•Purpose: determining whether there is a definite need for endodontic re- treatment in cases of well-conducted Tx of canals involving a temporary restoration of more than three months’ duration, based on suspected microleakage.
•In vitro microleakage studies: techniques and limitations:
1. Tracer characteristics. No tracer can mimic the clinical conditions and the presence of mixed flora precisely.
Studies used methylene blue, India ink, sodium 22 (22Na) bacteria or bacterial particles.
2. Measurement methods. Most of them qualitative. Leakage commonly is determined by depth of marker penetration, turbidity fluid transport, glucose penetration and radioactivity.
3. Experimental conditions. Thermocycling and repeated loading are important parameters actually mimic conditions in the mouth that cause degradation of coronal restorations.
4. Measurement time. leakage can occur at any time, as shown in various in vitro studies
5. Coronal restoration dimensions. inconsistent dimensions, illustrate the difficulty in evaluating sealing efficiency.
–Safavi et al. found a higher success rate of complete periradicular healing in teeth with permanent coronal restorations.
-Study of 1,010 RG of RCT treated teeth, quality of coronal restoration was more important than that of the RCT.
–Hommez et al, found that RG appearance of coronal restoration and homogeneity of the root fillings were equally important
-Several studies found the quality of the RCT treatment had a greater effect on PA status than did the coronal restorations.
-No clear evidence to support immediate replacement of well-obturated endodontic treatment that has lasted >3 months solely because of suspicions of microleakage. It may be prudent to make a new coronal restoration immediately and to observe the tooth for at least three months before placing the permanent crown.