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Novel Dental Cements Based On Cyanoacrylates

Novel Dental Cements Based On Cyanoacrylates. Susannah Tomlinson March 2007 Bill Hooper, Ken Evans, Oana Ghita. Aim/Overview. Aim: to study the setting characteristics of new cements using various techniques Cement compositions Applications Oscillating rheometry

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Novel Dental Cements Based On Cyanoacrylates

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  1. Novel Dental CementsBased On Cyanoacrylates Susannah Tomlinson March 2007 Bill Hooper, Ken Evans, Oana Ghita

  2. Aim/Overview Aim: to study the setting characteristics of new cements using various techniques • Cement compositions • Applications • Oscillating rheometry • Mid- and near-IR spectroscopy • Vickers hardness • Shear bond strength

  3. Cement Compositions (A.J.Bennetts, C.G. Wilde, and A.D. Wilson, UK patent GB 2386121) • Hybrids • Cyanoacrylate + GIC (acid solution + basic glass) • Set by: (1) cyanoacrylate polymerisation (2) GIC acid-base reaction • Similar to resin-modified GICs • Composites • Cyanoacrylate adhesive + acid-coated fillers (e.g. GIC (glass), hydroxyapatite, or wollastonite powders, etc.,coated with tartaric acid and poly(acrylic acid)) • Set by cyanoacrylate polymerisation

  4. Cyanoacrylates • Ethyl cyanoacrylate (R=C2H5) • n-butyl cyanoacrylate (R=C4H9) • Polymerisation initiated by water • ideal in oral environments Incorporation of cyanoacrylate is expected to improve adhesion

  5. Applications General adhesive Pre-fabricated surgical implants or prostheses Dental adhesives, restorative materials, luting agents, liners, and as endodontic cements

  6. Oscillating Rheometry Wilson rheometer Cement placed between one stationary plate and one oscillating Plates coated with GIC to prevent irreversible bonding Working time: when oscillation amplitude is 95% of original Setting time: when oscillation amplitude is 5% of original Ideal setting characteristics: high working:setting time ratio (close to 1) Time Oscillation amplitude

  7. Rheometry results All new cement formulations have similar or higher working-time:setting-time ratios than GIC

  8. Mid-IR and near-IR spectroscopy • Near-IR (transflectance set-up): • clear peaks related to cyanoacrylate • Mid-IR (diamond ATR): • clear peaks related to GIC

  9. Typical mid-IR spectra of hybrid cement Shows that the cyanoacrylate polymerisation is rapid Slow GIC reaction, continuing after cyanoacrylate polymerisation complete

  10. Extent of cyanoacrylate cure from near-IR Cyanoacrylate polymerisation rapid in hybrid, in agreement with mid-IR For the composite, shape of cyanoacrylate polymerisation profile possibly due to the limited amount of water adsorbed on the powder surface

  11. Ethyl cyanoacrylate/GIC hybrid Cyanoacrylate component 100% cured in ~10 min, which suggests that the increasing hardness is due to the continuing GIC acid-base reaction

  12. Ethyl cyanoacrylate/hydroxyapatite composite Hardness of composite correlated with cyanoacrylate extent of cure

  13. Shear bond strength to Al* *ASTM D 1002-05 using a single-lap-joint design

  14. Summary • New cements show favourable handling characteristics (high W:S time ratio) • In hybrid: cyanoacrylate polymerisation is rapid, while GIC reactions are slower, and continue after polymerisation is complete • Hybrid shows improved bond strength to metal • next experiments will study bonding to teeth

  15. Thanks for your attention!

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