Purpose: to determine whether there is a definite need for endodontic retreatment in cases of well-conducted treatment of root canals involving a temporary restoration of more than three months’ duration, solely on the basis of suspected microleakage.
A) In vitro microleakage studies: techniques and limitations:
1.Tracer characteristics: No tracer can mimic the clinical conditions and the presence of mixed flora precisely. Bacterial model’s main limitation is the ability to mimic clinically only leakage of bacteria of same size. 2.Measurement methods: Most of them are 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, yet much fewer studies addressed them.
4.Measurement time: Leakage can occur at any time, as shown in various in vitro studies
5.Coronal restoration dimensions: inconsistent dimensions in different studies and in clinical situations illustrate the difficulty in evaluating sealing efficiency.
B) Epidemiologic studies:
•Safavi et al found a higher success rate of complete periradicular healing in teeth with permanent coronal restorations.
•Ray and Trope’s Study of 1,010 PAs of endodontically treated teeth, quality of coronal restoration was substantially 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
•One has to consider the history of the treatment, the possibility of monitoring and follow-up and the option of apical surgery. Also, by removing the compromised coronal restoration, the clinician may be able to verify the color of the gutta-percha.
•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.