|Year : 2014 | Volume
| Issue : 2 | Page : 88-91
Polymerization shrinkage of six different fissure sealants
Yagmur Sener1, Murat Selim Botsali2, Ebru Kucukyilmaz3, Gul Tosun2, Selcuk Savas3
1 Department of Pediatric Dentistry, Faculty of Dentistry, Necmettin Erbakan University, Konya, Turkey
2 Department of Pediatric Dentistry, Selcuk University, Konya, Turkey
3 Department of Pediatric Dentistry, Izmir Katip Celebi University, Izmir, Turkey
|Date of Web Publication||11-Jul-2014|
Department of Pediatric Dentistry, Faculty of Dentistry, Izmir Katip Celebi University, Cigli, Izmir
Source of Support: None, Conflict of Interest: None
Objectives: The objective of this study was to evaluate and compare the polymerization shrinkage of six proprietary pit and fissure sealants (Helioseal F, Fissurit FX, Smartseal & loc F, Dyract Seal, Clinpro TM Sealant, Teethmate F-1). Materials and Methods: A total of 120 glass ring molds (8.5 mm in inner diameter and 2 mm in height) were prepared after which the internal surface of the molds were etched with hydrofluoric acid for 5 min. The test materials (n = 20/group) were placed into the molds and thereafter sandwiched between two glass slides. All groups were polymerized for 20 s using a high-intensity quartz tungsten halogen (HQTH) light unit (Optilux 501). The volumetric polymerization shrinkage for each pits and fissure sealant was measured using the specific density method modified by Puckett and Smith. All data were analyzed statistically using one-way analysis of variance and Tukey honest significant difference (HSD) test at P < 0.05. Results: A ranking for the shrinkage values were obtained as follows: Teethmate F-1 (7.40 ± 1.17%) > Clinpro TM Sealant (6.60 ± 1.54%) > Dyract Seal (5.38 ± 1.30%) > Smartseal & loc F (5.06 ± 1.22%) > Fissurit FX (4.30 ± 1.15%) > Helioseal F (3.30 ± 0.69%). Clinpro TM Sealant and Teethmate F-1 displayed the highest shrinkage values (P < 0.05). The lowest shrinkage values were obtained with Helioseal F (3.30 ± 0.69%) and Fissurit FX (4.30 ± 1.15%) (P < 0.05). Conclusion: Within the experimental conditions of the present study, sealant materials containing higher concentrations of fillers displayed lower polymerization shrinkage values.
Keywords: Filler concentrations, pit and fissure sealants, polymerization shrinkage
|How to cite this article:|
Sener Y, Botsali MS, Kucukyilmaz E, Tosun G, Savas S. Polymerization shrinkage of six different fissure sealants. J Res Dent 2014;2:88-91
|How to cite this URL:|
Sener Y, Botsali MS, Kucukyilmaz E, Tosun G, Savas S. Polymerization shrinkage of six different fissure sealants. J Res Dent [serial online] 2014 [cited 2019 Dec 7];2:88-91. Available from: http://www.jresdent.org/text.asp?2014/2/2/88/136645
| Introduction|| |
The prevalence and incidence of dental caries has declined remarkably since last few decades, though it is still prevalent worldwide. , The formations on the occlusal surfaces of the teeth, referred to as "pits" and "fissures," are the most susceptible sites for dental caries because of their specific anatomy and inability to provide adequate plaque elimination. ,
The use of systemic and local fluorides and the application of fissure sealants are the most important methods for preventing dental caries. ,, Although fluoride application is a useful method for controlling caries on smooth and approximal surfaces, fluorides are not equally effective in protecting the occlusal pits and fissures. , The use of fissure sealants is recognized as the most effective method for preventing or arresting caries development on the occlusal surfaces of high-risk children and adolescents. 
Today, there is a wide spectrum of sealing materials available. These materials differ in their base compound, polymerization method, filler type and content, material opacity/color, and fluoride content.  Resin-based sealants are bonded to the underlying enamel using the acid-etch technique. The preventive benefits of this treatment rely on the ability of the resin sealant to thoroughly fill pits, fissures, and/or morphological surface defects and remain completely intact and bonded to the enamel for a lifetime. , Thus, the success of this technique primarily depends on the marginal adaptation of the sealant affected by the shrinkage of the material during polymerization. ,
Polymerization shrinkage of resin-based materials occurs when monomer molecules are converted into a polymer network and exchange van der Waals spaces for covalent bond spaces.  This shrinkage may lead to the generation of internal stresses and the loss of marginal integrity. A reduction in the marginal integrity of the tooth/sealant interface results in gap formation and initiates microleakage. Microleakage is defined as the passage of bacteria, fluids, and other molecules through the restoration material to the tooth surface, and it is considered to be one of the main reasons for restoration failure. ,
To the best our knowledge, no study has compared the polymerization shrinkage of different pit and fissure sealants. The aim of this study was to evaluate and compare the polymerization shrinkage of six proprietary pits and fissure sealants. The tested null hypothesis was that there were no statistically significant differences in polymerization shrinkage between the different materials tested.
| Materials and methods|| |
A total of 120 glass molds (8.5-mm inner diameter and 2-mm height) were prepared using a low-speed Isomet saw (Buehler Ltd., Evanston, USA). The internal surfaces of the glass rings were roughened and etched for 5 min with Etch-It hydrofluoric acid (American Dental Supply, Easton, PA, USA). The glass molds were then weighed in air and in water with a Shimadzu AY220 electronic balance (Shimadzu Corp., Kyoto, Japan) to determine their density and volume.
A total of 6 different fluoride release pit and fissure sealants, namely, Helioseal F (Ivoclar Vivadent, Schaan, Liechtenstein), Fissurit FX (Voco, Cuxhaven, Germany), Smartseal & loc F (DetaxGmbh and Co, Ettlingen, Germany), Dyract Seal (DentsplyDeTrey GmbH, Konstanz, Germany), Clinpro™ Sealant (3M ESPE, St. Paul, MN, USA), and Teethmate F-1 (Kuraray, Kurashiki, Japan), were used [Table 1]. A total of 20 samples of each fissure sealant were placed in the glass molds, and the molds were sandwiched between two glass slides. A force of 5 N was applied for 30s to ensure that the sealant was well distributed within the mold. All the sample groups were polymerized for 20s using an Optilux 501 high-intensity quartz tungsten halogen (HQTH) light unit (Kerr Corporation, Washington DC, USA) with a 10-mm diameter light tip. The outputs of the light tips were calibrated using a Demetron digital curing radiometer (Kerr Corporation) at 850 mW·cm 2 , and the light output of the light curing unit was measured, both prior to sample exposure and after every 10 samples. The samples were stored under dark dry conditions at 37 °C for 24 h after light curing; then, they were weighed both in air and in water to determine their density and volume.
The volumetric polymerization shrinkage of each compound (n = 20) was determined using the specific density method, modified by Puckett and Smith,  with the following relationships:
V0 is the volume of the glass ring cylindrical hole (mm 3 ), D is the inner diameter of glass ring (mm), h is the glass ring height (mm), V1 is the volume of the glass ring (mm 3 ), W0 is the weight of the glass ring in air (g), W1 is the weight of the glass ring in water (g), ρT is the density of water at temperature T (g/mm 3 ), V2 is the volume of the glass ring + composite sample (mm 3 ), W2 is the weight of ring + composite sample in air (g), V3 is the volume of adhesive paste sample after polymerization (mm 3 ), W3 is the weight of ring 1 composite sample in water (g), and ΔV is the volumetric shrinkage (mm 3 ). Using the relations (1)-(2), it was found that
% shrinkage = 10 2 (ΔV /V0 ). (3)
The experimental results were recorded using Excel (Microsoft, Seattle, WA, USA). For all sample groups, the average values and their standard deviations were then calculated. These data were analyzed using the Statistical Package for the Social Sciences (SPSS) 20.0 computer program (SPSS, Chicago, IL, USA). A one-way analysis of variance followed by a Tukey honest significant difference (HSD) test was used to evaluate the hypothesis. Statistical significance was set at P < 0.05.
| Results|| |
The shrinkage values were in the following order: Teethmate F-1 (7.40 ± 1.17%) > Clinpro™ Sealant (6.60 ± 1.54%) > Dyract Seal (5.38 ± 1.30%) > Smartseal & loc F (5.06 ± 1.22%) > Fissurit FX (4.30 ± 1.15%) > Helioseal F (3.30 ± 0.69%). Although there was no statistically significant difference between the Helioseal and Fissurit FX materials (P > 0.05), there was a statistically significant difference between the Helioseal and other materials (P < 0.05). The highest shrinkage values were obtained from the Teethmate F-1 and Clinpro™ Sealant samples; these differences were significant compared with the other groups (P < 0.05). The mean values and standard deviations for all groups are presented in [Table 2].
|Table 2: The polymerization shrinkage mean values (%) and standard deviations of tested pits and fissure sealants|
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| Discussion|| |
The pits and fissures areas of the occlusal surfaces of posterior teeth are most susceptible to dental decay. Studies show that approximately 50% of all carious lesions occur on occlusal surfaces. , Pit and fissure sealants are considered an outstanding adjunct to oral health care preventive strategies related to occlusal caries onset and/or progression.  Polymerization shrinkage of resin-based restorative materials is a crucial factor in the application of these materials to the tooth surface and adversely affects the marginal integrity. ,, Therefore, high-shrinkage restorative materials cause poor marginal integrity and high microleakage, which enhance caries lesion progression underneath the restoration. , Although the penetration ability, marginal integrity, and microleakage of these sealants have been investigated in many studies, ,,, to our knowledge, no study has investigated polymerization shrinkage in these materials. Therefore, the main objective of this study was to evaluate the polymerization shrinkage of different pits and fissure sealants during polymerization.
Reducing polymerization shrinkage is important for improving the quality of resin-based pits and fissure sealant materials. To achieve this, manufacturers have increased the volume of inorganic filler, used different comonomers, and developed new monomers with low volumetric shrinkage for reducing the polymerization shrinkage. In the present study, six different filler types and fluoride-containing resin-based pits and fissure sealants were used. The volumetric polymerization shrinkage of resin-based materials is a source of concern to clinicians, as it may lead to failure of restorations. Numerous methods for the determination of shrinkage have been reported including measurements by mercury dilatometer or water dilatometer, measurements of linear contraction or density, and calculations based on "degree of conversion" measurements. ,,, Each method has limitations and disadvantages. In the current study, the volumetric polymerization shrinkage for each system was measured using the specific density method, modified by Puckett and Smith,  which is a simple, applicable, and well-established test method. This technique involves weighing the specimen before and after polymerization and using these values to calculate specific gravity prior to determining volumetric shrinkage.
Considering the results of the present study, the null hypothesis was rejected because significant differences in shrinkage were detected in the different materials tested under the same conditions. The results revealed differences in shrinkage between all groups. The data demonstrated that all sealants showed shrinkage to some degree. The greatest amount of polymerization shrinkage among the groups was observed in the Teethmate F-1 and Clinpro™ Sealant materials. This result is likely due to the amount of inorganic filler in these materials. Although Clinpro™ Sealant has minimal inorganic filler particles; Teethmate F-1 has no inorganic filler. It is known that the filler content is the most important factor that affects the amount of shrinkage in resin-based restorative materials. , In the present study, the minimum shrinkage value was observed in the Helioseal and Fissurit FX materials. Despite the fact that the Fissurit FX group has the highest inorganic filler content, Helioseal showed lower shrinkage, although the difference is not significant. Additionally, the Dyract Seal and Smartseal & loc F materials showed relatively low shrinkage values compared with the Clinpro™ Sealant and Teethmate F-1 materials.
Resin-based pit and fissure sealant materials are heterogeneous materials with two principal components: the resin matrix and the filler particles.  Other than the amount of filler content, the polymerization shrinkage depends on many factors, including the average molecular weight, size of the filler particles, type of filler material, composition of the resin matrix, and viscosity of the resin-based materials. ,, All these factors together may directly or indirectly affect the adaptability of the material to the tooth surface before and after polymerization.
| Conclusions|| |
Considering the limitations of this study, it was concluded that sealant materials containing higher concentrations of fillers exhibited lower polymerization shrinkage values.
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[Table 1], [Table 2]