A bstract Aim This study aims to compare the self-etch adhesive (SEA) and self-adhesive flowable composite (SAF) concerning tensile bond strength (TBS) and marginal integrity by microleakage ( µ LK) test in deciduous molars after artificial thermomechanical aging. Materials and methods 120 extracted primary molars were collected. Sixty teeth were mounted for testing TBS. Teeth were restored using SAF ( n = 30) and SEA-conventional flowable (CF) composite ( n = 30) and subjected to artificial thermal aging. Half the teeth ( n = 15) from each material were subjected to mechanical loading (SEA-TBS-L and SAF-TBS-L). The specimens with no-load (NL) served as control (SEA-TBS-NL and SAF-TBS-NL). Class V cavity prepared and restored with SAF ( n = 30) and SEA-CF ( n = 30) to test µ LK after thermal aging. The subgroups were as same as the TBS based on with or without mechanical loading (SEA- µ LK-L, SEA- µ LK-NL, SAF- µ LK-L, SAF- µ LK-L; n = 15 each). µ LK was determined by employing the dye immersion technique. Results Concerning TBS, there is a significant difference between SEA and SAF with load or no load. Concerning µ LK, there is a significant difference between the materials under loading and no difference was found when not mechanically loaded. Also, concerning both TBS and µ LK, a significant difference was observed between the load and no-load subgroups within each material. Conclusion SAF exhibited higher TBS than the SEA. Mechanical loading not only adversely affected the TBS but also increased the µLK of the compared materials. C linical S ignificance Restoring the primary teeth with SAF not only shortens the laborious operatory time but also yields good clinical serviceability with the good bond strength and minimal µ LK, thus preventing premature loss of teeth and consequential malocclusion. How to cite this article Kamatchi M, Ajay R, Gawthaman M, et al. Tensile Bond Strength and Marginal Integrity of a Self-adhering and a Self-etch Adhesive Flowable Composite after Artificial Thermomechanical Aging. Int J Clin Pediatr Dent 2022;15(2):204-209.