Evaluation of reproducibility of the chemical solubility of dental ceramics using ISO 6872:2015

Statement of problem The current chemical solubility method in the International Standards Organization (ISO) 6872 (2015) specifies only the total surface area of specimens for testing (≥30 cm2) but does not describe the morphology or geometry. This could impact the reproducibility of the test outcomes. Purpose The purpose of this in vitro study was to investigate the factors influencing the reliability of the ISO 6872:2015 “Dentistry-Ceramic materials” test for chemical solubility. Material and methods Chemical solubility analysis of a range of materials and specimen geometries was performed in accordance with ISO 6872:2015. Yttria-stabilized tetragonal zirconia polycrystal (Y-TZP), VITABLOCS Mark II, IPS e.max Press, and IPS e.max ZirPress materials were formed into a range of cubic and spherical geometries to comply with the 30-cm2 minimum surface area requirement. The surface microstructure of the specimens was analyzed using a scanning electron microscope, inductively coupled plasma optical emission spectrometry (ICP-OES) was used to analyze the solutes, and surface hardness of the specimens was measured by using a Vickers hardness tester before and after testing. An optimized solubility test was devised, which eliminated specimen handling once the specimens had been ground and polished. This modified test was performed on VITABLOCS Mark II and Y-TZP. Results The results of the original chemical solubility method of ISO 6872:2015 showed significantly variable findings for each tested material, with a predictable relationship between geometry and chemical solubility. The hardness values decreased significantly after the solubility testing. The optimized method showed significantly improved reproducibility of the chemical solubility measurement compared with the original ISO 6872:2015 test. Conclusions The results of the current chemical solubility standard method can be manipulated while still complying with the ISO 6872:2015 standard

Incidence of hip fracture in Saudi Arabia and the development of a FRAX model

Summary A prospective hospital-based survey in representative regions of Saudi Arabia determined the incidence of fractures at the hip. The hip fracture rates were used to create a FRAX® model to facilitate fracture risk assessment in Saudi Arabia. Objective This paper describes the incidence of hip fracture in the Kingdom of Saudi Arabia that was used to characterize the current and future burden of hip fracture, to develop a country-specific FRAX® tool for fracture prediction and to compare fracture probabilities with neighbouring countries. Methods During a 2-year (2017/2018) prospective survey in 15 hospitals with a defined catchment population, hip fractures in Saudi citizens were prospectively identified from hospital registers. The number of hip fractures and future burden was determined from national demography. Age- and sex-specific incidence of hip fracture and national mortality rates were incorporated into a FRAX model for Saudi Arabia. Fracture probabilities were compared with those from Kuwait and Abu Dhabi. Results The incidence of hip fracture applied nationally suggested that the estimated number of hip fractures nationwide in persons over the age of 50 years for 2015 was 2,949 and is predicted to increase nearly sevenfold to 20,328 in 2050. Hip fracture rates were comparable with estimates from Abu Dhabi and Kuwait. By contrast, probabilities of a major osteoporotic fracture or hip fracture from the age of 70 years were much lower than those seen in Abu Dhabi and Kuwait due to higher mortality estimates for Saudi Arabia. Conclusion A country-specific FRAX tool for fracture prediction has been developed for Saudi Arabia which is expected to help guide decisions about treatment