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Year : 2010  |  Volume : 21  |  Issue : 4  |  Page : 552-556
Evaluation of the antibacterial and physical properties of glass ionomer cements containing chlorhexidine and cetrimide: An in-vitro study

Department of Conservative Dentistry and Endodontics, Ragas Dental College and Hospital, Chennai, India

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Date of Submission17-Mar-2009
Date of Decision28-Sep-2009
Date of Acceptance23-Jan-2010
Date of Web Publication24-Dec-2010


Background: Incorporation of antibacterial agents frequently results in changes in the physical properties of restorative materials.
Materials and Methods: This in-vitro study investigated the antibacterial and physical properties of Glass ionomer cement (GIC) with chlorhexidine and cetrimide, to determine the optimal concentration, for incorporation of these agents to obtain antibacterial GICs for use with the Atraumatic restorative treatment approach. This was assessed using the agar diffusion test. Chlorhexidine diacetate and cetrimide were added to Glass ionomer cement type-IX (GIC-FUJI IX) at 1 and 2% W/W ratio. The experimental GIC specimens were placed on agar plates inoculated with Lactobacillus casei, and the area of inhibition was calculated after 48 hours.
Results: All the experimental GICs exhibited inhibition of bacteria, but the sizes were dependent on the concentration of the antibacterial agent. Incorporation of chlorhexidine diacetate and cetrimide, at 2%, significantly decreased the compressive strength, and the setting time was extended a little by the addition of any concentration of chlorhexidine and cetrimide.
Conclusions: The present study demonstrated that experimental GICs containing chlorhexidine diacetate and cetrimide were effective in inhibiting bacteria associated with caries, and incorporation of 1% cetrimide was optimal to give the appropriate antibacterial and physical properties.

Keywords: Chlorhexidine diacetate, cetrimide, glass ionomer cement

How to cite this article:
Deepalakshmi M, Poorni S, Miglani R, Rajamani I, Ramachandran S. Evaluation of the antibacterial and physical properties of glass ionomer cements containing chlorhexidine and cetrimide: An in-vitro study. Indian J Dent Res 2010;21:552-6

How to cite this URL:
Deepalakshmi M, Poorni S, Miglani R, Rajamani I, Ramachandran S. Evaluation of the antibacterial and physical properties of glass ionomer cements containing chlorhexidine and cetrimide: An in-vitro study. Indian J Dent Res [serial online] 2010 [cited 2019 Oct 22];21:552-6. Available from:
The prevalence of dental caries can be considered as one of the most important pathological process in human being and bacteria plays a key role in their development. The therapeutic procedures used in the treatment of caries do not always eliminate all the microorganisms in the residual tissues. [1] The persisting cariogenic bacteria, with the lack of hermetic seal, can cause recurrent caries, leading to failure of restoration. One possible solution to overcome this problem is to use dental materials with a bacteriostatic property. [2]

Conventional glass ionomer cements, introduced in 1972, by Wilson and Kent, is a tooth colored and chemically adhesive material, with a therapeutic action of anticariogenicity, and is being widely used in dentistry. The ability of glass ionomer cement to release fluoride continuously over an extended period of time, results in an anticariogenic potential showing a reduction in caries adjacent to the restoration. [3]

The minimal intervention approach for managing dental caries, which gained importance in the last decade is called Atraumatic Restorative Treatment (ART). [4] ART has been developed for treatment of caries in parts of world with limited access to dental treatment facilities, where demineralized tooth tissues are removed using hand instruments and the cavity is restored with adhesive restorative materials. [5] However, dental hand instruments alone do not remove carious dentin as effectively as rotary burs, and cariogenic bacteria can survive incarceration under GIC restorations for up to two years. Consequently, cavities treated by ART may have residual infected dentin, and if GIC is unable to arrest the carious process, the restoration will fail. [6] Research has shown that few ART restorations fail because of secondary caries development over a period of six years. [4] Since its introduction, major improvements have been made in the first ASPA Glass Ionomer Cement, but certain limitations still remain. The improvement of filling materials, to overcome the problems caused by incomplete removal of infected dentin, will be beneficial for further increasing the success rate of ART.

Several attempts in developing GIC with enhanced antibacterial effects by addition of bactericides, such as, chlorhexidine hydrochloride, cetyl pyridinium chloride, cetrimide, and benzalkonium chloride have been reported in the literature. The most appropriate choice of antibacterial agents to combine with GIC would be antiseptic agents that have proven to be useful in clinical dentistry, and are the ones that do not disturb the physical properties. Cationic disinfectants have been investigated both in-vitro and in-vivo for their antibacterial effects against various microorganisms. [6] Literature reveals that only chlorhexidine has been widely incorporated in GIC and all the studies have shown an increase in the antibacterial effects in vitro. [7],[8]

Chlorhexidine (CHX) and cetrimide (CT) are antiseptics with a wide spectrum of action and their use has been generalized over the past two decades. [2],[9] Incorporation of antibacterial agents frequently results in changes in the physical properties of restorative materials. Therefore, antibacterial GICs used in the ART approach require an optimum amount of antibacterial agents that do not jeopardize the basic properties of the parent material.

In an approach to enhance the antibacterial potential of glass ionomer cement type IX, we incorporated cationic antibacterial agents CHX diacetate and cetrimide into type IX GIC and investigated their antibacterial, physical, and chemical properties.

Hence, the aim of the present study is to evaluate the antibacterial and physical properties of glass ionomer cements containing chlorhexidine diacetate and cetrimide.

   Materials and Methods Top

A conventional powder and liquid FUJI IX Glass ionomer cement (GC Corporation, Tokyo, Japan) was used as a control. Experimental GICs were prepared by incorporating CHX diacetate powder (Smart Pharmaceuticals, Jalgoan, India) and cetrimide powder (Chennai chemicals) into the powder of Fuji IX at 1%, and 2% W/W concentration with P/L ratio 3.6:1(one scoop powder and one drop of liquid).

CHX diacetate, which is commercially available as a solid substance was added to Fuji type IX in order to obtain two groups of 1%, and 2% concentration (= content) of CHX diacetate in the GIC experimental formulation. For 1% CHX diacetate group, 1000 mg of Fuji type IX was proportioned on a mixing pad and weighed, to which 10 mg (1%) of CHX was added. For 2 % CHX diacetate group, 1000 mg of Fuji type IX was proportioned on a mixing pad and weighed, to which 20 mg (2%) of CHX was added .The same procedure was followed with the cetrimide groups also. The groups tested are presented in [Table 1].
Table 1: Grouping of specimens used for the study

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Agar diffusion test

Organism Lactobacilli casei that is commonly associated with active caries were used for the study. The antibacterial activity of the set materials against L. casei (ATCC 4646) was assessed using the agar diffusion test. All procedures were carried out under an aseptic laminar cabinet.

Five specimens were prepared for each experimental group. P/L (3.6:1) of each material was dispensed on a mixing pad and mixed for 30 seconds with a sterile plastic spatula and inserted into the stainless steel mold of 10 mm diameter and 2 mm thickness, within one minute, with a sterile dental instrument and allowed to set for 30 minutes at room temperature, after covering the surface with a glass slide.

Each strain from the stock culture stored in 50% glycerol at -20 degrees was cultivated in the Brain Heart Diffusion broth (Hi Media Laboratories Pvt. Ltd., Mumbai) at 37°C and a loopful of inoculum was transferred to 10 ml of the Brain Heart Infusion broth after incubation for 48 hours. Bacterial suspension of 350 μL was then spread on to the BHI agar plate and left for 30 minutes at room temperature.

The set disk-shaped specimens were placed on to a BHI agar plate, inoculated with bacterial strain, and left at 37°C for 48 hours. Zones of inhibition were measured in millimeters using a digital calliper at three different points. Sizes of the inhibition zones were calculated by subtracting the diameter of the specimen, 10 mm, from the average of the three measurements of the halo.

Compressive strength

The compressive strength was measured using the Universal testing machine. Eight cylindrical specimens per group were prepared using a plastic mold with an inner diameter of 4 mm and 6 mm height. The inner surfaces of the molds were coated with a thin layer of petroleum jelly and the experimental groups were hand-mixed and loaded into the mold with the help of a sterile dental instrument and stored at room temperature for 24 hours. Prior to testing, the molds were removed and the diameter of each specimen was determined using a micrometer gauge. The specimens were then placed between the plates of the universal testing machine (Ag - 100 KNG, Shimadzu). A compressive load along the long axis was applied using a crosshead speed of 1 mm/minute. The maximum force when the specimen fractured was recorded.

Setting time

The net setting time is the time measured from the end of mixing until the material sets. The test was undertaken in a climatic condition of 37°C, using a Vickers needle (300 g, 1.12 mm) with a flat end that was plane and perpendicular to the long axis of the needle. Five specimens per group were prepared in a plastic mold, having an inner diameter of 10 mm and 5 mm thickness, and positioned on aluminium foils and then filled to a level surface with mixed GIC. The upper surface was made flat by pressing down with a glass slide. The assembly comprising of mold, foil, and cement was placed in the cabinet. The indenter was carefully lowered vertically into the surface of the cement every 15 seconds.The net setting time was recorded as the time that elapsed between the end of mixing and time when the needle failed to make a complete circular indentation in the cement.

The results were tabulated and statistically analyzed using the SPSS package 10. The paired t test was used to analyze the zones of inhibition and compressive strength. The confidence limit was taken as 95%. [Table 2] shows the t values and P values obtained for the study.
Table 2: Distribution of agar diffusion test and compressive strength values of control and experimental GIC

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   Results Top

Agar diffusion test

[Figure 1] shows the results of the agar diffusion test against Lactobacillus Caseii. Sizes of the zone of inhibition produced by all the experimental GIC were significantly different from each other (P<0.05), except between the GIC with 2% w/w CHX and 1% w/w CT (P>0.05). GIC containing 2% w/w cetrimide exhibited significantly greater inhibition followed by the GIC containing 1% w/w cetrimide and 2% w/w chlorhexidine.
Figure 1: Mean inhibition zone sizes of the agar diffusion test for control and experimental GIC against L.caesei

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Compressive strength

[Figure 2] shows the mean compressive strength values of all the groups after 24 hours. The compressive strength values of all the GIC were significantly different from each other (P<0.05), except between GIC containing 2% w/w CHX and 2% w/w CT (P>0.05). The highest compressive strength was exhibited by the conventional GIC followed by the GIC containing 1% w/w cetrimide, and the least value was exhibited by the GIC containing 2% chlorhexidine.
Figure 2: Mean compressive strength of control and experimental GIC after 24 hours

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Setting time

[Table 3] shows the setting time of each material. All experimental GIC containing CHX and cetrimide exhibited a longer setting time than the control.
Table 3: Setting time for control and experimental GIC

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   Discussion Top

Glass ionomer cements are capable of releasing fluoride ions, which provide a significant anticariogenic property, but the reduction in the bacterial counts obtained by placing the conventional Glass ionomer cements is not reliable for ART restorations. Therefore, antibacterial GIC would provide an alternative approach to overcome this problem. [5]

FUJI IX is a high strength posterior restorative material and has been reported to release approximately 10 ppm of fluoride during 48 hours, but this amount of fluoride is too small to exhibit antibacterial action. Thus, studies have shown that few ART restorations fail because of secondary caries development. Caries inhibiting the effect of the CHX containing glass ionomer, without compromising its physical properties, was reported by Takahashi et al. [10]

Literature cites that CHX and CT are bactericidal agents used against pathogenic bacteria. [6] In the present study CHX and CT were incorporated in FUJI IX and the optimal concentration for clinical use was examined in terms of antibacterial and physical properties.

The agar diffusion test used in this study showed that the sizes of the inhibition zones produced against L.Casei were dependent upon the concentrations of CHX and CT incorporated into the Glass ionomer. The results of the present study were similar to previous studies by Botelho et al. [6] and Erickson et al., [7] who reported that antimicrobial activity was dependent upon the concentration of the disinfectant added, unlike the other studies done by Jedrychowski et al., [8] which indicated no effects of dose response.

The sizes of the inhibition zones produced against L. casei were dependent upon the concentration of CHX and CT added to the Glass Ionomer Cement. Two percent CHX-GIC and 2% CT-GIC groups produced greater inhibition zones when compared to 1% CHX-GIC and 1% CT-GIC groups. One of the main concerns is the inability of the method to distinguish between the bactericidal and bacteriostatic effect, which cannot be determined with the agar diffusion method. The test also does not provide any information about the viability of the test microorganism, within the inhibition zone. [5]

The ability of the restorative dental material to withstand the functional forces is an important requirement for their long-term clinical performance. To be acceptable clinically, modified materials must provide superior antimicrobial activity without compromising the physical properties. The most commonly used strength value to characterize dental cements is compressive strength.

Compressive strength of 2% CHX-GIC and 2% CT-GIC groups decreased significantly when compared to that of the control, but no influence was seen on compressive strength for 1% CHX-GIC and 1% CT-GIC groups, similar to a previous study done by Takahashi et al. [10] and Sebnum turken et al. [5] The reason for greater potency of the CT-GIC material could be due to the high elution rates of the antibacterial agent from the GIC or due to the synergistic interactions between the antibacterial agent and the GIC. Synergism has been shown to occur between the metal ions and cationic antibacterial agents [6] . It is interesting to note that Lactobacilli have been found to be the most resistant organisms to the inhibitory effects of GIC. [1] Furthermore, CT-GIC was found to be more effective when compared with CHX-GIC, which was similar to a previous study done by Botelho et al. [6] Chlorhexidine has also been seen to have long-term antibacterial properties because of its unique ability to bind to hydroxy apatite, whereby, a gradual release creates a bacteriostatic milleu over a prolonged period of time. [11]

A possible reason for decrease in the physical properties can be attributed to cationic salts, which hamper the setting reaction of the polyacrylic acid glasses, thereby extending the setting time, due to an interfered proton attack and leaching of ions from the glasses. [10],[12]

   Conclusion Top

Within the limitations of the present study it can be concluded that experimental GICs containing antibacterial mixtures are effective in inhibiting bacteria associated with caries. The addition of 1% CT to GIC (FUJI1X) is optimal to provide antibacterial effects without affecting the physical properties.

Further investigations are necessary to determine the effects of antibacterial GICs on complex biofilms and their possible interactions with the physical properties of the GICs.

   Acknowledgments Top

Thanks to Dr. Usha Rao, Faculty of the Microbiology Department, Ragas Dental College, for her invaluable guidance throughout the study.

   References Top

1.Herrera M, Castillo A, Baca P, Carriσn P. Antibacterial activity of glass-ionomer restorative cements exposed to cavity producing microorganisms. Oper Dent 1999;24:286-91.   Back to cited text no. 1
2.Bergenholtz G, Cox CF, Loesche WJ, Syed SA. Bacterial leakage around dental restorations: its effect on dental pulp. J Oral Pathol 1982;11:439-50.  Back to cited text no. 2
3.Mazzaoui SA, Burrow MF, Tyas MJ, Dashper SG, Eakins D, Reynolds EC. Incorporation of Casein phosphopeptide amorphous calcium phosphate in to a glass ionomer cement. J Dent Res 2003; 82:914-8.  Back to cited text no. 3
4.Frencken JE, Imazato S, Toi C, Mulder J, Mickenautsch S, Takahashi Y, et al. Antibacterial effects of chlorhexidine containing glass ionomer cement in vivo A pilot study Caries Res 2007;41:102-7.  Back to cited text no. 4
5.Tόrkόn LS, Tόrkόn M, Ertuπrul F, Ateώ M, Brugger S. Long-term antibacterial effects and physical properties of a chlorhexidine-containing glass ionomer cement. J Esthet Restor Dent 2008;20:29-45.  Back to cited text no. 5
6.Botelho MG. Inhibitory effects on selected oral bacteria of antibacterial agents incorporated in a glass ionomer cement. Caries Res 2003;37:108-14.   Back to cited text no. 6
7.Ribeiro J, Ericson D. In vitro antibacterial effect of chlorhexidine added to glass ionomer cements. Scand J Dent Res 1991;99:533-40.  Back to cited text no. 7
8.Jedrychowski JR, Caputo AA, Kerper S. Antibacterial and mechanical properties of restorative materials combined with chlorhexidine. J Oral Rehabil 1983;10:373-81.  Back to cited text no. 8
9.Emilson CG. Potential efficacy of chlorhexidine against mutants streptococci and human dental caries. J Dent Res 1994;73:682-91.  Back to cited text no. 9
10.Takahashi Y, Imazato S, Kaneshiro AV, Ebisu S, Frencken JE, Tay FR. Antibacterial effects and physical properties of glass-ionomer cements containing chlorhexidine for the ART approach. Dent Mater 2006;22:647-52.  Back to cited text no. 10
11.Duque C, Negrini Tde C, Hebling J, Spolidorio DM. Inhibitory activity of glass ionomer cements on cariogenic bacteria. Oper Dent 2005;30:636-40.  Back to cited text no. 11
12.Tam LE, Chan GP, Yim D. In vitro caries inhibition effects by conventional and resin-modified glass-ionomer restorations. Oper Dent 1997;22:4-14.  Back to cited text no. 12

Correspondence Address:
Mohanavelu Deepalakshmi
Department of Conservative Dentistry and Endodontics, Ragas Dental College and Hospital, Chennai
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0970-9290.74217

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