Cosmetic Tribune U.K. Edition

15Cosmetic TribuneApril 2014United Kingdom Edition Laser Dentistry - LaserWhitening - LaserTherapy Made in Britain QLDL130214RG No battery No power loss No expensive tips All-in-one Laser £3,300£3,300 Inc. VAT, Delivery, all Accessories plus Online & Hands on BILD training course inc. Proud Sponsors of T. +44 1227 780009 E. info@quicklase.com W. www.quicklase.com QuickLase QuickWhite @QLQW R esin bonding of the hu- man dentition has be- come a ‘standard’ in the United States and Canada. There are more than 80 dif- ferent bonding systems on the market today. We have seen them evolve through multi- ple generations in an attempt to ‘simplify’ the bonding pro- cess. Yet, as these agents have simplified, many in our prof- ession have seen many chal- lenges arise. A significant number of re- ports in the literature have been showing that the “immediate bonding effectiveness of con- temporary adhesives are quite favourable, regardless of the approach used (however) in the long term, the bonding ef- fectiveness of some adhesives drops dramatically.”1 The hy- drophillicity that both etch and rinse and self-etch bonding agents offer initially in the den- tin bonding process becomes a significant disadvantage in terms of long-term durability.2 It is this hydrophillicity of simplified adhesive systems combined with other operator- induced challenges that con- tribute to these failures. Tay, Carvalho, Pashley, et al. have reported repeatedly in the lit- erature of this problem.3,4 They continue to report that these bonding agents do not coagu- late the plasma proteins in the dentinal fluid enough to reduce this permeability. The fluid droplets contribute to the in- compatibility of these simpli- fied adhesives and dual-/auto- cured composites in direct res- torations and the use of resin cements for luting of in direct restorations. The term “water-tree” for- mation has been coined to describe this process, which originated from the tree- like deterioration patterns that were found within poly- ethylene insulation of under- ground electrical cables. It is now being applied to the water blisters formed by the transfer of dentinal fluid across the den- tin bonding interface. These “water blisters... act as stress raisers and form initial flaws that cause subsequent cata- strophic failure along the adhe- sive composite interfaces.” The previously mentioned plasma proteins are released by the dentin when subjected to acids and cause hydrolytic and enzymatic breakdown of the dentin and resin bonding agent interface.5 These enzymes are called matrix metalloprotein- ases (MMPs). Currently, there are only three methods of reducing these MMPs: two per cent chlorhex- idine solutions that are used prior to application of bond- Bioactive materials support proactive dental care Dr John C Comisi discusses bioactive materials page 16DTà T. +441227780009

Cosmetic Tribune U.K. Edition

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