Three-dimensional characterization and distribution of fabrication defects in bilayered lithium disilicate glass-ceramic molar crowns

The effect of adhesive failure and defects on the stress distribution in all-ceramic crowns

“…A previous study using micro-CT analysis showed that multiple pores ranging from 50 μm to 300 μm existed within the veneer and core of all-ceramic crowns [47]. Furthermore, Jian et al [17] reported that the pores located at or next to the veneer-core interface in bilayered lithium disilicate glass-ceramics have diameters ranging from roughly 440 μm to 1180 μm. In the present study, only pores (intrinsic or introduced by acid etching or airborne alumina particle air abrasion) located at the interface between the crown and cement were considered.…”

“…In the present study, only pores (intrinsic or introduced by acid etching or airborne alumina particle air abrasion) located at the interface between the crown and cement were considered. A defect pattern at the bonded interface was designed based on the literature [17,47] (Fig. 2(h) and 2(i)).…”

“…During the processes of manufacturing the restorations, several factors have been identified that may contribute to all-ceramic crown failures including [17]: (i) defects [18], (ii) residual stresses [19], and (iii) thermal residual stresses [20]. However, defects have been suggested to be the leading cause of failure [21].…”

“…However, defects have been suggested to be the leading cause of failure [21]. Defects such as pores, inclusion and small cracks may cause stress concentration and become the site of subcritical crack growth [17].…”

“…Meanwhile, the fabrication of glass-ceramics may introduce processing defects, and crown failures are influenced by the size and location of such defects [22,23]. Thus, it is worthwhile to explore the relationship between defects and the risk of crown failures [17].…”