Powder-liquid crown and bridge cements are stronger than paste-paste cements, University of Washington researchers report in the Journal of the American Dental Association (September 2009, Vol. 140:9, pp. 1125-1136).
The researchers tested 12 cements by using them to attach high-noble metal-ceramic copings to extracted human molars, then subjecting the copings to dislodgment forces along the apico-occlusal axis until they failed.
The researchers found that paste-paste resin-modified glass ionomer cements broke with removal stresses up to 2.8 megapascals (MPa), while the powder-liquid versions of the same cements could withstand up to 8.1 MPa.
The resin-modified versions held up as well as zinc phosphate cements (which the researchers tested separately), "therefore are reasonable choices in ideal clinical circumstances," the researchers wrote. "However, when the clinician desires additional retention, we strongly recommend use of the powder-liquid version of the cement."
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