Background and Aim: Current self-adhesive resin cements have become popular for esthetic restorations. The purpose of this study was to compare the microleakage of 2 self-adhesive resin cements and 2 etch and rinse versions of the same brands.Materials and Methods: Forty human third molars were randomly assigned to 4 experimental groups: 1-Rely X Unicem, 2- Rely X ARC+ Acid etch 37% + Single Bond, 3- Nexus 3 Acid etch 37% + Optibond Solo, and 4- Maxcem Elite. Microleakages of the specimens were then measured with a four point scoring system at both the cervical & occlusal areas, with the aid of a stereomicroscope. Microleakage scores were compared using Kruskul-Wallis analysis, followed by relative Dunn test.Results: The microleakage of Rely X Unicem and Nexus 3 were significantly less in the occlusal region (P<0.05), whereas in the cervical area there was no significant difference in microleakage between Rely X Unicem and Rely X ARC (P= 0.0087). The microleakage of Nexus 3 was significantly less than that of Rely X Unicem. Maxcem Elite showed the highestlevel of microleakage (P<0.05).Conclusion: Microleakage of both cements using etch & rinse adhesive systems were significantly lower in comparison with their self- etch counterparts both at the cervical & occlusal areas. (P<0.05).

Introduction: The aim of the present study was the comparison of radiopacity of different resin cement types using direct digital radiography by calibrating the calculations on the radiogram according to the dead pixel value on the phosphor plate for the first time in literature. Methods: The radiopacities of currently used ten different resin cements(G-CEM, I-CEM, Choice 2, Duo Link, TheraCem, eCEMENT DC, MaxCem Elite Chroma, BisCem, NX3, and Maxcem Elite), enamel and dentin were compared with the densitometer. The digital radiographs were acquired and Image J software was used to convert the images into numerical data for analysis. After the dead pixel calibration, the equivalent aluminum thickness value of each sample was calculated by the correlation analysis method. Results: According to test results, although there was no significant difference between G-CEM and I-CEM, all the materials, enamel and dentin had a significant difference from each other. MaxCem Elite had the highest radiopacity while G-CEM had the lowest. Conclusions: eCEMENT DC, MaxCem Elite Chroma, BisCem, NX3, and Maxcem Elite had higher radiopacity than dentin. Those with lower radiopacity than dentin (G-CEM, I-CEM, Choice 2, Duo Link, and TheraCem) should be carefully used in both subgingival located or radiolucent restorations and implant-supported prostheses. Dead pixel calibration enables materials to be evaluated more accurately and this method will also make it possible for the first time in literature to compare the same samples with each other on different phosphor plates.

Background and Aim: Dislodgment of prosthetic crowns is a common occurrence. In such cases, recementation is a suitable treatment option. The aim of this study was to compare the retention in cementation and recementation using different resin cements. Materials and Methods: In this in vitro, experimental study, 40 premolars were selected (n=10). They were standardized relative to some properties and then the wax patterns were prepared and cast. After 24 h, all specimens were decemented using Instron universal testing machine. The castings were then re-cemented and stored under the same conditions. After 24 h, the cemented copings were dislodged, and the separation load was recorded. Results: The highest and the lowest mean retention values belonged to Panavia F2 and Maxcem cements in both initial cementation and recementation groups, respectively. Paired sample t-test showed a significant difference in the retention of G-CEM group between initial cementation and recementation (P=0. 009). The two-factorial repeated measures ANOVA showed the significant effect of cement type on retention (P=0. 009), and there was a significant difference in retention between initial cementation and recementation (P=0. 006). The Tukey’ s HSD test revealed a significant difference in retentive strength between the Maxcem and Panavia F2 (P=0. 011). The lowest mean difference was observed between Bifix SE and Maxcem groups (-16. 75 kgf, P=0. 89). Conclusion: The maximum and minimum mean retention values belonged to Panavia F2 cement and Maxcem in both initial cementation and recementation groups, respectively. There was a significant difference between the initial cementation and recementation in G-CEM group.

Introduction: Today, much of the researches and innovations in dental materials are focused on simplification of the bonding procedures. The aim of this study was to assess shear bond strength (SBS) of three auto-adhesive dual-cured resin cements to dentin.Materials & Methods: In this in vitro experimental study, 40 intact human Third molars were selected and randomly divided into 4 groups of 10 teeth. Group I (Control group): After 15 seconds of etching and application of Excite DSC Bond (Ex), Varilink II (Var II) composite was injected into the plastic ring and light cured. Group II: RelyX Unicem (RX) was injected into the plastic ring and light cured after 30 seconds (according to manufacturer's instruction). Group III: Maxcem (Mc) was injected into the plastic ring and light cured after 30 seconds (according to manufacturer's instruction). Group IV: Multilink Sprint (MS) was injected into the plastic ring and light cured after 30 seconds (according to manufacturer's instruction). After thermal cycling (1000 cycle, 5-55oC), SBS were measured for each groups with a Zwick/Roell Universal Testing Machine. The data were analyzed by ANOVA and Scheffe tests.Results: The mean SBS and Standard deviations for groups I, II, III and IV were 12.95±2.64, 6.73±0.79, 3.01±0.90 and 4.60±0.75 MPa respectively. Statistical analysis revealed that: 1. The mean SBS of Var II was significantly higher than the other groups (P<0.05). 2. The mean SBS of Mc and MS were significantly lower than RX (P<0.05).3. The mean SBS of Mc and MS were not significantly different (P>0.05).Conclusion: Bond strength of the auto-adhesive dual-cured resin cements (RX, Mc, MS) to dentin was lower than Var II composite combined with Ex bond. Bond strength of RX was higher than Mc and MS.

Statement of Problem: For a luting agent to allow complete seating of prosthetic restorations, it must obtain an appropriate flow rate maintaining a minimum film thickness. The performance of recently introduced luting agents in this regard has not been evaluated.Purpose: To measure and compare the film thickness and flow properties of seven resincontaining luting cements at different temperatures (37oC, 25oC and 10oC).Material and Methods: Specimens were prepared from five resin luting cements; seT (SDI), Panavia F (Kuraray), Varioloink II (Ivoclar), Maxcem (Kerr), Nexus2 (Kerr) and two resin-modified glass-ionomer luting cements (RM-GICs); GC Fuji Plus (GC Corporation), and RelyX Luting 2 (3 M/ESPE). The film thickness and flow rate of each cement (n=15) was determined using the test described in ISO at three different temperatures.Results: There was a linear correlation between film thickness and flow rate for most of the materials. Cooling increased fluidity of almost all materials while the effect of temperature on film thickness was material dependent. At 37oC, all products revealed a film thickness of less than 25mm except for GC Fuji Plus. At 25oC, all cements produced a film thickness of less than 27mm except for seT. At 10oC, apart from seT and Rely X Luting 2, the remaining cements showed a film thickness smaller than 20 mm.Conclusion: Cooling increased fluidity of almost all materials, however. the film thickness did not exceed 35 mm in either condition, in spite of the lowest film thickness being demonstrated at the lowest temperature.