Lingual retainer materials: Comparative evaluation of wear resistance of flowable nanocomposites and universal composite: An in vitro study

Abstract

Background: A bonded fixed retainer is used to stabilize the alignment of the teeth. Different
composites have been introduced for this purpose. This study aimed to investigate the wear
resistance of flowable nanocomposite in comparison with microhybrid composite in an in vitro
situation.
Materials and Methods: In this in vitro study, 46 disk‑shaped specimens were divided into two
groups: Filtek Ultimate flowable composite and Z250 microhybrid composite. The samples were
prepared in 8 mm diameter and 3 mm thickness in an aluminum mold and light cured. They were
polished with 600 grit sandpaper to achieve a smooth surface. Two‑body wear test was accomplished
by the pin‑on‑disk device (under 15 N, 20 rpm for 1 h). Analyzing the weight and thickness of
specimens before and after the assay demonstrates the wear resistance. Data were analyzed using
the t‑test. P ≤ 0.05 was considered statistically significant.
Results: The Filtek Ultimate flowable composite shows no significant difference compared to Z250
microhybrid composite in thickness (P = 0.701) and weight (P = 0.939) of specimens.
Conclusion: Due to wear resistance of both materials, flowable composite can be recommended
as an alternative material for bonded fixed retainers.
Key Words: Composite resins, dental restoration wear, orthodontic retainers