# Ten Years of Micro-CT in Density and Maxillofacial Surgery: A Literature Overview
## 4 Micro-CT Analysis Combined with Other Techniques or Technologies  
In the last years, the microtomographic investigation has been often combined with other techniques and technologies, for example, it is applied as a preliminary step before destructive testing, to obtain data and models to be used for volumetric measurements in reverse engineering [65], computational and numerical applications. The analysis of the selected records allows detecting some studies, in which a multimethod approach was considered, incrementing the investigation power of micro-CT and its potential applications. Figure 2 summarizes the techniques and technologies that emerged in studies about combined and integrated applications with micro-CT.  
Firstly, it should be noted that micro-CT is not the only one tomography system applied in dentistry and MFS. As previously evidenced, some MFS devices and anatomical districts required to be acquired with systems allowing the scansion of objects with larger dimensions. Moreover, in clinical labs, some technologies are more common and routinely used. The cone beam volume CT or CBCT is another kind of tomography system, X-ray based, commonly employed to assess the quality and quantity of bone. Despite that, micro-CT is combined with it due to the higher accuracy for small dimensions, for example, to obtain gold standard measurements of graft volumes in maxillary sinus augmentation procedure [124] or to determine how microarchitecture influences the morphology [125]. In recent years, the power of the available commercial systems is continuously growing in terms of range of dimensions and resolutions. Figure 2: Main techniques and technologies applied with the micro-computed tomography (micro-CT) in the collected studies. Table 1 reports, as an example, the datasheets of the laboratory micro-CT and CBCT systems considered in the previous cited study [124] and of recent frequently used micro-CT models [67, 93, 99], also for larger object sizes [95], allowing the comparison of the technical specifications. Another volumetric imaging technology is the positron emission tomography (PET). It is a different technology, even if it is a tomography as well, which uses small amounts of radiotracers or radiopharmaceuticals to evaluate organ and tissue functions. It was applied with micro-CT to investigate bone regeneration induced by scaffolds [62]. The importance to establish standard protocols for marginal and internal fit assessment of fixed prosthesis was investigated considering the association of micro-CT with various other imaging techniques. The optical coherence tomography (OCT), the triple scan and cross-sectional method are some of the techniques combined with microtomographic data to measure the marginal and internal fit by superimposing the 3D scan data of the prosthesis and the abutment tooth [126]. Modified commercially available spectral domain OCT measurements were also compared with micro-CT for assessing the abrasion of the orthodontic surface sealants [127]. Traditional methods applied in tissue engineering studies are based on techniques such as histology, scanning electron, and fluorescence microscopy imaging [32]. Microscopy technologies required to be mentioned, as they are usually associated with micro-CT in various applications. Microstructural investigations made by both optical and scanning electron microscopy (SEM) are recorded in studies using transmission electron microscopy (TEM) to analyze adhesive/root dentin interface [71] and SEM for the quality assessment of composite fillings [70], porosity and size of silk scaffold [108], alginate samples with stem cells [109], and bone substitutes characterization in MFS [111]. SEM analysis with micro-CT was performed to characterize barrier membrane for bone augmentation in dentistry [128] and to study alloy composition of the metallic fixing lamina and microstructure of the deposits on the dental surface [94].