Experimental Study On Marginal Microleakage Of Bonded Amalgam Restorations Out-of Body

Objective To study the changing of the crack between obturator and the hole, with the adhensive of Prime&Bond NT, after enduring masticatory pressure under oral environment, so as to evaluate the significance and to approach the modus operandi of reducing the microleakage, and to increase the retention of obturator of Bonded Amalgam Restorations (BAR).Method Eighty exvivo molar and premolar without dental caries and prepared with the same cavity shape (class Ⅱ) were assigned into two groups equally at random, (group F and group C). One of the two groups(F)were filled with silver amalgam with the Prime&Bond NT technique. And the other group were filled with normal method. Fifteen minutes later , All of the specimens were dipped into artificial salivary for 48h. After that, each of the two groups was again divided into two respectively. (F1/F2 and C1/C2). F2 and C2 were take to have the test of temperature difference cycle under load and Pressure Test, ---put the specimens into 4℃—60℃ artificial salivary 200 times alternatively under load. Then put them under the piercer vertically and laterad . the value of the pressure was 60kg. Scanning election microscope (SEM) was used to measure the crack between obturator and the hole and record them according to buccal wall,tongue wall and pulpal wall.Results Statistic show that: there were no marked change between group F2 and group F1 under the test of pressurize. And there were no...