Seventh Generation Dentin Adhesive Bond Strength And Marginal Microleakage Study

Objective:To evaluate the bond strength and the marginal fitness of the Adper EasyTM one and Single bond 2 which were applied to both normal dentin (ND) and caries-affected dentine (CAD).Analysis the fracture type of the samples.Study the marginal microleakage of cavities filled with 3MP90 and P60 two different composit resins to provide a reference for clinical application.Methords:Experiment 20 sound molars were randomly divided into group A and B (removal of occlusal ename);20 occusal chronic caries molars were randomly divided into group C and D(under the guidance of the caries marker,the soft occusal caries and dentin were removed,the hard carried affected edntin were retained). Adper EasyTM one was applied for group A and C while Single bond 2 for group B and D.All samples were heaped with P60 to the height of 5mm.Use the low-speed saw to cut the teeth into the rectangular-shaped samples with 1 mm2 cross-section. The modes of group A,B,C,D were subjected to microtensile bond strength test. Interfacial morphologies were analyzed by Stereo-Microscopy. T-test was used for statistical analysis.Experiment2 Box-like cavities (5mm×3mm×2mm) were prepared on the facial surface of 40 freshly extracted molar teeth. Teeth were randomly divided into 4 groups of 10 teeth each. Cavities of group A and B were restored with composite 3MP90 while group C and D with P60. Adper EasyTM one was applied for group A and C. while 3M EPSE Single bond 2 for group B and D. After the thermocycling(×50,5℃-55℃), all teeth were stained with 1% methylene blue solution for 48h. Then the teeth were immersed in the artificial saliva for the next 24 hours. The depth of methylene penetration was measured under stereomicroscope at six points. T-test was used for statistical analysis.Results:The total-etching adhesive performed more effectively to both normal dentin and caries-affected dentin than Adper EasyTM One (P<0.05);For the same adhesives,the normal dentin present much higher bond strength than the caries-affected dentin(P<0.05).Failure mostly occur along the resin-dentin interface. Different depth of methylene penetration was obversed under stereomicroscope. The specimens leaked significantly severelier in gingival wall than occlusal wall. (P<0.05). No matter which bonding agent was applied,3M P90 showed much less marginal microleakage than 3Mp60 (P<0.05). With the same resin, no significant difference (P>0.05) of microleakage was observed between Adper EasyTM one and ESPE Single bond 2.Conclusions:The total-etching adhesive performed more effectively to both normal dentin and caries-affected dentin than Adper EasyTM One. For the same adhesive,the sound dentin yielded higher bond strength than the caries-affected dentin. Adper EasyTM One presented better marginal seal and its clinical procedures are simple. It can be widely used on clinic.