## 4 Discussion
Histomorphometry is considered the gold standard of bone quality assessment [12; 30; 62]. The examiner calculates the percentage of newly formed bone, bone marrow, and residual graft material from representative sections, which are widely accepted as short-term outcome measures for the integration of biomaterials in the augmented area. However, histomorphometry only allows for assessment in two dimensions, which is considered a significant limitation [22]. The results of histological measurements depend on the slice thickness and cutting direction of the histological sections [23; 24; 29]. Three-dimensional analysis of trabecular bone microarchitecture is important for the comprehensive assessment of bone quality. Serial sectioning, digitization of the sections, segmentation of the tissue types identified within the biopsy sample, and three-dimensional reconstruction of the sections enable analysis of trabecular microarchitecture. Convolutional neural networks enable quick and reliable classification of different tissue types on histological sections and assist three-dimensional reconstruction of serial sections [33; 41]. However, artifacts may cause bias in such a three-dimensional reconstruction [43]. Therefore, validation of the method presented is necessary with a modality that enables direct analysis of trabecular microarchitecture. MicroCT enables direct assessment of the three-dimensional trabecular structure in high resolution based on the radiodensity of the different tissues found in the biopsy samples. It is non-destructive and allows for further processing of the bone core biopsy sample for histology or biomechanical assays. A lack of information on tissues and cellularity is a limitation of microCT analysis [10; 12; 28]. Nevertheless, microarchitectural analysis of three-dimensional reconstructions of serial sections may combine the advantages of histomorphometric and microCT analysis, providing micromorphometric data as well as information on tissues and cellularity. Such a three-dimensional histological reconstruction can be used in clinical and preclinical biomaterial research for the postoperative evaluation of augmented bone. For the clinician, a comprehensive microarchitectural and histological assessment of implant recipient bone following dental implant placement may identify potential causes of implant failure. Because of the time-consuming demineralization, serial sectioning, and staining involved, the three-dimensional histological reconstruction method described in our study is not applicable as an intraoperative method to assess bone quality. Therefore, it may be used primarily in research. Another limitation of the method is its destructive nature, which precludes further testing of the biopsy specimen. A further limitation of the present study is that it was carried out in a single biopsy specimen and only three tissues (newly formed bone, residual graft material, and non-mineralized tissues) were differentiated within the histological sections. Further studies conducted with the three-dimensional histological reconstruction method described in our study to assess vascular structures and bone remodeling markers may be of interest. Another avenue of research may be the feasibility of the novel method of three-dimensional histological reconstruction in the assessment of soft tissues.