Effect of Composite Type and Placement Technique on Polymerization Shrinkage Stress Public Deposited

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  • March 19, 2019
Creator
  • Olafsson, Vilhelm
    • Affiliation: School of Dentistry, Department of Operative Dentistry
Abstract
  • Objective: To compare the polymerization shrinkage stress exerted on tooth structure by bulk-fill and conventional composite resins, via measuring cuspal strain. Materials and Methods: Fifty extracted maxillary premolars were mounted into phenolic rings and divided into 5 groups of 10. Strain gages were bonded to the buccal and lingual cusps. Proximal matrices were made with polyvinyl siloxane. Specimens received standardized MOD cavity preparations and strain gages were connected to a data acquisition unit. A 2-step self-etch adhesive (OptiBond XTR) was applied and the preparations were restored with materials placed and light-cured as follows: Filtek Supreme Ultra in 2mm increments (FSUI); Filtek Supreme Ultra in bulk (FSUB); SonicFill in bulk (SF); SureFil SDR flow in bulk, covered with a 2mm occlusal layer of Filtek Supreme Ultra (SDR/FSU); Tetric EvoCeram Bulk Fill in bulk (TEBF). A maximum strain value (in micro-strain, με) was obtained from each specimen. Data were subjected to one-way ANOVA and pairwise comparisons using LSMeans. Results: Mean maximum strain values and standard deviations were: FSUI: 730.6±104.8 με, FSUB: 1264.2±1418.8 με, SF: 539±75.9 με, SDR/FSU: 506.3±69.3 με, TEBF: 624.1±147.4 με. A significant difference was found between group FSUI and groups SF, SDR/FSU and TEBF (p=0.0002, p<0.0001 and p=0.0280, respectively), as well as between groups SDR/FSU and TEBF (p=0.0158). The FSUB group was excluded from the statistical analysis due to the high mean and standard deviation of the group, both the result of cuspal fractures due to shrinkage stress. Conclusions: The tested bulk-fill composite resins exerted less shrinkage stress on tooth structure than the incrementally placed conventional composite resin. Shrinkage stress generated by bulk-fill materials seems to be product-dependent. Bulk-filling with conventional composite resins is unpredictable and contraindicated.
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  • In Copyright
Advisor
  • Ritter, Andre
  • Ko, Ching-Chang
  • Swift, Edward
  • Donovan, Terence
  • Boushell, Lee
Degree
  • Master of Science
Degree granting institution
  • University of North Carolina at Chapel Hill Graduate School
Graduation year
  • 2015
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  • Chapel Hill, NC
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