Date of Award
Spring 2022
Document Type
Thesis
Degree Name
Master of Science (MS)
Department
Dentistry
First Advisor
Berzins, David
Second Advisor
Toth, Jeffrey
Third Advisor
Thompson, Geoffrey
Abstract
Purpose: The purpose of this in vitro study was to determine the edge-chipping toughness and the translucency of lithium silicate-based glass ceramics. Materials and Methods: Four lithium silicate/disilicate glass-ceramic materials, IPS e.max CAD and GC Initial LiSi blocks, and two zirconia-lithium silicate glass-ceramic materials, Vita Suprinity and Celtra Duo, were prepared and tested (n=20 specimens/group). Specimens (14 x 12 x 1.5 mm) were sectioned from commercially available chairside computer-aided design/computer-aided manufacturing (CAD-CAM) blocks, fired (if indicated), ground, and polished. Translucency was assessed via a spectrophotometer for each group. For edge chipping, specimens were adhered to a resin bed created in a customized steel specimen holder. A universal testing machine was utilized with a 120-degree sharp conical indenter, and the specimen's edge was positioned at distances ranging from 0.1 mm to 1 mm horizontally from the indenter tip. Translucency was compared with 1-way ANOVA and the edge toughness was evaluated with ANCOVA. Results: Significant differences in translucency parameter (TP) were found between the materials (p< .001). The statistical ranking of the TP was: GC Initial LiSi-HT>IPS e.max CAD-HT>Celtra Duo>IPS e.max CAD-MT=GC Initial LiSi-LT>Vita Suprinity. For the edge toughness (Te). The materials ranked was IPS e.max CAD HT> IPS e.max CAD MT>GC Initial LiSi HT>GC Initial LiSi LT>Vita Suprinity>Celtra Duo. The edge toughness Te in (N/mm) were 358.7, 281.7, 224.0, 220.7, 203.2, 192.1, respectively. Conclusion: The incorporation of tetragonal zirconia in zirconia-reinforced lithium silicate ceramics did not result in superior edge toughness. Moreover, Vita Suprinity was more opaque than other tested ceramics.
