A new method to measure the linear polymerization shrinkage of composites using a particle tracking method with computer vision

In-Bog Lee; Sun-Hong Min; Deog-Gyu Seo; Sun-Young Kim; Youngchul Kwon

doi:10.5395/JKACD.2010.35.3.180

Journal List > J Korean Acad Conserv Dent > v.35(3) > 1056408

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Lee, Min, Seo, Kim, and Kwon: A new method to measure the linear polymerization shrinkage of composites using a particle tracking method with computer vision

Basic Research

Journal of Korean Academy of Conservative Dentistry

Journal of Korean Academy of Conservative Dentistry 2010; 35(3): 180-187.

Published online: 31 May 2010

DOI: https://doi.org/10.5395/JKACD.2010.35.3.180

A new method to measure the linear polymerization shrinkage of composites using a particle tracking method with computer vision

In-Bog Lee, Sun-Hong Min, Deog-Gyu Seo, Sun-Young Kim, Youngchul Kwon

Department of Conservative Dentistry, School of Dentistry, Seoul National University, Seoul, Korea.

Correspondence to: In-Bog Lee. Department of Conservative Dentistry & Dental Research Institute, School of Dentistry, Seoul National University 275-1 Yoengeon-Dong, Jongno-Gu, Seoul, 110-786, Korea. Tel: 82-2-2072-3953, Fax: 82-2-2072-3859, inboglee@snu.ac.kr

Received 22 April 2010 Revised 25 April 2010 Accepted 26 April 2010

Abstract

Since the introduction of restorative dental composites, their physical properties have been significantly improved. However, polymerization shrinkage is still a major drawback. Many efforts have been made to develop a low shrinking composite, and silorane-based composites have recently been introduced into the market. In addition, many different methods have been developed to measure the polymerization shrinkage.

In this study, we developed a new method to measure the linear polymerization shrinkage of composites without direct contact to a specimen using a particle tracking method with computer vision. The shrinkage kinetics of a commercial silorane-based composite (P90) and two conventional methacrylate-based composites (Z250 and Z350) were investigated and compared. The results were as follows:

The linear shrinkage of composites was 0.33-1.41%. Shrinkage was lowest for the silorane-based (P90) composite, and highest for the flowable Z350 composite.
The new instrument was able to measure the true linear shrinkage of composites in real time without sensitivity to the specimen preparation and geometry.

Keywords: Composites, Silorane, Linear polymerization shrinkage, Computer vision, Particle tracking

Figures and Tables

Figure 1

Schematic diagram of computer vision system.

Figure 2

Specimen preparation for linear shrinkage measurement using computer vision.

Figure 3

A captured original image (left) and a binarized image (right) after filtering. The position of an object is determined by the area center method.

Figure 4

Algorithm to get the coordinate of an interesting particle from an image.

Figure 5

Linear shrinkage curves of composites as a function of time.

Figure 6

Linear shrinkage of composites at 10 min after curing.

Table 1

Composite resins used in this study.

Table 2

Linear polymerization shrinkage measured and calculated volume shrinkage of composites at 10 min.

Number in parenthesis is standard deviation.

Calculated volume shrinkage = 3× measured linear shrinkage.

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