Abstract
Objective: 1) to determine the moment during the redox polymerization reaction of dual cure cements at which to photo-activate the material in order to reduce the polymerization stress, and 2) to evaluate possible synergistic effects between adding chain transfer agents and delayed photo-activation. Methods: The two pastes of an experimental dual-cure material were mixed, and the polymerization kinetics of the redox phase was followed. The moment when the material reached its maximum rate of redox polymerization (MRRP) of cement was determined. The degree of conversion (DC) and maximum rates of polymerization (Rpmax) were assessed for materials where: the photoactivation immediately followed material mixing, at MRRP, 1min before and 1min after MRRP. Thio-urethane (TU) additives were synthesized and added to the cement (20% wt), which was then cured under the same conditions. The polymerization kinetics was evaluated for both cements photo-activated immediately or at MRRP, followed by measurements of polymerization stress, flexural strength (FS) and elastic modulus (EM). Knoop hardness was measured before and after ethanol storage. Results: Photo-activating the cement at or after MRRP reduced the Rpmax and the polymerization stress. Addition of TU promoted additional and more significant reduction, while not affecting the Rpmax. Greater hardness loss was observed for cements with TU, but the final hardness was similar for all experimental conditions. Addition of TU slightly reduced the EM and did not affect the FS. Conclusion: Delayed photo-activation and addition of TU significantly reduce the polymerization stress of dual-cured cements.
| Original language | English (US) |
|---|---|
| Journal | Journal of Dentistry |
| DOIs | |
| State | Accepted/In press - May 3 2017 |
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Keywords
- Polymerization stress
- Pre-polymerized additives
- Resin cement
ASJC Scopus subject areas
- Dentistry(all)
Cite this
Delayed photo-activation and addition of thio-urethane : Impact on polymerization kinetics and stress of dual-cured resin cements. / Faria-e-Silva, André L.; Pfeifer, Carmem.
In: Journal of Dentistry, 03.05.2017.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Delayed photo-activation and addition of thio-urethane
T2 - Impact on polymerization kinetics and stress of dual-cured resin cements
AU - Faria-e-Silva, André L.
AU - Pfeifer, Carmem
PY - 2017/5/3
Y1 - 2017/5/3
N2 - Objective: 1) to determine the moment during the redox polymerization reaction of dual cure cements at which to photo-activate the material in order to reduce the polymerization stress, and 2) to evaluate possible synergistic effects between adding chain transfer agents and delayed photo-activation. Methods: The two pastes of an experimental dual-cure material were mixed, and the polymerization kinetics of the redox phase was followed. The moment when the material reached its maximum rate of redox polymerization (MRRP) of cement was determined. The degree of conversion (DC) and maximum rates of polymerization (Rpmax) were assessed for materials where: the photoactivation immediately followed material mixing, at MRRP, 1min before and 1min after MRRP. Thio-urethane (TU) additives were synthesized and added to the cement (20% wt), which was then cured under the same conditions. The polymerization kinetics was evaluated for both cements photo-activated immediately or at MRRP, followed by measurements of polymerization stress, flexural strength (FS) and elastic modulus (EM). Knoop hardness was measured before and after ethanol storage. Results: Photo-activating the cement at or after MRRP reduced the Rpmax and the polymerization stress. Addition of TU promoted additional and more significant reduction, while not affecting the Rpmax. Greater hardness loss was observed for cements with TU, but the final hardness was similar for all experimental conditions. Addition of TU slightly reduced the EM and did not affect the FS. Conclusion: Delayed photo-activation and addition of TU significantly reduce the polymerization stress of dual-cured cements.
AB - Objective: 1) to determine the moment during the redox polymerization reaction of dual cure cements at which to photo-activate the material in order to reduce the polymerization stress, and 2) to evaluate possible synergistic effects between adding chain transfer agents and delayed photo-activation. Methods: The two pastes of an experimental dual-cure material were mixed, and the polymerization kinetics of the redox phase was followed. The moment when the material reached its maximum rate of redox polymerization (MRRP) of cement was determined. The degree of conversion (DC) and maximum rates of polymerization (Rpmax) were assessed for materials where: the photoactivation immediately followed material mixing, at MRRP, 1min before and 1min after MRRP. Thio-urethane (TU) additives were synthesized and added to the cement (20% wt), which was then cured under the same conditions. The polymerization kinetics was evaluated for both cements photo-activated immediately or at MRRP, followed by measurements of polymerization stress, flexural strength (FS) and elastic modulus (EM). Knoop hardness was measured before and after ethanol storage. Results: Photo-activating the cement at or after MRRP reduced the Rpmax and the polymerization stress. Addition of TU promoted additional and more significant reduction, while not affecting the Rpmax. Greater hardness loss was observed for cements with TU, but the final hardness was similar for all experimental conditions. Addition of TU slightly reduced the EM and did not affect the FS. Conclusion: Delayed photo-activation and addition of TU significantly reduce the polymerization stress of dual-cured cements.
KW - Polymerization stress
KW - Pre-polymerized additives
KW - Resin cement
UR - http://www.scopus.com/inward/record.url?scp=85026745296&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85026745296&partnerID=8YFLogxK
U2 - 10.1016/j.jdent.2017.07.014
DO - 10.1016/j.jdent.2017.07.014
M3 - Article
C2 - 28750778
AN - SCOPUS:85026745296
JO - Journal of Dentistry
JF - Journal of Dentistry
SN - 0300-5712
ER -