A standardized method to determine the effect of polymerization shrinkage on the cusp deflection and shrinkage induced built-in stress of class II tooth models.
In: Journal of the Mechanical Behavior of Biomedical Materials, Jg. 111 (2020-11-01), S. N.PAG
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Zugriff:
Using standardized aluminum tooth models, this study: 1) measured the deflection along the cusp wall of models with a Class II cavity restored using either bulk filling or horizontal incremental filling techniques, and 2) calculated the cusp deflection and built-in stress within the restored tooth models for both filling techniques using a finite element (FE) model. Standardized tooth models with Class II cavities 4 mm deep, 4 mm high and 6 mm wide were machined out of aluminum. The models were restored using Filtek Posterior Restorative A2 shade resin-based composite (RBC). Both bulk filling and horizontal incremental filling techniques were used to restore the tooth models. After photocuring for 20 s from a single peak wavelength light-curing unit (LCU) with a radiant exitance of 1.25 W/cm 2 , the deflection of the cusp wall surface was measured using a profilometer. A FE model was used to predict the cuspal deflection and built-in stress of the restored tooth models. The elastic modulus within the FE model was parameterized using cusp deflection data obtained on a bulk filled tooth model. An agreement was found between the measured and predicted cusp deflection only when considering partial stress relaxation within the first incremental layer for the two-layer incremental filling technique. The calculated built-in stress was significantly reduced within the RBC and along the cavity walls when the cavity was filled incrementally in a horizontal direction compared to when it was bulk filled, resulting in a significantly smaller cusp deflection. The FE model was first calibrated and then validated using measured cusp deflection data. Partial stress relaxation may play a significant role in the horizontal incremental filling technique. The model can be used to predict where the built-in stress within the tooth model occurs. This study explains why for a given RBC, a horizontal incremental filling and curing technique results in lower built-in stress within the restored tooth and lower cusp deflection compared to the bulk curing technique. Image 1 • Agreement between measured and predicted cuspal deflection along the model wall. • Bulk fill restoration led to greater cuspal deflection than for incremental filling. • Bulk fill restoration led to greatest built-in stress within the restored model. • Partial stress relaxation occurred within the first layer for incremental filling. [ABSTRACT FROM AUTHOR]
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Titel: |
A standardized method to determine the effect of polymerization shrinkage on the cusp deflection and shrinkage induced built-in stress of class II tooth models.
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Autor/in / Beteiligte Person: | Pottier, Jean Gabriel ; Gregg, Andrew ; Aregawi, Wondwosen ; Nasiri, Ehsan ; Fok, Alex ; Liu, Yi ; Kreplak, Laurent ; Price, Richard B. ; Labrie, Daniel |
Zeitschrift: | Journal of the Mechanical Behavior of Biomedical Materials, Jg. 111 (2020-11-01), S. N.PAG |
Veröffentlichung: | 2020 |
Medientyp: | academicJournal |
ISSN: | 1751-6161 (print) |
DOI: | 10.1016/j.jmbbm.2020.103987 |
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