Aim: The purpose of this study was to evaluate clinical and radiographical outcomes of computer guided flapless versus Free hand flap surgery for implants used to anchor All-on-4 fixed prosthesis in atrophied mandible.

Materials and methods: Twelve completely edentulous patients with atrophied mandibular ridges were randomly assigned into two groups Group1 (Free hand flap surgery, control): received 4 implants using the All on four protocol and free hand flap surgery and metal guide. Group2 (computer guided flapless surgery, study): received 4 implants using computer guided flapless surgery and stereolithographic surgical guide. Implants were immediately loaded by acrylic prosthesis then full arch ceramometal fixed prosthesis was used as a final restoration. Plaque Index, Gingival Index, pocket depth, stability of the implants, and crestal bone loss were evaluated at baseline, 3, 6 and 12 months after loading.

Results: The survival rate of the implants was 95.8% and 91.7% for group 1 and group 2. For both groups, implant stability significantly decreased from insertion to 3 months, and increased again at six months. For both techniques, crestal bone loss significantly increased with time. For all time intervals, flap group showed significant higher plaque index, gingival index, probing depth and crestal bone resorption than flapless group.

Conclusion: Within the limits of this short-term randomized trial regarding the small sample size, computer guided flapless approach may be recommended for all on four implant rehabilitation of edentulous mandibles than conventional flap surgical approach as it was associated with favorable clinical and radiographical peri-implant parameters.