In vitro Investigation of Mechanical Properties of Latest-Generation CAD-CAM Composites

This thesis conducted different in vitro investigations aimed at addressing
two critical issues in Computer-Aided Design/Computer-Aided Manufacturing
(CAD-CAM) materials for dental prostheses: fractures and debonding from
titanium implant abutment (Ti-base). Specifically, the work focused on
evaluating the mechanical performance of latest generation CAD-CAM
composites compared to established lithium-based glass-ceramic material.
Fatigue behavior was analyzed to provide a clinically relevant insight.
Interfacial fracture toughness approach was used to examine debonding
issue, comparing different CAD-CAM ceramic and composite materials.
Additionally, as flexural strength is the most common approach for analyzing
the properties of dental materials, this work also conducted a series of
analyses to determine the optimal statistical analysis of the flexural strength
data, and to provide deep insight into related intra-block inhomogeneity
and inter-block heterogeneity.
Despite latest generation dispersed-filler CAD-CAM composites having
shorter lifetimes than lithium-based glass-ceramic, they show similar
resistance to fatigue degradation. Time-dependent factors seem to
significantly influence composites fatigue at lower stress levels. Thus,
extended fatigue testing in water, despite being time-consuming and costly,
is essential for understanding material behavior under clinical conditions.
Moreover, this thesis reveals that the CAD-CAM composites differ from each
other; their microstructure and chemical composition substantially affect
their mechanical properties and the interface with Ti-base. Particularly,
novel microstructures, such as polymer-infiltrated ceramic networks (PICN),
exhibited a superior interface with Ti-base than dispersed filler composites.