Comparison of PMMA Bone Cements to a New Resin-Modified Glass-Ionomer

Poly(methyl methacrylate) (PMMA)-based resins are used extensively as bone cements. These cements act primarily as a filler that locks the prosthesis in place by conforming under pressure to the micro and macro irregularities of the surgically-prepared bone and/or prosthesis surface. This property makes the placement of prostheses technique sensitive and limits their use to primarily intact bone. Objective: To develop a bone cement with improved adhesion to bone and to compare its mechanical properties to those of two commercially available bone cements. Methods: DentStat^TM, a resin-modified glass-ionomer material (DentStat^TM) developed at NIDBR for dental applications, was tested for use as a bone cement against two commercially available PMMA bone cements (Surgical Simplex^® P, Stryker and Cobalt^TM HV, Biomet). Specimen preparation and testing protocols were based on existing ISO/ADA specifications. Discs of bovine bone were used for the shear bond strength testing. Data were analyzed using ANOVA and Tukey-Kramer HSD test (alpha=0.05). Results: The results are presented in the table [mean (st dev)], n=10. Materials with the same letter within a column are not significantly different (p>0.05). DentStat^TM was significantly different than the other brands in compressive strength and shear bond strength to cortical bone. DentStat^TM was significantly different from Surgical Simplex^® P in bond strength to cancellous bone. There were no differences among the test groups in diametral tensile strength.

Material	Compressive Strength (MPa)	Diametral Tensile Strength (MPa)	Shear Bond to Cortical Bone (MPa)	Shear Bond on Cancellous Bone (MPa)
Surgical Simplex® P	99.63 (7.55)    B	25.65 (6.66)   A	1.91 (0.73)   B	1.75 (0.77)      B
Cobalt G-HV	96.04 (5.43)    B	26.69 (2.49)   A	2.31 (0.45)   B	1.90 (0.55)   A,B
DentStatTM	170.18 (16.56)  A	28.91 (3.97)   A	7.79 (1.29)   A	2.56 (0.49)   A

Conclusions: In this study, DentStat^TM exhibited mechanical properties comparable to, or better than those of two commercially available bone cements. Further study is warranted and should focus on biocompatibility and adhesion to metallic and ceramic substrates to determine the viability of using DentStat^TM as a bone cement.