## 2 Material and Methods
### Quality Assessment of the Selected Studies and Data Extraction  
Concerning the methodological quality, each one of the selected studies was evaluated using the ToxRTool (Toxicological Data Reliability Assessment Tool) as a guide for evaluations of the inherent quality of toxicity data [10]. It consists of an 18-point rating checklist, which considers the description of methodological aspects of each study, such as identification of test substance, test system, study design and results analysis. Articles that do not reach 11 points are considered unreliable, between 11-14 points are reliable with restrictions, and studies with more than 15 points are considered reliable without restrictions. \begin{table}
\begin{tabular}{l l} \hline \hline
**Database** & **Search Key** \\ \hline \multirow{7}{*}{PubMed} & (\"tissue engineering\"[tiab] OR \"Bone repair\"[tiab] OR \"Bone therapy\"[tiab] OR \"bone regeneration\"[tiab] OR \\  & osteoblast\"[tiab] OR \"Bone tissue\" [tiab] OR \"bone cell\"[tiab] OR \"mesenchymal stem cell\"[tiab] OR \\  & \"Mesenchymal Migenitor Cell\"[tiab] OR \"Bone Marrow Stromal Cells\"[tiab] OR presoteoblast\"[tiab] OR \\  & osteocyte\"[tiab] AND (\"Strontium\"[Mesh] OR SR [tiab] OR SR2+[tiab] OR strontium [tiab] OR \\  & \"strontium-containing hydroxyapatite\" [Supplementary Concept] AND (\"Hydroxapatite\"[Mesh] OR \\  & Hydroxapatite\"[tiab] OR Ca10(PO4)6(OH)2 [tiab] OR \"triclum phosphate\"[tiab] OR \"bibnas calcium phosphate\"[tiab] OR BCP[tiab] OR beta-TCP[tiab] OR b-TCP[tiab] OR alpha-TCP[tiab] OR bruhsite[tiab] OR \\  & magnetite[tiab] OR duraplatite [tiab] OR HA[tiab] OR HA[tiab] OR HAP[tiab] OR \"amorphous calcium phosphate\"[tiab]OR \\  & \"calcium phosphate\"[tiab] AND (\"Biocompatible Materials\"[Mesh] OR biomaterial[tiab] OR \"smart material\"[tiab] OR \"Biomimetic Material\"[mesh] OR \"Biomimicry \\  & Material\"[tiab] AND (biocompatible\"[tiab] OR osteogenic\"[tiab] OR cytocompatibility\"[tiab] OR osteeoind\"[tiab] OR osteeoind\"[tiab] OR steoendot[tiab] OR \\  & osteeconduc[tiab] OR clinic\"[tiab] OR surg\"[tiab]) \\ \hline \multirow{7}{*}{Scopus} & TITLE-ABS-KEY (\"tissue engineering\" OR \"Bone therapy\" OR \"Bone regeneration\" OR osteoblast\" OR \"Bone tissue\" OR \"bone cell\"OR \"mesenchymal stem cell\"OR \"Mesenchymal Migenitor Cell\" OR \"Bone Narrow Stromal Cells\" OR preoteoblast\" OR osteocyte\") AND TITLE-ABS-KEY (\"sr OR sr2* OR strontium OR \\  & \"strontium-containing hydroxyapatite\") AND TITLE-BKS-KEY (\"Biocompatible Materials\" OR biomaterial\" OR \"smart material\"*\" OR \"Biomimetic Material\" OR \"Biomimicry Material\") AND TITLE-ABS-KEY (biocompatible\" OR osteogenic\" OR cytocompatibility\" OR osteeind\" OR osteeoconduc\" OR clinic\" OR surg\") AND (LIMIT-TO \\  & (DOCTYPE, “ar”)) \\ \hline \multirow{7}{*}{Web of Science} & (tw:(\"tissue engineering\" OR \"Bone repair\" OR \"Bone therapy\" OR \"bone regeneration\" OR osteoblast\" OR \"Bone tissue\" OR \"bone cell\" OR \"mesenchymal stem cell\" OR \"Mesenchymal Migenitor Cell\" OR \"Bone Marrow Stromal Cells\" OR preoteoblast\" OR osteocyte\")) AND (tw:(\"GR sr2+ OR strontium OR \\  & \"strontium-containing hydroxyapatite\")) AND (tw:(\"Biocompatible Materials\" OR biomaterial* OR \"smart material\"*\" OR \"Biomimetic Material\"*\")) AND (tw:(biocompatible\" OR osteogenic\" OR \\  & cytocompatible\" OR osteeodudud\" OR osteoporeoconduc\" OR clinic\" OR surg\")) AND (instance:\"regional\") AND (type:(\"article\")) \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Search strategies used in the three databases. The data extraction was divided into two parts: the first corresponded to data regarding the characteristics of the biomaterial under study, including the type of material, its format, the theoretical amount of strontium added during the synthesis, the amount of strontium that is released in solution and whether it was covering titanium. The second part aimed to extract results regarding the biological response to the biomaterial.