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ObjectiveTo evaluate the effect of different surface treatments of nickel chrome (NiCr) with the type of metal primer monomers on the conventional tensile bond strength (CTBS) of resin cement.MethodsForty disks of NiCr alloy were prepared for CTBS test and grouped as follows: group (1) no surface treatment (control group), group (2) oxide layer only, group (3) air abrasion, and group (4) air abrasion with an oxide layer. Each main group was subdivided into two subgroups (n = 5) depending upon the type of metal primer used for metal treatment. All specimens were bonded with resin cements. The CTBS was tested using a tensile testing machine. The data were statistically analyzed with One-way ANOVA, Two-way ANOVA, and T-test at 0.05 level of significance.ResultsSignificant differences in the mean value of the CTBS between different surface treatments (P ≤ 0.05) were observed. Tukey's test showed that air abrasion surface treatment had the highest mean value followed by the air abrasion with an oxide layer and oxide layer only. The control group showed the lowest value of significant difference compared to all treated groups (P ≤ 0.05).ConclusionsCTBS of self-adhesive resin cement to NiCr is dependent on surface treatment. Two types of the metal primer of different monomer contents 10-methacryloyloxydecyldihydrogenphosphate (MDP) or Thiophosphoricmethacrylate (MEPS) show similar behavior on the tensile bond strength.

The aim of this study was to evaluate the regional mechanical properties of flowable composites with different initiation systems under free and constrained conditions. Forty cavities fabricated in resin blocks with or without bonding treatment were bulk-filled with Estelite Flow Quick (EFQ) or Palfique Estelite LV (ELV), followed by light irradiation for 10 or 30 seconds. Each specimen was sliced to three slabs parallel to the long axis. The middle slab was serially sliced from top to bottom to harvest three sticks for ultimate tensile strength (UTS) measurement. The remaining slabs were polished for microhardness (KHN) measurement. The results indicated that the UTS and KHN of both flowable composites decreased toward the bottom of the cavity and increased with prolonged light irradiation time. At the upper cavity region, UТS values of the bonded groups were significantly lower than those of the unbonded groups, except for the 10-second light irradiation group of EFQ. As for KHN, the values did not change significantly for both flowable composites between the unbonded and bonded groups.

The aim of this study was to evaluate the micro-shear bond strength (µSBS) of one and two steps self-etch adhesive systems after enamel bleaching with photo-activated bleaching systems of different hydrogen peroxide (HP) concentration. Occlusal enamel of forty intact human molars were flattened and assigned into four groups. GI Unbleached, GII, GIII, and GIV were bleached with Pyrenees (3.5% HP), GC TiON (20% HP), and Hi-Lite (35% HP) respectively. Enamel treatment with one and two steps self-etch adhesives (Clearfil S3 Bond- S3, and Clearfil SE Bond-SE) then micro-tubes were fixed on enamel and filled with AP-X composite (n=5). Bond was tested with the universal testing machine. Data were analyzed using two-way ANOVA and Tukey’s tests at 5 % level of significance. The µSBS was significantly different between adhesives (F=154.46; p<0.05) and bleaching systems (F=77.33; p<0.05) with significant interaction. Specimens bonded with S3 shows a significantly lower μSBS than those bonded with SE (p<0.05) in all groups. For both adhesives the bleached groups demonstrate lower µSBS than unbleached except specimens bleached with Pyrenees and bonded with SE (p>0.05). A significant difference was observed between groups of the bleaching systems (p<0.05). Different peroxide concentrations photo-activated bleaching systems adversely affect μSBS of one and two steps self-etch adhesives. Low concentration system (Pyrenees) does not influence the bond strength of two steps adhesive.

Aims: To investigate the effect of mechanical and chemical surface treatments including (AL 2 O 3-110µm) and citric acid solution (30%) on the microhardness of zirconia ceramic. Materials and Methods: Twenty four cubic shaped specimens were prepared from partial sintering zirconia (IPS e.max ZirCAD MT).Specimens were randomly assigned into three main groups (GI, GII, and GIII) according to the surface treatment methods (n=8). Group I: zirconia surface left without surface treatment (control), Group II: In this group all specimens were subjected to sandblasting with 110 µm Aluminum oxide particles (Al2O3), while Group III: The surface was treated with citric acid solution 30% for 10 minutes. Force of Vickers microhardness was applied on the intaglio surface of the zirconia specimen at 0.5 kg for 30 seconds. Data were analyzed with one way ANOVA at 5% level of significance. Results: Sandblasting with AL2O3 110µm significantly increased the Vickers microhardness value of the zirconia surface. Chemical treatment with 30% citric acid did not exhibit any significant changes in comparison to the control group. Conclusions: Within the limitation of this in vitro study, the mechanical surface treatment of the zirconia surface with AL2O3 improves the surface microhardness.

AIMS:Microleakage is important for assessing the success of adhesive restorative materials. The aim of this study was to evaluate the microleakage of resin composite restorations bonded with three types of adhesive systems. MATERIALS AND METHODS: Twenty four sound human third molars were used. Class V cavities were prepared on the buccal surface by a diamond cylinder bur No. (1543M). Samples was assigned randomly to three groups (N = 8): Group Ι: Cavities were treated with total etch adhesive system (Adper Single Bond 2Adhesive, 3M ESPE, USA). Group II: Cavities are treated with one step self-etch adhesive system (OptiBond All In One, kerr, USA). Group III: Cavities were treated with two step self-etch adhesive system (CLEARFIL SE BOND, kurary, Japan). Cavities were restored in bulk technique withresin composite (Ceram X, DENTSPLY, USA). Restorations were polished and after storage in water for 24 hours at 37°C the samples were thermocycled between 5-50°C for 300 cycles in water baths then immersed in methylene blue solution for 24 hours. Dye leakage was assessed by examining longitudinal sections in a stereomicroscope at X10magnification. Data were analyzed with Kruskal-Wallis test and Mann-Whitney test at 5%significant level. RESULTS: A significant differences in microleakage were observed among restorations (p < 0.05).One step adhesive bonded restorations demonstrate significantly higher leakage value than two step. No significant differences were observed between total etch adhesive and self-etch adhesive (p>0.05).CONCLUSIONS: The microleakage of resin composite restoration was influenced by adhesive type. One step self-etch bonded restoration was more prone to leakage than total etch and two step bonded restoration.

Objective: To evaluate the ultimate tensile strength (UTS) of total and self- etch adhesives irradiated at different distances. Materials and Methods: Sixty cylindrical specimens of 0.78mm diameter and 10 mm length were prepared of two types of adhesive systems total etch Excite DSC (EX – Ivoclar Vivadent, Schaan, Liechtenstein) and one-step self-etch Clearfil S3 Bond (S3, Kuraray Medical Inc., Tokyo, Japan). Specimens of each adhesive were divided into three groups according to the light irradiation distance (0, 2, 4mm) (n=10). Each specimen was attached to universal testing machine (Digital Force Gauge, IMADA CO., LTD, Japan) and loaded at cross head speed of 1mm/min until failure. Data were analyzed using two-way ANOVA and Independent Student t-test at p< 0.05. Results: Mean UTS for total etch (24.63, 18.19, 17.26 Mpa) and for self-etch (12.68, 8.53, 7.58Mpa) at (0, 2, 4mm) distances. Specimens irradiated directly show significantly the highest UTS while those irradiated at 4mm show the lowest values (p<0.05). Excite DSC total etch adhesive have higher UTS than Clearfil S3 self-etch adhesive regardless of irradiation distance (p<0.05).Conclusions: The UTS of the evaluated adhesives was light irradiation distance and adhesive system dependant.