# SEM and FT-MIR Analysis of Human Demineralized Dentin Matrix: An In Vitro Study
## 4 Discussion  
An ideal bone graft should be biocompatible, biomechanically stable, capable of degrading over a certain time, and exhibit osteoconductive, osteogenic, and osteoconductive properties [22]. Although the gold standard is exemplified by autologous bone, the limited amount of bone available, the morbidity of the donor site, and the high rate of resorption affect its use. Therefore, alternative materials for autologous bone grafts are required. In recent years, it has been proposed that DDM be used as a potential bone graft. In Japan and Korea, this type of graft is widely used, as demonstrated by the number of  
Figure 7: The acquired SEM images of the specimens T0, T2, T5, T10, T60 at different magnifications: 400\(\times\), 2000\(\times\), and 8000\(\times\). scientific works published in the literature by scientific authors [23]. It has been shown that the preparation process, the size, and shape of the dentin particles seem to influence their osteoinductive and osteoconductive properties [17]. In summary, the concentration of the phosphate group (inorganic component of dentin, corresponding to the spectral peak at 1021 cm\({}^{-1}\)) and the carbonate group (inorganic component of dentin, corresponding to the spectral peak at 872 cm\({}^{-1}\)) decreased with increasing time of demineralization (T0 \(>\) T2 \(>\) T5 \(>\) T10 \(>\) T60). In addition, with increasing demineralization time, the number of exposed dental tubules in the same surface area increased, and the particles become more homogeneous and smoother. In the present study, the enamel and the cement were removed from the extracted teeth. In fact, the hydroxyapatite in the enamel is structured as highly crystalline calcium phosphate, while the dentin contains hydroxyapatite in low crystalline calcium phosphate form. In the first case, the high crystalline content is not easy to decompose by osteoclasts. Consequently, the resorption rate is slow, and the material's osteoconductivity is reduced. On the contrary, hydroxyapatite in dentin has a low crystalline structure, and this makes its resorption easier [11]. Bone tissues also contain low crystalline apatite. Recently, [PERSON] et al. [24] performed a randomized clinical trial comparing autologous whole tooth grafts and the autologous demineralized dentin grafts. The histological results showed a higher amount of newly formed bone and a smaller number of remnant grafts in the autologous demineralized dentin grafts group. The authors hypothesized that in the autologous demineralized dentin grafts group, the lower mineral content made particle degradation faster than that in the autologous whole tooth grafts group, and this allowed the release of growth factors earlier. Regarding the size of the particles, a clear consensus has not yet been reached on which precise size is most suitable for bone grafts. [PERSON] et al. [25] stated that the particle size of bone grafts should be between 100 \(\upmu\)m and 300 \(\upmu\)m. [PERSON] et al. [26] conducted an in vivo study testing the new bone formation capabilities of DDM grafts with different densities and particle sizes. The histomorphometric analysis demonstrated the superiority of the specimens with grafting particles sized between 250 \(\upmu\)m and 1000 \(\upmu\)m and spaces of 200 \(\upmu\)m between the particles compared to the results obtained with grafts with larger particles (1000-2000 \(\upmu\)m). [PERSON] et al. [12] reported better results in terms of new bone formation with particle sizes between 1200 \(\upmu\)m and 800 \(\upmu\)m compared to those obtained with smaller particle sizes. The authors also observed that the smaller particles underwent faster resorption than the larger ones. Therefore, it was suggested that the larger-sized particles (1200-800 \(\upmu\)m) offer a greater surface area than those of smaller sizes (180-212 \(\upmu\)m and 425-600 \(\upmu\)m) for the adhesion of osteoporgenitor cells and osteoblasts.