Cuspal flexure of composite-restored typodont teeth and correlation with polymerization shrinkage values

Taylor Enochs; Anne E Hill; Cassandra E Worley; Crisnicaw Veríssimo; Daranee Tantbirojn; Antheunis Versluis

doi:10.1016/j.dental.2017.09.019

Cuspal flexure of composite-restored typodont teeth and correlation with polymerization shrinkage values

Dent Mater. 2018 Jan;34(1):152-160. doi: 10.1016/j.dental.2017.09.019. Epub 2017 Oct 20.

Authors

Taylor Enochs¹, Anne E Hill², Cassandra E Worley³, Crisnicaw Veríssimo⁴, Daranee Tantbirojn⁵, Antheunis Versluis⁶

Affiliations

¹ College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA. Electronic address: tenochs1@uthsc.edu.
² Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA. Electronic address: ahill73@uthsc.edu.
³ Private Practice, Nashville, TN, USA. Electronic address: cassandraleding@gmail.com.
⁴ Department of Restorative Dentistry, University of Uberaba, Uberaba, MG, Brazil. Electronic address: crisnicaw@hotmail.com.
⁵ Department of Restorative Dentistry, College of Dentistry, University of Tennessee Health Science Center, Memphis, TN, USA. Electronic address: dverslui@uthsc.edu.
⁶ Department of Bioscience Research, College of Dentistry, University of Tennessee Health Science Center, 875 Union Ave, Memphis, TN 38163, USA. Electronic address: antheun@uthsc.edu.

PMID: 29061285
DOI: 10.1016/j.dental.2017.09.019

Abstract

Objective: The relationship between post-gel shrinkage, total shrinkage, and cuspal flexure was examined. Cuspal flexure was measured on restored typodont teeth, which offered a standardized tooth shape for comparison of shrinkage stress effects among restorative composites.

Methods: Six restorative composites were compared (Filtek LS, Venus Flowable, Tetric EvoCeram, Filtek Flowable, Esthet-X, and Filtek Supreme). Total shrinkage was determined from changes in projected surface area before and after polymerization (n=10). Post-gel shrinkage was determined with a biaxial strain gauge that measured strain development during polymerization (n=10). Cuspal flexure was determined using typodont maxillary second premolars with standard MOD slot preparation (n=10). Flexure was determined by comparing the three-dimensionally scanned cuspal surfaces before and after restoration. Restoration bonding to the typodont cavity was achieved by sandblasting and adhesive application. Bond integrity was verified by measuring dye penetration. Results were analyzed using ANOVA and Student-Newman-Keuls post hoc test (significance level 0.05). Pearson was used for correlations.

Results: Total and post-gel shrinkage were significant different for all composites (t-test; P<0.001). Depending on the composite, only 9-41% of the total shrinkage was recorded as post-gel shrinkage. Bond integrity of restored typodont teeth was 96-99%. Cuspal flexure correlated strongly with post-gel shrinkage, but there was no correlation with total shrinkage.

Significance: Cuspal flexure of restored typodont teeth showed the effect of shrinkage stress caused by polymerizing composite restorations, ensuring standardization while maintaining the effects of tooth/cavity geometry. Post-gel shrinkage gave a good indication to screen composites for the stress they may generate; total shrinkage had no direct correlation with stress.

Keywords: Composites; Cuspal flexure; Restorations; Shrinkage; Typodont tooth.

Publication types

Comparative Study
Research Support, Non-U.S. Gov't

MeSH terms

Bicuspid
Composite Resins / chemistry*
Dental Marginal Adaptation
Dental Restoration Failure
Dental Restoration, Permanent / methods*
Imaging, Three-Dimensional
In Vitro Techniques
Materials Testing
Pliability
Polymerization
Surface Properties

Substances

Composite Resins
Esthet-X
Filtek Flow
Filtek LS Low Shrink resin
Filtek Supreme Ultra
Tetric EvoCeram