Microleakage of novel glass ionomer restoration in cavities prepared by Er,Cr:YSGG laser: An in-vitro study

Osman Atas; Sema Celenk; Ahmet Aras

doi:10.4103/jioh.jioh_343_19

ORIGINAL RESEARCH

Year : 2020 | Volume : 12 | Issue : 4 | Page : 378-384

Microleakage of novel glass ionomer restoration in cavities prepared by Er,Cr:YSGG laser: An in-vitro study

Osman Atas¹, Sema Celenk², Ahmet Aras³
¹ Department of Pediatric Dentistry, Faculty of Dentistry, Firat University, Elazig, Turkey
² Department of Pediatric Dentistry, Faculty of Dentistry, Dicle University, Diyarbakir, Turkey
³ Department of Pediatric Dentistry, Faculty of Dentistry, Harran University, Sanliurfa, Turkey

Date of Submission	17-Dec-2019
Date of Decision	30-Jan-2020
Date of Acceptance	30-Jan-2020
Date of Web Publication	20-Aug-2020

Correspondence Address:
Dr. Ahmet Aras
Department of Pediatric Dentistry, Faculty of Dentistry, Harran University, Sanliurfa.
Turkey

Source of Support: None, Conflict of Interest: None

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DOI: 10.4103/jioh.jioh_343_19

Abstract

Aim: To compare the microleakage of novel materials containing glass ionomer, which are applied to standard class V cavities prepared by Er,Cr:YSGG (erbium, chromium-doped yttrium, scandium, gallium, and garnet) laser and by conventional diamond bur in primary teeth. Materials and Methods: Fifty non-carious primary molar teeth were randomly divided into five main groups and restored with various materials containing glass ionomers (Group 1: Equia System; Group 2: Fuji IX GP; Group 3: Fuji II LC; Group 4: Dyract Extra; and Group 5: Giomer). Each group was divided into two subgroups according to laser and conventional preparation methods. Results: As for the gingival margin, in terms of leakage values, no statistically significant difference was observed between drill and Er,Cr:YSGG laser although less microleakage values were obtained in Er,Cr:YSGG laser groups 1 and 4 (P > 0.05). Among groups prepared by drill, the lowest leakage rates observed at the gingival margin are Equia System, Giomer, Dyract Extra, Fuji II LC, and Fuji IX GP, respectively. Among groups prepared by Er,Cr:YSGG laser, the lowest leakage rates observed in the gingival edge are Equia System, Giomer = Dyract Extra, Fuji IX GP, and Fuji II LC, respectively. Conclusion: Occlusal and gingival microleakage scores were the lowest in the groups restored with Equia system in the cavities prepared by both diamond bur and laser system. Equia system consisting of high-viscosity glass ionomer cement and nano-filled surface coat G-Coat Plus materials could be used successfully in pediatric dentistry.

Keywords: Erbium, Chromium-Doped Yttrium, Scandium, Gallium, and Garnet Laser, Glass Ionomer, Microleakage, Restoration

How to cite this article:
Atas O, Celenk S, Aras A. Microleakage of novel glass ionomer restoration in cavities prepared by Er,Cr:YSGG laser: An in-vitro study. J Int Oral Health 2020;12:378-84

How to cite this URL:
Atas O, Celenk S, Aras A. Microleakage of novel glass ionomer restoration in cavities prepared by Er,Cr:YSGG laser: An in-vitro study. J Int Oral Health [serial online] 2020 [cited 2023 Jun 7];12:378-84. Available from: https://www.jioh.org/text.asp?2020/12/4/378/292763

Introduction

Modern operative dentistry is continuously improving with the emergence of new materials and the advancements in caries removal and cavity preparation techniques.^[1] In addition, there has been growing interest in the use of modern restorative techniques for cavity preparation as an alternative to conventional techniques, such as lasers. Of these, laser pretreatment of dental hard tissues in children provides numerous advantages over the conventional techniques in terms of patient comfort as it eliminates noise, pain, and vibration.^[2]

On the contrary, high-viscosity glass ionomer cements (GICs) have recently been introduced into the market, which have been reinforced by the optimization of powder/liquid ratio and particle size and distribution to reduce moist uptake, increase their hardness and wear performance, and to allow their usage in the sites subjected to the masticatory force.^[3] In addition, a new restorative material, named Equia, consisting of a highly viscous GIC and a nano-filled light-cured coating material, which has been suggested as a potential alternative to the composites in the posterior region and has been developed for permanent restoration of class I, II, and V cavities, has also been introduced within the last decade.^[4] On the contrary, hybrid restorative materials such as resin-modified glass ionomer cements (RMGICs) and polyacid-modified composite resins (compomers) combining the fluoride-releasing properties of GICs and the aesthetics and mechanical properties of composite resins have also been developed.^[5] Moreover, a new group of hybrid composite materials known as giomers, which are resin-based hybrid restorative materials comprising pre-reacted glass ionomer fillers, has also been recently introduced into the market.^[6],[7]

In this in vitro study, we aimed to investigate the effectivity of GICs on microleakage in class V cavities prepared by Er,Cr:YSGG (erbium, chromium-doped yttrium, scandium, gallium, and garnet) laser and by conventional diamond bur.

Materials and Methods

Setting and Design

This in vitro study included a total of 50 extracted human primary teeth with no carious. The total duration of the study was 3 months. The teeth collected for the experimentations were not extracted specifically for this study. Rather they were routinely collected from the dental clinics in the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Dicle University. The teeth were extracted for various reasons such as periodontal problem and orthodontic treatment. Among these extracted teeth, sound teeth and crack-free teeth were selected based on the inclusion criteria for our study. After the removal of soft-tissue remnants with a hand-scaling instrument and the cleaning of the pits and fissures with a rotating brush, the teeth were kept in distilled water at room temperature.

Study Method

Standard class V cavities (occlusal margin in enamel, gingival margin 1 mm coronal to the cementoenamel junction, 3 mm in mesiodistal length, 3 mm in occluso-gingival height, and 2 mm in depth) were prepared in the buccal aspects of each tooth, using a cylindrical and inverted cone diamond bur under water cooling (Diatech, Coltène/Whaledent AG, Altstätten, Switzerland).

A laser cavity was prepared in the lingual/palatal aspects of each tooth using an Er,Cr:YSGG laser system at a wavelength of 2.94 μm with a pulse repetition rate of 20 pulses per second (20 Hz) and a power output ranging from 0 to 6W (Waterlase MD, Biolase Technology Inc., San Clemente, CA, USA). The energy was delivered through a fiberoptic system with 750 μm of spot size at a distance of 2–3 mm. At the beginning of the cavity preparation process, irradiation was performed in a contact mode to remove the enamel with a focused beam of 6.0 W, as proposed by the manufacturer. The energy density was reduced to 3.0 W as the dentine was approached and ultimately was reduced to 1.0 W for dentin surface etching. All the procedures were performed under continuous air and water spray. The cavities prepared by Er,Cr:YSGG laser were also standard class V cavities (i.e., occlusal margin in enamel, gingival margin 1 mm coronal to the cementoenamel junction, 3 mm in mesiodistal length, 3 mm in occluso-gingival height, and 2 mm in depth).

After preparation, the teeth were randomly divided into five groups, with 10 teeth in each group. Subsequently, each group was further divided into two groups based on the operative technique used for cavity preparation: (1) diamond bur and (2) Er,Cr:YSGG laser system.

Group 1A: The cavities prepared by diamond bur were restored with EQUIA system (Fuji IX GP EXTRA and G-Coat PLUS) as proposed by the manufacturer. A Fuji IX GP EXTRA capsule was mixed in an automated mixer (Ultramat, SDI, Victoria, Australia) for 10s and was then applied to the cavity surface in bulk. Following the hardening process, the finishing and polishing procedures were performed. After removing the remnants over the surface with air and water spray and drying the restoration surface with air, the nano-filled G-Coat Plus coating (GC Tokyo, Japan) was applied on the entire surface with a microtip applicator for 10s. If the surface was not dried completely after the application of air drying, the coating was hardened with a light-emitting diode (LED) light source (Henry Schein, Melville, New York) for 10s.

Group 1B: The cavities prepared by Er,Cr:YSGG laser were restored with EQUIA system (Fuji IX GP EXTRA and G-Coat PLUS) in the same way as in Group 1A.

Group 2A: The cavities prepared by diamond bur were restored with a highly viscous GIC (Fuji IX GP) as proposed by the manufacturer. A Fuji IX GP capsule was mixed in an automated mixer (Ultramat, SDI, Victoria, Australia) for 10s and was then applied to the cavity surface in bulk. No surface coating was applied in any tooth.

Group 2B: The cavities prepared by Er,Cr:YSGG laser were restored with Fuji IX GP in the same way as in Group 2A.

Group 3A: The cavities prepared by diamond bur were restored with an RMGIC (Fuji II LC) as proposed by the manufacturer. Before application, a Fuji II LC capsule was mixed in an automated mixer (Ultramat, SDI, Victoria, Australia) for 10s and then was polymerized with an LED light source (Henry Schein). No surface coating was applied in any tooth.

Group 3B: The cavities prepared by Er,Cr:YSGG laser were restored with Fuji II LC in the same way as in Group 3A.

Group 4A: The cavities prepared by diamond bur were restored with a polyacid-modified composite resin (Dyract Extra) as proposed by the manufacturer. Prime&Bond, a one-step self-etching adhesive, was then applied to the cavity surface for 10s and after drying with low-pressure water spray, polymerization was performed using an LED light source (Henry Schein). Dyract Extra was applied to the surface in a single layer for 20s and then was polymerized using the LED light source.

Group 4B: The cavities prepared by Er,Cr:YSGG laser were restored with Dyract Extra in the same way as in Group 4A.

Group 5A: The cavities prepared by diamond bur were restored with a giomer adhesive system, FL-Bond II, and a flowable composite, Beautifil Flow Plus, as proposed by the manufacturer. FL-Bond II, a two-step, self-etching giomer adhesive system, was applied to the surface cavity. The primary layer was applied for 10s and then dried with air, and subsequently, the bonding agent was applied for 10s and then polymerization was performed using an LED light source (Henry Schein). Ultimately, Beautifil Flow Plus was applied over the surface in a single layer for 10s.

Group 5B: The cavities prepared by Er,Cr:YSGG laser were restored with FL-Bond II and Beautifil Flow Plus in the same way as in Group 5A.

After the completion of the restorations, the finishing and polishing procedures were performed, and the restoration surfaces were polished with finishing discs (Bisco Finishing Discs [BFD]; BiscoInc., Schaumburg IL, USA) underwater cooling, as proposed by the manufacturer. Subsequently, all the specimens were kept in a drying oven for 24h at 37°C and then were subjected to 1000 thermal cycles (NOVA, Konya, Turkey) in baths between 5°C ± 2°C and 55°C ± 2°C with an immersion time of 30s.

The specimen root ends, bifurcation points, the resorbed areas, and the areas that could have a negative effect on the microleakage testing were then sealed with a composite resin (Filtek Supreme XT Flow, 3M ESPE, Seefeld, Germany). The teeth were then placed on transparent, rectangular cold acrylic blocks and all the external surfaces were isolated with two layers of nail varnish (Flormar, Kocaeli, Turkey) except for 1 mm around the cavity margins. The specimens were kept in distilled water at room temperature for 24h before being immersed in 0.5% basic fuchsin for 24h. Subsequently, they were rinsed under tap water followed by the removal of the stained remnants and then were kept at room temperature for drying. The teeth were divided into two sections in the isomet device (Isomet, Buehler Ltd., Lake Bluff, IL, USA) underwater cooling to divide the restorative materials along the buccopalatinal plane. The resultant sections were examined under a stereomicroscope (Leica Microsystems, Sijhih, Taiwan) with the aid of a digital camera at ×30 magnification and were scored by two independent researchers based on the severity of microleakage by using these scores: 0= no dye penetration; 1= dye penetration up to one-third of the cavity walls; 2= dye penetration up to two-thirds of the cavity walls; 3= dye penetration beyond the final one-third of the cavity walls, without reaching the axial walls; and 4= dye penetration along the axial walls [Figure 1] and [Figure 2].

Figure 1: Microleakage in a cavity prepared by Er,Cr:YSGG (erbium, chromium-doped yttrium, scandium, gallium, and garnet) laser and restored with EQUIA system (occlusal score 0 and gingival score 0)

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Figure 2: Microleakage in a cavity prepared by diamond bur and restored with Fuji IX GP (occlusal score 2 and gingival score 1)

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Statistical analysis: Data were analyzed using Statistical Package for the Social Sciences software program, version 23.0 (IBM, Chicago, Illinois). For the determination of the sample size of the method, a statistical power test (G*Power software) was performed. The minimum estimated sample size for each group was 10 samples, calculated considering 80% power and a significance level of 0.05, according to a previous study.^[8] Mean and standard deviation (SD) were calculated for descriptive statistics. With histograms and Shapiro–Wilk tests, we checked if the data were normally distributed. The microleakage scores were compared among the groups using Kruskal–Wallis test, and binary comparisons were performed with the nonparametric Mann–Whitney U test at 95% confidence interval. An α value of 0.05 was considered significant.

Results

The mean microleakage scores of the groups are presented in [Table 1]. The difference between the mean microleakage scores between the groups in the gingival (P < 0.01) and occlusal (P < 0.001) regions was found to be statistically significant. The Mann–Whitney U test indicated no significant difference among the occlusal and gingival regions (P > 0.05) [Table 2].

Table 1: The mean microleakage scores of the groups compared with Kruskal–Wallis test

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Table 2: Comparison of occlusal and gingival regions with Mann–Whitney U test

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The occlusal microleakage score was lower in the cavities prepared by Er,Cr:YSGG laser in Groups 1, 4, and 5 and was lower in the cavities prepared by diamond bur in Groups 2 and 3; however, no significant difference was found between the cavities prepared by Er,Cr:YSGG laser and those prepared by diamond bur with regard to occlusal microleakage scores (P > 0.05) [Figure 3].

Figure 3: Average occlusal microleakage scores of the groups

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Similarly, gingival microleakage scores were lower in the cavities prepared by Er,Cr:YSGG laser in Groups 1 and 4 and were lower in the cavities prepared by diamond bur in Groups 2, 3, and 5 and no significant difference was found between the cavities prepared by Er,Cr:YSGG laser and those prepared by diamond bur with regard to gingival microleakage scores (P > 0.05) [Figure 4].

Figure 4: Average gingival microleakage scores of the groups

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Discussion

Microleakage is a major cause of restoration failure and repeated restoration, and thus the prevention of microleakage is a hallmark of successful restoration.^[9]

The emergence of new restorative materials and the use of various restoration techniques for the elimination of microleakage have recently emerged as a major concern in the literature. In line with these developments, laser systems have emerged as popular techniques in modern operative dentistry, and dental lasers have rapidly emerged as important new treatment option.^[10]

GICs are commonly performed in pediatric dentistry practice mainly because they can be easily and rapidly applied to the cavity, adhere to moist tooth structure without any pretreatment, release fluoride, and can be recharged. Moreover, although composite resin materials are the most commonly preferred restorative materials, GICs have recently emerged as an alternative to composite materials due to the advancements in their mechanical and esthetical properties.

Literature indicates that there is no consensus as to whether laser systems lead to greater, similar, or less microleakage as compared to conventional techniques, whereas some studies showed that laser systems provide greater or less microleakage compared to conventional techniques.^{[2],[8],[11],[12],[13]} Some other studies proposed that they provide similar microleakage scores.^{[14],[15],[16]} Moreover, as the studies comparing Er,Cr:YSGG laser with conventional techniques had no findings suggesting that the former are superior to the latter, further laboratory and clinical studies are needed.

The findings of our study seem to be supported by the findings of the studies by Bahrololoomi et al.,^[16] Quo et al.,^[17] Rossi et al.,^[18] and Delmé et al.^[19] Although these studies found significant differences among the restorative materials with regard to microleakage, they found no significant difference between the cavities prepared by diamond bur and those prepared by laser systems with regard to microleakage. On the contrary, the studies by Quo et al.,^[17] Rossi et al.,^[18] and Delmé et al.^[19] showed that the administration of conventional GICs led to greater microleakage as compared to the administration of RMGICs. In our study, however, no significant difference was found between the cavities restored with high-viscosity GICs (Fuji IX GP) and those restored with RMGICs (Fuji II LC) with regard to microleakage and between the cavities prepared by diamond bur and those prepared by Er,Cr:YSGG laser with regard to occlusal and gingival microleakage scores.

High-viscosity GICs have been mechanically reinforced by the optimization of the powder/liquid ratio and the particle size and distribution and also by the release of calcium ions and the achievement of faster hardening.^[20],[21] Moreover, high-viscosity GICs have recently been introduced into the market to eliminate the inadequate mechanical and physical properties of conventional GICs. Meaningfully, this might be the reason as to why GICs provided similar outcomes to those of Fuji II LC in our study with regard to microleakage score. On the basis of these findings, we consider that the use of high-viscosity GICs in lieu of conventional GICs may provide more beneficial outcomes, similar to the physical and mechanical outcomes of RMGICs. The analysis of microleakage scores in our groups showed that both occlusal and gingival microleakage scores were the lowest in Groups 1A and 1B. On the contrary, a significant difference was found among the cavities prepared by diamond bur and by laser system in Groups 1, 2, and 3 (P < 0.05).

In our study, it was also found that the coating of the restoration surface with a coating material led to lower microleakage scores, as was previously shown by Karaoğlanoğlu et al.^[22] and Chuang et al.^[23] In addition, restoration with Fuji IX GP Extra led to lower occlusal microleakage scores in the cavities prepared by both diamond bur and laser system compared to restoration with Fuji IX GP and Fuji II LC with no administration of coating. This difference was statistically significant for the cavities prepared by both diamond bur and laser system (P < 0.05). We consider that the lower occlusal and gingival microleakage scores in our specimens that were restored with Fuji IX Extra and coated with GC Fuji Coat compared to the specimens restored with Fuji IX GP and Fuji II LC in the cavities prepared by both diamond bur and laser system could be associated with the superior coating of the restoration surface achieved by GC Fuji Coat and with its prevention of microspace or microcrack formation both within the cement itself and between the cement and the tooth surface through the inhibition of hydration within a short period and of dehydration over a long period. On the contrary, Fuji IX GP Extra and GC Fuji Coat have been collectively introduced as the EQUIA system by the manufacturer.

In our study, the lowest occlusal and gingival microleakage scores were in the cavities prepared by diamond bur and were in the specimens restored with EQUIA system, Giomer, Dyract Extra, Fuji II LC, and Fuji IX GP, respectively. In the cavities prepared by diamond bur, no significant difference was found among the cavities restored with Giomers, Dyract Extra, and Fuji II LC with regard to gingival microleakage scores (P > 0.05). However, the cavities restored with Fuji II LC had significantly higher occlusal microleakage scores as compared to the cavities restored with EQUIA system, Giomers, and Dyract Extra among the cavities prepared by diamond bur (P < 0.05).

The literature reviews indicate that there are a limited number of clinical and laboratory studies reporting on giomers, which are newly developed restorative materials. In our study, similar to the study by Yadav et al.,^[24] the administration of giomers and compomers established no significant difference between the cavities prepared by diamond bur and laser system with regard to occlusal and gingival microleakage scores (P > 0.05).

In our study, the lowest occlusal microleakage scores in the groups restored with laser system were found in the groups restored with EQUIA system, Dyract Extra, Giomers, Fuji II LC, and Fuji IX GP, respectively, whereas the highest occlusal microleakage scores were found in the groups restored with Fuji IX GP. Although no significant difference was found between the groups restored with Fuji IX GP and those restored with Fuji II LC (P > 0.05), a significant difference was found among the groups restored with EQUIA system, Giomers, and Dyract Extra (P < 0.05). On the contrary, the lowest gingival microleakage scores in the groups restored with laser system were found in the EQUIA system, Giomers, Dyract Extra, Fuji IX GP, and Fuji II LC groups, respectively, whereas the highest occlusal microleakage scores were found in Fuji II LC groups. In addition, a significant difference was found among the three lowest levels of gingival microleakage, including EQUIA system, Giomers, and Dyract Extra (P < 0.05).

The present findings confirm that both occlusal and gingival microleakage scores were the lowest in the groups restored with Equia system. Moreover, the Equia system led to the lowest microleakage scores in the cavities prepared by both diamond bur and laser system. The Equia system, consisting of high-viscosity GIC and nano-filled G-Coat Plus coating, can be a safe and successful restorative material in pediatric dentistry practice. We recommend that high-viscosity GICs can be a better alternative to conventional GICs in pediatric operative dentistry.

Ethical policy and institutional review board statement

Ethical approval for this study was obtained from the Local Ethics Committee of the Faculty of Dentistry, Dicle University (reference number 2014-11). The study was carried out at Research Laboratory, Faculty of Dentistry, Erciyes University, Kayseri, Turkey.

Financial support and sponsorship

This research was supported by the Research Fund of Dicle University (DUBAP), Diyarbakir, Turkey (reference number 15-DH-04).

Conflicts of interest

There are no conflicts of interest.

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