IADR Abstract Archives
Is there Degradation of Methacrylates In Acidic Acetone-Water Adhesive Formulation?
Objectives: Self-etching adhesives contain acidic and di-functional methacrylates and besides water - acetone or alcohol as solvent. Shelf life depends on the chemical stability of these monomers in solution. The degradation of methacrylates is widely discussed in literature. Our study focused on the stability of 4-META and UDMA during product shelf life of iBOND Universal (Kulzer GmbH).
Methods: Fresh iBOND Universal and expired iBOND Universal (stored at RT) were investigated by LC-MS, SBS and DC.
Liquid Chromatographic Mass Spectroscopy (LC-MS):
The amount of ingredients were monitored by LC-MS for fresh and expired iBOND Universal.
Shear Bond Strength Testing (SBS):
iBOND Universal was applied according to its instruction for use in self-etch mode on human dentine (n=8 for each group). Venus Diamond composite (A2) was bulk filled in cylindrical plastic molds and cured for 20s. Both, adhesive and composite were cured separately using a LED LCU (Translux WAVE, Kulzer). Shear bond strength was measured according ISO 29022 (Ultradent method) after 24 hours water storage at 37°C.
Degree of Conversion (DC) – FTIR measurement:
The DC was determined with FTIR-measurement by calculating 817cm-1 area before and after curing iBOND Universal using a Translux WAVE for 10s.
Results: For the di-functional monomer UDMA the analyzed content in formulation was unchanged between fresh and expired material.
For the acidic monomer 4-META minor degradation was found between fresh and expired material during room temperature storage.
Additional bond strength testing proved the unaffected performance of shortly expired material compared with initial values of fresh material. The same holds true for the degree of conversion which shows that the initiator system stays vital over the shelf life.
Conclusions: In iBOND Universal no degradation of UDMA was found during shelf life. For 4-META only minor degradation occurred, but with no relevance on product performance as proven by bond strength and degree of conversion.
Methods: Fresh iBOND Universal and expired iBOND Universal (stored at RT) were investigated by LC-MS, SBS and DC.
Liquid Chromatographic Mass Spectroscopy (LC-MS):
The amount of ingredients were monitored by LC-MS for fresh and expired iBOND Universal.
Shear Bond Strength Testing (SBS):
iBOND Universal was applied according to its instruction for use in self-etch mode on human dentine (n=8 for each group). Venus Diamond composite (A2) was bulk filled in cylindrical plastic molds and cured for 20s. Both, adhesive and composite were cured separately using a LED LCU (Translux WAVE, Kulzer). Shear bond strength was measured according ISO 29022 (Ultradent method) after 24 hours water storage at 37°C.
Degree of Conversion (DC) – FTIR measurement:
The DC was determined with FTIR-measurement by calculating 817cm-1 area before and after curing iBOND Universal using a Translux WAVE for 10s.
Results: For the di-functional monomer UDMA the analyzed content in formulation was unchanged between fresh and expired material.
For the acidic monomer 4-META minor degradation was found between fresh and expired material during room temperature storage.
Additional bond strength testing proved the unaffected performance of shortly expired material compared with initial values of fresh material. The same holds true for the degree of conversion which shows that the initiator system stays vital over the shelf life.
Conclusions: In iBOND Universal no degradation of UDMA was found during shelf life. For 4-META only minor degradation occurred, but with no relevance on product performance as proven by bond strength and degree of conversion.