 Hello everyone welcome back to another session in dentistry and more today's topic in conservative dentistry is GIC or glass anoma cement? glass anoma cement is gaining a lot of popularity Among the clinicians nowadays because of its two wonderful properties one is a direct bonding that is it bonds to the tool structure by chemical bonding We know the amalgam restorative material which needs a lot of cavity preparation and it needs 90 degree butt joint But this is a direct bonding so it requires very minimal preparation and The second property is the fluoride release As we all know the fluoride can prevent carries so the restorative material itself can attribute to carries prevention So let's learn GIC in detail So glass anoma cement is a tooth-colored material introduced by Wilson and 1972 so the material was based on the reaction between two things one is glass particles that is silica or silicate glass particles and That is a powder and polyacrylic acid So they bond chemically to the tooth structure and release fluoride for relatively very long a period So it was introduced by Wilson and Canon in 1972 basically it has got glass silicate glass particles and polyacrylic acid So the classification so it is a all-in-one cement it has got many Uses in dentistry the type one is looting cement can be used for looting Then restorative cement then type 3 is liner and base cement type 4 is fissure sealant type 5 is Ortho brackets cementation and type 6 is core builder so you can see A to Z Function as a restorative material or as a cement So the composition so as I said it has got silicate glass particles and acid The powder includes or it is we can say acid soluble calcium fluoro alumino silicate glass So the powder includes silica 42 percentage alumina around 29 percentage aluminum fluoride around 1.6 calcium fluoride 15.7 then sodium fluoride 9.3 percent Aluminium phosphate and 3.8 percentage so this fluoride portion act as ceramic flex and strontium barium or zinc oxide provide the radio opacity whereas the liquid So polyacrylic acid in the form of copolymer with a Traconic acid and malic acid and Also, we have tartaric acid which improves handling characteristics and also Increase the working time and we have water which is a medium of reaction and hydrates the reaction products So the setting reaction setting reaction when we mix the powder and liquid what happens is So this is a glass. Okay, and this is a glass particle And is a silica glass particle So when the powder and liquid are mixed the surface of the glass particles are attacked by acid, okay, so there will be acid attack So what happens is? Calcium aluminum sodium Fluoride ions are leached into a quest medium. So this is the medium So there will be Release of calcium sodium Fluoride into the A quest medium from all the glass particles all this will be released So calcium poly salts are formed first Okay Then forward by aluminum poly salts which cross link with poly anion chain So the sit cement which consists of unreacted powder particle surrounded by silica gel in amorphous matrix of Hydrated calcium and aluminum poly salts So this calcium poly salt is Responsible for the initial sit and aluminum poly salt for the it forms a dominant phase And what a place we have very important role in structure of cement And after hardening fresh cement is extremely prone to the cracking and crazing due to the drying of loosely bound water Hence the cement must be protected by application of varnish or vaseline. We used to apply vaseline or the newly created restoration So the setting time setting time is For the type one it is photo five minutes and For type two it is seven minutes and it's basic properties compressive strength That is 150 Megapascal, but in recent time the compressive strength of GSA is so much improved because of the newer technology so newer interaction of other materials which is combining with GSE and improving this Compressive strength almost as similar as our amalgam. So this is 150 mega Pascal tensile strength is 6.6 mega Pascal And hardness Is 49 k That is no hardness number So regarding the solubility and Disintegration okay solubility and disintegration solubility So initial solubility is high due to the leaching of intermediate products. So the complete setting reaction takes place in 24 hours. So cement should be protected from saliva during this period so we used to ask the patients who get this restoration done to try to avoid the or try to avoid the contact of water In that particular area. So to prevent that we used to apply Vaseline And what about the adhesion? That is a unique property of GSE because glass aromas cement bonds chemically to the tool structure Bonding is due to the reaction occurs between carboxyl group. Okay Carboxyl group This is of acid. Okay carboxyl group of acid it reacts with the Calcium okay, so this is minus this is plus calcium group of our hydroxy appetite So these two will be chemically bonding so this is from the cement and this is the calcium of our enamel So bonding with enamel is higher than that of dentin obviously because enamel has higher mineral content So regarding the aesthetics that is GSE's tooth colored material and available in different shades, but it is definitely inferior to composites composite has got excellent finish The GSE it lacks that translucency so it cannot be That much recommended to the anterior teeth. Okay, and it has got rough surface structure And there's potential for discoloration and staining Regarding the biocompatibility it has got good biocompatibility That is pulpal response to GIC cement is favorable And it is mild basically due to the high buffering capacity of hydroxy appetite and large molecular weight of polyacrylic acid Which prevents entry into Dental tubules the large molecular size of acid So it cannot prevent the dental tubules And the anti-karyogenic properties that is the most important one anti-karyogenic properties because of its fluoride release So initially it has got large amount of fluoride release, but later it will be So if we take the fluoride release it is like this So there is initial exponential phase where high amount of fluoride is released then it is going in a flat phase But the thing is when we apply sodium fluoride or any other type of fluoride This GSE will take up the fluoride ions and it act as a reservoir So next is the manipulation. How do we mix this? manipulation so the enamel and dentine should be first cleaned And should be swapped with polyacrylic acid for five seconds. Then after conditioning two surfers should isolate Then we need to mix the powder and liquid by three is to one ratio So the first increment is incorporated rapidly to produce a homogeneous milky consistency then Mixing is done in folding technique. That is folding method So this is the folding method It is done to preserves the gel structure preserves gel structure Okay, if we do proper folding the gel structure won't be disturbed So the finished mix should have a glossy surface and it should be Protected from water by using a vaseline or varnish And the final finishing can be done after 24 hours So the main advantages are The excellent adhesion that is a chemical bonding to the tooth good marginal seal anti-karyogenic property biocompatibility and minimal cavity preparation required Whereas the disadvantages low fracture resistance low wear resistance water sensitivity And less aesthetic compared to composite And the uses uses the classification itself gives the various uses that is it can be used for luting core buildup for eroded area mainly for class 3 class 5 restoration orthodontic bracket adhesive for a traumatic restorative treatment for lamination or sandwich technique Now let's learn what is sandwich technique So sandwich technique it's a commonly asked question sandwich So sandwich we know there is there should be two materials. So here we have GAC and composite So if this is our tooth and this is the cavity Okay So what we are going to do is we are going to place two materials So it is developed by McLean So it combines the beneficial properties of GIC and composite So after cavity preparation Condition the cavity to develop good adhesion with GIC Then place type 3 GIC into the prepared cavity. So this is our GIC So after setting H the enamel and GIC Okay, so We need to etch both the enamel. So this is the enamel and GIC. So we are going to do etching because composite needs etching and bonding agent It is not like direct bonding So we need to etch the cavity and GIC So for using ortho phosphoric acid we etch the cavity for 15 seconds So this will improve micromechanical bond to composite resin Then we apply a thin layer of bonding agent because composite Placement requires a prior bonding agent then only the mechanical bond will be happening And finally place the composite resin over the GIC. Okay, so here we apply the composite And using a curing light we cure the restoration So deeper section it has GIC and above it has composite So this is the sandwich technique So the advantages of sandwich techniques are polymerization shrinkage is less due to the reduced bulk of composite because we are not using completely composite if it is completely there will be polymerization shrinkage And favorable pulpal response because GIC is near to the pulp Chemical bond to the tooth we have chemical bonding here And anti-karyogenic property with GIC better strength finishing aesthetics of power laying composite So we are keeping GIC towards the pulp We have good pulpal response with respect to GIC and good aesthetics with respect to composite So on towards the occlusion side we have composite and towards the pulpal side we have GIC And we have few modifications with respect to GIC So modifications are So modifications of GIC The first one is water-settable GIC So water-settable GIC So the main problem of conventional GIC was its water sensitivity It is so much problem facing with water The water has to be kept away from its during the sitting reaction So this water-settable GIC Liquid is delivered in a freeze dried form which is incorporated into the powder Liquid used is a clean water So liquid is providing as a freeze dried form So the second one is resin modified GIC It consists of that is a powder consists of The ion leachable fluoraminosilicate glass particles and a initiator for light curing Whereas the liquid consists of water polyacrylic acid With metacrylate hydroxy ethyl metacrylate monomer It has got good strength that is the strength is improved with the resin modification Similarly metal modified GIC So glass anomer have been modified to addition of filler particles to improve strength Fracture toughness and resistance to wear So it has got silver alloy mix which is known as Miracle mix So it is made by mixing of spherical silver amalgam alloy powder with glass anomer powder And the next one is serment Serment is bonding of silver particles to glass anomer particles by fusion through High temperature sintering Okay High temperature sintering process that is serment And the last one is compomer Okay compomer compomer Is composite resin that uses an anomer glass Which is a major component of glass anomer as the filler So small quantity of dehydrated poly alkinoic acid Incorporated with filler particles So setting reaction is by light activation So adhesive system used with compomer is based on acid etch found with all composite resin So compomer is nothing but a composite resin which uses The anomer glass which is a major component of glass anomer Okay So the small quantity of this poly alkinoic acid incorporated with filler particles And the setting reaction is by light activation And adhesive system used with compomer is based on acid etch found with all composite resin So that is All about GIC glass anomer cement So we learned its classification its composition setting reaction manipulation advantages disadvantages Modification and also sandwich technique. So sandwich technique can be asked as a short note So hope you understood this very basic topic. So I'll come up with a new topic in conservative industry. Thank you