Microstructural investigation of hybrid CAD/CAM restorative dental materials by micro-CT and SEM

Dent Mater. 2024 Jun;40(6):930-940. doi: 10.1016/j.dental.2024.04.006. Epub 2024 May 9.

Abstract

Objectives: An increasing number of CAD/CAM (computer-aided design/computer-aided manufacturing) hybrid materials have been introduced to the dental market in recent years. In addition, CAD/CAM hybrid materials for additive manufacturing (AM) are becoming more attractive in digital dentistry. Studies on material microstructures using micro-computed tomography (µ-CT) combined with scanning electron microscopy (SEM) have only been available to a limited extent so far.

Methods: One CAD/CAM three-dimensional- (3D-) printable hybrid material (VarseoSmile Crown plus) and two CAD/CAM millable hybrid materials (Vita Enamic; Voco Grandio), as well as one direct composite material (Ceram.x duo), were included in the present study. Cylindrical samples with a diameter of 2 mm were produced from each material and investigated by means of synchrotron radiation µ-CT at a voxel size of 0.65 µm. Different samples from the same materials, obtained by cutting and polishing, were investigated by SEM.

Results: The 3D-printed hybrid material showed some agglomerations and a more irregular distribution of fillers, as well as a visible layered macrostructure and a few spherical pores due to the printing process. The CAD/CAM millable hybrid materials revealed a more homogenous distribution of ceramic particles. The direct composite material showed multiple air bubbles and microstructural irregularities based on manual processing.

Significance: The µ-CT and SEM analysis of the materials revealed different microstructures even though they belong to the same class of materials. It could be shown that µ-CT and SEM imaging are valuable tools to understand microstructure and related mechanical properties of materials.

Keywords: 3D printing; Additive manufacturing; CAD/CAM; Hybrid materials; Microtomography; SEM; Subtractive manufacturing; µ-CT.

MeSH terms

  • Ceramics / chemistry
  • Composite Resins / chemistry
  • Computer-Aided Design*
  • Dental Materials* / chemistry
  • Materials Testing*
  • Microscopy, Electron, Scanning*
  • Printing, Three-Dimensional
  • Surface Properties*
  • X-Ray Microtomography*

Substances

  • Dental Materials
  • VITA Enamic
  • Composite Resins