Yeon-Gil G. Jung, S Wuttiphan, I M. Peterson, Brian R. Lawn
A study is made of crack patterns in two model coating/substrate bilayer systems conceived to simulate crown and tooth structures, at opposite extremes of elastic/plastic mismatch: porcelain on glass-infiltrated alumina (soft/hard); and glass-ceramic on composite resin (hard/soft). Hertzian contacts are used to investigate the evolution of fracture damage in the coating layers, as functions of contact load and coating thickness. The crack patterns differ radically in the two bilayer systems: in the porcelain coatings, cone cracks initiate at the coating top surface; in the glass-ceramic coatings, cone cracks again initiate at the top surface, but additional, upward extending transverse cracks initiate at the internal coating/substrate interface, with the latter dominant. The substrate is thereby shown to have a profound influence on the damage evolution to ultimate failure in the bilayer systems. However, the cracks are highly stabilized in both systems, with wide ranges between the loads to initiate first cracking and to cause final failure, implying damage-tolerant structures. Finite element modeling is used to evaluate the tensile stresses responsible for the different crack types. The clinical relevance of these observations is considered.
, Wuttiphan, S.
, Peterson, I.
and Lawn, B.
Damage Modes in Dental Layer Structures, Journal of Dental Research, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=850004
(Accessed December 3, 2023)