Welding between two or more pieces of metal is a widely used practice in various fields of medicine such as dentistry which also makes use of the support of dental laboratories where complex welding procedures are applied. The welding techniques available today are many and also very different from each other; they often require very different background knowledge, just as the results obtained may differ. Welds can be made at various stages of making a product that will be used on the patient; for example some welds are made directly by the manufacturer during the industrial processing phase. We then move on to the more common welding techniques carried out in dental laboratories and finally we also arrive at the intraoral welding carried out by the clinician inside the patient's oral cavity. This enormous variety of conditions in which those who practice welding can find themselves presupposes the application of the most appropriate technique; this review looks at the different methods and fields of application.

Aseptic implant loosening after total joint replacement is partially influenced by material-specific factors when cobalt-chromium alloys are used, including osteolysis induced by wear- and corrosion products, and stress shielding. Here, we aim to characterize a hybrid material consisting of alumina-toughened zirconia ceramics (ATZ) and additively manufactured Ti-35Nb-6Ta (TiNbTa), joined by a glass solder. The structure of the joint, static and fatigue shear strength, the influence of accelerated aging, and the cytotoxicity using an elution assay with human osteoblasts is characterized. Furthermore, the biomechanical properties of functional demonstrators of a femoral component for total knee replacements are evaluated. TiNbTa-ATZ specimens showed a homogenous joint with statistical distributed micro-pores and a slight accumulation of Al-rich compounds at the glass solder-TiNbTa interface. The static shear strength was 26.4 ± 4.2 MPa (Ti-ATZ reference: 38.2 ± 14.4 MPa, p = 0.117), all specimens survived 107 cycles of shear loading to 10 MPa, and aging did not reduce the strength. TiNbTa-ATZ did not impair the proliferation and metabolic activity of human osteoblasts. Functional demonstrators of TiNbTa-ATZ provided a maximum bearable extension-flexion moment of 40.7 ± 2.2 Nm. Biomechanical and biological properties of TiNbTa-ATZ demonstrate potential application for endoprosthetic implants.