the disease of dental caries dates back to ancient times and is the most common disease besetting human race . in spite of various preventive methods , dental caries it has been shown to be a very useful adjunct to restorative dentistry because of its unique ability to release fluoride , which is mainly responsible for its cariostatic action . moreover , glass ionomer cement bonds chemically to enamel and dentin , thereby reducing the need for a retentive cavity preparation ; thus , also preserving the sound tooth structure following the principle of because of these properties , glass ionomer cement is the material of choice in atraumatic restorative treatment ( art ) . because atraumatic restorative treatment ( art ) is practiced using hand instruments only , there is a possibility of insufficient caries removal ; therefore , such kind of cavities require a restorative material with good antibacterial efficacy . thus , therapeutic benefits may be gained by reinforcing glass ionomer cements with additional antibacterial agents . such agents should not affect the physicomechanical properties of the glass ionomer cement . among the antiseptics , a new antibacterial agent of interest is triclosan , a broad spectrum antimicrobial , which has been extensively used in mouthwashes and dentifrices . compressive stress results when the body is subjected to two sets of forces in the same straight line but directed toward each other . shear bond strength is the maximum amount of force required to break the interface between a bonded restoration and the tooth surface with the failure occurring in or near the adhesive interface . tensile stress results in a body when it is subjected to two sets of forces that are directed away from each other in the same straight line . considering the importance of compressive strength , diametral tensile strength and shear bond strength of restorative materials , the purpose of the study undertaken was to evaluate and compare the compressive strength , diametral tensile strength , and shear bond strength of gic type ix , chlorhexidine - incorporated gic , and triclosan - incorporated gic . this in vitro study was carried out in the department of pedodontics and preventive dentistry , d.j . college of dental sciences and research , modinagar , ghaziabad , in collaboration with apex laboratories , mohanagar . for the evaluation of compressive strength and diametral tensile strength restorative pellets of gic type ix , 0.5 , 1.25 , and 2.5% concentrations of chlorhexidine - incorporated gic and triclosan - incorporated gic were prepared . for the evaluation of shear bond strength the desired concentrations of gic powder , chlorhexidine salt , and triclosan powder were obtained using an analytical digital scale . chlorhexidine - gic ( chx - gic ) : three different proportions of chx - gic were prepared based on the concentration of chlorhexidine . 0.5% chx - gic : prepared by adding 0.015 g of chlorhexidine to 2.985 g of glass ionomer powder;1.25% chx - gic : prepared by adding 0.037 g of chlorhexidine to 2.96 g of glass ionomer powder;2.5% chx - gic : prepared by adding 0.075 g of chlorhexidine to 2.925 g of glass ionomer powder . 0.5% chx - gic : prepared by adding 0.015 g of chlorhexidine to 2.985 g of glass ionomer powder ; 1.25% chx - gic : prepared by adding 0.037 g of chlorhexidine to 2.96 g of glass ionomer powder ; 2.5% chx - gic : prepared by adding 0.075 g of chlorhexidine to 2.925 g of glass ionomer powder . triclosan - gic ( t - gic ) : similarly , 0.5 , 1.25 , and 2.5% concentrations of triclosan - incorporated gic were prepared . autoclavable plastic molds of standardized dimensions ( 4 mm diameter , 6 mm thickness ) were used for the preparation of all restorative pellets . immediately after mixing , the material was placed into plastic molds by a plastic instrument and covered with acetate strips on both sides . this assembly was then placed into an incubator at 37  1c and 95  5% relative humidity for 1 h to simulate oral conditions . the pellets were then removed from the molds and ground on 500-grit silicon carbide paper for finishing . occlusal dentin samples were obtained from 35 primary human molars ( five molars for each group ) . the buccal enamel was reduced to a flat surface using a diamond disk , and was polished thereafter . the dentin surface was conditioned using polyacrylic acid for 10 s followed by air - water spray for 10 s. then , the restorative materials from various groups were mixed and placed on the buccal surface of the tooth . a block of glass ionomer cement of dimension 4  3  2 mm was prepared . after that the specimens were stored in an incubator at 37  1c and 95  5% relative humidity for 24 h. thereafter , the division of samples was done accordingly [ table 1 ] . for the compressive strength testing , restorative pellets were placed with the flat ends up between the plates of the instron universal testing machine ( instron 1500hdx ) . a compressive load was applied at a crosshead speed of 1 mm / min until the restorative pellet fractured . for the diametral tensile strength testing , the restorative pellets were placed on the instron universal testing machine such that the diameter of the pellet coincided with the direction of the force . a crosshead speed of 1 mm / min was used and the force was applied until the pellets fractured . the specimens were placed in the lower assembly of the instron universal testing machine one by one . a sharp knife - like mandrel was attached to the upper assembly and was suspended downwards toward the glass ionomer cement block . the force with which the restoration block was dislodged was recorded and shear bond strength was calculated . the data was statistically analyzed using independent t - test and intercomparison among various groups was done using dunnett test and post hoc test . for the evaluation of compressive strength and diametral tensile strength restorative pellets of gic type ix , 0.5 , 1.25 , and 2.5% concentrations of chlorhexidine - incorporated gic and triclosan - incorporated gic were prepared . for the evaluation of shear bond strength the desired concentrations of gic powder , chlorhexidine salt , and triclosan powder were obtained using an analytical digital scale . chlorhexidine - gic ( chx - gic ) : three different proportions of chx - gic were prepared based on the concentration of chlorhexidine . 0.5% chx - gic : prepared by adding 0.015 g of chlorhexidine to 2.985 g of glass ionomer powder;1.25% chx - gic : prepared by adding 0.037 g of chlorhexidine to 2.96 g of glass ionomer powder;2.5% chx - gic : prepared by adding 0.075 g of chlorhexidine to 2.925 g of glass ionomer powder . 0.5% chx - gic : prepared by adding 0.015 g of chlorhexidine to 2.985 g of glass ionomer powder ; 1.25% chx - gic : prepared by adding 0.037 g of chlorhexidine to 2.96 g of glass ionomer powder ; 2.5% chx - gic : prepared by adding 0.075 g of chlorhexidine to 2.925 g of glass ionomer powder . triclosan - gic ( t - gic ) : similarly , 0.5 , 1.25 , and 2.5% concentrations of triclosan - incorporated gic were prepared . autoclavable plastic molds of standardized dimensions ( 4 mm diameter , 6 mm thickness ) were used for the preparation of all restorative pellets . immediately after mixing , the material was placed into plastic molds by a plastic instrument and covered with acetate strips on both sides . this assembly was then placed into an incubator at 37  1c and 95  5% relative humidity for 1 h to simulate oral conditions . the pellets were then removed from the molds and ground on 500-grit silicon carbide paper for finishing . occlusal dentin samples were obtained from 35 primary human molars ( five molars for each group ) . the buccal enamel was reduced to a flat surface using a diamond disk , and was polished thereafter . the dentin surface was conditioned using polyacrylic acid for 10 s followed by air - water spray for 10 s. then , the restorative materials from various groups were mixed and placed on the buccal surface of the tooth . a block of glass ionomer cement of dimension 4  3  2 mm was prepared . after that the specimens were stored in an incubator at 37  1c and 95  5% relative humidity for 24 h. thereafter , the division of samples was done accordingly [ table 1 ] . for the compressive strength testing , restorative pellets were placed with the flat ends up between the plates of the instron universal testing machine ( instron 1500hdx ) . a compressive load was applied at a crosshead speed of 1 mm / min until the restorative pellet fractured . for the diametral tensile strength testing , the restorative pellets were placed on the instron universal testing machine such that the diameter of the pellet coincided with the direction of the force . a crosshead speed of 1 mm / min was used and the force was applied until the pellets fractured . the specimens were placed in the lower assembly of the instron universal testing machine one by one . a sharp knife - like mandrel was attached to the upper assembly and was suspended downwards toward the glass ionomer cement block . the force with which the restoration block was dislodged was recorded and shear bond strength was calculated . the data was statistically analyzed using independent t - test and intercomparison among various groups was done using dunnett test and post hoc test . the mean values of compressive strength , diametral tensile strength , and shear bond strength of various groups are depicted in table 2 . independent t - test revealed that gic type ix ( group 1 ) showed the highest values followed by 0.5% t - gic ( group 3a ) and the least values were found in 0.5% chx - gic ( group 2c ) . mean values of compressive strength , diametral tensile strength , and shear bond strength ( mpa ) of various groups table 3 depicts the intragroup comparison of compressive strength , diametral tensile strength , and shear bond strength of various concentrations of chx - gic . dunnett test showed that 0.5% chx - gic was significantly better ( p < 0.05 ) than 1.25% and 2.5% chx - gic . intergroup comparison of compressive strength , diametral tensile strength and shear bond strength of various concentrations of chx - gic ( chlorhexidine - gic ) table 4 depicts the intragroup comparison of compressive strength , diametral tensile strength , and shear bond strength of various concentrations of t - gic . dunnett test showed that 0.5% t - gic was significantly better ( p < 0.05 ) than 1.25% and 2.5% t - gic . intergroup comparison of compressive strength , diametral tensile strength and shear bond strength of various concentrations of t - gic ( triclosan - gic ) thus , to evaluate if 0.5% chx - gic and 0.5% t - gic are comparable , in terms of all the abovementioned physical properties , to gic type ix , an intercomparison of mean values was done using post hoc test [ table 5 ] . intergroup comparison of mean difference of compressive strength , diametral tensile strength and shear bond strength of gic type ix with 0.5% chx - gic ( chlorhexidine - gic ) and 0.5% t - gic ( triclosan - gic ) this intercomparison shows that no significant difference ( p > 0.05 ) in compressive strength , diametral tensile strength , and shear bond strength existed between gic type ix ( group 1 ) , 0.5% chx - gic ( group 2a ) and 0.5% t - gic ( group 3a ) . art has been practiced using hand instruments only , therefore , there is a possibility of insufficient caries removal . literature has shown that microorganisms have been found to be viable for at least a period of two years under the glass ionomer cement restoration . thus , therapeutic benefits may be gained by reinforcing glass ionomer cements with additional antibacterial agents . chlorhexidine diacetate is a more stable antibacterial material , not prone to decomposition , and can be easily blended with gic . triclosan at low concentrations acts as a bacteriostatic and at high concentrations as bactericidal . to evaluate which concentration of chlorhexidine and triclosan is best suited for our purpose various concentrations were used , i.e. 0.5% , 1.25% , and 2.5% . all the concentrations have been shown to provide adequate antibacterial property to gic type ix . in an in vitro study in 2008 , trkn et al . used 0.5% , 1.25% , and 2.5% concentrations of chlorhexidine - containing gic to study the long - term antibacterial effects and physical properties . in another study by deepalakshmi et al . , glass ionomer cements containing chlorhexidine and cetrimide at concentrations of 1% and 2% were used to evaluate their antibacterial and physical properties . the results of the current study demonstrated that the mean value of compressive strength , diametral tensile strength , and shear bond strength was found to be the highest in gic type ix . the above result may be attributed to the fact that gic type ix is characterized by having smaller glass particles and higher powder to liquid ratio . this is said to give the gic type ix higher strength , greater wear resistance , and increased flexural strength . this result was in accordance to a study done by ahluwalia et al . in 2012 , in which the authors found that the diametral tensile strength of gic type ix ( 12.61 mpa ) was higher than 1% chx - gic ( 12 mpa ) . when the various concentrations of t - gic and chx - gic were compared with each other , it was found that 0.5% t - gic and 0.5% chx - gic have the highest values of compressive strength , diametral tensile strength , and shear bond strength in their respective groups . the common finding in both the intragroup comparisons points out that the physical properties abruptly decrease in a concentration - dependent manner . in addition , the results manifest that 1.5% and 2.5% concentration of antibacterials incorporated into gic type ix might not be suitable for clinical use because increase in the concentration adversely affects the physical properties of the parent material . because of the vitrification of gic with chlorhexidine and triclosan at higher concentrations , many of these carboxylic ( cooh ) groups are prevented from participating in these coordination complexes . a possible reason for the decrease in physical properties at a concentration of more than 2% chlorhexidine can be attributed to the fact that cationic salts hamper the setting reaction of the polyacrylic acid glasses , thereby extending the setting time , because of interfered proton attack and leaching of ions from the glasses . the intercomparison between gic type ix ( control ) , 0.5% chx - gic ( group 2a ) , and 0.5% t - gic ( group 3a ) discernibly signified that 0.5% t - gic and 0.5% chx - gic exhibit physical properties comparable to gic type ix , which indicates that these maybe considered as viable options for use in pediatric dentistry along with physical properties within the higher acceptable range . it can be concluded that the compressive strength , diametral tensile strength , and shear bond strength values of 0.5% t - gic and 0.5% chx - gic were comparable to gic type ix . we recommend that further studies should be conducted to test various antibacterial glass ionomer cements in a randomized clinical trial . because a smaller sample size was used in this study , further studies with a larger sample size are required to authenticate the results . clinical impact of various other factors such as occlusal forces needs to be investigated in further studies .