A comparison of the wear resistance and hardness of indirect composite resins.
BACKGROUND
Various new, second-generation indirect composites have been developed with claimed advantages over existing tooth-colored restorative materials. To date, little independent research has been published on these materials, and the properties specified in the advertising materials are largely derived from in-house or contracted testing.


OBJECTIVE
Four second-generation indirect composites (Artglass, belleGlass, Sculpture, and Targis) were tested for wear resistance and hardness against 2 control materials with well-documented clinical application. Human enamel was also tested for comparison.


METHODS
Twelve specimens of each material were fabricated according to the manufacturers' directions and subjected to accelerated wear in a 3-body abrasion, toothbrushing apparatus. Vickers hardness was measured for each of the tested materials, and energy dispersive x-ray (EDX) spectroscopy was performed to determine the elemental composition of the composite fillers. The statistical tests used for wear and hardness were the Kruskal-Wallis 1-way ANOVA test with Mann-Whitney tests and 1-way ANOVA with multiple comparisons (Tukey HSD). The Pearson correlation coefficient was used to determine the existence of a relationship between the hardness of the materials and the degree to which they had worn. The level of statistical significance chosen was alpha=.05.


RESULTS
The control material Concept was superior to the other composites in wear resistance and hardness and had the lowest surface roughness. Significant relationships were observed between depth of wear and hardness and between depth of wear and average surface roughness. Enamel specimens were harder and more wear resistant than any of the composites. EDX spectroscopy revealed that the elemental composition of the fillers of the 4 new composites was almost identical, as was the composition of the 2 control composites.


CONCLUSIONS
The differences in wear, hardness, and average surface roughness may have been due to differences in the chemistry or method of polymerization of the composites. Further research in this area should be encouraged. It was also apparent that the filler present in the tested composites did not exactly fit the manufacturers' descriptions.
Mandikos
M N
MN
School of Dental Medicine, State University of New York at Buffalo, Buffalo, NY, USA. mmandikos@ceodental.com
McGivney
G P
GP
Davis
E
E
Bush
P J
PJ
Carter
J M
JM
D000180:Acrylic Resins / Q000737:chemistry; D000704:Analysis of Variance; D003188:Composite Resins / Q000737:chemistry* / Q000145:classification; D003743:Dental Enamel / Q000648:ultrastructure; D003764:Dental Materials / Q000737:chemistry; D019554:Dental Restoration Wear; D003793:Dental Restoration, Permanent; D004577:Electron Probe Microanalysis; D005899:Glass Ionomer Cements / Q000737:chemistry; D006244:Hardness; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D012823:Silicate Cement / Q000737:chemistry; D013223:Statistics as Topic; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014099:Toothbrushing
D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; C069352:Concept resin; D003764:Dental Materials; D005899:Glass Ionomer Cements; D008689:Methacrylates; D011108:Polymers; D011140:Polyurethanes; C110370:belleGlass; C111282:dental polyglass; D012823:Silicate Cement; C074277:ethoxylated bis-phenol A dimethacrylate