Aim: This systematic review aims to evaluate the evidence available on the clinical effectiveness such as survival rate, gingival health, and patient/parent acceptance of various fixed space maintainers vs band and loop (B&L) space maintainers (BLSMs) in mixed dentition. Materials and methods: A comprehensive electronic search and synthesis of existing evidence was conducted using databases such as PubMed Central, Cochrane Database of Systematic Reviews, Google Scholar, LILACS, and Science Direct from 2012 to 2022 for randomized controlled trial (RCT) that describes the clinical efficiency of unilateral fixed space maintainer compared to conventional BLSM. Results: Out of 52 RCTs, 46 were excluded based on inclusion and exclusion criteria. Only six split-mouth RCT comparing BLSM with other unilateral fixed space maintainers were included in the final review. Conclusion: Within the limitations of the study, fiber-reinforced space maintainers exhibit better parental acceptance than conventional BLSM. Conventional B&L demonstrate higher survivability, followed by fiber-reinforced composite space maintainer. Gingival health on all the space maintainers shows fair results. Clinical significance: This systematic review holds significant clinical implications by specifically examining the split-mouth RCT, which makes it unique from the previous literature and enhances evidence-based decision-making.