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Article

Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials

by
Ahmed J. Abuzinadah
1,2,
Yasser M. A. Merdad
1,3,
Reem S. Aldharrab
2,4,
Wejdan A. Almutairi
2,
Hanin E. Yeslam
1,3,* and
Fatin A. Hasanain
1,3
1
Department of Restorative Dentistry, Faculty of Dentistry, King Abdulaziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
2
Faculty of Dentistry, King Abdulaziz University, P.O. Box 80209, Jeddah 21589, Saudi Arabia
3
Advanced Technology Dental Research Laboratory, Faculty of Dentistry, King Abdulaziz University, Jeddah 21589, Saudi Arabia
4
National Guard Health Affairs, P.O. Box 9515, Jeddah 21423, Saudi Arabia
*
Author to whom correspondence should be addressed.
J. Compos. Sci. 2024, 8(12), 508; https://doi.org/10.3390/jcs8120508
Submission received: 29 October 2024 / Revised: 2 December 2024 / Accepted: 2 December 2024 / Published: 5 December 2024

Abstract

:
Background: This study aims to compare the compressive strength and microhardness of four tooth-colored restorative materials: bulk fill glass hybrid (GH), resin-modified glass ionomer (RMGIC), conventional glass ionomer (CGIC), and resin-based composite (RBC). Methods: Stainless steel molds were used to prepare 20 specimens for each material. Half of the specimens were subjected to 10,000 thermal cycles; the materials were subjected to compressive strength and microhardness tests. Mean values were statistically compared using a one-way ANOVA Test and Bonferroni pairwise comparisons. Results: GH (147.03 ± 20.19 MPa) had lower compressive strength than RBC (264.82 ± 30.95 MPa) but showed no significant difference with CGIC (130.19 ± 30.38 MPa) and RMGIC (183.52 ± 18.45 MPa). RMGIC’s compressive strength also significantly fell short of RBC (p < 0.05), but it significantly increased after thermocycling (160.14 to 183.52 MPa). As for microhardness, no significant difference was found between the groups. Thermocycling significantly increased the microhardness of CGIC (from 24.27 to 31.8 ± 2.66). Conclusion: Resin-based materials outperformed the other materials. Glass hybrid restorative material performed as well as resin-modified glass ionomer regarding compressive strength; however, further studies are necessary before considering glass hybrids for use as a permanent restoration.

1. Introduction

The dental field is continuously developing biocompatible restorative materials with desirable mechanical and aesthetic properties. In contemporary dental practice, resin-based composites (RBC) have become the most widely used materials for direct and sometimes indirect cavity restorations [1,2]. Several key factors influence the compressive strength and microhardness of these materials. These include the type and amount of filler particles, the resin matrix’s composition, and the degree of conversion. Filler particles enhance mechanical strength and hardness by providing structural reinforcement, while the resin matrix binds these particles together, contributing to the material’s overall durability [3]. The degree of conversion, determined by curing time and light intensity, also plays a crucial role in achieving optimal compressive strength and microhardness [1,2,4].
Another notable restorative material is glass ionomer cement (GIC), which was first reported by Alan Wilson and Kent in the early 1970s [5]. GIC is composed of a combination of fluoro-alumino-silicate powder, a liquid polymer/co-polymer of carboxylic acid, water, and tartaric acid [5,6]. GIC utilizes an acid–base reaction to set and provides a range of advantages. These include releasing fluoride, the ability to recharge fluoride from the surrounding oral environment, chemically bonding directly to the tooth structure through chelation, effectively inhibiting bacterial growth, preventing enamel decalcification [6,7,8,9], and promoting tooth structure remineralization [10,11]. GICs have certain limitations, particularly in terms of mechanical properties like brittleness, low wear resistance, fracture toughness, and flexural strength, along with their limited working time, long setting time, and sensitivity to desiccation and moisture in the early phase of setting [12,13].
In the late 1980s, the dental community developed resin-modified glass ionomer (RMGIC) materials to overcome these limitations [13,14,15]. These RMGICs share the same composition as conventional GIC (CGIC) but include a methacrylate monomer and a free radical initiator. This modification allows the RMGIC to participate in acid–base reactions and undergo both light-activated and chemically activated polymerization [15,16]. This resulted in a material demonstrating extended working time, faster setting time on demand, and enhanced mechanical properties compared to CGICs [13,17]. The potential for remineralization of RMGICs extends up to 3 mm from the restorative margin [15]. Nonetheless, their strength, wear resistance, and aesthetic qualities still fall short of resin-based composite restorations, limiting their application as final definitive restorations for permanent teeth [13,15]. As a result, GIC restorations are more likely to crack, wear down, or break, leading to further decay or damage to the tooth [18].
Manufacturers have modified the composition and structure of GICs to improve their mechanical properties without compromising their remineralization properties. In recent years, various modified GIC-based restorative materials have been introduced to the dental market, with claims of improved mechanical properties comparable to those of permanent restorations [14,15]. A notable example is the glass hybrid (GH), known for its ability to release and recharge fluoride, as indicated by manufacturers. This feature has generated some debate in the literature regarding its classification as a dental bioactive restorative material. The term “bioactive material” is often used broadly in dentistry to include substances that have a chemical effect. However, whether these materials and their derivatives genuinely possess true bioactive properties remains an arguable issue [14,19,20,21,22,23]. This material blends ultrafine, highly reactive glass particles within a CGIC matrix and incorporates a higher-molecular-weight polyacrylic acid [24]. The fillers are evenly distributed within the material’s matrix [25]. Collectively, these changes are said to enhance mechanical properties, wear resistance, and acid erosion resistance compared to GIC and its variants [8,26]. Furthermore, GH’s resin-containing coat aimed at improving the compressive strength and microhardness of the resultant restoration [27]. The resulting restoration had a reportedly superior glass-like look. Promoted as a bulk fill definitive restorative material with greater strength than RMGICs, it recently showed a one-year clinical success rate comparable to resin-based composites in a randomized controlled clinical trial [28]. However, these claims that GH material’s mechanical and physical attributes are stable and as good as those of resin-based composites needed further verification.
Clinical decision-making regarding material selection is greatly influenced by the mechanical and biological properties of these materials. This is especially true for patients with a high risk of dental caries. Even though some studies in the literature have explored the mechanical properties of new GH materials, further investigation is needed to compare their mechanical properties to permanent restorative and other long-term temporary materials. The current research compared the compressive strength and microhardness of four tooth-colored restorative materials: GH (Equia Forte, GC Europe N.V, Leuven, Belgium), an RMGIC (Fuji II, GC Europe N.V, Leuven, Belgium), a CGIC (Fuji IX, GC Europe N.V, Leuven, Belgium), and a nanohybrid RBC (Tetric-N-Ceram Bulk Fill, Ivoclar Vivadent Inc., Schaan, Liechtenstein). The aim of this study was to assess the performance of GH, without the influence of the resin coat, which could be lost from the restoration surface with intraoral use, and to compare it to that of other commonly used tooth-colored resin and GIC restorative materials.
The null hypothesis was that there is no difference in compressive strength and microhardness between GH, CGIC, RMGIC, and RBC materials. The second null hypothesis stated that there is no difference in terms of compressive strength and microhardness of these restorative materials before and after thermocycling for 10,000 cycles.

2. Materials and Methods

The present in vitro study obtained approval from the Ethics Committee of the School of Dental Medicine, King Abdulaziz University, under the reference number 19-12-19.

2.1. Study Design

The study was designed to assess four distinct restorative materials: resin glass hybrid (GH) (Equia Forte, (GC Europe N.V., Leuven, Belgium)), resin-modified glass ionomer (RMGIC) (Fuji II, (GC Europe N.V., Leuven, Belgium)), conventional glass ionomer (CGIC) (Fuji IX, (GC Europe N.V., Leuven, Belgium)), and nanohybrid resin-based composite (RBC) (Tetric N Ceram Bulk Fill, Ivoclar Vivadent Inc., Schaan, Liechtenstein). Their composition is listed in Table 1.

2.2. Specimen Preparation

Cylindrical stainless steel molds, adhering to ISO standard 9917-1 [29], were used to prepare the specimens for compressive strength evaluation. These molds possessed dimensions of 4 mm in diameter and 6 mm in height and featured an inner surface composed of two halves, securely held together by an external plastic ring (Figure 1). Twenty specimens of each material were fabricated.
All material specimens were meticulously prepared following their manufacturer’s instructions regarding curing and handling techniques. Stringent measures were taken to prepare the mold for the fabrication of each material specimen, ensuring a smooth surface without voids or bubbles. This involved the cleaning of molds with alcohol between each specimen preparation, followed by rinsing with water and thorough drying to prevent interference with the material’s setting. A layer of release agent (Isolit—Mould Release Agent, Dentsply Sirona, Charlotte, NC, USA) was applied to the mold’s interior for easy specimen removal without damage. The study then commenced following the demonstrated study design in Figure 2.
A clear glass slab with a thickness of 4 mm was placed beneath the bottom surface of the molds while condensing the tested materials within to ensure a uniform and smooth surface. The thick glass slab provided a hard surface against which the material could be condensed within the mold adequately. For CGIC, RMGIC, and GH, capsules were activated with a GIC applicator (GC CAPSULE APPLIER III, GC Europe N.V., Leuven, Belgium) before mixing with an amalgamator (Silamat S3, Ivoclar Vivadent Inc., Schaan, Liechtenstein) for 10 s, after which the mixture was injected into the molds at room temperature. The RBC material, not provided in capsule form, was condensed into the molds using a plastic instrument in a single increment to minimize the chance of voids between increments and resembling its clinical use as a bulk filling material. A mylar strip and a 1 mm thick glass slide were placed on top of the mold and pressed gently to squeeze out excess uncured material, ensure a smooth surface, and minimize the possibility of voids within the specimens. The CGIC specimens underwent a chemical setting process at room temperature for a duration of 5 min before removing the glass slide from on top of the mold and disassembling the mold parts. On the other hand, GH, RMGIC, and RBC specimens were light cured using a mono-wave LED light curing unit (Elipar, 3M ESPE, St Paul, MN, USA). The light cure tip was applied perpendicular to the specimen surface from both the top and bottom sides for 20 s per side. Subsequently, the specimens were removed from the molds by disassembling the two mold parts. Excess cured materials on the side were removed using a sharp # 12 scalpel blade, and both the top and bottom surfaces of the specimens were polished using silicon carbide papers with grits of 400, 600, 800, and finally 1200 [30,31], which were used in an automated polishing machine under copious water cooling.
All specimens were stored in distilled water at room temperature for 24 h before being randomly divided into two groups: for each material, half of the specimens (n = 10) were tested immediately, while the other half (n = 10) underwent thermocycling in distilled water baths at 5 °C and 55 °C. This aging process involved 10,000 cycles, each lasting 30 s with a 5 s dwell time. This thermocycling aging process would correspond to approximately one year of intraoral use [32]. Both groups were further divided in half into two subcategories (n = 5): one for compressive strength testing and the other for microhardness testing (Figure 2).

2.3. Compressive Strength Testing

The compressive strength test was performed on both groups, immediately after testing and after thermocycling for each material (n = 40). Each specimen was loaded to fracture using the universal testing machine (Instron 5944, Instron Corp, Norwood, MA, USA). The test was conducted at room temperature (24 °C) following the ISO 9917-1:2007 [29] standards. The compressive strength was determined by loading the whole flat surface of the specimen at a crosshead speed of 0.5 mm/min. The highest recorded reading at the point of specimen failure was registered. Two sub-groups of randomly selected specimens were tested (n = 5/group) as follows: Immediate strength test group: Tested after 24 h of storage in distilled water at room temperature. Aged/thermocycler strength test group: Tested after undergoing 10,000 cycles of thermocycling between 5 °C and 55 °C. The compressive strength testing of the specimens is demonstrated in Figure 3.

2.4. Microhardness Testing

Vickers microhardness evaluation was conducted to determine the material’s hardness when exposed to low applied loads. For each specimen, each indentation was made using a force equivalent to 300 g (0.3 kg force). This was applied to the specimens in both the immediate testing and thermocycling groups for each material (n = 40) using a diamond indenter for a duration of 15 s [30,31,33,34]. Each specimen received three indentations uniformly arranged in a circular pattern at the center of the specimen’s top surface. The indentations were spaced at least 1 mm apart from each other and from the specimen’s margins [34,35]. The two diagonal lengths of each indentation were measured using a microscope with 40× magnification. These measurements were then converted into a microhardness value (VHN) using the following equation:
HV = 1.854 × P/d2
In this equation, HV represents the microhardness in kg/mm2, P is the applied load in kilograms force, and d is the average length of the diagonals in mm [27]. The average HV value for each specimen was recorded.
Material specimens’ sub-groups of randomly selected specimens were tested (n = 5/group) as follows: Immediate microhardness test group: tested after 24 h of storage in distilled water at room temperature. Aged/thermocycler microhardness test group: tested after undergoing 10,000 cycles of thermocycling between 5 °C and 55 °C.
The Vickers microhardness test results of the specimens in each group are demonstrated in Figure 4.

2.5. Statistical Analysis

The statistical analysis was conducted using SPSS version 25 (IBM SPSS Statis Armonk, NY, USA). Quantitative variables were described by calculating the Mean, Standard Deviation (SD), Range (Minimum–Maximum), Standard Error (SE), 95% confidence interval of the mean, and coefficient of variation. Sample size calculation was conducted using the G* Power 3.1.9.7 software, showing a total sample size of 80 (5 per subgroup) that was sufficient to detect an effect size of 0.5 at a power of 80% and an alpha error of 0.05. The chosen sample size was in accordance with what has been reported in previous studies [36,37,38,39].
Shapiro–Wilk test revealed the normal distribution of the results, so parametric tests were conducted. The independent sample t-test was used to analyze the effect of thermocycling for each material, in terms of compressive strength and microhardness. For each test, different materials were compared using a one-way analysis of variance (ANOVA). In cases where the ANOVA test showed statistical significance, multiple comparison post hoc tests using the Bonferroni method were to be conducted at a significance level of p < 0.05.

3. Results

The investigation into the effect of thermocycling on the mean compressive strength of each material compared to non-thermocycled specimens using an independent sample t-test revealed the following. Overall, the results indicated that thermocycling did not significantly impact the tested materials’ mean compressive strength (p < 0.05). The exception was the RMGIC group, which exhibited a statistically significant increase in mean compressive strength after thermocycling (p > 0.05).
Descriptive statistics are demonstrated in Figure 5 to evaluate differences in mean compressive strength among the various materials after aging. The one-way analysis of variance (ANOVA) demonstrated statistically significant differences between the groups (p < 0.05). Subsequent Bonferroni pairwise multiple comparisons provided detailed insights: The CGIC and GH groups exhibited significantly lower mean compressive strengths compared to the other groups (p < 0.05). Additionally, the GH group, while demonstrating lower mean compressive strength than RBC (p < 0.05), did not exhibit a significant difference when compared to that of the CGIC and RMGIC groups (p > 0.05). Meanwhile, the RMGIC group displayed compressive strength similar to that of GH. Still, it significantly exceeded the CGIC group (p < 0.05) while falling significantly short of the RBC group (p < 0.05). Remarkably, RBC group had a significantly higher mean compressive strength compared to all other groups (p < 0.05).
As for the mean microhardness values for the tested material groups, the analyses did not reveal any statistically significant differences between the material groups before and after thermal aging by thermocycling (p < 0.05), except for the CGIC group, which displayed a statistically significant increase in mean microhardness value after thermocycling when compared to the non-thermocycled group (p < 0.05). Upon assessing inter-material differences in mean microhardness values after aging, one-way analysis of variance (ANOVA) did not identify statistically significant variations. Therefore, multiple comparisons were not performed. Descriptive statistics are displayed in Figure 6. One-way ANOVA test was not statistically significant. Therefore, post hoc test was not performed.

4. Discussion

The main goal of the current study was to assess two specific physical properties, compressive strength and microhardness, of a recently introduced formulation of GH restorative material. The GH was compared against some commonly used dental restorative materials: CGIC, RMGIC, and a nanohybrid RBC. The secondary aim of our study was to evaluate the impact of 10,000 thermal cycling cycles, representing one year of intraoral use [32,40,41], on the compressive strength and microhardness of GH, CGIC, RMGIC, and RBC restorative materials.
The null hypothesis that there is no significant difference in compressive strength between the four investigated restorative materials was partially rejected as this study revealed that GH performed as well as the CGIC and RMGIC, but significantly lower than RBC. This is in accordance with previous studies that indicated the lower compressive strength of GH restorative materials compared to resin-based composite materials, even when coated with a resin coat [9,42,43]. On the other hand, a previous clinical study on non-carious lesion restorations and a recent clinical trial on the clinical success of GH compared to RBCs concluded their almost equal success rate. However, these studies did not investigate the hardness or strength of the materials [28,44]. The GH group exhibited a slightly higher compressive strength value compared to the CGIC group. It is possible that the reason for this result is due to the specimens receiving additional light-curing exposure. The heat generated by the light curing unit might have enhanced the polymerization reaction and the high molecular weight (Mw) of polyacrylic acid, which promoted an increase in the formation of polysalt bridges and crosslinking within the set material’s structure [9,45]. Regarding acid–base reactions, the abundance of carboxylic acid groups plays a crucial role that can be increased by achieving an optimized molecular weight (Mw). Thus, this potentially increases the number of carboxylic acid groups per molecule, leading to a higher number of acid-base reactions. This ultimately results in a more efficient chemical cure process. Therefore, optimizing Mw can be a useful strategy to enhance the yield and quality of the material [7,45,46,47]. The results of the current study were consistent with previous reports comparing GH to different brands of CGIC and RMGIC. According to these previously conducted studies, GH performs significantly better in terms of compressive strength than CGIC. However, when compared to RMGIC and RBC, the compressive strength of GH material was lower [7,9,48,49,50]. Additionally, the immersion of CGICs in distilled water may positively influence their strength due to the maturation of the cement matrix aided by the abundance of carboxylic acid groups forming more glass ionomer particles within the set material [51]. This might have led to the properties of the GH and other CGICs to be comparable in the current study where all samples were stored for 24 h and then thermocycled in distilled water.
As for the microhardness, the null hypothesis that there is no significant difference between the materials in regard to microhardness was accepted as there was no statistical significance between all study groups at a significance level of 0.05. When comparing the microhardness values in the current study, the results showed that the tested RBC had the highest microhardness value, indicating that it is the most durable and resistant to wear. The second highest value was found for RMGIC, followed by CGIC and GH. This information suggests that the resin-based composite and RMGIC are more suitable for dental restorations that require high strength and durability, while CGIC and GH may be more suitable for restorations subjected to lower occlusal forces. It is well known that RBCs typically contain a higher concentration of fillers than other dental restorative materials. The high filler concentration in resin-based composite provides several advantages, such as improved strength, durability, and wear resistance. On the other hand, RMGIC, CGIC, and GH contain a lower amount of fillers, which may result in reduced mechanical properties compared to RBC. Previous studies in the literature documented that the higher the filler loading of a material, the higher the material’s resistance to indentation [52,53].
The investigation into the effect of thermocycling on the compressive strength and microhardness of various restorative dental materials revealed significant findings. Specifically, thermocycling did not significantly impact the compressive strength of most materials tested, except for the RMGIC, which exhibited a statistically significant increase post-thermocycling. In contrast, the microhardness of the materials remained largely unaffected by thermocycling, except for the CGIC, which demonstrated a significant increase. The impact of thermocycling on dental restorative materials varies widely across studies. While some investigations report no significant changes in the compressive strength of RBCs and GICs after thermocycling, others indicate improvements or reductions in mechanical properties [7,18,27,48,50,53,54]. These differences emphasize the diverse reactions of materials and point to the necessity for more research to comprehend how thermocycling affects dental restorative materials.
As with all in vitro studies, this study had limitations. The main limitation was that the clinical behavior and longevity of any material could not be predicted from only two physical properties tested in vitro. The study found limitations in the restorative materials tested. GH had lower compressive strength than the bulk fill RBC, which may limit its use as a permanent restoration. RMGIC had similar strength to GH but was not as strong as RBCs. However, CGICs have other limitations in mechanical properties, such as brittleness, low wear resistance, fracture toughness, and flexural strength. Also, they have a limited working time and long setting time and are sensitive to desiccation and moisture during early setting. These limitations can restrict their use as definitive restorations in permanent teeth. Additional studies are needed to determine the long-term efficacy of GH and other modified GIC-based restorative materials for use as durable, strong, and aesthetic definitive restorations. Conducting additional tests to evaluate bond strength, wear resistance, and optical properties would provide valuable information on the potential performance of the tested materials. Another limitation of this study was the relatively small sample size used for each subgroup, which resulted in a statistical power of only 80% to detect a large difference of 0.5 in the measured properties. This may affect the applicability of the findings to a broader population and detect smaller differences in microhardness between the tested materials. However, in the current study, it was noted that the microhardness results of the RMGIC group showed the highest standard deviation among the tested groups. However, the relatively lower standard deviation in the rest of the groups allowed for reasonable conclusions to be drawn from the study results. To allow for more definitive conclusions, future studies with larger sample sizes are advised. The strengths of the study include its use of standardized materials, methods, and testing protocols. The study also compares four different restorative materials commonly used in dental practice, providing valuable information for dentists and researchers. Finally, the study concluded with recommendations for further research, highlighting the importance of continued investigation of the various marketed restorative materials.

5. Conclusions

It can be concluded that glass hybrid restorative material exhibits comparable compressive strength and microhardness to resin-modified glass ionomer and conventional glass ionomer. Resin-based composites demonstrated the highest compressive strength and microhardness values among all the tested materials. The study results showed statistically insignificant differences in surface microhardness across all groups. However, the glass hybrid restorative material exhibited around 40% lower microhardness values than the other tested materials. Therefore, further studies are necessary to evaluate its long-term effectiveness for permanent restorations.

Author Contributions

Conceptualization, A.J.A., F.A.H. and H.E.Y.; methodology, A.J.A., F.A.H., H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; software, H.E.Y.; validation, A.J.A., F.A.H., Y.M.A.M. and H.E.Y.; formal analysis, A.J.A., F.A.H., H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; investigation, A.J.A., F.A.H., H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; resources, A.J.A., F.A.H., H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; data curation, A.J.A., F.A.H., H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; writing—original draft preparation, A.J.A., Y.M.A.M., R.S.A. and W.A.A.; writing—review and editing, A.J.A., F.A.H., H.E.Y. and Y.M.A.M.; visualization H.E.Y., Y.M.A.M., R.S.A. and W.A.A.; supervision, F.A.H. and H.E.Y. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

The present in vitro study obtained approval from the Ethics Committee of the School of Dental Medicine, King Abdulaziz University, under the reference number 19-12-19.

Informed Consent Statement

Not applicable.

Data Availability Statement

Data are available upon request.

Acknowledgments

The authors would like to thank the ATDRL, Faculty of Dentistry, King Abdulaziz University, Saudi Arabia for their technical support.

Conflicts of Interest

The authors declare no conflicts of interest.

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Figure 1. Specimen fabrication mold to produce specimens measuring 6 mm in thickness and 4 mm in diameter.
Figure 1. Specimen fabrication mold to produce specimens measuring 6 mm in thickness and 4 mm in diameter.
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Figure 2. Study design detailing group assignment of specimens.
Figure 2. Study design detailing group assignment of specimens.
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Figure 3. Compressive strength testing of specimens in the universal testing machine.
Figure 3. Compressive strength testing of specimens in the universal testing machine.
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Figure 4. Microhardness testing of the specimens.
Figure 4. Microhardness testing of the specimens.
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Figure 5. Compressive strength measurements in MPa of tested restorative materials, comparing their performance before and after aging by thermocycling. Bonferroni post hoc comparisons group results are reported with significance level set at p < 0.05; different uppercase letters in mean column indicate significant differences. * represents significant difference after thermocycling at p < 0.05.
Figure 5. Compressive strength measurements in MPa of tested restorative materials, comparing their performance before and after aging by thermocycling. Bonferroni post hoc comparisons group results are reported with significance level set at p < 0.05; different uppercase letters in mean column indicate significant differences. * represents significant difference after thermocycling at p < 0.05.
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Figure 6. Microhardness measurements (Vicker’s) of the tested restorative materials, comparing their performance before and after aging. * represents a significant difference after thermocycling at p < 0.05 using t-test.
Figure 6. Microhardness measurements (Vicker’s) of the tested restorative materials, comparing their performance before and after aging. * represents a significant difference after thermocycling at p < 0.05 using t-test.
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Table 1. Materials composition and manufacturer.
Table 1. Materials composition and manufacturer.
Material NameAbbreviationMaterial TypeManufacturerComposition
Fuji IXCGICConventional glass ionomerGC Europe N.V., Leuven, BelgiumPowder: 95% fluoroaluminosilicate glass, 5% polyacrylic acid.
Liquid: 50% distilled water, 40% polyacrylic acid and tartaric acid, 10% polybasic carboxylic acid.
Equia ForteGHGlass hybridGC Europe N.V., Leuven, BelgiumPowder: 95% strontium-fluoroaluminosilicate glass, 5% polyacrylic acid.
Liquid: 40% aqueous polyacrylic acid.
Fuji IIRMGICResin-modified glass ionomerGC Europe N.V., Leuven, BelgiumPowder: 100% fluoroaluminosilicate glass.
Liquid: 35% 2-Hydroxyethyl methacrylate (HEMA), 25% distilled water, 24% polyacrylic acid, 6% tartaric acid and 0.10% camphorquinone bisphenol A-glycidyl methacrylate (Bis-GMA) and traces of triethylene glycol dimethacrylate (TEGDMA).
Tetric-N-Ceram Bulk FillRBCNanohybrid bulk fill resin-based compositeIvoclar Vivadent Inc., Schaan, LiechtensteinMonomers: 20% bisphenol-A glycidyl methacrylate (Bis-GMA), ethoxylated bisphenol-A-glycidyl methacrylate (Bis-EMA), urethane dimethacrylate (UDMA).
Fillers: 81% Barium glass, ytterbium trifluoride, mixed oxide, silicon dioxide, prepolymers. Initiators: <1 wt.% Camphorquinone.
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MDPI and ACS Style

Abuzinadah, A.J.; Merdad, Y.M.A.; Aldharrab, R.S.; Almutairi, W.A.; Yeslam, H.E.; Hasanain, F.A. Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials. J. Compos. Sci. 2024, 8, 508. https://doi.org/10.3390/jcs8120508

AMA Style

Abuzinadah AJ, Merdad YMA, Aldharrab RS, Almutairi WA, Yeslam HE, Hasanain FA. Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials. Journal of Composites Science. 2024; 8(12):508. https://doi.org/10.3390/jcs8120508

Chicago/Turabian Style

Abuzinadah, Ahmed J., Yasser M. A. Merdad, Reem S. Aldharrab, Wejdan A. Almutairi, Hanin E. Yeslam, and Fatin A. Hasanain. 2024. "Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials" Journal of Composites Science 8, no. 12: 508. https://doi.org/10.3390/jcs8120508

APA Style

Abuzinadah, A. J., Merdad, Y. M. A., Aldharrab, R. S., Almutairi, W. A., Yeslam, H. E., & Hasanain, F. A. (2024). Microhardness and Compressive Strength of Bulk Fill Glass Hybrid Material and Other Direct Restorative Materials. Journal of Composites Science, 8(12), 508. https://doi.org/10.3390/jcs8120508

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