Volumetric contraction in some tooth-coloured restorative materials.
BACKGROUND
Much of the concern about the setting contraction of tooth-coloured restorative materials has been focused on the composite resins. This study investigated setting contraction of a range of glassionomer materials and included, for comparison, products from other groups of restorative materials.


METHODS
A deflecting disk method was used to determine the volumetric contraction of three conventional (non-light cured) glass-ionomer cements (GICs), two restorative, one "lining" consistency and one adhesive/lining consistency resin-modified glass-ionomers (RMGIs), two resin adhesives, three restorative composite resins and two compomers. The influence of powder:liquid ratio on two hand-mixed materials was also examined.


RESULTS
The light-cured materials (including RMGIs) showed substantially greater per cent contraction at 5 minutes than did the three conventional GICs (not light cured) and a substantially greater proportion of the 30-minute contraction had occurred at 5 minutes for these light-cured materials. Their further contraction after 1 hour was generally less than 5 per cent of the 1 hour contraction.


CONCLUSIONS
Although the conventional GICs contract more slowly in the first 5 minutes, by 30 minutes the current restorative GICs and RMGIs exhibit a volumetric setting contraction that is comparable with the composite resins and compomers and is generally in the range of 2-3 per cent.
Bryant
R W
RW
Faculty of Dentistry, The University of Sydney, New South Wales, Australia. bryantr@dental.wsahs.nsw.gov.au
Mahler
D B
DB
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D020770:Compomers / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry*; D005899:Glass Ionomer Cements / Q000737:chemistry*; D006801:Humans; D008298:Maleates / Q000737:chemistry; D008422:Materials Testing; D019279:Resin Cements / Q000737:chemistry; D013499:Surface Properties; D013997:Time Factors
D020770:Compomers; D003188:Composite Resins; D003764:Dental Materials; C088486:Dyract; C118368:F2000 cement; C452225:Filtek A110 composite resin; C438835:Filtek P60 Composite Resin; C444701:Filtek Z250; C439808:Fuji IX GP Fast; D005899:Glass Ionomer Cements; D008298:Maleates; C467912:Photac-Fil Quick; D019279:Resin Cements; C425844:Scotchbond Multi-Purpose Plus; C084550:Vitremer; C061499:Ketac-Bond; C067790:Vitrabond; C084541:Fuji glass-ionomer lining cement; D017438:Bisphenol A-Glycidyl Methacrylate; C081713:Visio-Bond; C040964:Ketac-Fil