There is mounting clinical and laboratory evidence that the flexure of the dental crown following intracoronal composite shrinkage may be related to a number of clinical and biological phenomena, including early dentin bond failure, crack initiation and propagation, and possibly post-operative symptoms. A major goal of this proposal is the determination of the extent and possible clinical significance of these effects in an in vitro experimental model with servohydraulic control and direct strain read out from intact and restored human teeth. The hypothesis to be tested is that polymerization contraction of composite restorative materials results in decreased longevity of the restoration due to internal stress development, early dentin bond failure, alterations in occlusal contacts, and crack initiation and propagation of the natural tooth structure. The biomechanics of composite polymerization kinetics and its effects on tooth structure will be investigated by: 1) strain gage characterization of polymerization contraction strain and stress, 2) evaluation of the deformation of the composite restored tooth through strain gage measurement, 3) evaluation of the response of the composite restored tooth during simulated occlusal loading in an artificial mouth and 4) validated finite element analysis of the restored tooth complex. It is hoped that these studies will increase the knowledge base of the biomechanical interactions internally, at significant boundaries and on the surface of the restored tooth complex. From this, new criteria in materials development can be determined and a sounder basis for materials choice, treatment planning, and fabrication of intracoronal restorations can be developed.

Agency
National Institute of Health (NIH)
Institute
National Institute of Dental & Craniofacial Research (NIDCR)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29DE009431-02
Application #
3462314
Study Section
Oral Biology and Medicine Subcommittee 1 (OBM)
Project Start
1992-08-01
Project End
1994-06-30
Budget Start
1993-08-01
Budget End
1994-06-30
Support Year
2
Fiscal Year
1993
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Type
Schools of Dentistry
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Sakaguchi, R L; Berge, H X (1998) Reduced light energy density decreases post-gel contraction while maintaining degree of conversion in composites. J Dent 26:695-700
Sakaguchi, R L; Ferracane, J L (1998) Stress transfer from polymerization shrinkage of a chemical-cured composite bonded to a pre-cast composite substrate. Dent Mater 14:106-11
Sakaguchi, R L; Versluis, A; Douglas, W H (1997) Analysis of strain gage method for measurement of post-gel shrinkage in resin composites. Dent Mater 13:233-9
Versluis, A; Douglas, W H; Sakaguchi, R L (1996) Thermal expansion coefficient of dental composites measured with strain gauges. Dent Mater 12:290-4
Versluis, A; Douglas, W H; Cross, M et al. (1996) Does an incremental filling technique reduce polymerization shrinkage stresses? J Dent Res 75:871-8