Three independent researchers (CRS, CBS, and RSN) conducted data extraction and validity assessment of the studies that met the inclusion criteria. Data was extracted focusing on the animal model, study groups, treatment start, duration of the treatment, period of examination, implant specification, evaluation methods, and results (outcomes), according to what was reported in each study (i.e., histomorphometry, biomechanical, microtomography, and serum analysis).

Any qualitative and/or quantitative bone-related parameters which could explain the effects of the systemic administration of non-radioactive Sr on bone tissue of the animals, determining if and how this substance interacts with the bone tissue and bone-tissue regeneration, were included as relevant outcomes.

Quality assessment of the studies was made according to SYRCLE’s risk of bias tool for animal studies [28]. All ten domains (sequence generation, baseline characteristics, allocation concealment, random housing, performance blinding, random outcome assessment, detection blinding, incomplete outcome data, selective outcome reporting, and other sources of bias) of SYRCLE’s tool were individually evaluated in terms of the risk of bias (no summary scores for the studies were included). Three reviewers (CRS, CBS, and RSN) independently assessed the studies for their quality. When there was a disagreement regarding the assessed data, a consensus meeting was carried out.