A crown for clinically investigating microleakage

This investigation evaluated a cast crown with an access port for in vivo microleakage studies. Fifteen complete cast crowns containing an access port in the facial surface were cast. The gingival margins of the crowns were modified to test the sealing ability of the access port. Each casting was thermocycled 750 times at 5 degrees to 60 degrees C over a 24-hour period. Air pressure of 90 psi followed by 28 mm Hg vacuum was applied for 1 hour each during immersion of the devices in silver nitrate solution. Castings were embedded in acrylic resin and sectioned with a diamond saw through the sealing device. Scanning electron microscopy and energy dispersive spectroscopy analysis revealed no leakage with the 13 test devices and 100% leakage with the controls. The device should be effective for use in human subjects.