In vitro toothbrush-dentifrice abrasion of two restorative composites.

ABSTRACT

BACKGROUND: Surface wear can be a problem with directly placed composites. PURPOSE: This study evaluated the in vitro wear and surface roughness of two composites at different cycle intervals after being subjected to toothbrush-dentifrice abrasion. MATERIALS AND METHODS: Twenty specimens of a microhybrid, Filtek Z250 (3M ESPE, St. Paul, MN, USA), and a nanofill composite, Filtek Supreme (3M ESPE), were prepared according to the manufacturer's directions. Each specimen was subjected to toothbrush-dentifrice abrasion (250 g vertical load) using a deionized water-dentifrice slurry (Close-Up, Lever Ponds Ltd., La Lucia, ZA) and toothbrush heads (Oral-B 40, Oral-B Laboratories, Delmont, CA, USA). A brushing sequence of 10,000, 20,000, 50,000, and 100,000 strokes was performed for all samples at a rate of 1.5 Hz. At baseline and each cycle interval, a surface profilometer was used to determine average surface roughness, Ra. At the same intervals, vertical loss of material was measured with a precision micrometer. Data were analyzed using repeated-measures analysis of variance at p value .05. Analyses with atomic force microscopy (AFM) and scanning electron microscopy (SEM) were also performed. RESULTS: After 20,000, 50,000, and 100,000 cycles, Filtek Supreme showed less significant wear than Z250. Filtek Supreme demonstrated higher surface roughness than Z250 after 50,000 and 100,000 cycles. However, AFM and SEM images indicated a more uniform surface topography for Filtek Supreme than for Z250. Abrasion wear and surface roughness increased with each cycle interval for both materials. CONCLUSIONS: Although the initial performance of both materials was similar, a greater number of brushing cycles revealed differences between the wear resistance and generated surface roughness of the materials. CLINICAL SIGNIFICANCE: The wear resistance and roughness results of Filtek Supreme suggest that it is suitable for clinical use, mainly in areas that are more subject to abrasive wear, such as Class V restorations.