title: Cement-cement interface strength: influence of time to apposition.
abstract: Cement-cement interfaces were created under simulated operating-room conditions. In order to analyze the effect of time to apposition on interface strength, two cement surfaces were brought together 1, 2, 4, and 6 min after 1 min of mixing and 45 s of waiting. Cement-cement interface strength was evaluated with the use of a three-point bending to failure test. Scanning electron microscopy (SEM) images of the failed interface were obtained. The mean interface strength decreased when the cement-cement interface was time delayed. Compared to bulk cement, interface strength in time-delayed groups decreased 8% after 1-min delay (p=.037), 18% after 2-min delay (p=.0004), 20% after 4-min delay (p=.0005), and 42% after 6-min delay (p<.0001). No statistically significant differences in interface strength were found between the 2- and 4-min delayed groups (p=.73). SEM images revealed that after 6-min delay, up to 50% of the cement surface can remain unbonded, explaining the decrease in strength of the cement-cement interface as a function of time to apposition. This laboratory study indicates that time to apposition plays a critical role in cement-cement interface strength. If any cementing technique involves the joining of two cement surfaces, it is recommended that the two cement surfaces be mated together within 5 min and 45 s after the start of mixing (1 min mixing; 45 s waiting; 4 min delay), in order to obtain a strong cement-cement interface bond. Delay beyond this can result in substantial reduction in the strength of the cement-cement interface bond.
authors.affiliation: The J. Vernon Luck Sr. M.D. Orthopaedic Research Center at Orthopaedic Hospital, 2400 South Flower Street, Los Angeles, California 90007.
authors.forename: S H
authors.initials: SH
authors.lastname: Park
authors.forename: M
authors.initials: M
authors.lastname: Silva
authors.forename: J S
authors.initials: JS
authors.lastname: Park
authors.forename: E
authors.initials: E
authors.lastname: Ebramzadeh
authors.forename: T P
authors.initials: TP
authors.lastname: Schmalzried
mesh_terms: D000268:Adhesiveness; D001843:Bone Cements / Q000737:chemistry*; D004868:Equipment Failure; D006813:Humidity; D008422:Materials Testing; D020366:Methylmethacrylate / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D013314:Stress, Mechanical; D013499:Surface Properties; D013696:Temperature; D013997:Time Factors
chemical_list: D001843:Bone Cements; D020366:Methylmethacrylate