Year : 2007 | Volume
: 25 | Issue : 3 | Page : 133--136
Comparison of antibacterial properties of two fluoride-releasing and a nonfluoride-releasing pit and fissure sealants
V Menon Preetha1, ND Shashikiran2, V.V.S Reddy2,
1 Department of Pedodontics and Preventive Dentistry, KLES Institute of Dental Sciences, Belgaum, Karnataka, India
2 Department of Pedodontics and Preventive Dentistry, College of Dental Sciences, Davangere, Karnataka, India
N D Shashikiran
Department of Pedodontics and Preventive Dentistry, College of Dental Sciences, Davangere
Occlusal pits and fissures are the most susceptible sites for the development of dental caries and prevention is difficult in the areas of occurrence. Although only 12.5% of all the tooth surfaces are occlusal, these surfaces develop more than two-thirds of total caries experienced by children. The fate of the bacteria is of significance when they are inadvertently sealed by a dental sealant. This study aimed in examining the antibacterial properties of three commercially available sealants, viz., Teethmate-F, Helioseal-F and Helioseal. Antibacterial testing was done by disc diffusion method. Selective agars were used to grow Streptococcus mutans and Lactobacillus acidophilus, which are implicated in the pathogenesis of dental caries. Statistical analysis was carried out using student«SQ»s t test. The study proved that Helioseal-F and Helioseal did not possess antibacterial properties and Teethmate-F was the only sealant that showed antibacterial properties.
|How to cite this article:|
Menon Preetha V, Shashikiran N D, Reddy V. Comparison of antibacterial properties of two fluoride-releasing and a nonfluoride-releasing pit and fissure sealants.J Indian Soc Pedod Prev Dent 2007;25:133-136
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Menon Preetha V, Shashikiran N D, Reddy V. Comparison of antibacterial properties of two fluoride-releasing and a nonfluoride-releasing pit and fissure sealants. J Indian Soc Pedod Prev Dent [serial online] 2007 [cited 2020 Apr 5 ];25:133-136
Available from: http://www.jisppd.com/text.asp?2007/25/3/133/36564
Fluoride, the pivot of preventive dentistry, continues to be the cornerstone of caries prevention programmes. The success of fluoride in caries prevention of smooth surfaces has made dental caries primarily a disease of pits and fissures of teeth. Occlusal pits and fissures are the most susceptible sites for the development of dental caries and they occur in areas where prevention is difficult.  Although only 12.5% of all the teeth surfaces are occlusal, these surfaces develop more than two-thirds of the total caries in children. 
Pit and fissure sealants were introduced in 1967, and their effectiveness was recognized by American Dental Association in 1971.  The susceptibility of the occlusal surfaces of the permanent molars to dental caries has increased the applicability of pit and fissure sealants.
The clinical diagnosis of incipient carious lesions in posterior teeth is complicated by the depth, narrowness and complexity of the pits and fissures. Consequently, such lesions may remain undetected and inadvertently be sealed with a dental sealant.  The fate of the bacteria is of significance then.
Additional protection could be afforded against any subsequent deterioration of the bond at the resin-tooth interface if the sealant possesses some antibacterial property.  Since Streptococcus mutans and Lactobacillus acidophilus are associated with the initiation of dental caries and the progression of the established lesion, respectively, a reduction in the number of these bacteria in the resin-tooth interface would be expected to influence the caries incidence. 
This study was performed to assess the antibacterial properties of pit and fissure sealants and to compare the antibacterial properties of fluoride-releasing and nonfluoride-pit and fissure sealants.
Materials and Methods
The antibacterial properties of three different commercially available pit and fissure sealants, were studied. This included two fluoride-releasing sealants and a nonfluoride-releasing sealant on two microorganisms, which were laboratory isolates from the clinical samples of saliva.
The commercially available pit and fissure sealants used for the present study were as follows:
Teethmate-F1 (Kuraray Co Ltd., Japan)Helioseal-F (Vivadent, Germany)Helioseal (Vivadent, Germany)
The microorganisms in this study were Streptococcus mutans and Lactobacillus acidophilus and the culture media used to isolate the strains were Mitis Salivarius agar and Rogosa SL, respectively.
Saliva samples were obtained from healthy children with rampant caries. Saliva samples were collected using a sterile micropipette and transferred to a sterile bottle with 3 ml of brain heart infusion (BHI) broth as the transport medium.
Samples obtained were grown in BHI broth and incubated anaerobically for 18 hours at 37°C. The obtained growths were introduced into the selective agar. This was subcultured and incubated anaerobically for 48 hours. The test microorganisms were identified using gram staining. The pure bacterial strains obtained in the selective agar plates were again transferred into BHI broth under sterile conditions and incubated for 18 hours anaerobically. Further, sterile cotton swab dipped in this broth was streaked onto the selective agar plates and incubated anaerobically for 48 hours. Mitis salivarius agar was used for S. mutans and Rogosa selective agar was used for Lactobacillus acidophilus.
Assays of test microorganisms were done on selective agars by lawn culturing each organism from the pure culture. Three wells were prepared on each agar plate using a standard bore with a diameter of 5 mm, into which 3 different sealants were placed. The sealants were allowed to drop into each well until it was filled without allowing the tip to touch the agar. They were then polymerized for 20 seconds by light cure. The agar plates were further incubated at 37°C anaerobically for 48 hours for the growth to become appreciable. The antimicrobial properties of materials were assessed, which were apparent from the circular zones of bacterial inhibition (halo) around each material [Figure 1],[Figure 2]. The diameters of these zones of bacterial inhibition were measured. The measurement was repeated 4 times for each zone of inhibition.
Mean and standard deviation were noted. The antibacterial efficacy of sealants on Streptococcus mutans and Lactobacillus-acidophilus was analyzed by student's t test.
The diameter of the zone of inhibition was measured after a period of 2 days. The measurements were repeated four times to minimize the errors. The mean zone of inhibition was calculated; subsequently, statistical analysis was carried out.
[Table 1],[Table 2] show the zone of inhibition of Teethmate-F1 against Streptococcus mutans and Lactobacillus acidophilus respectively as recorded in 15 petri plates.
[Table 3] shows Teethmate-F1 with a mean zone of inhibition 11.763 ± 0.391 mm against Streptococcus mutans and 13.583 ± 0.318 against Lactobacillus acidophilus ; however, Helioseal-F and Helioseal did not show any zone of inhibition for Streptococcus mutans and Lactobacillus acidophilus .
The antibacterial activity of the sealants against Streptococcus mutans and Lactobacillus acidophilus was analyzed by student's t 'test.
Results revealed a statistically significant difference in the inhibition between Streptococcus mutans and Lactobacillus acidophilus by Teethmate-F1 ( P 
Modern sealants were developed as a primary preventive agent to be placed on sound teeth surfaces; however, the shades of Hyatt's philosophy emerged soon. As the sealants occluded the fissures, questions regarding whether the caries could progress beneath a sealant soon arose. After a number of studies, a clear answer was obtained. When the sealant is placed over an incipient carious lesion, caries does not progress, provided the sealant remains intact. Sealant is retained on the carious teeth just as well on the sound teeth and neither the lesion nor microbiologic counts progress under an intact sealant.  Reviews have concluded that the evidence is strong that caries-active lesions become caries inactive beneath the intact sealant. , The presence of Streptococcus mutans and Lactobacilli in the residual flora found in the dentin beneath some of the sealant-treated sites was an important finding. Both the microorganisms have been implicated in dental caries, and both of them apparently have greater survival capabilities in sites where the availability of nutrients is limited as beneath a sealant. Most clinical studies of pit and fissure sealants agree that a positive relationship exists between the sealant retention and the caries protection benefits, both in preventing and inhibiting the incipient caries in enamel and dentin.
The inhibition of caries progression is consistent with the bacteriologic observation that the lesion tends to become sterile over time.  Combining the benefits of fluoride release from glass ionomer cements and good retention and seal from resins, pit and fissure sealants with fluoride have been developed. There are two methods of fluoride incorporation in fissure sealants. In the first case, the fluoride is added to unpolymerized resin in the form of a soluble fluoride salt. After the sealant is applied to the tooth, the salt dissolves and fluoride ions are released; Helioseal-F is based on this procedure. In the second method, an organic fluoride compound is chemically bound to the resin. Fluoride release is by means of a diffusion/exchange mechanism in which anions from the oral fluids diffuse to the charge sites and exchange with fluoride, which diffuses onto the surface and is released into the solution; Teethmate F-1 is based on this method. 
The mechanism of fluoride release from fluoride fissure sealants remains speculative. The release might occur from the insoluble sealant material as a result of porosity. It might also occur because the fluoride ions or the fluoride glass is not tightly bound to the polymerized resin molecules. The release in fluoride glass containing sealants may also be due to fluoride glass grains depositing on the surface of the resin.
As the fluoride uptake increases, the enamel resistance to caries also increases. Hence, the use of a fluoridated resin-based sealant may provide an additional anticariogenic effect. With the ability to release fluoride into local environment, the supplemental pits and fissures and nonfissured enamel adjacent to such a sealant may benefit from the continuous and prolonged release of low levels of fluoride and decreases the risk of caries development. Fluoride-releasing sealants have shown antibacterial properties as well as greater resistance to artificial caries in comparison to nonfluoridated sealants.
Antibacterial testing can be done in one of the following ways, namely, diffusion technique and dilution technique. In this study, diffusion technique was carried out because it is known that the sealant placed within the tooth may exert its antimicrobial activity by direct contact with microorganism by diffusion.
Godoy et al. measured the amount of fluoride released by various fluoridated sealants. Results showed that Teethmate F-1 released significantly more fluoride in comparison to Helioseal-F.  In a similar study conducted by Loyola-Rodriguez and Garcia-Godoy, Teethmate F-1  was the only material that showed antibacterial activity against several strains of Streptococcus mutans and Streptococcus sobrinus .
Going et al.  have demonstrated that sealant treatment resulted in 89% reversal from the caries-active state to a caries-inactive state. The acid etching procedure itself reduced the number of cultivable microorganisms by approximately 95%. Results of the present study showed that fluoride released by the sealant is able to produce an inhibitory effect against Streptococcus mutans and Lactobacillus acidophilus .  These three factors - etching, sealing and antibacterial activity of fluoride are together almost a guarantee to inhibit the cariogenic bacteria under the sealants.
Results revealed that Teethmate F-1 was the only sealant that showed zones of inhibition against both the bacteria and hence the only active material with antibacterial properties. The other 2 sealants used, namely, Helioseal-F and Helioseal failed to show zones of inhibition. The significant difference in antibacterial action by two fluoride-releasing sealants suggests that the formulation of the compound has an effect on the antibacterial property.
Ideally, sealants and fluoride should be used to supplement each other. With the protection of smooth surfaces by some form of fluoride and the protection of pit and fissures by the routine use of sealants, we now have the means to nearly eradicate dental caries.
The treatment of moderate to deep carious lesion by sealant application is not a reasonable alternative to conventional cavity preparation and restoration. However, it may be stated that the dentist's fear of sealing in caries inadvertently is unfounded and should no longer be a concern.
We acknowledge the assistance provided by all the teaching and nonteaching staff of the Department of Pedodontics, College of Dental Sciences, Davangere.
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