Objective:

The aim was to study the corrosive-wear characteristics of two commercial microfil resins composites - one homogenous and the other heterogenous.

 

Methods:

The materials were (1) homogenous (Virtuoso- DenMat) and (2) heterogenous (A-110 - 3M). The degradation characteristics of the two materials have been reported (2003 IADR Abst. #3028). For corrosive-wear evaluation, circular cavities drilled into MACOR (Corning) ceramic discs, were filled with respective composites, cured, ground flat and corroded in a 0.1N NaOH solution at 60^oC for 2 weeks for subsurface degradation. Following corrosion, the specimens were subject to wear test in an automatic tooth-brushing machine. The details of the procedure have been reported [J. Biomed Mater Res (Appl Biomater) 53, 371, 2000]. Undegraded specimens were also subject to toothbrush abrasion under the same conditions for evaluation of their abrasive - wear. Corrosive- and abrasive-wear were measured in terms of volume loss (mm³) using a surface profilometer. The surface morphology after wear tests was examined by SEM.

Results:

The data, mean (st.dev.), are shown in Table below:

Brand	Abrasive Wear (mm3)	Corrosive Wear (mm3)
Virtuoso	0.109 (0.010)	1.189 (0.085)
A110	0.104 (0.004)	2.192 (0.143)

The abrasive-wear for the two materials was not different (p= 0.426) from each other. Corrosion increased the wear of both materials.  However, Virtuoso exhibited significantly (p< 0.001) less corrosive wear than A-110. The surface of each material following abrasive- wear was relatively flat. After corrosive-wear Virtuoso displayed the same topography. However, the worn surface of corroded A-110 was undulating with protruding prepolymer blocks. The above findings have been explained on the basis of degradation characteristics of the two materials (2003 IADR abstract #3028).

Conclusion:

The corrosive-wear of microfil composites is affected by their nature - homogenous or heterogenous.