جستجوی مقالات مرتبط با کلیدواژه « Resin modified glass ionomer » در نشریات گروه « پزشکی »

The present study aimed to compare the shear bond strength (SBS) of the resin-modified glass ionomer (RMGI) to primary dentin using different dentin conditioners.

The dentin surfaces of 80 primary molars were conditioned using four different methods etching with 37% phosphoric acid, 10% polyacrylic acid, 5% NaOCl, and no surface treatment. Dentin surfaces were restored with RMGI Fuji Π LC cylinders. After 24 h, the shear bond strength tests were performed using Universal Testing Machine. Statistical analysis was performed using One-Way ANOVA followed by Tamhane Post hoc Test. A p-value less than 0.05 was considered statistically significant.

Phosphoric acid produced the highest shear bond strengths, compared to all tested groups, which showed statistically significant differences with groups 3 and 4 (P=0.043, P<0.001). Subsequently, Polyacrylic acid showed a significantly higher SBS than group 4 (P=0.046). Conditioning with NaOCl significantly increased the bonding strength of RMGI compared to the untreated group (P=0.001). Untreated dentin had the lowest SBS compared to other tested groups.

The conditioning step effectively improved the SBS of RMGI to primary dentin. Dentin conditioning with 37% Phosphoric acid for 5 sec showed the highest shear bond strength of RMGI.

Nowadays, new techniques are used to control dental caries that have the ability to kill cariogenic bacteria. Recently, the addition of antibiotics to glass ionomers has been proposed to reduce the overall number of saliva bacteria. The aim of this study was to compare the antimicrobial effect and compressive strength of resin- modified glass ionomer (RMGI) containing different antibiotics on Streptococcus mutans.

A total of 120 specimens were prepared in 3 groups (n=40) including RMGI containing doxycycline with a concentration of 1.5%, RMGI containing a combination of ciprofloxacin, metronidazole and minocycline with a concentration of 1.5%, and RMGI without antibiotics as control group. To measure the antibacterial effect, the disk diffusion method and counting of Streptococcus mutans bacterial colonies were used and then the compressive strength test was performed. Data were collected into SPSS25 and analyzed by ANOVA and Kruskal-Wallis tests and the significance level was considered α=0.05.

The mean number of bacterial colonies in the RMGI group containing doxycycline in all three time intervals 1, 24 hours and 7 days was significantly lower than the specimens in the RMGI group containing the triple antibiotic (P<0.001). The mean compressive strength of the two experimental groups was lower than the control group but was not statistically significant (P=0.326).

The addition of antibiotics at a concentration of 1.5% to RMGI resulted in a favorable antibacterial property with no significantly change in the compressive strength.

Solubility is among the negative characteristics of dental materials leading to structural degradation of cements and decreased longevity of restorations. The present study sought to assess the water sorption and solubility of FujiCem resin-modified glass ionomer (RMGI) and G-Cem self-adhesive resin cement in water and acid.

In this experimental study، 5 discs were fabricated from each understudy cement for solubility testing in lactic acid and 5 other disc-shaped specimens were made for evaluation of water sorption and solubility. Specimens were immersed in distilled water for 7 days and immediately weighed afterwards (M2). Discs were then transferred to a desiccator again to reach a constant weight of M3. Water sorption and solubility were calculated using the respective equations. For acid solubility testing، specimens were immersed in lactic acid for 24h. Independent t-test was applied for statistical analysis of results.

Solubility in distilled water was 0. 0000139±0. 0001μg/m3 for FujiCem and 0. 0000016±0. 000005μg/m3 for G-Cem (P=0. 480). Water sorption was 0. 0000197±0. 000234 for FujiCem and 0. 0000025±0. 00004 for G-Cem (P<0. 001). Acid solubility was 0. 0059414±0. 0016 for FujiCem and 0. 0039115±0. 0016μg/m3 for G-Cem (P=0. 348).

The two understudy cements had no significant difference in water or acid solubility but FujiCem RMGI showed greater water sorption than G-Cem self-adhesive resin cement.

Nano-sized hydroxyapatite nano particles (nHA) have optimal biological properties and by incorporating them into the restorative materials, we can benefit from these properties. The present study sought to assess the effect of incorporation of various amounts of nHA on the mechanical properties (compressive and flexural strengths) of a resin modified glass ionomer.

In this experimental study, a total of 252Fuji II LC improved GI samples were divided into 6 groups including a control group (0%) and the nHA groups (1%, 2%, 5%, 7% and 10% based on mass percent). Of the samples, 108 were fabricated for the flexural strength testing using a two-piece aluminum mold (2x2x25 mm) according to ISO standard 4049. In each group, a total of 18 samples in 3 subgroups (6 samples each) were fabricated. All samples were removed from the mold after 80 seconds of light irradiation. A total of 144 samples made for compressive strength testing using a two-piece brass mold (4x6 mm) according to ISO standard 9917. Thus, in each group, a total of 24 samples in three subgroups (8 samples each) were fabricated and removed from the mold after 80 seconds of light irradiation. After removal from the mold, all samples were stored in an incubator at 37˚C and 100% moisture and underwent flexural and compressive strength testing with the primary load of 2 N and crosshead speed of 0.5 mm/min-1in a Zwick testing machine after one day, one week and one month. Data were analyzed using normal statistical tests of one-way ANOVA and Tukey’s HSD (Post Hoc). In order to assess the correlation of time (in groups with various mass percentages of HAP) with understudy outcomes, one way ANOVA was employed and P<0.05 was considered statistically significant.

Study results showed that incorporation of 5% nHA resulted in a significant increase in flexural strength after 30 days (17.4 MPa increase)(P<0.05). Also, if the nHA weight percent exceeded 5%, flexural strength suffered a dramatic drop after one month(28.9 MPa reduction). This study also showed that addition of 5% NHAP significantly increased flexural elastic modulus after one month (2.2 GPa increase). Addition of NHAP to resin modified glass ionomer caused a small increase in compressive strength and compressive elastic modulus which was not statistically significant (about 1MPa increase).

Addition of nHA to resin modified glass ionomers (Fuji II LC improved) not only does not reduce compressive strength, but also can increase flexural strength which would be the greatest if nHA is added in an amount of 5%.

In different investigations, the destructive effect of ultrasonic scalers on the margins of composites has been studied, but there are very few studies on the effects of ultrasonic scalers on the microleakage of poly-acid modified composite resin and resin modified glass ionomers. The main purpose of this study was to evaluate the marginal microleakage of class V preparations restored with resin modified glass ionomer and poly-acid modified composite resin before and after scaling with an ultrasonic scaler.

This in vitro study was performed on 160 premolar teeth. Standard class V cavities were prepared on the buccal surfaces of the selected teeth. Occlusal and cervical margins were placed entirely in enamel and cementum, respectively. Teeth were randomly divided to two groups of eighty, each. For one half of each group, (40 teeth) resin modified glass ionomer and for the other half, polyacid modified composite resin was used. Each one of the binary groups was subdivided to two groups. First subgroup was restored with Fuji II Lc (Fuji Japan) and Vitremer (3M USA ) and the second subgroup was restored with F2000 compomer (3M USA) and Compoglass(Vivadent Germany). For bonding to enamel, dentinte,cementum Singlebond (3M USA) and Adhese 2 (Vivadent Germany) were used and all of the restorations were done according to instructions of the manufacturers. In ten teeth of each group, ultrasonic scaling was done and in the other ten teeth, scaling was not done. After that, all of the teeth were thermocycled and immersed in fuschin. After cutting the microleakage was evaluated. The data was analyzed by Mann – Whitney, Kruskal – Wallis and Wilcoxon tests and significant border was 0.05 .

The results showed that the degree of microleakage in enamel margins of poly –acid modified resin composites was lower than resin modified glass ionomers and in all groups and subgroups, the microleakage in enamel and cementum after scaling was significantly more than the groups without scaling.

Use of resin modified glass ionomers in class V restorations has no advantages over polyacid modified composite resins.