Correlation between surface roughness and microhardness of experimental composites with varying filler concentration.
OBJECTIVE
The purpose of this study was to investigate the influence of the surface roughness on the surface microhardness of experimental composites with varying filler concentration.


METHODS
Experimental resin composites were formulated by mixing Bis-GMA and TEGDMA in a 50/50% weight ratio and CQ/EDAB were added to make the material photosensitive. Silanized glass particles were incorporated in the resin blend in two concentrations: C50 with 50% and C75 with 75% in weight ratio. The surface roughness and the surface microhardness measurements were determined after every three finishing procedures with #280-, #600- and #1200-grit wet sandpapers, respectively. The data were analyzed statistically by Two Way ANOVA and Tukey's test, and comparisons were conducted using the Spearman's correlation test (p > 0.05).


RESULTS
The surface roughness and surface microhardness were negatively associated (r = - 0.68) and the finishing procedures of both composites resulted in harder and smoother surfaces than the initial ones. Additionally, in a smooth circumstance, the higher content of fillers has not resulted in a composite with better microhardness and smoothness.


CONCLUSIONS
Finishing procedures decreased the surface roughness and consequently improved the surface microhardness of the composites evaluated.


CONCLUSIONS
Finishing and polishing procedures are effectives in reducing the surface roughness amplitude of composite materials and in improving their surface microhardness. Thus a microhardness test and any hardness evaluation must be conducted only after a properly finished and polished surface is achieved.
PhD Student, Department of Operative Dentistry, School of Dentistry Federal University of Pelotas, Pelotas, RS, Brazil. eliseumunchow@hotmail.com
Eliseu Aldrighi
EA
Munchow
Marcos Brito
MB
Correa
Fabricio Aulo
FA
Ogliari
Evandro
E
Piva
Cesar Henrique
CH
Zanchi
D000704:Analysis of Variance; D017438:Bisphenol A-Glycidyl Methacrylate; D003188:Composite Resins / Q000737:chemistry*; D003775:Dental Polishing; D006244:Hardness; D008422:Materials Testing; D053758:Nanoparticles; D017319:Photosensitizing Agents; D011092:Polyethylene Glycols; D011109:Polymethacrylic Acids; D012821:Silanes; D018709:Statistics, Nonparametric; D013499:Surface Properties
D003188:Composite Resins; D017319:Photosensitizing Agents; D011109:Polymethacrylic Acids; D012821:Silanes; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate