Time-dependent visco-elastic creep and recovery of flowable composites

Authors: Baroudi, Kusai; Silikas, Nick; Watts, David C.

Source: European Journal of Oral Sciences, Volume 115, Number 6, December 2007 , pp. 517-521(5)

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Abstract:

Creep behaviour of flowable composites was evaluated in relation to their filler fraction and the postcure period. Solid cylindrical specimens were prepared (4 × 6 mm) using steel moulds, with thorough light curing from multiple directions at 600 mW cm⁻². The specimens were divided into two groups (n = 3/material) as follows: group I, loaded 5 min after preparation; and group II, loaded after storage for 1 month in water at 37 ± 1°C. A constant compressive stress of 36 MPa was applied to each specimen for 2 h followed by removal of the weight for 2 h of strain recovery. Axial strain measurements were obtained continuously over the total analysis time of 4 h. The maximum creep strain ranged from 2.04 to 7.69% and from 1.03 to 6.12% for groups I and II, respectively. Flowables that had the highest percentage of filler produced the lowest creep strain. The creep response decreased with 1 month of preload storage. Clinically, the finding of this study suggests that flowable composites are unsuitable for stress-bearing areas.

Keywords: creep; filler fraction; flowable composites; viscoelasticity

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1600-0722.2007.00487.x

Affiliations: 1: Biomaterials Research Group, The University of Manchester, School of Dentistry and Photon Science Institute, Manchester, UK

Publication date: 2007-12-01