Objective: This systematic review assesses and compares the use of fixed retainers manufactured by CAD CAM and conventional methods in patients undergoing orthodontic treatment. Methodology: Data from the selected studies were collected using customised data collection forms. Primary analysis involved assessing the stability of orthodontic treatment over time through measurements taken from dental casts and assessing the impact on periodontal health. Secondary aspects involved an evaluation of the rates at which retainers failed and gathered valuable insights from outcomes reported by patients. Results: Seven randomised controlled trials (RCTs) were included involving 601 participants. During the initial 6 months, no notable variations in the distance between canine teeth or the length of the dental arch were noted when comparing CAD/CAM retainers with conventional retainers. Nevertheless, it's noteworthy that CAD/CAM retainers exhibited superior performance compared to stainless steel retainers (single strand). Significant differences in Little's irregularity index, was evident at 3-month and 6-month intervals. Distinctions with limited clinical significance were noted in multi-stranded stainless-steel retainers at 6-month follow-up assessment. Regarding oral health aspects, CAD/CAM retainers displayed lower plaque index scores compared to traditional retainers. In terms of durability, most retainers demonstrated comparable failure rates. In one study, CAD/CAM retainers were associated with a greater rate of failure, which resulted in the premature termination of that specific study. Conclusion: CAD/CAM fixed retainers offer a promising alternative to traditional options and may promote better periodontal health due to lower plaque index scores. Nevertheless, to assess their effectiveness and long-term durability, more studies are needed, particularly regarding failure rates. In the absence of comprehensive evidence, the utilisation of customisation of CAD/CAM retainers is advisable for individual clinical cases. © 2025 Elsevier B.V., All rights reserved.