TY - JOUR
T1 - Shrinkage forces due to polymerization of light-cured dental composite resin in cavities
AU - Arakawa, Kazuo
N1 - Funding Information:
This work was supported by the Ministry of Education, Culture, Sports, Science and Technology (MEXT) Japan , as part of the “Highly-Functional Interfaces Science: Innovation of Biomaterials with Highly Functional Interface to Host and Parasite” project. The author would like to express his gratitude to Mr. T. Mada from Kyushu University for his help in performing the experiments, Mr. S. Yamaguchi and Mr. Y. Takahata from Kuraray Medical Ltd. for their useful advice and for supplying the materials.
PY - 2010/12
Y1 - 2010/12
N2 - A new method has been developed for determining shrinkage forces due to polymerization of light-cured dental composite resin in artificial cylindrical cavities. The cavities were fabricated in stainless steel plates, and shrinkage forces were measured using a load cell inserted from the rear of the plate in place of the floor of the cavity. The cavities were 3 mm in diameter, and depths varied from 0.5 to 3.5 mm to study the effect of light intensity. Cavities were filled with a composite resin after being prepared with a bonding agent and were then irradiated for 20 s with a light-curing unit at a power of 300 mW/cm2. To study the effects of boundaries, two conditions were employed: a free surface condition without any restriction on the top surface of the cavity, and a constrained surface condition in which the top surface of the resin was bonded to a 1 mm thick transparent polymethyl methacrylate (PMMA) plate. The shrinkage forces were measured as functions of time and the cavity depth, and the following results were obtained. For both conditions, the force increased with time, mostly during the irradiation stage (20 s), and then increased slightly after the irradiation. The force measured at 300 s increased gradually with the cavity depth and exhibited a maximum value before decreasing gradually. The cavities with constrained surfaces yielded much greater shrinkage forces for any given cavity depth than those with free surface conditions.
AB - A new method has been developed for determining shrinkage forces due to polymerization of light-cured dental composite resin in artificial cylindrical cavities. The cavities were fabricated in stainless steel plates, and shrinkage forces were measured using a load cell inserted from the rear of the plate in place of the floor of the cavity. The cavities were 3 mm in diameter, and depths varied from 0.5 to 3.5 mm to study the effect of light intensity. Cavities were filled with a composite resin after being prepared with a bonding agent and were then irradiated for 20 s with a light-curing unit at a power of 300 mW/cm2. To study the effects of boundaries, two conditions were employed: a free surface condition without any restriction on the top surface of the cavity, and a constrained surface condition in which the top surface of the resin was bonded to a 1 mm thick transparent polymethyl methacrylate (PMMA) plate. The shrinkage forces were measured as functions of time and the cavity depth, and the following results were obtained. For both conditions, the force increased with time, mostly during the irradiation stage (20 s), and then increased slightly after the irradiation. The force measured at 300 s increased gradually with the cavity depth and exhibited a maximum value before decreasing gradually. The cavities with constrained surfaces yielded much greater shrinkage forces for any given cavity depth than those with free surface conditions.
UR - http://www.scopus.com/inward/record.url?scp=77958574981&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=77958574981&partnerID=8YFLogxK
U2 - 10.1016/j.polymertesting.2010.09.008
DO - 10.1016/j.polymertesting.2010.09.008
M3 - Article
AN - SCOPUS:77958574981
SN - 0142-9418
VL - 29
SP - 1052
EP - 1056
JO - Polymer Testing
JF - Polymer Testing
IS - 8
ER -