|Year : 2013 | Volume
| Issue : 3 | Page : 169-174
Scanning electron microscope analysis of sealant penetration and adaptation in contaminated fissures
Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, Riyadh, Saudi Arabia
|Date of Web Publication||11-Sep-2013|
Department of Pediatric Dentistry and Orthodontics, College of Dentistry, King Saud University, P.O. Box 60169, Riyadh 11545
Source of Support: King Saud University, College of Dentistry
Research Center, project no. F1203., Conflict of Interest: None
| Abstract|| |
Objective: The objective of this study is to evaluate the penetration and adaptation of two different sealant materials applied under different conditions of contamination using scanning electron microscope (SEM) analysis. Materials and Methods: A total of 56 extracted human third molar teeth were randomly assigned into eight equal groups. The treatment groups were defined by the combination of two sealant materials (glass ionomer fissure sealant "Fuji Triage" or resin-based fissure sealant "Clinpro TM") and four surface conditions (dry condition, water contamination, saliva contamination or saliva contamination and air-drying). Penetration depth, sealant adaptation and fissure types were evaluated under SEM after sectioning the teeth. Tukey's test and multiple linear regression analyses were used for statistical analysis. Results: No significant difference in the sealant penetration and adaptation was found between both materials under dry conditions. However, under wet contaminations, resin-based sealant showed less adaptation and penetration with a significant difference when compared to glass ionomer sealant (P < 0.05). The multiple linear regression analyses revealed significant impact of different materials and types of contamination on the sealant penetration and adaptation. Conclusion: Glass ionomer sealant has better fissure penetration and more intimate adaptation than resin-based sealant under wet contamination conditions.
Keywords: Contamination, scanning electron microscope, sealant adaptation, sealant penetration
|How to cite this article:|
Al-Jobair A. Scanning electron microscope analysis of sealant penetration and adaptation in contaminated fissures. J Indian Soc Pedod Prev Dent 2013;31:169-74
|How to cite this URL:|
Al-Jobair A. Scanning electron microscope analysis of sealant penetration and adaptation in contaminated fissures. J Indian Soc Pedod Prev Dent [serial online] 2013 [cited 2019 Nov 13];31:169-74. Available from: http://www.jisppd.com/text.asp?2013/31/3/169/117970
| Introduction|| |
Pit and fissure sealants have demonstrated an efficient preventive way and have significantly reduced caries in occlusal surfaces of primary and permanent posterior teeth.  First permanent molars are the most caries susceptible teeth during the 1 st year after eruption when the tooth is not fully matured and oral hygiene is difficult to maintain.  After this period, the risk of dental caries is lower and the consequence of sealant loss is less important. 
However, sealant retention is the main determinant in maintaining a caries-preventive effect, which depends mostly on its penetration into fissures and its adaptability to the fissures walls.  Optimal sealant adaptation is necessary in order to prevent marginal microleakage. Variations in sealant retention occur among different sealant systems which might be related to many factors. These factors may include some technical errors such as salivary contamination, material characteristics and fissure morphology. ,,
Current resin-based sealant materials are unable to tolerate even minute amount of contamination, which is difficult to avoid in some clinical situations.  Some investigators have sought several ways to re-establish the morphology of etched enamel such as washing, re-etching of contaminated surfaces or using intermediate bonding layer. ,,
Other investigators have tested different sealant system like glass ionomer cement to overcome problems associated with resin-based sealant system. ,,, Glass ionomer cement was introduced as sealant material with consideration of its properties like continuous fluoride release and ability to bond chemically with untreated enamel.  Newly introduced glass ionomer fissure sealant is claimed to work in moist field with no need for isolation or bonding agent.
Consequently, this study was designed to evaluate the penetration and adaptation of two different sealant materials; glass ionomer fissure sealant (Fuji Triage) and resin-based fissure sealant (Clinpro TM ) when applied under different conditions of contamination using scanning electron microscope (SEM) analysis. The null hypothesis to be tested was that there is no statistically significant difference in penetration and adaptation between glass ionomer and resin-based fissure sealants under: (1) dry conditions and (2) wet conditions.
| Materials and Methods|| |
A total of 56 non-carious extracted human third molars were used in this study. Teeth were cleaned with water/pumice slurry using a dental prophylactic cup and then were stored in distilled water. The teeth were then randomly assigned into eight groups (seven teeth each). The treatment groups were defined by the combination of two sealant materials and four surface conditions. The sealant systems employed in this study are shown in [Table 1].
Preparation of the occlusal surfaces
Occlusal surfaces of groups 1, 2, 3 and 4 were conditioned with 40% polyacrylic acid (GC Corporation, Tokyo, Japan) for 10 s, then rinsed with water for 10 s then dried, while the occlusal surfaces of groups 5, 6, 7 and 8 were acid etched with 37% phosphoric acid gel (3M ESPE, St Paul, USA) for 15 s then rinsed with water for 10 s and air-dried until a frosted appearance of the occlusal surface appeared. Each group was then subjected to four different surface contamination conditions as follows: ,
No contamination at all. A dry surface was available for sealing.
A drop of water was syringed on the occlusal surface of the enamel and left undisturbed for 10 s. The excess of water was then blotted with a small sponge leaving moist shiny enamel surface.
A drop of fresh human saliva was syringed on the occlusal surface of the enamel and left undisturbed for 10 s. The excess of saliva was then blotted with a small sponge leaving moist shiny enamel surface.
Saliva contamination and air-drying
A drop of fresh human saliva was syringed on the occlusal surface of the enamel for 10 s then, the surface was air dried for 5 s.
For all groups involving salivary contamination, saliva was obtained from a single donor at the time of the experiment by extracting whole saliva from the floor of the mouth using a pipette. 
Both sealant materials were manipulated according to the manufacturer's instructions. For groups 1, 2, 3 and 4, Fuji Triage was triturated for 10 s then applied directly on the occlusal surface and carefully spread with a small soft brush and light cured for 40 s using a halogen curing light (3M ESPE, Elipar TM 2500). Clinpro TM sealant was applied to the occlusal surface of groups 5, 6, 7 and 8; with a needle tip syringe and carefully spread with a small soft brush and light cured for 20 s.
After sealing of the fissures, the root portions were cut off and then the crown portions were mounted on acrylic blocks covering the whole crown, then sectioned buccolingually, with a water-cool diamond saw (Precision Saw, Isomet 2000/BUEHLER, USA). Four sections were obtained from each tooth (1 mesial, 2 center and 1 distal sections). The specimens were allowed to dry for 24 h before subjecting them to gold sputtering. For this, the specimens were mounted on aluminum stubs using double-sided adhesive tape; they were mounted in such a way that area to be studied faced upward. The mounted surfaces were then coated with a thin layer (25 nm thickness) of pure gold using an ion sputtering unit. The stubs were then placed in the vacuum chamber of the SEM. The accelerating voltage, angle of tilt and the aperture were adjusted to suit the specimen to optimize the quality of the micrograph. The surface were scanned and observed on the screen under different magnifications (×13 to ×1500).
Examination of sealant penetration
The depth of sealant penetration into fissures was expressed in percentages  and calculated at a magnification of ×13 to ×15. The distance between the most superficial and the deepest points of the central fissure was calculated and expressed as the fissure's total depth. The measurement corresponding to the length of the central fissure filled with the sealing material was divided by the measurement corresponding to its total depth to obtain the percentage of the sealant penetration.
Examination of sealant adaptation
Sealant adaptation was expressed as the gap width. The gaps between the sealant and tooth surface were measured under higher magnification (×300 to ×1500) by placing the two indicator marks at two extremes of the gaps along the lateral walls and the distance between them was recorded as given by the computer. The minimum and the maximum gaps were recorded then the mean was calculated for each section in μm. 
Examination of fissure types
The micromorphological types of the fissure were classified as follow: (1) U type, (2) V type, (3) Y1 type and (4) Y2 type.  For statistical purpose, U and V types were combined together as wide and shallow fissures while Y1 and Y2 types were combined together as narrow and deep fissures.
Data were statistically analyzed using the SPSS version 16. Tukey's test was conducted to test whether there were significant differences in the sealant penetration and adaptation values among the different groups. Pearson Chi-square test was used to test the distribution of fissure types among the groups. Multiple regression analyses were used to analyze the impact of different materials, types of contamination and fissure types on the sealant penetration and adaptation.
| Results|| |
The penetration and adaptation results of Fuji Triage and Clinpro fissure sealants tested under different contamination conditions are shown in [Table 2]. All groups showed some degree of penetration and adaptation failure. As shown in [Table 2], under dry conditions, no significant difference in the sealant penetration and adaptation was found between both materials (P > 0.05) [Figure 1], [Figure 2], [Figure 3] and [Figure 4], a and b]. Thus the first part of the null hypothesis was not rejected. However, under wet contaminations, significant statistical difference was found in the penetration and the adaptation between Clinpro and Fuji Triage (P < 0.05) [Figure 1], [Figure 2], [Figure 3] and [Figure 4], c and d]. Therefore, the second part of the null hypothesis was rejected. Fuji Triage penetrated and adapted well to the fissures under wet conditions while Clinpro penetrated and adapted well under dry conditions. Fissure types were distributed between the groups without statistical difference as shown by the Chi-square test (P = 0.263) [Table 3]. The multiple linear regression analyses revealed significant impact of material types, types of contamination and fissure types on the sealant penetration as shown in [Table 4]. The same impact factors affected the sealant adaptation with the exception of fissure types.
|Table 2: Penetration and adaptation of fissure sealants of different treatment groups|
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|Table 4: The significant impact factors on the performance of fissure sealants|
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|Figure 1: Scanning electron microscope pictures showing penetration of sealant into fissures in different Clinpro groups; (a) dry, (b) dried saliva, (c) water, (d) saliva|
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|Figure 2: Scanning electron microscope pictures showing penetration of sealant into fissures in different Fuji Triage groups; (a) dry, (b) dried saliva, (c) water, (d) saliva|
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|Figure 3: Scanning electron microscope pictures showing gaps along lateral wall of fissures in different Clinpro groups; (a) dry, (b) dried saliva, (c) water, (d) saliva|
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|Figure 4: Scanning electron microscope pictures showing gaps along lateral wall of fissures in different Fuji Triage groups; (a) dry, (b) dried saliva, (c) water, (d) saliva|
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| Discussion|| |
The preventive benefits of the pit and fissure sealants are only guaranteed when the sealant is absolutely retained with adequate adaptation to the enamel.  In this study, penetration and adaptation of resin-based and glass ionomer fissure sealants were evaluated under different contamination conditions using SEM analysis. The use of SEM provides a mean of direct visual observation of penetration and adaptation of sealant materials to enamel walls due to its magnification and depth of focus. In the present study, numerical measurements were used rather than rating score systems in the assessment of sealant penetration and adaptation. The presence of computer software that calculates the measurements gives reflecting results better than personal estimation using a scoring system.
The results of the present study revealed a good performance of Fuji Triage in relation to its adaptation to the fissure walls under wet and dry surface conditions. This is in accordance with the results of Topaloglu and Alpoz  who found that there was no difference in microleakage scores in Fuji Triage groups under contaminated or uncontaminated conditions. In contrary, Peng et al.,  found that Fuji Triage showed a significant increase in the microleakage when saliva was introduced during application of Fuji Triage sealant. Other investigators showed better results in marginal microleakage when glass ionomer was placed under wet contaminated surfaces. , Regarding sealant penetration, Fuji Triage showed better penetration than Clinpro under wet contamination conditions, which might be due to the combination of low viscosity and moisture insensitivity of Fuji Triage sealant material. Droz et al.,  found that glass ionomer sealant (Ionosit) penetrated fissures better than resin-based and compomer sealants. Selecman et al.,  also found that Fuji Triage showed superior result in sealant penetration among other tested materials.
Clinpro, on the other hand, behaved very well under dry condition without any contamination. It penetrated deeply into the fissures with the best adaptation among the tested groups. The micromechanical retention provided through porosities maximize the surface area of bonding.  In addition, the low viscosity of this material which is maintained until it is light cured, permits better penetration and adaptation into the fissures resulting in a bond with a deeper enamel layer.  In a moisture controlled environment, Ashwin and Arathi  found that there is no difference in microleakage between resin-based sealant and Fuji glass ionomer sealant, which is in agreement with the result of the present study as related to the presence of gaps.
Findings of this study indicated that there was no negative effect of the dried saliva contamination on the penetration and adaptation of Clinpro fissure sealant. This is not in agreement of previous works, which showed that saliva contamination of etched enamel even for a single second, resulted in a persistent coating which blocked the porosities of etched enamel.  However, this result is in agreement with Duangthip and Lussi  who found that there was no negative effect of dried saliva contamination on the sealing quality of resin-based sealant. Conversely, wet contaminants either water or saliva unfavorably affected the penetration and the adaptation of Clinpro fissure sealant. This result is in accordance with many previous studies. , Most of the porosities created after etching are blocked with moisture when the enamel is wet. This causes a lack of resin penetration, which results in tags of insufficient numbers and length and subsequently a shallow level of fissure penetration and wide gaps formed along the enamel sealant interface. 
Fissure depth and types are of great effects on the penetration of sealing materials. In the present study, both materials displayed the greatest penetration in the shallow and wide fissures while deep and narrow fissures revealed the lowest degree of penetration. This result agrees with previous researches in which sealant penetration is significantly related to the fissure types and depth. , No effect of fissure types on sealant adaptation was found in this study which is in agreement with Grewal and Chopra. 
The results of this study propose that resin-based fissure sealant can be used under moisture controlled environment whereas glass ionomer sealant might be used when resin sealants are contraindicated. However, glass ionomer sealants may have poorer retention rates than their resin-based counterparts, , but a little amount of sealant remnants on the fissures releases fluoride and provides protection against caries attack. , Conversely, some clinical studies showed better retention of glass ionomer when used as fissure sealant in primary and permanent molar teeth. , Recently, Antonson et al.,  reported that resin-based and glass ionomer sealants exhibited similar retention rates at 24 months.
Nevertheless, glass ionomer may provide good sealant in the treatment of young children or children with special needs who are incapable to follow meticulous isolation methods. Moreover, glass ionomer sealant can be used in the treatment of permanent first or second molars that are partially erupted and in a situation where a "transitional" sealant may be considered before placement of a "permanent" resin sealant. ,
In the present study, the glass ionomer and resin-based fissure sealants, however, were compared only with respect to their penetration and adaptation under different contamination conditions. Moreover, no thermocycling was used as loss of sealant of saliva and water contaminated specimens was a concern. In this perspective, other parameters such as long-term retention, integrity of the sealant and shear bond strength of the sealant must be considered when comparing both materials. In spite of the limitations, the study gives some information to carry additional clinical researches into the use of glass ionomer as a material of fissure sealant in children.
| Conclusions|| |
Based on the results of this study, the following conclusions can be made:
- Glass ionomer sealant has better fissure penetration and more intimate adaptation than resin-based sealant under wet contamination conditions.
- Resin-based sealant has the best marginal adaptation under a moisture controlled environment.
- Sealant penetration and adaptation are influenced by the type of material and enamel surface contamination.
| Acknowledgment|| |
The study was registered and funded by King Saud University, College of Dentistry Research Center, project no. F1203.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]
[Table 1], [Table 2], [Table 3], [Table 4]