Journal of Dental Medicine

Background and Aim: Cementation is one of the most critical steps of the porcelain restoration technique. However, limited information is available concerning the bond strength of current ceramic bonding systems. The aim of this study was to evaluate the shear bond strength of three dual-cure resin cements to IPS-Empress2 ceramics.

Materials and Methods: In this experimental study, 30 pairs of IPS-Empress 2 ceramic discs were fabricated with 10 and 8 mm diameters and 2.5 mm thickness. After sandblasting and ultrasonic cleaning, the surfaces of all specimens were etched with 9% hydrofluoric acid for 60 seconds. Then, the three groups of 10 bonded specimens were prepared ceramic bonding resin systems including Panavia F2, Variolink II and Rely X ARC. After storage in 37±1c water for 24 hours and thermocycling in 5c and 55c water for 500 cycles with 1-minute dwell time, the shear bond strengths were determined using Instron machine at speed of 0.5mm/min. Data were analyzed by One Way ANOVA test. For multiple paired comparisons, the Tukey HSD method was used. The mode of failure was evaluated by scanning electro microscope (SEM). P<0.05 was considered as the limit of significance.

Result: Significant differences were found between different cement types (P<0.05). Variolink II provided the highest bonding values with IPS-Empress2. A combination of different modes of failure was observed.

Conclusion: Based on the results of this study, according to the highest mode of cohesive failure, Variolink II seems to have the strongest bond with IPS-Empress2 ceramics.

Background and Aim: Sodium hypochlorite can remove the organic phase of the demineralized dentin and it produces direct resin bonding with hydroxyapatite crystals. Therefore, the hydrolytic degradation of collagen fibrils which might affect the bonding durability is removed. The aim of this study was to evaluate the effect of collagen fibrils removal by 10% NaOCl on dentin shear bond strength of two total etch and self etch adhesive systems.
Materials and Methods: Sixty extracted human premolar teeth were used in this study. Buccal surface of teeth were grounded until dentin was exposed. Then teeth were divided into four groups. According to dentin surface treatment, experimental groups were as follows: Group I: Single Bond (3M) according to manufacture instruction, Group II: 10% NaOCl+Single bond (3M), Group III: Clearfil SE Bond (Kuraray) according to manufacture instruction, and Group IV: Clearfil SE Bond primer. After that, the specimens were immersed in 50% acetone solution for removing extra monomer. Then the specimens were rinsed and dried. 10% NaOCl was applied and finally adhesive was used. Then composite was bonded to the treated surfaces using a 4 2 mm cylindrical plastic mold. Specimens were thermocycled for 500 cycles (5-55ºC). A shear load was employed by a universal testing machine with a cross head speed of 1mm/min. The data were analyzed for statistical significance with One-way ANOVA, Two-way ANOVA and Tukey HSD post-hoc tests.
Results: The mean shear bond strengths of groups were as follows: Single Bond=16.8±4.2, Clearfil SE Bond=23.7±4.07, Single Bond+NaOCl=10.5±4.34, Clearfil SE Bond+NaOCl=23.3±3.65 MPa. Statistical analysis revealed that using 10% NaOCl significantly decreased the shear bond strength in Single Bond group (P=0.00), but caused no significant difference in the shear bond strength in Clearfil SE Bond group (P=0.99).
Conclusion: Based on the results of this study, NaOCl treatment did not improve the bond strength in self etch adhesive and caused a significant decrease in the bond strength of total etch adhesive system.

Background and Aim: Evaluation of shear bond strength and microleakage of bonding agents is important as these properties play main roles in adhesion of composite to dental tissues. Microleakage results in bacterial penetration into dentin tubules and enamel surfaces and causes sensitivity and recurrent caries followed by destruction of composite filling. Insufficient shear bond strength results in early failure of filling in low masticatory forces. The main goal of this study was to compare the microleakage and shear bond strength of an experimental adhesive and Scotchbond multi-purpose (MP) adhesive system.
Materials and Methods: In this experimental study, sixty extracted caries free human molar teeth were randomly assigned into 4 groups of 15 each for shear bond strength. Variables were bonding agents, enamel and dentin. Twenty teeth assigned into 2 groups of 10 each were used for valuation of the microleakage. Microleakage and shear bond strength were performed according to ISO TR 11405. All data were analyzed with parametric and non-parametric tests according to their normality distribution. Also, Weibull distribution performed on data.
Results: Data obtained from both microleakage and shear bond strength tests showed no significant difference between the experimental bonding and Scotchbond MP bonding (P>0.05). Furthermore, there was no significant difference between the microleakage of occlusal and gingival parts of both bondings (P>0.05).
Conclusion: Experimental adhesive bonding showed acceptable results regarding microleakage and shear bond strength. It may be concluded that the experimental dentin bonding had a comparable performance quality with that of commercial system.

Background and Aims: The aim of this in vitro study was to compare shear bond strength of metal brackets bonded to dental porcelain on the basis of presence or absence of silane, type of acid [hydrofluoric acid (HF) or phosphoric acid (H3PO4)] and roughness of porcelain surface (glazed or deglazed) within mouth-like environment.
Materials and Methods: Eighty glazed ceramic disks were randomly divided into 8 groups of 10 disks: group 1 [HF+silane], group 2 [deglazed+HF+silane], group 3 [HF], group 4 [deglazed+HF], group 5 [H3PO4+silane], group 6 [deglazed+H3PO4+silane], group 7 [H3PO4], group 8 [deglazed+H3PO4]. Then the brackets were bonded and thermocycled. After that, shear bond strength test was done using the Zwick device and the type of bond failure was determined under stereomicroscope at 4X magnification. 3-way ANOVA and Kruskal-Wallis were used for statistical analyses.
Results: The shear bond strength for the test groups were as follows: group (1):13.05±7.7 MPa , group (2):25.16±10.66 MPa, group (3):6.7±5.86 MPa, group (4):15.39±8.97 MPa, group (5):12.76±7.91 MPa, group (6):13.57±7.85 MPa, group (7):0.54±0.67 MPa, group (8): 9.34±6.52 MPa. The type of bond failure in all groups was adhesive failure except for group 2. No significant difference in the interaction between (glazed or deglazed), (presence or absence of silane), and type of acid was found (P>0.05).
Conclusion: Under the conditions of this study, the best clinical method was the use of 37% phosphoric acid and silane that resulted in the optimal clinical strength and adhesive bond failure.