Background and Aim: Stability of mini-screws in bone depends on mechanical factors in the primary phase and biological factors after osseointegration. mini-screws can transfer thermal shocks in the oral cavity to bone marrow. It has been shown that impaired osseointegration and inflammation can lead to failure of mini-screws. The aim of this study was to compare the tissue response to implanted mini screws with and without composite coating of the head. Materials and Methods: In this animal study, mini-screws with 1. 4mm diameter and 6mm length were implanted in the maxilla of 12 male rabbits. One mini-screw was implanted in each of the right and left quadrants of the maxilla. The right side miniscrews received composite coating on their head. The left side mini screws did not receive coating. In the next three months, cold (1° C) and warm (40° C) water were injected into their mouth 10 times daily. After three months, the rabbits were sacrificed, and paraffinized tissue blocks were prepared. The tissue reaction was examined under light microscopy. The paired t-test and Wilcoxon signed rank test were used for statistical analysis. Results: The mean rate of osseointegration of mini-screws with and without composite coatings was 32. 1± 5. 3 and 20. 4± 3. 43, respectively. The rate of osseointegration was significantly higher around mini-screws with composite coating than mini-screws without coating (P<0. 001). In both groups, the newly formed bone was woven and no inflammatory reaction was noted. Conclusion: The rate of osseointegration of mini-screws with composite coatingof the head was higher than that of mini-screws without it.