Tooth deformation patterns in molars after composite restoration

Daranee Tantbirojn, Antheunis Versluis, Maria R. Pintado, Ralph DeLong, William H. Douglas

Research output: Contribution to journalArticlepeer-review

146 Scopus citations


Objective. Residual stresses from polymerization shrinkage in composite restorations deform a tooth. This may cause debonding, enamel crack propagation, and post-operative sensitivity. Deformation due to shrinkage has been measured previously at a few discrete points. The purpose of this study was to analyze cuspal deformation pattern of the occlusal portion of molars for various cavity types and sizes after restoration with a light-initiated composite. Methods. Five extracted human molars were successively prepared as Class I, Class II OM, large Class II OM, and large Class II MOD. The cavities were filled with a light-curing composite using a dentin adhesive system. The occlusal portion of the unrestored cavity and the restoration were digitized with a profilometer. The digitized data of the unrestored and restored tooth were used to calculate the cuspal contour change with Cumulus software. Deformation was visualized as a color contour map. Results. Cuspal deformation showed up in the contour map as a reduction of buccal and lingual contour perpendicular to the surface. Large Class II MODs exhibited the highest cuspal deformation, followed by large OM restorations. Cuspal deformations in Class I and small Class II OM restorations were not significantly different. Significance. When a composite restoration was cured, the surrounding tooth deformed due to polymerization shrinkage. Cavity type and size affected how much cusps moved inward as a result of polymerization shrinkage. This study quantified and visualized the pattern of cuspal deformation.

Original languageEnglish (US)
Pages (from-to)535-542
Number of pages8
JournalDental Materials
Issue number6
StatePublished - Jul 2004

Bibliographical note

Funding Information:
Based in part on abstract No. 499, presented at the 80th IADR meeting in San Diego, March 6–9, 2002. The authors thank Matt Heinzen for his assistance with the Cumulus analysis. Materials used in the study were supplied by 3M ESPE (St Paul, MN, USA). This study was supported by the Minnesota Dental Research Center for Biomaterials and Biomechanics, University of Minnesota, a Faculty Developing Grant, Chulalongkorn University, Bangkok, Thailand, and a grant from NIH/NIDR (R01-DE12225).


  • Composite restoration
  • Cusp flexure
  • Deformation
  • Polymerization shrinkage
  • Shrinkage stress


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