The effect of resin thickness on polymerization characteristics of silorane-based composite resin.
OBJECTIVE
This study examined the influence of the resin thickness on the polymerization of silorane- and methacrylate-based composites.


METHODS
One silorane-based (Filtek P90, 3M ESPE) and two methacrylate-based (Filtek Z250 and Z350, 3M ESPE) composite resins were used. The number of photons were detected using a photodiode detector at the different thicknesses (thickness, 1, 2 and 3 mm) specimens. The microhardness of the top and bottom surfaces was measured (n = 15) using a Vickers hardness with 200 gf load and 15 sec dwell time conditions. The degree of conversion (DC) of the specimens was determined using Fourier transform infrared spectroscopy (FTIR). Scratched powder of each top and bottom surface of the specimen dissolved in ethanol for transmission FTIR spectroscopy. The refractive index was measured using a Abbe-type refractometer. To measure the polymerization shrinkage, a linometer was used. The results were analyzed using two-way ANOVA and Tukey's test at p < 0.05 level.


RESULTS
The silorane-based resin composite showed the lowest filler content and light attenuation among the specimens. P90 showed the highest values in the DC and the lowest microhardness at all depth. In the polymerization shrinkage, P90 showed a significantly lower shrinkage than the rest two resin products (p < 0.05). P90 showed a significantly lower refractive index than the remaining two resin products (p < 0.05).


CONCLUSIONS
DC, microhardness, polymerization rate and refractive index linearly decreased as specimen thickness linearly increased. P90 showed much less polymerization shrinkage compared to other specimens. P90, even though achieved the highest DC, showed the lowest microhardness and refractive index.
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
Sung-Ae
SA
Son
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
Hyoung-Mee
HM
Roh
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
Bock
B
Hur
Department of Dental Materials, School of Dentistry, Pusan National University, Yangsan, Korea.
Yong-Hoon
YH
Kwon
Department of Conservative Dentistry, School of Dentistry, Pusan National University, Yangsan, Korea.
Jeong-Kil
0000-0001-6333-8138
JK
Park
Polymerization; Resin thickness; Silorane-based composite resin