Guest guest Posted January 31, 2012 Report Share Posted January 31, 2012 Please tell me what is marginal ditching? Is it marginal shrinkage? Sent from my iPhone Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 31, 2012 Report Share Posted January 31, 2012 HI I have just seen your email both marginal ditching and material shrinkage are entirely different however they both relate to the inherent properties of the material. Marginal ditching occur in brittle materials when they are subjected to high forces ( ex: Amulgum subjected to high compressive stresses) they tend to fail ( breakage). therefore they should have sufficient thickness since they are brittle. That`s why the CSA of amulgum is Ideally 90 Degrees to provide adequate thinness of material at the margins of the restoration. However the shrinkage occur following material polymerization , wethere its light curing or self curing. The sequel of polymerization: 1.stress are created at the margins 2. micogaps between the restoration and the cavity walls 3. microleakage 4. recurrent caries and discolorations A lot of methods are employed t reduce the PS of composites both in the material design and methods of application. ex reducing the thickness of composite, incremental packing, curing through the walls, light reflecting wedges. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 31, 2012 Report Share Posted January 31, 2012 thanks for elaborate explaination. From: ebtessam elhamalawy <ebtessamhamalawy@...> " " < > Sent: Tuesday, 31 January 2012 3:59 PM Subject: Re: Amalgam HI I have just seen your email both marginal ditching and material shrinkage are entirely different however they both relate to the inherent properties of the material. Marginal ditching occur in brittle materials when they are subjected to high forces ( ex: Amulgum subjected to high compressive stresses) they tend to fail ( breakage). therefore they should have sufficient thickness since they are brittle. That`s why the CSA of amulgum is Ideally 90 Degrees to provide adequate thinness of material at the margins of the restoration. However the shrinkage occur following material polymerization , wethere its light curing or self curing. The sequel of polymerization: 1.stress are created at the margins 2. micogaps between the restoration and the cavity walls 3. microleakage 4. recurrent caries and discolorations A lot of methods are employed t reduce the PS of composites both in the material design and methods of application. ex reducing the thickness of composite, incremental packing, curing through the walls, light reflecting wedges. Quote Link to comment Share on other sites More sharing options...
Guest guest Posted January 31, 2012 Report Share Posted January 31, 2012 CSA: The angle between the unprepared external tooth surface and the prepared surface of the cavity. THE margins of the prepared cavity. Quote Link to comment Share on other sites More sharing options...
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