Different lingual retainer composites and the microleakage between enamel-composite and wire-composite interfaces

To assess microleakage of enamel-composite and wire-composite interfaces when retainer wires were bonded with two orthodontic and a flowable composites.

Forty-five freshly extracted human mandibular canine teeth were used in this study. Teeth were separated into three groups of 15 teeth each. Round stainless-steel wire of 0.36-in. diameter in three groups was bonded to enamel by Transbond XT (3M Unitek), Transbond LR (3M Unitek), and Venus Flow (Heraeus Kulzer) composites. Specimens were further sealed with nail varnish, stained with 0.5% basic fuchsine for 24 hours, sectioned and examined under a stereomicroscope, and scored for microleakage for the enamel-composite and wire-composite interfaces from mesial and distal margins. Statistical analysis was performed by Kruskal-Wallis and Mann-Whitney U-tests.

Little or no microleakage was determined at the mesial and distal sides for three composites in two different interfaces, and these findings were not statistically significant (P > .05). No statistically significant differences were observed among all composite groups for the microleakage with either of the interfaces. Venus Flow in the enamel-composite interface and Transbond LR in the wire-composite interface exhibited no microleakage.

The presence of wire in the mesial portion of the lingual retainer did not increase the microleakage at the enamel-composite and wire-composite interfaces in all groups. The microleakage results in this study support the use of all these composites in routine orthodontic practice.