# Ten Years of Micro-CT in Density and Maxillofacial Surgery: A Literature Overview
## 4 Micro-CT Analysis Combined with Other Techniques or Technologies
[PERSON] et al. presented an integrated approach applying intra-oral scanner, CBCT, micro-CT, 3D printing, and stereomicroscopy for temporary restoration of auto-transplanted teeth [67]. Micro-CT represents also a methodology for automatic segmentations [130,131] and elaborations of accurate 3D models [132], even if some limitations in spatial resolutions and missing information have to be considered [133,134]. The possibility to create 3D micro-CT models based on reconstructed images has relevance in implementing numerical studies aimed to determine the more realistic operative conditions. CAD models can be easily elaborated, and after imported for post evaluations by other techniques. It allows obtaining information of the structure of the materials usable as input in computational studies, such as finite element analysis (FEA), simulating realistic different conditions. FEA, a well-known computational numerical method was applied in dentistry and supported by microtomographic analysis to assess new models [135] or based on micro-CT reconstructed models and 3D images [136; 131]. The main objectives detected of the numerical simulations implemented in literature are related to the evaluation of mechanical properties, the prediction of forces necessary to drill the cortical and trabecular bone [137], the biomechanical properties of the periodontal ligament [138], and the stress distribution in premolar under various occlusal loadings scenarios [139] or in root dentin [140]. Numerical analyses can be associated with the traditional destructive techniques for the mechanical characterization of structures and for the validation of the simulated data. Experimental mechanical testing techniques, performed respecting international standards or experimental protocols, continue to contribute and to corroborate with microtomographic, histomorphometric, and numerical data [91,116]. Finally, even if the information was collected in a record that is a review study not focused on micro-CT and, as it was not discussed previously [141], it is covered in this section for underlining the role of micro-CT in relation to the numerical method fractal analysis (FA). The FA is a mathematical method by which irregular, complex, and similar forms on various scales can be evaluated. The fractal dimension (FD) is the quantitative outcome [141]. In dentistry, the FA was employed in several studies. [PERSON] et al., in their recent work about the use of FA in dental images, showed that FD was used on micro-CT images of porous titanium granules, bone graft materials, to assess the bone mineral density and, it was observed positive and negative correlations of FD values and other parameters such as histomorphometric analysis and radiographic bone density. Furthermore, they evidenced that few studies using this exam were carried out despite the high quality of micro-CT images and the importance of this aspect for a high-quality FA. The main causes are correlated to the high cost and the necessity of a bone sample that seems to preclude the use of micro-CT with FA. The power of the previously identified new role of the micro-CT in reference to the other technologies is particularly evident, not only in supporting clinical practice for acquiring the best evidence but also, for the regulatory purposes that are essential for medical applications. As already recognized for AM in a recent guideline [16], the micro-CT could represent a useful tool for the quality control of products and workflow. This last aspect has relevance for companies, but particularly for clinicians that often become themselves manufacturers in routine use of manufacturing techniques for custom applications in lab environments. The variability of the processes often requires keeping more parameters under control.