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Year : 2019  |  Volume : 7  |  Issue : 1  |  Page : 4-7

Compressive strength of three different restorative materials (in vitro study)

1 Department of Restorative Dental Sciences, College of Dentistry, Damascus University, Damascus, Syria
2 Department of Restorative Dental Sciences, Alfarabi Colleges of Dentistry and Nursing, Riyadh, Saudi Arabia
3 Department of Prosthodontic Dental Sciences, Alfarabi Colleges of Dentistry and Nursing, Riyadh, Saudi Arabia
4 Department of Restorative Dental Sciences, College of Dentistry, Buraydah Colleges, Buraydah, Saudi Arabia

Date of Web Publication26-Jun-2019

Correspondence Address:
Dr. Mazen Doumani
Department of Restorative Dental Sciences, Alfarabi Colleges of Dentistry and Nursing, Riyadh
Saudi Arabia
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/INJO.INJO_13_19

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Objective: This study aimed to compare the compressive strength of zinc-reinforced glass ionomer (ZRGI) restorations with high-viscosity glass ionomer (HVGI) cement and posterior composite restorations. Materials and Methods: Twenty-four cylindrical blocks (6 ± 0.1mm height, 4 ± 0.1mm diameter) were prepared from the three studied materials using a prefabricated Teflon mold and were divided into three equal groups. The compressive strength test was performed by Instron mechanical test system model 1195. Statistical analysis was performed depending on analysis of variance and least significant difference tests at 95% significance level. Results: Posterior composite restoration showed the highest compressive strength (239MPa), whereas there was no difference between ZRGI and HVGI (154MPa and 151MPa, respectively). Conclusions: Although the compressive strength of ZRGI was close to that of HVGI, this fact does not give ZRGI any preference, but it is possible that improvements can be reflected. Other properties can be studied later. We recommend not to rely on ZRGI as permanent restoration instead of posterior composite resin restoration.

Keywords: Conventional, compressive strength, glass ionomer, high-viscosity, posterior composite

How to cite this article:
Seirawan MY, Doumani M, Seirawan MK, Habib A, Dayoub M. Compressive strength of three different restorative materials (in vitro study). Int J Oral Care Res 2019;7:4-7

How to cite this URL:
Seirawan MY, Doumani M, Seirawan MK, Habib A, Dayoub M. Compressive strength of three different restorative materials (in vitro study). Int J Oral Care Res [serial online] 2019 [cited 2023 Mar 25];7:4-7. Available from: https://www.ijocr.org/text.asp?2019/7/1/4/259112

  Introduction Top

Glass ionomer cements (GICs) were first invented by Wilson and Kent[1] nearly 47 years ago. GICs are composed of a calcium fluoroaluminosilicate glass powder and an aqueous solution of an acrylic acid homo- or copolymer (polyelectrolyte).[2] Available glass ionomer can be divided into two major categories, conventional glass ionomer cements (CGICs) and resin-modified GICs. CGICs are used by dentists because of their biocompatibility, low cytotoxicity,[3] fluoride release, and limited micro leakage.[4] However, they also have less-desirable physical and mechanical properties such as susceptibility to dehydration, low fracture toughness, and flexural strength.[5] Several modifications have been introduced with the purpose of enhancing their mechanical properties and expanding their indications and clinical applications.[6],[7] Nowadays, resin-modified glass ionomer and resin composites are available, with superior values of mechanical strength when compared to conventional cements. A new zinc-reinforced glass ionomer (ZRGI) restorative material was introduced (ChemFil Rock; Dentsply Caulk, Germany) and is claimed to have improved properties including hardness, wear resistance, and fracture toughness. ZRGI is thought to be up to 25% stronger than other glass ionomer materials. ZRGI is composed of calcium-aluminum-zinc-fluoro-phosphor-silicate glass, polycarboxylic acid, iron oxide pigments, titanium dioxide pigments, tartaric acid, and water.[8] So this in vitro study was designed to compare the compressive strength (CS) of the ZRGI with high-viscosity glass ionomer (HVGI; Fuji IX GP Fast; GC, Japan) and posterior composite restorations (Posterior ROK; SDI, Australia).

  Materials and Method Top

Twenty-four cylindrical blocks (6 ± 0.1mm height, 4 ± 0.1mm diameter) [Figure 1] were prepared from the three studied restorative materials using a prefabricated Teflon mold [Figure 1], and were divided into three equal groups as follows:

  • Group I (n = 8): ZRGI restorative material (ChemFil Rock, Dentsply Caulk, Germany, Lot 111007004)
  • Group II (n = 8): HVGI (Fuji IX GP Fast; GC, Japan, Lot 01171192)
  • Group II (n = 8): posterior composite restorations (Posterior ROK; SDI, Australia, Lot 0988991)

Figure 1: Cylindrical blocks (6 ± 0.1mm height, 4 ± 0.1mm diameter)

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The capsules of glass ionomer were mixed using the amalgamator (YDM LK-H 11, SN: 212061321; Guangzhou, China). The light curing device used was Optilux 500 (SN: 20707079; Kerr, San Antonio, Texas, United States). The specimens (after being stored in an oven at 37°C for 1h) were gently removed from the moulds, immersed in distilled water, and kept in an oven at 37°C for 23h prior to testing. Specimens were subjected to CS testing using a universal testing machine (Instron 1195; Instron, United Kingdom) using a claw with 2cm in diameter, under a crosshead speed of 0.75mm/min until specimen fracture. The CS was calculated using the following equation: CS = 4Fd2 (where F is the maximum applied load [kg/mm2] and d is the diameter of the specimen). The resulted value was multiplied by 9.81 to get the CS in megapascals. Data were collected and statistical analysis was performed with analysis of variance (ANOVA) and least significant difference (LSD) test at 95% significance level.

  Results Top

The specimens in the three groups of study were subjected individually to the compressive forces (measured in kilograms) and those values were recorded in [Table 1].
Table 1: The compressive forces (measured in kilograms)

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The same values were converted to megapascals and recorded in [Table 2]; then the mean of the CSs in each group was calculated and recorded in the same table.
Table 2: The CSs (measured in megapascals) and the means of the CSs in each group

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The one-way ANOVA was performed to compare each group with others and results were recorded in [Table 3].
Table 3: One-way ANOVA

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LSD test was performed (at 95% significance level) due to presence of significant statistical differences between the groups of study; the result is shown in [Table 4].
Table 4: LSD test

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The ANOVA test revealed a significant statistical difference between ZRGI, HVGI, and posterior composite restorations. The significant statistical difference was toward the group of posterior composite restorations. The means of CSs in posterior composite restorations (239MPa) are higher than the other two groups ZRGI (154MPa) and HVGI (151MPa).

  Discussion Top

Restorations should afford the masticatory forces that occur in the oral cavity for prolonged periods and to provide enough strength and resistance to fracture. Dental materials are characterized on ease of handling with suitable mechanical properties and versatile usage. The most important mechanical property is CS of materials because restoratives usually replace a large bulk of tooth structure and they should provide sufficient strength to resist intraoral masticatory forces.[2]

Glass ionomer restoratives (GIs) have found application in restorative procedures, even if some of them were not specifically developed for this purpose, because the advantages of new GI materials are that they do not require more procedures for consistent application, as they adhere directly to the dental hard tissues. However, recent studies have shown that new GIs have the physical properties suitable to restore missed bulk of teeth and rebuild cores as they are resistant to moisture contamination and they have high strength toward tension and forces.[9] It is clear from the results of this study that posterior composite restorations showed the highest CS among the three studied materials, which are ZRGI, HVGI, and resin composite. This result was already expected, as ever that ZRGI or HVGI is based on enhanced properties of glass ionomer series and they have been accepted in variable indications. But in fact till this time they cannot compete properties of resin composite, especially in the high-risk restorations, and this result is probably inspired and conducted from other similar studies.[10],[11] The manufacturers of ChemFil Rock also suggest that this material is suitable for occlusal and proximal restorations in permanent and primary teeth (http://dentsplymea.com/products/restorative/glass-ionomers/chemfil-rock) and this is not compatible with the result of recent study. The studies about the CS of ZRGI are very rare because of the modernity of this material. Dowling et al.[12] did his study in 2012 to compare the CS between ZRGI and types of HVGI cement; there was no significant statistical difference, so he suggested revising the ISO standards in specimen design to get more accurate results.

In this study, there was no significant difference between the CS means of each ZRGI and HVGI unlike the result of the study by Syrek et al.,[13] which found that CS of HVGI was superior than that of ZRGI and that can be explained by the difference between circumstances of each experiment, or status of the Instron machine tip because in both results of the two studies, the CS means are in the regular range that the manufacturers had confined.[13]

Molina et al.[14] found the CS of ZRGI was higher than that of HVGI. But honestly the type of HVGI in their study was hand mixed; so the consistency and the properties perhaps had been affected, as well as the increment of itaconic acid in the liquid of ZRGI, may explain the higher resistance, which is acting as network modifiers that accelerate the maturation of the ZRGI, all that may be considered the reason of this superiority.

However, this result was in accordance with the study conducted by Jayanthi and Vinod[15] about the CS test values of composites, which were found to be superior than those for GIs. Also the same result was obtained by Lerech et al.[16] All CS means of three tested materials were found higher than the minimum value (>100MPa), which recommended for amalgam. In general perspective, we can compare ZRGI with the similar types of HVGI which did not show a better CS than posterior composite restorations.

  Conclusion Top

Within the limits of this study, posterior composite restoration has the highest CS compared with ZRGI and HVGI, and other types of glass ionomer still need more improvements.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

  References Top

Wilson AD, Kent BE. A new translucent cement for dentistry. The glass ionomer cement. Br Dent J 1972;132:133-5.  Back to cited text no. 1
Xie D, Brantley WA, Culbertson BM, Wang G. Mechanical properties and microstructures of glass-ionomer cements. Dent Mater 2000;16:129-38.  Back to cited text no. 2
Costa CA, Ribeiro AP, Giro EM, Randall RC, Hebling J. Pulp response after application of two resin modified glass ionomer cements (RMGICs) in deep cavities of prepared human teeth. Dent Mater 2011;27:e158-70.  Back to cited text no. 3
Cehreli SB, Tirali RE, Yalcinkaya Z, Cehreli ZC. Microleakage of newly developed glass carbomer cement in primary teeth. Eur J Dent 2013;7:15-21.  Back to cited text no. 4
Topbasi B, Öveçoglu ML, Türkmen C. Flexural strength and fracture surface characterization of glass-ionomer cements stored in water. Oral Health Dent Manag 2003;2:18-26.  Back to cited text no. 5
Gerdullo ML, Nakamura SCB, Suga RS, Navarro MFL. Resistência à compressão e à tração diametral de cimentos de ionômero de vidro indicados para cimentação. Rev Odontol Univ São Paulo 1995;9:17-22.  Back to cited text no. 6
Pimenta LAF, Lovadino JR, Giannini M. Resistência ao Cisalhamento de Dois Materiais Híbridos em Esmalte. Rev Assoc Paul Cir Dent 1997;51:587-90.  Back to cited text no. 7
Upadhyay NP, Kishore G. Glass ionomer cements—the different generations. Trends Biomater Artif Organs 2005;18:158-65.  Back to cited text no. 8
Product specification for ChemFil Rock. Konstanz, Germany: Dentsply DeTrey; 2011.  Back to cited text no. 9
Piwowarczyk A, Ottl P, Lauer HC, Büchler A. Laboratory strength of glass ionomer cement, compomers, and resin composites. J Prosthodont 2002;11:86-91.  Back to cited text no. 10
Koenraads H, Van der Kroon G, Frencken JE. Compressive strength of two newly developed glass-ionomer materials for use with the atraumatic restorative treatment (ART) approach in class II cavities. Dent Mater 2009;25:551-6.  Back to cited text no. 11
Dowling AH, Fleming GJ, McGinley EL, Addison O. Improving the standard of the standard for glass ionomers: An alternative to the compressive fracture strength test for consideration? J Dent 2012;40:189-201.  Back to cited text no. 12
Syrek A, Peez R, Zerguine R, Guggenberger R, Braun P, Lachermeier B, et al. Compressive strength of a new glass ionomer restorative. A paper presented in the IADR General Session and Exhibition, Cape Town, South Africa, 2014.  Back to cited text no. 13
Molina GF, Cabral RJ, Mazzola I, Lascano LB, Frencken JE. Mechanical performance of encapsulated restorative glass-ionomer cements for use with atraumatic restorative treatment (ART). J Appl Oral Sci 2013;21:243-9.  Back to cited text no. 14
Jayanthi N, Vinod V. Comparative evaluation of compressive strength and flexural strength of conventional core materials with nanohybrid composite resin core material an in vitro study. J Indian Prosthodont Soc 2013;13:281-9.  Back to cited text no. 15
Lerech SB, Tarón SF, Dunoyer AT, Arrieta JMB, Caballero AD. Compressive strength of glass ionomer and composite resin. In vitro study. Revista Odontológica Mexicana 2017;21: 107-11.  Back to cited text no. 16


  [Figure 1]

  [Table 1], [Table 2], [Table 3], [Table 4]


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