In vitro wear, surface roughness and hardness of propanal-containing and diacetyl-containing novel composites and copolymers based on bis-GMA analogs.
OBJECTIVE
To evaluate the effect of two additives, aldehyde or diketone, on the wear, roughness and hardness of bis-GMA-based composites/copolymers containing TEGDMA, propoxylated bis-GMA (CH(3)bis-GMA) or propoxylated fluorinated bis-GMA (CF(3)bis-GMA).


METHODS
Fifteen experimental composites and 15 corresponding copolymers were prepared combining bis-GMA and TEGDMA, CH(3)bis-GMA or CF(3)bis-GMA, with aldehyde (24 mol% and 32 mol%) or diketone (24 mol% and 32 mol%) totaling 30 groups. For composites, hybrid treated filler (barium aluminosilicate glass/pyrogenic silica; 60 wt%) was added to monomer mixtures. Photopolymerization was affected by 0.2 wt% each of camphorquinone and N,N-dimethyl-p-toluidine. Wear (W) test was conducted in a toothbrushing abrasion machine (n=6) and quantified using a profilometer. Surface roughness (R) changes, before and after abrasion test, were determined using a rugosimeter. Microhardness (H) measurements were performed for dry and wet samples using a Knoop microindenter (n=6). Data were analyzed by one-way ANOVA and Tukey's test (alpha=0.05).


RESULTS
Incorporation of additives led to improved W and H values for bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA systems. Additives had no significant effect on the W and H changes of bis-GMA/CF(3)bis-GMA. With regard to R changes, additives produced decreased values for bis-GMA/CH(3)bis-GMA and bis-GMA/CF(3)bis-GMA composites. Bis-GMA/TEGDMA and bis-GMA/CH(3)bis-GMA copolymers with additives became smoother after abrasion test.


CONCLUSIONS
The findings correlate with additives ability to improve degree of conversion of some composites/copolymers thereby enhancing mechanical properties.
Prakki
Anuradha
A
Department of Operative Dentistry, Endodontics and Dental Materials, University of São Paulo, Bauru Dental School, Bauru, São Paulo 17043-170, Brazil.
Cilli
Renato
R
Mondelli
Rafael Francisco Lia
RF
Kalachandra
Sid
S
D000447:Aldehydes / Q000737:chemistry; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry*; D019554:Dental Restoration Wear; D003799:Dental Stress Analysis; D003931:Diacetyl / Q000737:chemistry; D006244:Hardness; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry; D013499:Surface Properties
D000447:Aldehydes; D011108:Polymers; D017438:Bisphenol A-Glycidyl Methacrylate; C005556:propionaldehyde; D003931:Diacetyl