Purpose: The aim of the present animal study was to evaluate the changes of stability and peri-implant bone formation of double-microthreaded implants with respect to 6 different drilling techniques. Materials and Methods: Mandibular 2nd, 3rd, and 4th premolars were extracted bilaterally in 12 mongrel dogs. After one month healing, total 60 double-microthreaded implants were installed using 6 different drilling techniques and divided into 6 groups depending on the techniques used. One, two, three, and four weeks later the animals were sacrificed. Insertion torque value (ITV) was measured at the time of implant installation, and implant stability quotient (ISQ) was measured at the time of installation and animal sacrifice. Implant installation sites were prepared for histomorphometric analysis. Bone area (BA) and bone to implant contact (BIC) ratio were evaluated. Results: There were statistically significant differences for ITV with respect to the drilling techniques used, but all ITV were greater than 30 Ncm. ISQ decreased during the first two weeks after installation, and then it started to increase for all groups. BIC values showed statistically significant differences between all groups up to 3rd week after installation, but no difference found at 4th week. Conclusion: The primary stability of an implant can be affected by undersized drilling techniques used to some extent until the secondary stability provided by newly formed bone plays a fundamental role for the stability of an implant during early phase of osseointegration. (JOURNAL OF DENTAL IMPLANT RESEARCH 2012;31(2):38-43)