Assessment of polymerization contraction stress of three composite resins.
OBJECTIVE
The purpose of this study was to measure the development of contraction stress of three composite resin restorative materials during photo-polymerization: a micro-hybrid composite (Filtek Z250, 3M ESPE, St. Paul, MN, USA); a nano-filled composite (Filtek Supreme, 3M ESPE, St. Paul, MN, USA); and a low-shrinkage composite (AElite LS, Bisco Inc., Schaumburg, IL, USA).


METHODS
Curing shrinkage stress was measured using a stress-analyzer. Composites were polymerized with a halogen-curing unit (VIP, Bisco Inc., Schaumburg, IL, USA) for 40 s. The contraction force (N) generated during polymerization was continuously recorded for 150 s after photo-initiation. Contraction stress (MPa) was calculated at 20, 40, 60 and 150 s. Data were statistically analyzed.


RESULTS
The low-shrinkage composite AElite LS exhibited the lowest stress values compared to other materials (p<0.05). Statistical analysis did not show significant differences between Filtek Z250 and Filtek Supreme.


CONCLUSIONS
The low-shrinkage composite showed lower contraction stress than micro-hybrid and nano-filled composite. Ideally, non-shrinking resins would represent the ultimate solution to overcome polymerization contraction and stress-related problems.
Cadenaro
Milena
M
Department of Biomedicine, Division of Dentistry and Biomaterials, University of Trieste, Via Stuparich 1, I-34129 Trieste, Italy.
Biasotto
Matteo
M
Scuor
Nicola
N
Breschi
Lorenzo
L
Davidson
Carel L
CL
Di Lenarda
Roberto
R
D003188:Composite Resins / Q000737:chemistry* / Q000528:radiation effects; D003764:Dental Materials / Q000737:chemistry* / Q000528:radiation effects; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008027:Light; D008422:Materials Testing; D011108:Polymers / Q000737:chemistry / Q000528:radiation effects; D013314:Stress, Mechanical; D013696:Temperature; D013997:Time Factors
C485363:Aelite LS; D003188:Composite Resins; D003764:Dental Materials; C474035:Filtek Supreme; C444701:Filtek Z250; D011108:Polymers