Under the conditions of these in vitro leakage studies , it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer , did not produce significant effects
The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro .
Effects of dentin age and bonding on microgap formation.
This study compared the effectiveness of dentin adhesives  in extracted molars from younger ( 16 - 26 ) and older ( 58 - 87 ) human subjects . Extracted molars were selected to be restored with one of two dentin bonding agents ( n = 22 per group ) . Opposite sides of each molar were ground flat and a 3 mm x 3 mm cylindrical preparation was milled into each surface . The opposing surfaces of each molar were then r and omly restored with either a dentin bonding system that adhered to the dentin smear layer or one which bonded to the dentin after the smear layer was removed . All sample s were examined at x150 to determine both the maximum gap in micrometers and extent of the gap in degrees . There were significantly shorter ( P < 0.05 ) microgaps in older dentin with a bonding system that removed smear layer . This bonding system also produced shorter gaps in older dentin than in younger dentin . However , there was no statistically significant difference in the percentage of gap-free margins between age groups
Under the conditions of these in vitro leakage studies , it is concluded that smear layer removal improves the fluid-tight seal of the root canal system whereas other factors such as the obturation technique or the sealer , did not produce significant effects
The purpose of this systematic review was to determine whether smear layer removal reduces leakage of obturated human teeth in vitro .