The main problem with ceramics as biomaterials is that they are brittle. One focus of research and development has been on improving the materials’ fracture strength and thereby increasing the clinical success rates for dental, all-ceramic restorations. The most advanced dental ceramics should, according to in vitro testing, be able to withstand human mastication forces. Still, fractures occur more often than we like. Comparison of clinical observations and in vitro trials seeks to explain how and why these fractures occur. Fractographic analysis is a methodology used to investigate un expected failures. Fractures in a brittle material leave tell-tale features on the fracture surfaces that can reveal both the origin of the fracture and the direction of crack propagation through the structure. Until very recently, fractography has only been applied to dental ceramics to a very limited extent. The method has revealed that fractures which occur in vivo usually start in the cervical margin, while fractures that have been produced in vitro usually start occlusally. This explains the discrepancy between fracture load in vitro and clinical fracture rates. Through simulation in vitro of clinical fracture behavior, we gain an understanding that suggests different strategies for tooth preparation and crown design.

Frakturer i keramer: Forskning og klinisk erfaring
Øilo M, Kvam K, Tibballs JE.
Aktuel Nordisk Odontologi 2014; Munksgaard Forlag 2014; 103-115