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Updated: Jan 15, 2026
Author Spotlight: Establishing an Accurate Microhardness Testing Protocol for Craniofacial Tissues
Published on: April 26, 2024
Terrestrial radiotherapy alters microhardness and surface micromorphology of dental restorative materials: an in
Apoorva Walia1, Laxmish Mallya1, Athiyamaan Ms2
1Department of Conservative Dentistry and Endodontics, Manipal College of Dental Sciences Mangalore, Manipal Academy of Higher Education, Manipal, India.
Background:
Therapeutic radiotherapy, commonly used in the treatment of head and neck cancers, may alter the mechanical and surface properties of restorative dental materials. Understanding these changes is essential for ensuring the long-term success of restorations in oncology patients.
Methods:
An in vitro study was conducted on 90 disc-shaped specimens (n = 30 each) of three restorative materials: 3M™ Filtek™ Bulk Fill, Charisma Topaz One, and Cention N. Samples were subjected to two radiation protocols: (i) 70 Gy in 35 fractions (2 Gy/day), and (ii) 45 Gy in 5 fractions (9 Gy/day). Vickers microhardness testing and scanning electron microscopy (SEM) were performed 48 h post-irradiation.
Results:
Filtek™ Bulk Fill exhibited the highest pre-radiation hardness (83.1 ± 2.3 HV), followed by Charisma Topaz One (74.5 ± 2.8 HV) and Cention N (69.8 ± 2.1 HV). After exposure to 70 Gy, a statistically significant reduction in microhardness was observed across all materials (p < 0.05), with Bulk Fill remaining the least affected (74.3 ± 2.1 HV). SEM images confirmed surface degradation in all groups, with varying degrees of filler particle exposure.
Conclusions:
Ionizing radiation alters both microhardness and surface morphology of restorative materials, with bulk-fill composites demonstrating greater resilience. These findings warrant further investigation in vivo to understand long-term clinical implications.
