J Korean Acad Conserv Dent.  2007 May;32(3):248-259. 10.5395/JKACD.2007.32.3.248.

The effect of intermittent composite curing on marginal adaptation

• Yun YH
• Park SH

• KMID: 2175879
• DOI: http://doi.org/10.5395/JKACD.2007.32.3.248

Abstract

The aim of this research was to study the effect of intermittent polymerization on marginal adaptation by comparing the marginal adaptation of intermittently polymerized composite to that of continuously polymerized composite. The materials used for this study were Pyramid (Bisco Inc., Schaumburg, U.S.A.) and Heliomolar (Ivoclar Vivadent, Liechtenstein). The experiment was carried out in class II MOD cavities prepared in 48 extracted human maxillary premolars. The samples were divided into 4 groups by light curing method; group 1- continuous curing (60s light on with no light off); group 2- intermittent curing (cycles of 3s with 2s light on & 1s light off for 90s); group 3- intermittent curing (cycles of 2s with 1s light on & 1s light off for 120s); group 4- intermittent curing (cycles of 3s with 1s light on & 2s light off for 180s). Consequently the total amount of light energy radiated was same in all the groups. Each specimen went through thermo-mechanical loading (TML) which consisted of mechanical loading (720,000 cycles, 5.0 kg) with a speed of 120 rpm for 100 hours and thermocycling (6000 thermocycles of alternating water of 50degrees C and 55degrees C). The continuous margin (CM) (%) of the total margin and regional margins, occlusal enamel (OE), vertical enamel (VE), and cervical enamel (CE)) was measured before and after TML under a x 200 digital light microscope. Three-way ANOVA and Duncan's Multiple Range Test was performed at 95% level of confidence to test the effect of 3 variables on CM (%) of the total margin: light curing conditions, composite materials and effect of TML. In each group, One-way ANOVA and Duncan's Multiple Range Test was additionally performed to compare CM (%) of regions (OE, VE, CE). The results indicated that all the three variables were statistically significant (p < 0.05). Before TML, in groups using Pyramid, groups 3 and 4 showed higher CM (%) than groups 1 and 2, and in groups using Heliomolar, groups 3 and 4 showed higher CM (%) than group 1 (p < 0.05). After TML, in both Pyramid and Heliomolar groups, group 3 showed higher CM (%) than group 1 (p < 0.05). CM (%) of the regions are significantly different in each group (p < 0.05). Before TML, no statistical difference was found between groups within the VE and CE region. In the OE region, group 4 of Pyramid showed higher CM (%) than group 2, and groups 2 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). After TML, no statistical difference was found among groups within the VE and CE region. In the OE region, group 3 of Pyramid showed higher CM (%) than groups 1 and 2, and groups 2,3 and 4 of Heliomolar showed higher CM (%) than group 1 (p < 0.05). It was concluded that intermittent polymerization may be effective in reducing marginal gap formation.

Keyword

Intermittent polymerization; Marginal adaptation; Polymerization shrinkage; Light curing

MeSH Terms

Bicuspid
Dental Enamel
Humans
Polymerization
Polymers
Water
Polymers
Water

Figure

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  Figure 1 Schematic drawing of cavity preparation.

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  Figure 2 Upper view of the shutter appliance.

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  Figure 3 Metallic fixer with a tooth (R&B, Daejeon, Korea).

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  Figure 4 Gap on margin between the tooth and the resin (× 200).

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  Figure 5 Continuous margin between the tooth and the resin (× 200).

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  Figure 6 Chewing simulator (R&B, Daejeon, Korea).

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  Figure 7 Experimental procedures.

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  Figure 8 Marginal adaptations before loading in the regions (Pyramid). T: total margin, OE: occlusal enamel margin, VE: vertical enamel margin, CE: cervical enamel margin The letters represent the results of Duncan's Multiple Range Test.

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  Figure 9 Marginal adaptations before loading in the regions (Heliomolar). T: total margin, OE: occlusal enamel margin, VE: vertical enamel margin, CE: cervical enamel margin The letters represent the results of Duncan's Multiple Range Test.

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  Figure 10 Marginal adaptations after loading in the regions (Pyramid). T: total margin, OE: occlusal enamel margin, VE: vertical enamel margin, CE: cervical enamel margin The letters represent the results of Duncan's Multiple Range Test.

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  Figure 11 Marginal adaptations after loading in the regions (Heliomolar). T: total margin, OE: occlusal enamel margin, VE: vertical enamel margin, CE: cervical enamel margin The letters represent the results of Duncan's Multiple Range Test.

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