Poly-Ether-Ether-Ketone versus dead-soft coaxial bonded retainers: a randomized clinical trial. Part 2: periodontal health and microbial biofilm assessment.

This article reports on a single-centre randomized clinical trial comparing the effects of Poly-Ether-Ether-Ketone (PEEK) fixed retainers and Dead-soft coaxial (DSC) fixed retainers on periodontal health and bacterial biofilm over a six-month retention period in orthodontic patients. The study assessed periodontal indices—including plaque index, bleeding on probing, periodontal pocket depth, gingival index, calculus index, and alveolar bone height—as well as bacteriological counts of aerobic, facultative anaerobic, mutans streptococci, and lactobacilli at multiple time points. Results indicated that both PEEK and DSC retainers had comparable impacts on periodontal health and bacterial accumulation, with only minor, statistically but not clinically significant differences observed; no adverse effects were reported. The findings suggest that PEEK retainers may be a viable alternative to conventional DSC retainers, though the authors recommend further long-term studies to confirm durability and clinical performance.