advancement of two fields. Firstly, significant improvements in SXRD detectors are beginning the reliable quantification of amorphous diffraction patterns for the first time [59]. Secondly, advances in the multi-scale modelling of carbon fibre composites have facilitated the quantification of fibre strains within a composite structure in a rapid and reliable manner.…”

Digital image correlation in dental materials and related research: A review

“…In particular, the accurate measurement of microscale strain in the dentin interface region is crucial because it can be a performance indicator for predicting overall dental condition. Using this approach, residual strain existing at the interfaces between porcelain veneer and zirconia ceramic core can be quantified [73]. Another example of the combined methodology was conducted by an application of digital volume correlation (DVC) to X-ray nano-CT image of elephant tusk [74].…”