Abstract: Objective To compare the accuracy of two methods of flap and flaplss in the posterior region when using the CAD/CAM template. Methods Cone Beam CT data and plaster models were selected from 20 patients with posterior teeth implantation. The flap and flapless resin models were fabricated by 3D printing technique. The surgical guides were used to simulate dental implant placement on the two kinds of models, respectively. The preoperative and postoperative implant position deviations were calculated and then accuracies of the two surgical procedures were compared. Results The top deviations of the flap and the flapless way were（0.95±0.36）mm，（1.33±0.43）mm, respectively. The bottom deviations were（1.53±0.56）mm,（1.94±0.30）mm, respectively. The angle deviations were（3.45±1.10）°，（3.31±1.55）°, respectively. The depth deviations were（0.75±0.47）mm，（1.43±0.41）mm, respectively. Conclusion There is a statistically significant difference in the deviation of the implant between flap and flapless methods, while there is no statistical difference in angle deviation. CAD/CAM guided implant flap approach is more accurate than the flapless procedure in distance deviation.

Key words: [Key words] CAD / CAM template, accuracy, flap, flapless