Materials and methods. 100 extracted human anterior primary teeth were divided, based on the preparation methods, into four groups each consisting of 25 subjects : conventional (A), labial surface bevel (B), conventional + air abrasion (C), and labial surface bevel + air abrasion (D). After restoring cavities, tensile failure load of samples was measured in Newton by Universal testing machine at a crosshead speed of 1 mm per minute. The data were analyzed by Kruskal-Wallis and Mann Whitney U tests using SPSS software. 

  Results. There were statistically significant differences between groups A and C (P = 0.003), groups A and B (P < 0.001), groups A and D (p < 0.001), groups B and C (P = 0.028), groups B and D (p = 0.027), and also groups C and D (p < 0.001). Group D demonstrated the highest mean tensile failure load. 

  Conclusion. Labial surface bevel treated by air abrasion showed significantly more retention of composite restoration.