جستجوی مقالات مرتبط با کلیدواژه "سمان های دندانی" در نشریات گروه "پزشکی"

Micro leakage is one of the major causes of failure to repair and subsequent caries. The difference in the structure of enamel and dentin in deciduous teeth can affect the selection of bonding agents. The purpose of this study was to compare the micro leakage of class 5 restorations using self-etch universal bonding and fifth-generation total etching in primary anterior teeth.

In this in-vitro study, 45 healthy anterior deciduous extracted teeth were randomly divided into three groups of 15 each. Class 5 cavities were created on the buccal surface of all teeth. Then restoration was done in first group by using Universal Self-etch Bonding Saremco, in the second group using Universal Self-Bonding G Permio Bond and in the third group using 5th generation Total-etch TNT Tetric-Bond, and using Filtek Z250 composite. Micro leakage was investigated using methylene blue based on the intensity of 0 to 3.

In Tetric-N Bond group, 33.3% had no micro leakage, 53.3% had first degree micro leakage, and 13.3% had second degree micro leakage. In group G Permio Bond, 33.3% had first degree micro leakage, 53.3% had second degree micro leakage and 13.3% had third degree micro leakage. In Saremco-Bond group, all teeth had grade 3 micro leakage. The distribution of micro leakage intensity in the Saremco group was significantly different from the Tetric-N group (p= 0.000) and the G-permio group (p= 0.002).

The results of the present study showed that the Universal Self-etching Saremco Unibond had more micro leakage than the other two bonds.

The aim of this study was to compare the retention of zirconium oxide ceramic copings at a 24 degree convergence angle with four different types of cement. In this experimental study, 40 first and second premolars were randomly divided into four groups (n = 10). After preparing the specimens, zirconia copings were cemented using RelyX Ultimate, Panavia F, resin-modified GI and zinc phosphate cements under a 5-kg force, followed by thermocycling (3000 rounds 5-55°C) for 24 hours in water with pH = 7 and a temperature of 37°C. Then the copings were separated under a tensile strength in an electromechanical universal testing machine at a strain rate of 0.5 mm/min and their retention was measured. Data were analyzed using SPSS 25 with Kruskal- Wallis and Mann-Whitney tests. The means and standard deviations of retention in the RelyX Ultimate, Panavia F, resin-modified GI and zinc phosphate groups were 7.17 ± 1.13, 4.26 ± 0.37, 2.72 ± 0.43 and 2.3 ± 0.57 MPa, respectively, with significant differences between the groups (p value < 0.001). Based on the results of this study, the retention of ceramic copings of zirconium oxide at a 24-degree convergence angle was different in terms of the cement type, with RelyX Ultimate cement exhibiting the highest retention.

  One of the important factors in the success of implant-supported prostheses is the marginal fit of abutment-restorations. The aim of this study was to evaluate the effect of screw access channel filling method and cement type on the marginal adaptation of implant-supported fixed restorations. One of the important factors in the success of implant-supported prostheses is the marginal fit of abutment-restorations. The aim of this study was to evaluate the effect of screw access channel filling method and cement type on the marginal adaptation of implant-supported fixed restorations. In this experimental in vitro study, 40 implant analogs were mounted in autopolymerizing acrylic resin blocks using a dental surveyor. Forty two piece titanium abutments were placed in each implant analog and torque up to 35 N cm. The following acrylic blocks of implants were randomly divided into 2 groups, including 20 abutment samples fully filled by the silicone, and 20 abutments sample filled partially with silicon. The marginal discrepancy of samples was measured from 4 sides with a magnification of ×50 by stereomicroscope before final cementation. In each study group, 10 samples were cemented by zinc-oxide eugenol temporary cement and 10 other samples with zinc-oxide non-eugenol temporary cement. The marginal discrepancy was measured at the same points again. Data were analyzed with ANOVA and, t-test (α=0.05). In all surfaces there were no significant differences in the mean marginal discrepancy between the group in which screw access channels were partially filled and the group in which screw access channels were completely filled before (P˃0.05)and after (P=0.052) cementation. However after cementation significant differences were found between the means of marginal discrepancy in two cement types (P=0.02). Non-eugenol cement showed significantly higher marginal discrepancy than eugenol cement (P=0.03). The mean marginal discrepancy in both full and partial access cavity filling groups did not differ significantly, but a marginal discrepancy with the use of non-eugenol cement was greater than eugenol cement