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Hydrolytic stability of self-etching adhesive systems.
Ulrich Salz1, Jörg Zimmermann, Frank Zeuner
1Research and Development, Ivoclar Vivadent, Schaan, Liechtenstein. Ulrich.salz@ivoclarvivadent.com
The Journal of Adhesive Dentistry
|August 2, 2005
Summary
New acrylic monomers demonstrate superior hydrolytic stability compared to conventional methacrylates, enhancing the longevity and performance of dental adhesives. This breakthrough improves the shelf life and effectiveness of self-etching enamel-dentin primers.
Area of Science:
- Dental Materials Science
- Polymer Chemistry
- Adhesive Dentistry
Background:
- Conventional methacrylate monomers in dental adhesives are susceptible to hydrolysis, compromising bond strength and shelf life.
- Acidic aqueous conditions accelerate the degradation of ester-based methacrylate monomers.
- Developing hydrolytically stable monomers is crucial for improving the durability of dental restorative materials.
Purpose of the Study:
- To evaluate the hydrolytic stability of novel acrylic ether phosphonic acid and bis(acrylamide) monomers.
- To compare the stability of these new monomers against conventional methacrylates under acidic conditions.
- To assess the potential of these monomers in self-etching enamel-dentin primers through shear bond strength testing.
Main Methods:
- Synthesis and characterization of acrylic ether phosphonic acid and bis(acrylamide) monomers using NMR spectroscopy.
- Hydrolytic stability assessment via NMR spectroscopy and HPLC, comparing with MDP, 4-META, TEGDMA, and GDMA.
- Shear bond strength testing of primers formulated with new monomers against commercial total-etch and self-etch systems, with long-term aging studies.
Main Results:
- Conventional methacrylate monomers showed significant degradation (up to 90%) under acidic aqueous conditions after 16 weeks at 42°C.
- The newly synthesized acrylic phosphonic acid and bis(acrylamide) monomers exhibited excellent stability under the same harsh conditions.
- A self-etching primer incorporating these stable monomers demonstrated high shear bond strength values to enamel and dentin.
Conclusions:
- Ether- or amide-linked polymerizable analogues offer improved hydrolytic stability over conventional ester derivatives in dental adhesives.
- The use of these novel, stable monomers can significantly increase the shelf life of dental adhesives.
- Enhanced hydrolytic stability of comonomers promises improved performance and durability of adhesive bonds in dental applications.