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. 2015 Mar-Apr;18(2):154-8.
doi: 10.4103/0972-0707.153055.

Comparison of variation in the light curing cycle with a time gap and its effect on polymerization shrinkage, degree of conversion and microhardness of a nanohybrid composite

Arunajatesan Subbiya  1 , Newbegin Selvakumar Gold Pearlin Mary  1 , Malathi Suresh  1 , Paramasivam Vivekanandhan  1 , Malarvizhi Dhakshinamoorthy  1 , Vridhachalam Ganapathy Sukumaran  1
Affiliations

Comparison of variation in the light curing cycle with a time gap and its effect on polymerization shrinkage, degree of conversion and microhardness of a nanohybrid composite

Arunajatesan Subbiya et al. J Conserv Dent. 2015 Mar-Apr.

Abstract

Background: Giving a time gap and distance during curing can decrease the polymerization shrinkage.

Aim: To evaluate the effect of time gap and distance between the curing tip and restoration on the polymerization shrinkage, degree of monomer conversion (DOC), and microhardness of a nanohybrid composite.

Materials and methods: A total of 50 standardized cylindrical specimens (Z350, 3M ESPE) were fabricated using a brass mould. The curing was done in contact with the sample surface for 20 seconds in the control group. In the four experimental groups, curing was initiated at 1-cm distance, followed by variation in the time gap and the curing cycle. The polymerization shrinkage, DOC, microhardness was calculated.

Statistical analysis: One-way analysis of variance (ANOVA) and post hoc-Dunnett test were used to analyze the data.

Results: Curing at 1-cm distance for 10 seconds with a gap of 10 seconds and finishing the curing cycle with 20 seconds at 0 cm proved to be an appropriate technique to reduce the polymerization shrinkage without significantly affecting the DOC and microhardness.

Conclusion: A simple innovative modification of varying the distance of curing and a time gap in the curing cycle can decrease the polymerization shrinkage without affecting the DOC and microhardness.

Keywords: Curing distance; polymerization shrinkage; time gap.

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Conflict of interest statement

Conflict of Interest: None declared.

Figures

Figure 1
Figure 1
Schematic representation of the jig during fabrication and curing of samples
Figure 2
Figure 2
Degree of monomer conversion FTIR spectra
Figure 3
Figure 3
Polymerization shrinkage
Figure 4
Figure 4
Degree of conversion and microhardnes
See this image and copyright information in PMC

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