INTRODUCTIONWhen restoring an affected tooth, if margins between the composite restoration and the affected tooth are open, micro-leaks can occur. produce1. Microleaks are a phenomenon in dentistry resulting from an imperfect bond that allows the movement of bacteria and fluids between the restoration and the tooth of interest2. When a composite restoration is placed and undergoes polymerization via hardening, shrinkage occurs. Research has shown that the percentage of gaps between composite restorations can be variable; between 14% and 54%3. This can lead to an increased risk of microleaks and is of concern to both the dentist and the patient. Other causes of microleaks include: continuous light curing methods4 and home pre-restorative whitening5. The effects of microleaks include: increased sensitivity, secondary caries, discoloration of the composite material, restoration failure and/or pulp pathology or pulp death1. The existence of microleaks in dental restorations was first identified in scientific research in 19126. In a study by Harper (1912), air pressure was used to penetrate the surface between an amalgam restoration and cavity preparation7. By applying pressure through a hole in the pulp floor, Harper was able to quantify the amount of pressure needed to establish leakage due to the emergence of bubbles at the edges of the restoration. Research has come a long way since Harper first identified microleaks. Adaptations of new materials used in the placement of composite restorations, such as BondAband, a light-cured glass-ionomer cement, have been shown to reduce marginal microleaks in posterior restorations8. A reduction in microleaks has also been demonstrated through the use of a ...... middle of paper ...... air pressure test. Tooth Rev.1912; 26: 1179-1198.7. Aziz RD, Gonzalez NAG, Kasim NHA. Microleak test. Annals of Dentistry 1997; 4(1): 31-37.8. Chapman Kenneth W., Crim Gary A. Reducing microleakage in class II restorations: an in vitro study. Opera Dent 1994; 25(11): 781-785.9. Siso HS, Kustarci A, Göktolga EG. Microleaks in composite resin restorations after antimicrobial pretreatments: effect of KTP laser, chlorhexidine gluconate and Clearfil Protect Bond. Opera Dent. 2009; 34(3): 321-327.10. Gharizadeh N, Moradi K, Haghighizadeh MH. A study of microleaks in Class II composite restorations using four different curing techniques. Opera Dent. 2007; 32(4): 336-40.11. Bagis YH, Baltacioglu IH, Kahyaogullari S. Comparison of microleakage and lamination methods of silorane-based resin composite in large MOD class II cavities. Opera Tooth. 2009; 34(5): 578-585.