title: 3D full field strain analysis of polymerization shrinkage in a dental composite.
abstract: OBJECTIVE
  The objective of this research was to study the polymerization shrinkage in a dental composite using 3D digital image correlation (DIC).
  
  
  METHODS
  Using 2 coupled cameras, digital images were taken of bar-shaped composite (Premise Universal Composite; Kerr) specimens before light curing and after for 10 min. Three-dimensional DIC was used to assess in-plane and out-of-plane deformations associated with polymerization shrinkage.
  
  
  RESULTS
  The results show the polymerization shrinkage to be highly variable with the peak values occurring 0.6-0.8mm away from the surface. Volumetric shrinkage began to significantly decrease at 3.2mm from the specimen surface and reached a minimum at 4mm within the composite. Approximately 25-30% of the strain registered at 5 min occurred after light-activation. Application of 3D DIC dental applications can be performed without the need for assumptions on the deformation field.
  
  
  CONCLUSIONS
  Understanding the local deformations and strain fields from the initial polymerization shrinkage can lead to a better understanding of the composite material and interaction with surrounding tooth structure, aiding in their further development and clinical prognosis.
authors.affiliation: Department of Civil Engineering & Mechanics, University of Wisconsin-Milwaukee, WI 53211, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Martinsen
authors.forename: Rani F
authors.initials: RF
authors.lastname: El-Hajjar
authors.forename: David W
authors.initials: DW
authors.lastname: Berzins
mesh_terms: D000465:Algorithms; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D055115:Light-Curing of Dental Adhesives / Q000379:methods; D010781:Photography; D058105:Polymerization; D013314:Stress, Mechanical; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials; C507210:premise composite resin
keywords: Dental composite stress analysis; Dental composites; Digital Image Correlation; Polymerization; Polymerization shrinkage; Strain