Stability and failure rate during 3 years of fixed retention: A follow-up of an randomized clinical trial on adolescents with four different lingual retainers.

OBJECTIVE: To evaluate stability outcomes and failure rates associated with four types of lingual retainers: (1) dead-soft wire, (2) multistrand stainless steel (SS) wire, (3) CAD/CAM nitinol, and (4) connected bonding pads (CBPs) after 3 years of retention. METHODS: This study enrolled 96 patients (66 females, 30 males) with a median age of 19 years with four types of lingual retainers: (1) 0.016 × 0.022-inch dead-soft wire, (2) 0.0215-inch five-strand SS wire, (3) 0.014 × 0.014-inch CAD/CAM nitinol wire, and (4) CBPs. The irregularity index, intercanine distances, and arch lengths were obtained and used to evaluate mandibular stability. Failure rates were also assessed during this study. Data were statistically analysed. RESULTS: Irregularity increased, whereas intercanine width and arch length decreased after 3 years of retention. The greatest irregularity was associated with the CBPs and the least with the CAD/CAM retainers. Changes in stability measurements were significantly higher in the dead-soft wire and CBPs than those in the CAD/CAM nitinol and multistrand SS wires. Parallel to these changes, the frequency of failure yielded similar results with the same significance between the groups. The failure rate of CBPs, in contrast to the CAD/CAM nitinol and multistrand SS wires, was significantly higher in the right quadrant (P < .05). CONCLUSION: After taking the 3-year results into consideration, CAD/CAM nitinol and multistrand SS wires were found to be more successful than the others in maintaining mandibular stability. The most failures were observed with CBPs after 3 years of retention.

Effects of different lingual retainers on periodontal health and stability.

OBJECTIVES: To evaluate the effects of different lingual retainers on periodontal health and stability of mandibular anterior teeth at the 1-year follow-up. MATERIALS AND METHODS: One hundred thirty-two patients were randomly allocated to four groups using different lingual retainers: group 1, 0.016 × 0.022-in dead-soft wire; group 2, 0.0215-in 5-strand stainless steel wire; group 3, 0.014 × 0.014-in computer-aided design/computer-aided manufacturing nitinol retainer (Memotain); group 4, connected bonding pads. Plaque, gingival, and calculus indexes were used to evaluate periodontal health, and Little's irregularity index, intercanine width, and arch length measurements were performed to evaluate stability. All measurements were performed at each time point (debonding and 3, 6, 9, and 12 months). RESULTS: The mean value of the gingival index obtained in group 3 was lower than the mean value for all other groups. The mean value of the calculus index was the lowest in group 3, and there was a significant difference between group 3 and groups 1 and 2. No differences were found among the groups in terms of plaque index, intercanine width, and arch length. The least irregularity was obtained in groups 2 and 3. There were no significant differences between these groups and groups 1 and 4. CONCLUSIONS: Gingival inflammation and calculus accumulation were the lowest in group 3 (Memotain). The irregularity for Memotain and stainless steel retainers was less than or the other groups. However, no clinically significant worsening of periodontal health or relapse were seen in any groups after 1 year.