|Year : 2021 | Volume
| Issue : 4 | Page : 189-192
Effect of the Resin-Based Adhesive Coating on the Shear Punch Strength of Aesthetic Restorative Materials
Najmeh Mohammadi1, Rafat Bagheri2, Lida Vaziri Borazjani1
1 Department of Pediatric Dentistry, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
2 Department of Dental Material Sciences, Biomaterials Research Center, School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran
|Date of Submission||21-Nov-2021|
|Date of Decision||23-Nov-2021|
|Date of Acceptance||30-Nov-2021|
|Date of Web Publication||21-Dec-2021|
Department of Dental Materials, Shiraz Dental School, Shiraz University of Medical Sciences, Shiraz 43111
Source of Support: None, Conflict of Interest: None
Introduction: This study aimed to investigate the effect of G-Coat Plus (GCP) on the shear punch strength (SPS) of conventional glass ionomer cements (CGICs) and resin composites (RCs). Materials and methods: In this experimental study, four groups of restorative materials (two CGICs (Equia Forte Fil and Fuji Bulk), and two RCs (Aura Bulk fil and Filtek Z250) were used. Twenty specimens were prepared for each material. GCP was applied on the first subgroup (n = 10). The specimens were stored in distilled water at 37°C, and SPS values were measured after 24 hours. Two-way analysis of variance and independent t test were used for data analysis. Results: RCs showed significant higher SPS values compared to the CGICs (P < 0.001). All materials tested showed increased SPS values after applying GCP (P < 0.05). Conclusion: Applying GCP significantly improves the SPS of tooth-colored restorative materials used in this study.
Keywords: Glass ionomer cement, nano-filled surface coating, resin composite, shear punch strength
|How to cite this article:|
Mohammadi N, Bagheri R, Borazjani LV. Effect of the Resin-Based Adhesive Coating on the Shear Punch Strength of Aesthetic Restorative Materials. Dent Hypotheses 2021;12:189-92
|How to cite this URL:|
Mohammadi N, Bagheri R, Borazjani LV. Effect of the Resin-Based Adhesive Coating on the Shear Punch Strength of Aesthetic Restorative Materials. Dent Hypotheses [serial online] 2021 [cited 2023 Feb 6];12:189-92. Available from: http://www.dentalhypotheses.com/text.asp?2021/12/4/189/333013
| Introduction|| |
Direct tooth-colored restorative materials including resin composites (RCs) and glass ionomer cements (GICs) have become popular in dentistry. In clinical situations, characteristics such as biocompatibility, adhesion to the tooth structure, absence of marginal leakage, and acceptable mechanical properties are considered to choose an appropriate material.
The RCs are usually preferred due to their color matching, desirable bonding, and less damage to the tooth structure. However, some clinical failures of these materials have been reported. Glass ionomer cement restoratives (GICRs) have been used in a wide variety of clinical applications. Their key features are chemical bond to the enamel and dentin and cariostatic function. However, due to inferior mechanical properties, use of GICRs is limited to the nonstress bearing areas, and the sandwich technique.
Considerable efforts have been made to improve properties of GICRs. Variety of surface-coating agents including petroleum jelly, cocoa butter, waterproof varnishes, and even nail varnishes has been used in the past.,, However, the washed out of those coatings by the oral masticatory wear was reported.
Recently, a nano-filled resin-based coating, G-Coat Plus (GCP; GC Co, Tokyo, Japan), was introduced. GCP is a low-viscosity methyl methacrylate-based nano-filled resin that seals surface defects of the underlying material and protects it against abrasive wear and fracture. The surface protection is important during initial days of GICRs maturation until peak strength is achieved.,
Improvement of the mechanical properties of coated GICRs has been reported in previous studies., The study by Sukumaran and Mensudar exhibited increased mechanical strength of three different types of coated-GICs (Fuji II, Fuji IX, and Fuji II LC). Bagheri et al. also found that coating significantly increased the flexural strength of conventional GIC (CGIC) of Fuji IX (GC Co).
Although a recent study investigated the effect of GCP on the mechanical properties of RCs, data about coated RCs are still limited. This study aimed to investigate the effect of GCP on the shear punch strength (SPS) of two types of CGICs and two types of RCs. The null hypothesis is that surface coating does not improve the SPS of restorative materials.
| Materials and Methods|| |
In this experimental study, approved by ethics committee of Shiraz Dental School, a total of 80 specimens, in four groups [two CGICs of Equia Forte Fil (GC Co) and Fuji Bulk (GC Co) and two RCs of Aura Bulk fil (SDI, Bayswater, VIC, Australia) and Filtek Z250 (3M ESPE, St Paul, MN 55144-1000, USA)], were prepared.
Every group had two subgroups (n = 10): coated (GCP; GC Co) and uncoated. Disc-shaped specimens (10 mm diameter × 1 mm thickness) were prepared using plastic molds and cured by a LED unit (Radii plus LED; SDI). After removing the specimens from the molds, 1000, 1500, and 2000-grit silicon carbide papers were used to eliminate the excess material. Washing in an ultrasonic bath was performed between each grinding.
A thin coat of GCP was applied on the top surface of the specimens in the coating subgroups. Gentle air blowing for 5 seconds and light curing for 20 seconds were performed. All specimens were stored in distilled water at 37°C and tested after 24 hours.
Shear punch strength test
Gentle pressure of the restraining screw stabilized the specimen in the shear punch jig of the universal testing machine (Zwick/Roll Z020; Zwick GmbH & Co, Ulm, Germany) [Figure 1]. A flat-ended 3.2-mm diameter stainless steel rod at a crosshead speed of 1 mm/minute was used to penetrate the disc, and the maximum load was recorded. To calculate the SPS values in MPa the following formula was used:
Shear punch strength (MPa) = N/π × D × T
where N is the applied force, D is the punch diameter (mm), and T is the thickness of the specimen (mm).
Data were analyzed using SPSS, version 22 (IBM Corp, Armonk, NY, USA). Kolmogorov–Smirnov test was employed for assessing normality assumption of data. Two-way analysis of variance (ANOVA) was applied to investigate interactions between the materials and the coating. One-way ANOVA was used to compare different variables between the materials, and posthoc t test was performed to show significant differences in subgroup comparisons. The level of significance was set at 0.05.
| Results|| |
The normality assumption was held in all cases. The mean SPS values and related standard deviations for all groups of the study are shown in [Table 1].
|Table 1 Mean ± standard deviation (MPa) of shear punch strength values of all materials in coated and uncoated subgroups|
Click here to view
Results of two-way ANOVA indicated a statistically significant interaction between adhesive coating and the restorative materials (P < 0.001). Therefore, one-way ANOVA analysis was conducted and showed that the differences of the SPS values of the restorative materials with or without coating were significant (P < 0.001). No significant difference between two RCs was observed, but two CGICs showed statistically significant differences (P < 0.05) with higher SPS value for Fuji Bulk. Moreover, GCP significantly improved the SPS of all tested materials (P < 0.05).
| Discussion|| |
SPS test is used to evaluate the effects of occlusal or incisal forces on the clinical properties of restorative materials.,,, Performing this test, we polished the specimen to obtain flat parallel surfaces to be supported evenly while pressing the punch through it. Furthermore, modified shear punch test jig with a screw clamp was used for the present study. Hence, bending of the samples during application of the force is prevented.
The GCP is recommended to improve the mechanical properties of restorative materials. Infiltration of GCP protects the materials against crack initiation, fills porosities, reinforces the materials, and inhibits the water movement across the restoration surface.,,,,,,
Based on our results, GCP significantly increased the SPS values of all materials, so the null hypothesis is rejected. This could be related to the ability of GCP to provide a toughened laminated layer that disperses the mechanical stresses. Hence, adequate mechanical properties are sustained to endure forces.
Similar to our results, other researches also showed improved mechanical properties (shear punch, fracture toughness, and flexural strength) of coated GICRs., Higher flexural strength of coated GIC of Fuji IX GP extra (GC) and micromechanical interlocking between the GCP and this material were reported. Bagheri et al. also observed a significant increase in the fracture toughness of RMGIC (resin-modified glass ionomer cement) of Fuji II LC (GC Co, Japan) coated by GCP.
Unlike our result, Pilo et al. showed that coating decreased the SPS of three types of high-strength GICs: Ketac Molar (3M ESPE AG, Landsberg am Lech, Germany), Ionofil Molar AC (VOCO AC, Cuxhaven, Germany), and Fuji IX GP Fast (GC Co). Early exposure to water also increased the SPS of GICRs of Fuji IX GP Fast (GC Co), Ketac Molar, and Ketac Molar Quick (3M ESPE) in the study by Wang et al.
The proposed explanation for these adverse effects may be the fact that surface coating interferes with the hydration process and strength increasing by the bound water. Other reasons justifying the diversity of the results are different formulations of GICRs, diversity of the structure of the hardened materials, and various mechanical tests. Extended water storage time in some studies is another factor that affects the mechanical properties based on the composition and water sorption tendency.
Fuji Bulk demonstrated higher SPS values than Equia Forte Fil in our study. Ultra-fine glass particles embedded in a stronger matrix having higher molecular weight polyacrylic acid is the probable reason for better results of Fuji Bulk.
Based on our results, GCP application significantly improved the mean SPS values of RCs. Close to our results, applying GCP prevented microleakage and decreased possible replacement of nanohybrid composite restorations (Ceram-x, Dentsply Asia) in the clinical study by Kumar et al.
However, Moghaddasi et al. by evaluating other mechanical features reported no significant differences between flexural strength values of coated and uncoated specimens of Aura bulk fil (SDI), IPS Empress Direct (Ivoclar Vivadent, AG, Liechtenstein), Filtek Z250, and Filtek P60 (3M ESPE).
Two types of RCs demonstrated comparable SPS values in the present study. But microhybrid composite of Filtek Z250 having higher contents of inorganic fillers of zirconia and silica particles, exhibited better mechanical properties than that of nanohybrid composite of Aura Bulk fil in other studies.,
Furthermore, GCP demonstrated better results in comparison with another coating of Fortify Plus in terms of decreasing microleakage of RC restorations (Clearfil Majesty ES‑2, Kuraray, Tokyo, Japan). The nano-sized filler particles in the matrix of GCP were considered as the cause of its excellence.
According to the reported means of maximum occlusal bite force for different dentition stages (176 N in early primary stage, 240 N in late primary stage, 289 N in early mixed stage, 433 N in late mixed stage, and 527 N in the permanent dentition stage, respectively), coated CGICs of Equia Forte Fil and Fuji Bulk can almost endure these forces up to the late mixed dentition. Considering other advantages of GICRs, they are suggested as suitable restorative materials in pediatric dentistry.
Although the results were in favor of applying GCP, only short-term performance of this coating was evaluated in this study. Therefore, further long-term clinical studies to determine the effect of occlusal wear or aging on the coated restorations are required.
| Conclusion|| |
Considering the limitations of this study, it was concluded that applying GCP significantly improved the SPS of restorative materials. RCs used in our study showed significant higher SPS values than CGICs.
GCP is recommended to be applied on CGIC and RC restorations increasing the SPS of the materials in the first 24 hours of application.
The authors thank the Vice-Chancellery of Shiraz University of Medical Sciences for supporting this research (grant #15987). The authors also thank Dr Vosughi for contribution in statistical analysis.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Cramer N, Stansbury J, Bowman C. Recent advances and developments in composite dental restorative materials. J Dent Res 2011;90:402-16.
Bagheri R, Taha N, Azar M, Burrow M. Effect of G‐Coat Plus on the mechanical properties of glass‐ionomer cements. Aust Dent J 2013;58:448-53.
Bagheri R, Palamara JE, Mese A, Manton DJ. Effect of a self‐adhesive coating on the load‐bearing capacity of tooth‐coloured restorative materials. Aust Dent J 2017;62:71-8.
Chesterman J, Jowett A, Gallacher A, Nixon P. Bulk-fill resin-based composite restorative materials: a review. Br Dent J 2017;222:337-44.
Sukumaran VG, Mensudar R. To evaluate the effect of surface coating on three different types glass ionomer restorations. Biomed Pharmacol J 2015;8:445-9.
Tyas M, Burrow M. Adhesive restorative materials: a review. Aust Dent J 2004;49:112-21.
Magni E, Zhang L, Hickel R, Bossù M, Polimeni A, Ferrari M. SEM and microleakage evaluation of the marginal integrity of two types of class V restorations with or without the use of a light-curable coating material and of polishing. J Dent 2008;36:885-91.
Pilo R, Ben-Amar A, Barnea A, Blasbalg Y, Levartovsky S. The effect of resin coating on the shear punch strength of restorative glass ionomer cements. Clin Oral Investig 2017;21:1079-86.
Tiwari S, Nandlal B. Effect of nano-filled surface coating agent on fluoride release from conventional glass ionomer cement: an in vitro trial. J Indian Soc Pedod Prev Dent 2013;31:91-5.
] [Full text]
Serra M, Navarro M, Freitas S, Carvalho R, Cury J, Retief D. Glass ionomer cement surface protection. Am J Dent 1994;7:203-6.
Kamatham R, Reddy SJ. Surface coatings on glass ionomer restorations in pediatric dentistry-worthy or not? J Indian Soc Pedod Prev Dent 2013;31:229-33.
] [Full text]
Klinke T, Daboul A, Turek A, Frankenberger R, Hickel R, Biffar R. Clinical performance during 48 months of two current glass ionomer restorative systems with coatings: a randomized clinical trial in the field. Trials 2016;17:239.
Bonifácio CC, Werner A, Kleverlaan CJ. Coating glass-ionomer cements with a nanofilled resin. Acta Odontol Scand 2012;70:471-7.
Moghaddasi N, Tavallali M, Jafarpour D, Ferooz R, Bagheri R. The effect of nanofilled resin-base coating on the mechanical and physical properties of resin composites. Eur J Dent 2021;15:202-9.
Ikejima I, Nomoto R, McCabe JF. Shear punch strength and flexural strength of model composites with varying filler volume fraction, particle size and silanation. Dent Mater 2003;19:206-11.
Roydhouse RH. Punch-shear test for dental purposes. J Dent Res 1970;49:131-6.
Mount G, Makinson O, Peters M. The strength of auto‐cured and light‐cured materials. The shear punch test. Aust Dent J 1996;41:118-23.
Nomoto R, Carrick TE, McCabe JF. Suitability of a shear punch test for dental restorative materials. Dent Mater 2001;17:415-21.
Leirskar J, Nordbø H, Mount GJ, Ngo H. The influence of resin coating on the shear punch strength of a high strength auto-cure glass ionomer. Dent Mater 2003;19:87-91.
Bagheri R, Mese A, Burrow MF, Tyas MJ. Comparison of the effect of storage media on shear punch strength of resin luting cements. J Dent 2010;38:820-7.
Wang X, Yap AUJ, Ngo H. Effect of early water exposure on the strength of glass ionomer restoratives. Oper Dent 2006;31:584-9.
Jafarpour D, Mese A, Ferooz M, Bagheri R. The effects of nanofilled resin-based coatings on the physical properties of glass ionomer cement restorative materials. J Dent 2019;89:103177.
Perera D, Yu SC, Zeng H, Meyers IA, Walsh LJ. Acid resistance of glass ionomer cement restorative materials. Bioengineering 2020;7:150.
Kumar AA, Hariharavel V, Narayanan A, Murali S. Effect of protective coating on marginal integrity of nanohybrid composite during bleaching with carbamide peroxide: a microleakage study. Indian J Dent Res 2015;26:167-9.
] [Full text]
Hepdeniz OK, Temel UB, Ugurlu M, Koskan O. The effect of surface sealants with different filler content on microleakage of Class V resin composite restorations. Eur J Dent 2016;10:163-9. [Full text]
Owais AI, Shaweesh M, Abu Alhaija ES. Maximum occusal bite force for children in different dentition stages. Eur J Orthod 2013;35:427-33.