Variation in powder/liquid ratio of a restorative glass-ionomer cement used in dental practice.
This study investigates the powder/liquid ratios of a glass-ionomer restorative (ChemFil II, Dentsply) mixed in clinical practice. Twenty-two dental surgery assistants (11 from general practice; 11 from a dental hospital) mixed this cement as they would for clinical use. Samples were taken of three mixes from each assistant and the powder/liquid ratios were derived from weight loss on dehydration. A wide range of ratios were obtained, but in no case was the manufacturer's recommended ratio of 6.8:1 achieved. The consistency measured in accordance with BS 6039 showed the cement at 6.8:1 to be less fluid than the requirements of the standard and other glass-ionomer restoratives. When tested at the mean ratio used in practice, 5.0:1, the consistency complied with BS 6039, but the compressive and diametral strengths did not, being about half the values found at 6.8:1. It was concluded that this restorative was often mixed in practice at much lower powder/liquid ratios than that recommended by the manufacturer and that this would impair the cement's mechanical properties.
Billington
R W
RW
Biomaterials Department, Institute of Dental Surgery, London.
Williams
J A
JA
Pearson
G J
GJ
D005899:Glass Ionomer Cements / Q000737:chemistry* / Q000592:standards; D008422:Materials Testing / Q000379:methods; D011208:Powders / Q000737:chemistry; D012823:Silicate Cement / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D005899:Glass Ionomer Cements; D011208:Powders; D014867:Water; C054101:ChemFil II; D012823:Silicate Cement