Shear bond strength of three different fixed retainers: Stainless steel wires versus fiber reinforced composite (An in Vitro study)

Abstract

Background and Objectives: Long term preservation of lingual retainer after active orthodontic treatment is mandatory in oral cavity to prevent teeth relapse to its original place before treatment which is documented in orthodontics and considered as a success factor of lingual bonded retainers. This in vitro study is conducted to evaluate and compare the bond strength (shear bond strength) of three different fixed lingual retainers using a specific retainer composite and fracture modes of different retainer’s wire/adhesive combination. Methods: One‐hundred twenty extracted human upper premolar teeth (60 pairs) were divided into three groups(40 for each group) bonded with three different types of retainer wires (db Straight‐8strand flattened nickel free braided wire 0.028 x 0.008 inches UK, 3M 0.0175; multi‐stranded wire and Speed korean orthodontic fiber reinforced splint (2 mm x 200 mm ‐ FS‐2) which were bonded to the lingual surface of the teeth as fixed retainers by specific adhesives (Transbond LR, 3M). The specimens were debonded using a Universal Instron machine to measure shear bond strength. The site of failure was recorded for each specimen was calculated. Statistical analyses were provided using one‐way analysis of variance with inter‐group comparison using the least significant difference. Results: There was a statistically high significant difference among all three retainers groups (p < 0.001); db Straight‐8 braid flat soft wire debonding force was (130±29.6N), followed by Speed fiber reinforced splint group (107.5±18.9 N), whereas the minimum was observed 3M Unitek coxial multi strand wire group(76±27.6 N).The site of failure was pre‐ dominantly at the wire composite interface except in FRC was in enamel/composite inter‐ face. Conclusion: db straight‐8 wire delivered higher shear bond strength, followed by fiber rein‐ forced splint retainer group, whereas 3M multi‐strand wire had the least shear bond strength.