Three experimental inhomogeneous microfilled composites (IMC) containing spherical prepolymerized particles with an interpenetrating network (IPN) were compared with the reference materials Estic MF, Adaptic and the amalgam Dispersalloy in vitro. With surface roughness tests, different polishing procedures were investigated. In addition an SEM analysis of the margins of Class I fillings using a replica technique was performed. With the same technique the proximal boxes of Class II fillings were analysed to further determine the best method to handle the materials clinically. The experimental materials showed a superior adaptation to the walls of proximal boxes of Class II cavities than the reference materials. This superiority was increased by the use of a filled bonding agent. The influence of viscosity, filler load and glass transition point on adaptation and polymerization shrinkage are discussed. It was concluded that especially designed diamonds with very fine abrasive particle size (40 micrograms and 15 micrograms) are the best for finishing and contouring composite fillings. Based on the results of this study it is recommended to use the experimental material for clinical investigations.

Bisphenol A-Glycidyl Methacrylate↗

PubMed1984

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

Two experimental inhomogeneous microfilled composites 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 fillings in mandibular molars. After 3 and 6 months of clinical use, wear of the material was measured with a replica technique and a modified surface roughness test. The failure mode was analysed with SEM photographs also using a replica technique. After 6 months the wear of the composites in the occlusal contact area was more than twice as high as the substance loss of amalgam. It was concluded that the composites were not suitable for fillings bearing occlusal load. However, the failure mode seen in the SEM for B-21 indicated that the IPM 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 contained also barium glass spheres to obtain radiopacity. This hybrid construction failed due its wear mode.

Bite Force↗

PubMed1984

In vivo and in vitro wear of potential posterior composites.

The influence of cavity size, material composition, and curing mechanism on wear resistance of Class II MOD resin restorations was analyzed quantitatively. Wear resistance tends to increase both as cavity size decreases, and also from chemical- to light- to heat-cured. As to wear, among the composite resins tested, there was no acceptable resin-based amalgam substitute.

Chemical Phenomena↗

PubMed1984