Nano-computed tomography: current and future perspectives

The development of novel imaging technologies amplifies the excellence of scientific dental research. Significant technological advances in imaging have been introduced over the years in the field of restorative dentistry and endodontics. X-ray micro-computed tomography (micro-CT) systems were developed in the early 1980s, producing voxels in the range of 5 50 μm. These micro-CT systems offer a reproducible technique for three-dimensional assessment. Because the imaging process is non-destructive, the same samples can be examined many times and continue to be available after scanning for additional biological and mechanical testing. In recent years, micro-CT systems have rapidly gained importance as essential components of many academic and industrial research laboratories, and have been used in examining a wide range of specimens including teeth, bone, and materials. Newer generations of micro-CT systems also enable in vivo imaging of small live animals. In general, classical experimental methods used for studying root canal morphology are destructive and produce irreversible changes to the specimens. Hence, the micro-CT has gained increasing significance in the study of the root and root canal morphology because of its non-invasive nature. Results continue to demonstrate high levels of complexity of the root canal system, and many canals are described as nonclassifiable. This technology has been also advocated for use in evaluating changes in root canal geometry before and after endodontic preparation. The high resolution data obtained by this modern imaging modality accompanied by the ability to accurately match and compare the same preand post-instrumentation slices yields a valid approach for accurate assessment. Other applications included the evaluation of root canal filling quality and the efficacy of the file systems to remove filling materials in instances of retreatment. Ultra-high spatial resolution ‘nano-CT’ devices have become available as a result of the continuous technological advancements in the development of CT systems. NanoCT systems, which generally use a nano-focal spot source (< 400 nm), have been employed to analyze cartilage and bone tissues, material quality, and imaging of vascular networks. The nano-CT system allows clear visualization of structures on the level of cells as well as internal ultrastructure of bone trabeculae and submicron hard tissue cracks. This is attributed to the advanced technical characteristics of the nano-CT system owing to the excellent contrast resolution of the flat-panel detector. In addition, the device is equipped with a granite base and precise rotation unit, which makes it very stable during the data acquisition process. The ability to obtain faster scans is another advantage compared to micro-CT. In dental research, high-resolution nano-CT systems have also been found to be ISSN 2234-7658 (print) / ISSN 2234-7666 (online) http://dx.doi.org/10.5395/rde.2016.41.3.236 Letter to editor