A three-dimensional obturation and complete coronal and apical seal is one the important aims of root canal treatment. Since microorganisms may remain in the root canal system after instrumentation, a tight apical seal is desired to prevent bacteria and their by-products from invading the apex. A perfect apical seal is also desired to prevent apical percolation. One of the major objectives of tooth restoration is the protection of exposed dentine against bacteria and their toxins. The interface between the restoration and dental hard tissue is an area of clinical concern as insufficient sealing can result in marginal discoloration, secondary caries, and pulpitis. For that reason, adequate sealing is essential for the optimal clinical performance Prevention of microleakage in endodontically treated teeth is most important for patients who rely on the combined expertise and quality care of dentist/endodontist colleagues. Microleakage is arguably the single most important risk factor for apical periodontitis.