Stability, survival, and patient satisfaction with CAD/CAM versus conventional multistranded fixed retainers in orthodontic patients: a 6-month follow-up of a two-centre randomized controlled clinical trial

Abstract

Objectives The primary aim of this two-arm parallel two-centre randomized controlled trial was to compare computer-aided design and computer-aided manufacturing (CAD/CAM) versus conventional multistranded fixed retainers (FRs) in terms of stability over 6 months. Secondary outcomes were failure rates and patient satisfaction. Methods Patients were randomized to CAD/CAM or conventional FRs in both arches, in 1:1 ratio and blocks of four. Allocation concealment was secured by using sequentially numbered envelopes. Patients were blinded. Retainers were bonded at the end of orthodontic treatment (T0), and patients were recalled after 1 (T1), 3 (T3), and 6 (T6) months. First-time retainer failures were recorded and digital impressions were taken. Arch widths and lengths, as well as Little’s Irregularity Index (LII), were measured. Additionally, patients answered satisfaction questionnaires. Linear mixed models were applied for measurements and patient satisfaction. Survival analyses were estimated with Kaplan-Meier curves, along with Cox-regression modelling. Results One hundred and eighty-one patients were randomized (98 in Centre 1, and 83 in Centre 2): Ninety in the CAD/CAM group and 91 in the conventional group. Three subjects dropped out at baseline, as they did not attend any of the follow-up appointments.168 patients attended the T6 visit. There were no significant differences in arch dimensions between T0 and T6, whilst the LII was different only in the CAD/CAM group (mean difference: 0.2 mm; 95% confidence interval: 0.1 to 0.4; P < 0.001). Within 6 months, 39 upper retainers (19 out of 88 CAD/CAM and 20 out of 90 conventional retainers) and 52 lower retainers failed (26 out of 88 CAD/CAM and 26 out of 90 conventional retainers), with no significant difference between the survival of both types of retainers (hazard ratios conventional to CAD/CAM: upper arch: 0.99 [P =0.99], lower arch: 0.93 [P = 0.80]). There were no significant changes in patient satisfaction between the groups. No harms were observed. Conclusions There were no clinically significant differences in LII, arch widths and lengths between CAD/CAM and conventional retainers after 6 months. There was no difference in failures and in patient satisfaction between both types of FRs. Registration ClinicalTrials.gov NCT04389879.

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

“…According to the results, no significant differences were found between CAD/CAM nitinol and multistrand SS wire retainers that supported the stability and failure results of short‐term studies 10–15 . The CAD/CAM nitinol retainer may be replaced as a gold standard, considering stability and frequency of failure.…”

“…In addition, the failure rate of CBPs was significantly higher than According to the results, no significant differences were found between CAD/CAM nitinol and multistrand SS wire retainers that supported the stability and failure results of short-term studies. [10][11][12][13][14][15] The CAD/CAM nitinol retainer may be replaced as a gold standard, considering stability and frequency of failure. Even so, the high cost of CAD/ CAM nitinol retainers may be a critical issue when routinely used in clinical practice.…”

“…Regarding CAD/CAM retainers, their short-term results (6 or 12 months) have been observed to be satisfactory in terms of stability and failure in recent years. [10][11][12][13][14][15] However, there is insufficient data about their long-term stability and failure rates.…”

The prevalence of the failure of fixed orthodontic bonded retainers: a systematic review and meta-analysis

“…A total of 3484 participants with 4540 FOBR were included in the 34 studies, with participants age ranging from 9 to 60 years. Out of the 34 included studies in this review 6 were conducted in Switzerland [ 29 , 31–33 , 43 , 56 ], 5 studies were conducted in Turkey [ 30 , 36 , 37 , 39 , 54 ], 3 studies in Italy [ 28 , 47 , 48 ], USA [ 12 , 26 , 49 ] and Iran [ 25 , 46 , 50 ], 2 studies were conducted in Germany [ 45 , 51 ], Sweden [ 27 , 40 ], Saudi Arabia [ 44 , 53 ], Norway [ 35 , 57 ], and UK [ 34 , 38 ], and 1 study in China [ 55 ], Belgium [ 52 ], Canada [ 41 ], and Pakistan [ 42 ]. The majority of studies included ( n = 26) were conducted in a university hospital setting where the participants were treated by both specialist orthodontists as well as postgraduate students under supervision.…”

“…The percentage of participants lost to follow up in the studies ranged from 0% to 38%. Interventions evaluated in the identified studies included: nine studies comparing multi-stranded wire (MSW) versus fibre-reinforced retainers [ 25 , 26 , 28 , 42 , 45 , 46 , 48 , 50 , 52 ], nine studies comparing different dimensions of wire [ 12 , 19 , 32 , 36 , 37 , 39 , 41 , 44 , 51 ], six studies comparing direct versus indirect bonding [ 29–31 , 33 , 36 , 54 ], three studies comparing different types of composite bonding material [ 30 , 47 , 53 ], three studies comparing CAD/CAM versus lab made fixed retainers [ 35 , 38 , 49 ], two studies comparing bonding with liquid resin versus without liquid resin composite [ 55 , 57 ], two studies assessing vacuum formed retainer verses bonded retainers [ 34 , 40 ], and one study comparing light cured and chemical cure composite [ 43 ].…”