TY - JOUR
T1 - Do low-shrink composites reduce polymerization shrinkage effects?
AU - Tantbirojn, D.
AU - Pfeifer, C. S.
AU - Braga, R. R.
AU - Versluis, A.
N1 - Funding Information:
This study was supported by a Non-Tenured Faculty Grant (3M Foundation) and materials donated by GC. We gratefully acknowledge technical support from David G. Augustson, digitization advice from Dr. Ralph DeLong, and silorane conversion measurement help from Dr. Jeffrey W. Stansbury. Part of this study was presented at the 2010 IADR General Session in Barcelona, Spain: Versluis A, Tantbirojn D, DeLong R (2010) . Coronal deformation in premolars restored with low-shrink composites. J Dent Res 89(Spec Issue B):abstract 3064, www.dentalresearch.org .
PY - 2011/5
Y1 - 2011/5
N2 - Progress in polymer science has led to continuous reduction of polymerization shrinkage, exemplified by a new generation of "low-shrink composites". The common inference that shrinkage stress effects will be reduced in teeth restored with such restoratives with lower shrinkage was tested in extracted human premolars. Mesio-occluso-distal slot-shaped cavities were cut and restored with a conventional (SupremePlus) or low-shrink (RefleXions, Premise, Kalore, and LS) composite (N = 5). We digitized the coronal surfaces before and 10 min after restoration to determine cuspal deflection from the buccal and lingual volume change/area. We also determined the main properties involved (total shrinkage, post-gel shrinkage, degree of conversion, and elastic modulus), as well as microleakage, to verify adequate bonding. It was shown that, due to shrinkage stresses, buccal and lingual surfaces pulled inward after restoration (9-14 microns). Only Kalore and LS resulted in significantly lower tooth deformation (ANOVA/Student-Newman-Keuls post hoc, p = 0.05). The other two low-shrink composites, despite having the lowest and highest total shrinkage values, did not cause significant differences in cuspal deflection. Deflection seemed most related to the combination of post-gel shrinkage and elastic modulus. Therefore, even for significantly lower total shrinkage values, shrinkage stress is not necessarily reduced.
AB - Progress in polymer science has led to continuous reduction of polymerization shrinkage, exemplified by a new generation of "low-shrink composites". The common inference that shrinkage stress effects will be reduced in teeth restored with such restoratives with lower shrinkage was tested in extracted human premolars. Mesio-occluso-distal slot-shaped cavities were cut and restored with a conventional (SupremePlus) or low-shrink (RefleXions, Premise, Kalore, and LS) composite (N = 5). We digitized the coronal surfaces before and 10 min after restoration to determine cuspal deflection from the buccal and lingual volume change/area. We also determined the main properties involved (total shrinkage, post-gel shrinkage, degree of conversion, and elastic modulus), as well as microleakage, to verify adequate bonding. It was shown that, due to shrinkage stresses, buccal and lingual surfaces pulled inward after restoration (9-14 microns). Only Kalore and LS resulted in significantly lower tooth deformation (ANOVA/Student-Newman-Keuls post hoc, p = 0.05). The other two low-shrink composites, despite having the lowest and highest total shrinkage values, did not cause significant differences in cuspal deflection. Deflection seemed most related to the combination of post-gel shrinkage and elastic modulus. Therefore, even for significantly lower total shrinkage values, shrinkage stress is not necessarily reduced.
KW - cusp flexure
KW - elastic modulus
KW - polymerization shrinkage
KW - tooth deformation
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U2 - 10.1177/0022034510396217
DO - 10.1177/0022034510396217
M3 - Article
C2 - 21282725
AN - SCOPUS:79955872316
SN - 0022-0345
VL - 90
SP - 596
EP - 601
JO - Journal of dental research
JF - Journal of dental research
IS - 5
ER -