|Year : 2015 | Volume
| Issue : 1 | Page : 15-20
Comparative evaluation of antimicrobial and physical properties of a newer dentin bonding agent with cetylpyridinium chloride: An in vitro study
AR Prabhakar, Archana P Betur, Raju Siddalingappa Orekondi
Department of Pedodontics and Preventive Dentistry, Bapuji Dental College and Hospital, Davangere, Karnataka, India
|Date of Web Publication||7-Dec-2015|
Archana P Betur
Department of Pedodontics and Preventive Dentistry, Bapuji Dental College and Hospital, Davangere - 577 004, Karnataka
Source of Support: None, Conflict of Interest: None
Context: Though adhesive systems in restorative dentistry possess many advantages, secondary caries is still a problem to be contended with. Addition of antibacterial agents could possibly be a potential remedy for this recurring problem. Aims: To evaluate and compare in vitro the antimicrobial property, microleakage, and shear bond strength of G-Bond (one component self-etching light cured adhesive) with different concentrations of cetylpyridinium chloride (CPC). Settings and Design: In vitro intergroup experimental randomized control trial. Subjects and Methods: The in vitro study with the study groups Group I: G-Bond, Group II: G-Bond with 1% CPC, and Group III: G-Bond with 3% CPC was tested against the clinical isolates of Streptococcus mutans through the direct contact test determining the turbidometric bacterial growth using spectrophotometer. The microleakage was tested using dye penetration method and the shear bond strength of the three groups was tested using universal testing machine. Statistical Analysis Used: The data were analyzed using paired t-test, one-way ANOVA, followed by post-hoc Tukey's test. For all the tests, a P ≤ 0.05 was considered for statistical significance. Results: G-bond with 3% CPC showed the highest rate of antibacterial activity against S. mutans than other two groups (highly significant P < 0.001). However, microleakage and shear bond strength between the groups did not show any statistically significant change. Conclusions: G-Bond with 3% CPC additive was effective against S. mutans.
Keywords: Cetylpyridinium chloride, direct contact test, G-Bond, microleakage, self-etching bonding agent, shear bond strength
|How to cite this article:|
Prabhakar A R, Betur AP, Orekondi RS. Comparative evaluation of antimicrobial and physical properties of a newer dentin bonding agent with cetylpyridinium chloride: An in vitro study. Int J Oral Health Sci 2015;5:15-20
|How to cite this URL:|
Prabhakar A R, Betur AP, Orekondi RS. Comparative evaluation of antimicrobial and physical properties of a newer dentin bonding agent with cetylpyridinium chloride: An in vitro study. Int J Oral Health Sci [serial online] 2015 [cited 2019 Nov 12];5:15-20. Available from: http://www.ijohsjournal.org/text.asp?2015/5/1/15/171154
| Introduction|| |
The adhesive system is widely used for direct restorations in dentistry because of its excellent esthetics and acceptable mechanical properties. Bonding techniques allow more conservative tooth preparations, less reliance on macromechanical retention, and less removal of unsupported enamel which have enabled variable cavity designs to preserve intact tooth structure with downsized cavities. The infiltration of the adhesive resins into demineralized dentin also results in a resin-dentin impregnation zone that not only provides strong bonding, but also an excellent hermetic seal.
Adhesive dentistry which began in 1955 with a paper by Dr. Michael Buonocore on the benefits of acid etching has developed enormously since then. The major element of the adhesive dentistry being the dental adhesives have also shown a tremendous improvement from no-etch to total-etch to self-etch systems. The evolution of such products not only improved the physical properties, but also the convenience. However, in spite of considerable improvements, the polymerization shrinkage and resultant contraction gaps in the tooth restoration interface still continues to be a significant problem.
It is a well-known fact that the cariogenic bacteria invade along the tooth restoration interface is the main cause of secondary caries and damage to the pulp, thus necessitating either the replacement of the restoration or ending with the pulpal therapy.
Thus, increased attention is to be focused on the restorative materials possessing inherent antibacterial property, which can eliminate the residual bacteria causing damage.
Significant trials of incorporating antibacterial components into dental adhesive systems have been investigated including methacryloyloxydodecyl pyridinium bromide, methacryloyloxyethyl cetyl dimethyl ammonium chloride, chlorhexidine and chitosan and cetyl pyridinium chloride (CPC) with different concentrations with varying degrees of success.
CPC is one such effective antibacterial agent. The mechanism of antibacterial activity of CPC is ascribed to the positive charge of the pyridinium group. Different concentrations of CPC when added to the polymerized resins, have even shown satisfactory bacteriostatic and bactericidal effects.
Thus, the aim of the present study was to evaluate and compare the antibacterial and physical properties of a newer dentin bonding agent when incorporated with different concentrations of CPC.
| Subjects and Methods|| |
Experimental materials used
G-Bond ™ (one component self-etching light cured adhesive, GC Corporation, Tokyo, Japan), Filtek Z 350 XT universal composite restorative material (3M ESPE, made in USA), and CPC (CPC, Hi-Media Laboratories, Mumbai, India) were used as the tested materials.
The study groups considered in the study [Table 1].
The antimicrobial property
A clinical isolate of Streptococcus mutans naturally resistant to bacitracin was grown aerobically from a frozen stock culture in brain heart infusion (BHI) broth containing 8 µl/ml bacitracin for 48 h at 37°C before use.,
Direct contact test
Direct contact test measures the optical density which is the turbidometric determination of bacterial growth in the 96 well microtiter plate at 37°C and recorded at subsequent intervals using the microplate reader.
A 96 well microtiter plate was divided into three groups of 24 well each as mentioned in [Table 1]. Each group was again subdivided into three subgroups of 8 wells each, being the experimental group, the positive control group, and the negative control group as mentioned in [Table 2].
In each experimental subgroup, a sterile microtiter plate was held vertically and the side walls of 8 wells were coated with 15 µl of respective materials of three study groups as mentioned in [Table 1] without flowing and wetting the bottom of the well, which could interfere with the light path through the microplate well and lead to false readings. Then, a 10 µl bacterial suspension [1 × 106 bacteria] was placed on the tested material and the plate was incubated in the vertical position for 1 h at 37°C. After that, the plate was held horizontally and the BHI broth supplemented with 20 µg/ml bacitracin (200 µl) was added to each well and gently mixed for 2 min. In the same manner, the samples of the subgroups, positive control, and negative control were also prepared.
The data were recorded by placing the microtiter plate in the microplate reader at 37°C and the optical density was measured at 600 nm at regular intervals of 30 min, 1 h, 4 h, 6 h, 24 h, 48 h, and 7 days.,
Fifteen therapeutically extracted impacted third molars were prepared with Class V cavities of standardized dimensions of 3.00 mm × 2.00 mm × 2.00 mm (l × h × w) on both buccal and lingual surfaces at the cementoenamel junction using a straight fissure diamond bur and measured using a periodontal probe to maintain uniformity. Then, the teeth were randomly allocated into three groups of 5 each [Table 1].
The prepared surfaces were applied with respective materials of three study groups as mentioned in [Table 1] with an applicator tip using a light brushing motion, and left undisturbed for 10 s. The teeth surfaces were gently air thinned for 5 s, then polymerized with a conventional halogen light source for 20 s. Filtek Z 350 XT universal composite restorative material was placed in all the teeth and light polymerized for 40 s. All the restorations were finished and polished. The teeth were thermocycled for 1000 cycles in separate water baths of 5°C and 55°C with a dwell time of 60 s in each bath and transfer time of 3 s.
The root apices of the teeth were sealed and 2 coats of nail varnish was applied to the entire tooth surface, leaving a 2.00 mm window around the restoration margin. The teeth were immersed in 1% methylene blue dye solution for 24 h at room temperature.
All the teeth were sectioned buccolingually through the center of the restoration using a water cooled slow speed handpiece; thus, getting a total of 30 samples of 10 per group. The microleakage was evaluated using a stereomicroscope to determine the extent of dye penetration.
Shear bond strength
Thirty therapeutically extracted impacted third molars were randomly assigned to three groups of 10 each [Table 1]. Flat dentin surfaces were created on each tooth with slow speed diamond disk under water coolant. Then, each tooth was mounted in a chemically cured acrylic resin such that 3–4 mm of the coronal dentin was exposed.
The flat dentin surfaces of all the groups were applied with respective materials of three study groups as mentioned in [Table 1] using a light brushing motion, leaving undisturbed for 10 s. The teeth surfaces were gently air thinned for 5 s, then polymerized with a conventional halogen light source for 20 s. Filtek Z 350 XT universal composite restorative material cylinder was placed over the adhesive with the help of a split Teflon mold of 4 mm height and 3 mm diameter and light polymerized for 40 s. Then, the mold was removed.
Each specimen was loaded into universal testing machine. The shear bond strength was measured at a crosshead speed of 0.5 mm/min until fracture occurred using universal testing machine.
Paired t-test was performed to analyze the changes in the antimicrobial efficacy of the different groups. Chi-square test was performed to analyze the scorings obtained for the microleakage. One-way ANOVA was used for multiple group comparison followed by post-hoc Tukey's test for pair wise comparison. Chi-square test was used for microleakage and shear bond strength. For all the tests, a P = 0.05 or less was considered for statistical significance.
| Results|| |
The result of antimicrobial efficacy showed that Group III, that is, G-Bond with 3% CPC showed the highest rate of antibacterial activity against S. mutans than the other two groups. On intergroup comparison, the difference was found to be statistically highly significant (P < 0.001) [Table 3] and [Graph 1[Additional file 1]].
|Table 3: Values of one-way ANOVA followed by post-hoc Turkey's test for group wise comparisons of the experimental groups of Group I, Group II, and Group III|
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The results of microleakage [Table 4] and [Graph 2[Additional file 2]] showed that there was no statistically significant change in the intergroup comparison.
|Table 4: Intergroup comparison of the mean, median, and range of the scorings of microleakage|
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The results of shear bond strength [Table 5] and [Graph 3[Additional file 3]] showed that there was no statistically significant change in the intergroup comparison.
|Table 5: Intergroup comparison of the mean and range of the values of the SBS|
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| Discussion|| |
The antimicrobial property
Self-etching adhesives have been introduced in an attempt to simplify the clinical application procedure and reduce the technique sensitivity and risk of the primed surface being contaminated.
The dentin bonding agent is the component that comes into contact with the dentin substrate at the first stage of restoration in an adhesive system. If the dentin bonding agents possessed antibacterial activity, residual bacteria could be eliminated, thereby preventing the secondary caries.
CPC is a well-known and effective antibacterial agent, its wide use as an over-the-counter drug, and an oral hygiene aid is regulated by food and drug administration. It acts through the positive charge of the pyridinium group which attracts the negatively charged cell membrane of bacteria, eventually causing bacteriolysis. Namba et al. has shown that 1% and 3% CPC when added to dentin bonding agent possessed significant contact bacteriostatic activity even after getting immobilized in resin matrix.
The direct contact test employed in this study has many advantages over the agar diffusion tests, and has been proved with its efficacy by Weiss et al., Shalhav et al., and Fuss et al. It relies on a direct and close contact between the test microorganism and the tested materials and is virtually independent of the diffusion properties of both the tested material and the media.
In the present study, the antibacterial activity of the freshly polymerized resin bonding agent was examined from 30 min to 7 days because the logarithmic growth phase of a bacterial cycle had a range of up to 7 days. Observations from this study showed that tested material of G-Bond with 3% CPC showed maximum antibacterial activity.
The results are in accordance with the study done by Imazato et al., and Feuerstein et al. who showed the antibacterial activity against S. mutans and the capability to disinfect cavities containing residual bacteria.
Among the different techniques, dye penetration method is the most widely method to assess microleakage because of its sensitivity, ease of use, and convenience. The leakage was assessed in this study by dye penetration technique using scoring given by Micheal staninec and Holts criteria. According to Azoubel and Veeck, methylene blue dye should be used in leakage studies because of its small particle size, ease of visualization, and large dissemination into dentinal tubules.
Shear bond strength
Different mechanical tests such as tensile bond strength and shear bond strength have been proposed to assess the bonding performance of restorative materials. Although it suffers criticism, shear testing has been widely used to evaluate the bonding ability of adhesive materials to dental structure.
According to the study done by Elsaka, addition of antibacterial agent, i.e. chitosan to dentin bonding agent has not hampered the microtensile bond strength of the overall restoration. However, no previous studies which have added the antibacterial agents to dentin bonding agents have checked for the shear bond strength property.
Thus, the observations obtained in this study can be attributed to the strong adhesion between the dentin bonding agent and the tooth even after the addition of CPC. Thus, the microleakage and shear bond strength of the dentin bonding agent groups used in this study proves to be having no statistically significant change in their values.
| Conclusion|| |
Within the limitations of our study, the antibacterial effect of G-Bond with 3% CPC may prove to be of most efficient against S. mutans. Another advantage noted in our study was that this combination did not adversely affect the microleakage and shear bond strength of the resin cement.
Hence, its use may be beneficial during the treatment of deep caries where there are chances of leaving behind the residual bacteria, as this would overcome the consequences to be faced further and achieve a better prognosis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4], [Table 5]