Effects of surface coating on the flexural strength of fluoridereleasing restorative materials after water aging for one year

Fluoride release and flexural strength of four ion-releasing restorative materials: An in vitro comparative study

Background

This study aimed to determine the fluoride release and flexural strength of four ion-releasing restorative materials.

Material and Methods

A total of 80 samples of four different materials were prepared in standardized molds: Ketac Universal, Beautifil II, Cention N, and Equia Forte Fil. The fluoride release was quantified at 1, 3, 7, 14, and 28 days post-immersion using an ion-selective electrode. The flexural strength was measured with a universal testing machine after 7 days of immersion in deionized water. A one-factor intergroup ANOVA with Welch's robust variance and Games-Howell's post hoc was employed. To compare related measures, a Friedman test with Bonferroni's adjusted post hoc was employed. The p-value was set at 0.05.

Results

At 7 days, significant differences were observed in the flexural strength of the four ion-releasing restorative materials (p<0.001). The flexural strength values from highest to lowest were as follows: Cention N (97.10 ± 4.99 MPa), Beautifil (82.77 ± 5.30 MPa), Equia Forte Fil (31.38 ± 7.68 MPa), and Ketac Universal (19.23 ± 2.94 MPa). In addition, at 3 and 7 days, the highest amount of fluoride released was observed for Cention N compared to the other ion-releasing restorative materials (p<0.05). Conversely, Beautifil II released the lowest amount of fluoride at 3, 7, 14, and 28 days (p<0.05) compared to the other ion-releasing restorative materials.

Conclusions

The immersion of all ion-releasing restorative materials in deionized water for seven days resulted in significant differences in flexural strength. Cention N had the highest value, while Ketac Universal had the lowest. All ion-releasing restorative materials released fluoride at all test times, with Ketac Universal releasing the most at 1, 14, and 28 days, and Cention N releasing it at 3 and 7 days. Beautifil II showed the lowest fluoride release at all evaluated times, exhibiting a nearly constant release over time compared to the other materials. Key words:Fluoride release, flexural strength, glass ionomer.

Clinical Performance of Glass Ionomer Cement in Load-Bearing Restorations: A Systematic Review

Glass ionomer cement (GIC) is a self-adhesive dental restorative material composed of a polyacrylic acid liquid and fluoro-aluminosilicate glass powder. It is commonly used for cementation during dental restoration. This study aimed to systematically review the existing literature regarding the clinical performance of GIC in load-bearing dental restorations. A comprehensive literature search was conducted in EBSCO, PubMed, Embrace, and Cochrane databases. Only randomized controlled trials (RCTs) were included in the search, and a broad search technique was used, where inclusion and exclusion criteria were applied. After a thorough evaluation, 12 RCTs were extensively reviewed, and whether GIC is suitable for load-bearing restorations was determined. Significant variations in staining surface or margin, color match, translucency, esthetic anatomical form, retention, material fracture, marginal adaptation, surface luster, occlusal contour, wear, and approximal anatomical form indicated the unsuitability of GIC. By contrast, significance differences in patient view and periodontal response indicated that GIC is suitable. No significant differences in postoperative sensitivity, recurrence of caries, or tooth integrity were observed. Nevertheless, the results of the review demonstrated that the clinical performance of GIC is comparable to that of traditional restorative materials with regard to the parameters analyzed. GIC is a suitable restorative material for load-bearing restorations regarding surface margin, esthetic anatomical form, material retention and fracture, marginal adaptation, occlusal contour, wear, and approximal anatomical form. It reduces other parameters, such as postoperative sensitivity, recurrence of caries, and tooth integrity.

Effect of protective coating agents on microleakage and flexural strength of glass ionomer cement and zirconomer. an in vitro study

PURPOSE

The objective of this study was to assess the microleakage and flexural strength of glass ionomer cement (GIC) and modified GIC (Zirconomer) when coated with protective coating agents such as COAT-IT and G-COAT plus.

METHODS

Sixty tooth specimens were grouped into two groups based on the type of restorations (GIC (n = 30) and Zirconomer (n = 30)). The samples were further divided into three subgroups (n = 10) based on the protective coating agent (Petroleum jelly, G-COAT Plus, or COAT IT) applied. This study evaluated the microleakage at the occlusal and cervical margins of class V restoration after being subjected to dye penetration and sectioning. Each specimen was viewed under a 40 × microscope and was given scores based on the depth of dye penetration. They were statistically analyzed using the Kruskal-Wallis test and compared within the groups using the Mann- Whitney Test. In addition, flexural strength was assessed using standardized cuboid (25 × 2 × 2 mm) specimens of restorative materials with and without protective coating agents. The mean flexural strength data of all the subgroups were statistically evaluated using a one-way analysis of variance (ANOVA) and compared within the subgroups using the student t test.

RESULTS

A statistically significant difference was found when occlusal margin microleakage scores were evaluated with G-COAT Plus demonstrating the lowest occlusal margin microleakage when applied over GIC restoration. The increasing order of occlusal margin microleakage scores is as follows: GIC with G-COAT Plus, Zirconomer with COAT-IT, GIC with COAT-IT, GIC, Zirconomer with G-COAT Plus, and Zirconomer. However, the cervical margin microleakage scores revealed no significant difference. While flexural strength was found to be highest for the GIC group coated with G-COAT Plus, it was observed that there was a significant improvement in the flexural strength of both GIC and Zirconomer when coated with either of the protective coating agents.

CONCLUSION

Within the limitations of this in vitro study, it was observed that the application of protective coating agents can significantly reduce the potential microleakage and improve the flexural strength of the restorative material especially when zirconia-reinforced GIC is the restorative material.

Clinical comparison of different glass ionomer-based restoratives and a bulk-fill resin composite in Class I cavities: A 48-month randomized split-mouth controlled trial

OBJECTIVE

The aim of this study is to compare the retention rates (primary outcome) of high-viscosity glass ionomer (GI), glass carbomer (GC), zirconia-reinforced GI (ZIR), and bulk-fill (BF) composite resin restorations. Secondary outcomes included anatomical form, marginal adaptation, marginal discoloration, color match, surface texture, post-operative sensitivity and secondary caries.

METHODS

Two calibrated operators placed 128 restorations in 30 patients with a mean age of 21 years. The restorations were evaluated by one examiner at baseline and at 6, 12, 18, 24, and 48 months using the modified US Public Health Service criteria. The data were statistically analyzed using Friedman test. Differences between restorations were analyzed using Kruskal-Wallis test.

RESULTS

After 48 months, 23 patients and 97 restorations (23 GI, 25 GC, 24 ZIR, and 25 BF) were evaluated. Patient recall rate was 77%. No significant difference was observed between the retention rates of the restorations (p > 0.05). GC showed significantly lower results than the other three fillings in terms of anatomical form (p < 0.05). There was no significant difference in the anatomical form and retention between GI, ZIR, and BF (p > 0.05). No significant change was observed in the postoperative sensitivity or secondary caries for any of the restorations (p > 0.05).

CONCLUSIONS

GC restorations showed statistically lower anatomical form values, indicating lower wear resistance than the other materials. However, no significant difference was observed in the retention rates (as primary outcome) as well as the other secondary outcomes of the four different restorative materials after 48 months.

CLINICAL SIGNIFICANCE

GI-based restorative materials and BF composite resin restorations in Class I cavities yielded satisfactory clinical performance after 48 months.

Effects of Protective Surface Coating on Fluoride Release and Recharge of Recent Uncoated High-Viscosity Glass Ionomer Cement

The ability to release and recharge fluoride is a property of glass ionomer cement materials, which is an advantage for patients with a high caries risk. The purpose of this study was to evaluate the amount of released and recharged fluoride in recent uncoated high-viscosity glass ionomer cement (KetacTM Universal AplicapTM) with different surface coatings and at different time points. In total, 135 cylindrical-shaped specimens were equally divided into the following three groups: KetacTM Universal AplicapTM, KetacTM Molar AplicapTM, and KetacTM Fil Plus AplicapTM. The different coatings performed on each group were as follows: uncoated, coated with KetacTM Glaze, and coated with G-Coat PlusTM. The amounts of released and recharged fluoride were measured at 24 h and at weeks 1, 2, 3, and 4. The recharging agent was a 1.23% APF gel. KetacTM Universal AplicapTM showed the highest released fluoride at all time points and the highest recharged fluoride at weeks 1, 2, and 3. Both the KetacTM Glaze- and G-Coat PlusTM-coated specimens presented significantly lower released and recharged fluoride ions than the uncoated group at all time points (p < 0.001). Coating with G-Coat PlusTM significantly decreased the released and recharged fluoride compared to the coating with KetacTM Glaze at almost all time points (p < 0.05), except for weeks 1 and 2. The application of coating agents reduced the amount of released and recharged fluoride by the KetacTM Universal AplicapTM.

Comparison of the effect of preheating on the flexural strength of giomer and nanohybrid composite resin

Background. Considering the increased use of preheating and novel resin-based materials to restore teeth, the present study investigated the impact of preheating on the flexural strength of a giomer and compared it with a nanohybrid composite resin. Methods. Two restorative materials (Beautifil II giomer and Alpha III nanohybrid composite resin) were used. Thirty rod-shaped samples (adding up to 60 samples) were prepared from the materials above and divided into two subgroups: with and without preheating (n=15). Before sample preparation, the giomer and nanohybrid composite resin tubes were preheated at 68ºC for 15 minutes in the preheating subgroups. In the subgroups without preheating, the tubes were kept in a room at 25ºC. Then the flexural strength was compared between the two groups with two-way ANOVA at a significance level of P<0.05. Results. The results showed significantly higher flexural strength in the preheated subgroups than in the non-preheated subgroups (P<0.001). In addition, the mean flexural strength values were significantly higher in the giomer groups than in the nanohybrid composite resin groups (P<0.001). Conclusion. Preheating increased the studied materials' flexural strengths significantly. The flexural strength of the giomer restorative material was higher than that of the nanohybrid composite resin, irrespective of preheating.