A Technique for Evaluating Dental Adhesives
A method is proposed for evaluating the strength of an adhesive joint. It is basically a fracture mechanics approach which recognizes that the strength of a joint depends on adhesive thickness, elastic properties of adhesive and teeth, joint geometry, sizes of flaws, and other factors. The "blister" technique is proposed as a useful means of quantitatively determining the quality of an adhesive joint.
Fracture Studies of Adhesion
Controlled fracture techniques were successfully applied to the study of adhesion. A new parameter, interfacial work of fracture (Wi), was defined and measured for porcelain-gold specimens and for enamel-composite specimens. Wi measurements coupled with factographs indicated that a "highly etched" enamel surface may not give the strongest bond.
Fracture surface of polystyrene: Mackerel pattern
Characteristic markings of concentric bands are formed on the fracture surface of tensile specimens under certain loading conditions. The marking form in the fast crack growth region of the mirror area of fracture. Optical and electron optical microscope techniques have been used to study the morphology of the markings. It is shown that in this region the crack propagates along the interface between the craze, in which the crack nucleated, and the bulk material. The mackerel pattern is caused by the crack jumping from one craze–matrix interface to the other.