J Korean Acad Conserv Dent.  2011 Nov;36(6):483-489. 10.5395/JKACD.2011.36.6.483.

Effect of glycerin on the surface hardness of composites after curing

• Park HH
• Lee IB

• KMID: 2176601
• DOI: http://doi.org/10.5395/JKACD.2011.36.6.483

Abstract

OBJECTIVES
The purpose of this study was to examine the effect of glycerin topical application on the surface hardness of composite after curing.
MATERIALS AND METHODS
A composite (Z-250, 3M ESPE) was packed into a disc-shaped brass mold and light cured according to one of the following protocols. Group 1 (control) was exposed to air and light cured for 40 sec, group 2 was covered with a Mylar strip and light cured for 40 sec, group 3 was surface coated with glycerin and light cured for 40 sec, and group 4 was exposed to air and light cured for 20 sec and then surface coated with glycerin and cured for additional 20 sec. Twenty specimens were prepared for each group. The surface hardnesses of specimens were measured with or without polishing. Five days later, the surface hardness of each specimen was measured again. Data were analyzed by three-way ANOVA and Tukey's post hoc tests.
RESULTS
The surface hardnesses of the unpolished specimens immediately after curing decreased in the following order: group 2 > 3 > 4 > 1. For the polished specimens, there was no significant difference among the groups. Within the same group, the hardness measured after five days was increased compared to that immediately after curing, and the polished specimens showed greater hardness than did the unpolished specimens.
CONCLUSIONS
The most effective way to increase the surface hardness of composite is polishing after curing. The uses of a Mylar strip or glycerin topical application before curing is recommended.

Keyword

Composite; Glycerin; Mylar strip; Polishing; Surface hardness

MeSH Terms

Copper
Fungi
Glycerol
Hardness
Light
Polyethylene Terephthalates
Zinc
Copper
Glycerol
Polyethylene Terephthalates
Zinc

Figure

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  Figure 1 Schematic illustrations of surface treatments and curing for the four groups.

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  Figure 2 Vickers surface hardnesses (HV) of the four groups according to surface polishing and measurement time. Group 1, light cured in air; Group 2, light cured with Mylar strip; Group 3, light cured with glycerin; Group 4, light cured in air + additional light cured with glycerin.

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