## 3 Results
### Quality Assessment  
Of the selected papers, all passed the quality assessment as at least reliable with restrictions and presented a good study design (Table 2). The main reasons for the lower scores in the quality assessment of the studies using the ToxRTool were due to the lack of identification of the cell origin, cell passage number, or handling methods. In vivo studies did not mention animal care practices or discussed the origin of animals but not the housing or feeding conditions. Some studies lacked either positive or negative controls. Many studies also did not report the number of replicates and provided little information on statistical tests. Furthermore, 31 articles (59.6%) presented results regarding the amount of strontium released by the biomaterial (Table 3), information that is of great importance for the adequate analysis of the results. Figure 1: Systematic steps according to PRISMA Statement. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Publication** & **Publication** & **Publication** & **Publication** & **Publication** & **Publication** & **Publication** \\ \hline
**In Vitro Studies** & **4** & **3** & **6** & **3** & **2** & **18** \\ \hline [PERSON] et al. [11] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [12] & 4 & 2 & 4 & 3 & 2 & 15 \\ [PERSON] et al. [13] & 4 & 4 & 6 & 3 & 2 & 19 \\ [PERSON] et al. [14] & 4 & 3 & 5 & 3 & 2 & 17 \\ [PERSON] et al. [15] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [16] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [17] & 4 & 2 & 5 & 3 & 2 & 17 \\ [PERSON] a et al. [18] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [19] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [20] & 4 & 2 & 4 & 3 & 2 & 15 \\ [PERSON] et al. [21] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [22] & 4 & 1 & 5 & 3 & 2 & 15 \\ [PERSON] et al. [6] & 4 & 3 & 6 & 3 & 2 & 18 \\ [PERSON] et al. [23] & 4 & 3 & 6 & 3 & 2 & 18 \\ [PERSON] et al. [24] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [25] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [26] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [27] & 4 & 1 & 5 & 3 & 2 & 15 \\ [PERSON] et al. [28] & 4 & 3 & 6 & 3 & 2 & 18 \\ [PERSON] et al. [29] & 4 & 3 & 6 & 3 & 2 & 18 \\ [PERSON] et al. [30] & 4 & 2 & 4 & 3 & 2 & 15 \\ [PERSON] et al. [31] & 4 & 3 & 5 & 3 & 2 & 17 \\ [PERSON] et al. [32] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [33] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [34] & 4 & 1 & 3 & 2 & 2 & 12 \\ [PERSON] et al. [35] & 4 & 3 & 5 & 3 & 2 & 17 \\ [PERSON] et al. [36] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [37] & 4 & 3 & 6 & 3 & 2 & 18 \\ [PERSON] et al. [38] & 4 & 3 & 5 & 2 & 2 & 16 \\ [PERSON] et al. [39] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [40] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [41] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [42] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [43] & 4 & 2 & 5 & 2 & 2 & 15 \\ [PERSON] et al. [44] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [45] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [46] & 4 & 2 & 6 & 3 & 2 & 17 \\ [PERSON] et al. [47] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [48] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [49] & 4 & 2 & 3 & 3 & 2 & 14 \\ [PERSON] et al. [50] & 4 & 2 & 3 & 3 & 2 & 14 \\ [PERSON] et al. [51] & 4 & 1 & 4 & 3 & 2 & 14 \\ [PERSON] et al. [51] & 4 & 2 & 3 & 3 & 2 & 14 \\ [PERSON] et al. [52] & 4 & 3 & 5 & 3 & 2 & 17 \\ [PERSON] et al. [53] & 4 & 1 & 4 & 3 & 2 & 14 \\ [PERSON] et al. [54] & 4 & 2 & 5 & 3 & 2 & 16 \\ [PERSON] et al. [55] & 4 & 2 & 6 & 3 & 2 & 17 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Quality assessment of the in vitro and in vivo studies according to the ToXRTool. The main types and presentations of the biomaterials, as well as their theoretical concentrations of strontium added or incorporated, are presented in Table 3, ranging from powders to scaffolds for bioengineering purposes, and presenting from 0.5 to 100% Sr substitution in the calcium site.