In vivo evaluation of occlusal wear of two experimental composites versus amalgam

Abstract
Experimental inhomogeneous microfilled composites (2) with spherical prepolymerized particles and an interpenetrating network (IPN), which provides a stable bond between prepolymerized spheres and the matrix (B-21 and B-51), and amalgam were used for Class II MOD [mesio-occlusodistal] fillings in mandibular molars. After 3 and 6 mo. of clinical use, wear of the material was measured with a replica technique and a modified surface roughness test. The failure mode was analyzed with SEM [scanning electron microscope] photographs also using a replica technique. After 6 mo. the wear of the composites in the occlusal contact area was more than twice as high as the substance loss of amalgam. The composites were not suitable for fillings bearing occlusal load. The failure mode seen in the SEM for B-21 indicated that the IPN leads to a stable incorporation of the spherical prepolymerized particles into the matrix. Due to its good surface characteristics B-21 should be further investigated for its use as an anterior composite. B-51 was especially designed as a posterior composite. Beside the construction elements of B-21 it also contained barium glass spheres to obtain radiopacity. This hybrid construction failed due its wear mode.