IADR Abstract Archives
Chemical Interaction of a Novel Functional Monomer With Hydroxyapatite/Dentin
Objectives: The functional monomer 10-methacryloxydecyl dihydrogen phosphate (10-MDP) ionically bonds to hydroxyapatite (HAp). The low dissolution rate of 10-MDP’s calcium salt in water confirmed its bond stability. However, more hydrolysis-resistant functional monomers are needed to improve bond durability. Our previous study revealed a favorable bonding potential of the fluoro-carbon monomer 6-methacryloyloxy-2,2,3,3,4,4,5,5-octafluorohexyl dihydrogen phosphate (MF8P) to dentin. Here, we aimed to unravel the adhesive mechanism of the 12-carbon analog 8-methacryloyloxy-2,2,3,3,4,4,5,5,6,6,7,7-dodecafluorooctyl dihydrogen phosphate (MF12P; Kuraray Noritake: KN) to HAp and dentin using NMR and XRD, as well as to determine its bonding potential to dentin using a micro-tensile bond strength (µTBS) approach.
Methods: Synthetic HAp particles (Pentax) were added to 15wt% MF12P ethanol solution for 5 min, followed by washing with ethanol and air-drying. The MF12P-reacted powder was analyzed using solid-state 31P CP-MAS and 1H MAS NMR. XRD was used to analyze the 20-sec interaction of 15wt% MF12P in ethanol with dentin. In order to measure the µTBS, 15wt% MF12P ethanol solution, containing 1wt% photo-initiator, was applied on 600-grit SiC-ground human dentin for 20 sec. After air drying, Clearfil AP-X (KN) composite was bonded to dentin using the 10-MDP-free Clearfil SE Bond (KN). The µTBS was measured after 24 h (‘immediate’) and 150,000 thermocycles (‘aged’). The resultant adhesive-dentin interface was ultra-structurally characterized using TEM. 10-MDP and MF8P were used as controls.
Results: NMR confirmed rapid adsorption of all monomers onto HAp. XRD of the monomers applied onto dentin revealed three characteristic peaks, representing the respective monomer_Ca-salt formation. While no significant difference in ‘immediate’ µTBS was found among the three monomers, the ‘aged’ µTBS remained more stable for MF12P (Table). TEM confirmed tight adhesive-dentin interfaces with clear monomer_Ca-salt formation.
Conclusions: The functional monomer MF12P readily adsorbed onto HAp and resulted in more stable bonding, confirming MF12P is a good candidate functional monomer for durable bonding.
Methods: Synthetic HAp particles (Pentax) were added to 15wt% MF12P ethanol solution for 5 min, followed by washing with ethanol and air-drying. The MF12P-reacted powder was analyzed using solid-state 31P CP-MAS and 1H MAS NMR. XRD was used to analyze the 20-sec interaction of 15wt% MF12P in ethanol with dentin. In order to measure the µTBS, 15wt% MF12P ethanol solution, containing 1wt% photo-initiator, was applied on 600-grit SiC-ground human dentin for 20 sec. After air drying, Clearfil AP-X (KN) composite was bonded to dentin using the 10-MDP-free Clearfil SE Bond (KN). The µTBS was measured after 24 h (‘immediate’) and 150,000 thermocycles (‘aged’). The resultant adhesive-dentin interface was ultra-structurally characterized using TEM. 10-MDP and MF8P were used as controls.
Results: NMR confirmed rapid adsorption of all monomers onto HAp. XRD of the monomers applied onto dentin revealed three characteristic peaks, representing the respective monomer_Ca-salt formation. While no significant difference in ‘immediate’ µTBS was found among the three monomers, the ‘aged’ µTBS remained more stable for MF12P (Table). TEM confirmed tight adhesive-dentin interfaces with clear monomer_Ca-salt formation.
Conclusions: The functional monomer MF12P readily adsorbed onto HAp and resulted in more stable bonding, confirming MF12P is a good candidate functional monomer for durable bonding.