Osseodensification outperforms conventional implant subtractive instrumentation: A study in sheep

Six endosteal implants were inserted bilaterally in the ilium of five sheep totaling 60 implants (n = 30 acid-etched and n = 30 as-machined). Each animal received three implants of each surface. The osteotomy sites were prepared as follows: (i) subtractive conventional-drilling (R): 2 mm pilot, 3.2 mm and 3.8 mm twist drills; (ii) osseodensification clockwise-drilling (CW), and (iii) osseodensification counterclockwise-drilling (CCW) with Densah Burs (Versah, Jackson, MI, USA) 2.0 mm pilot, 2.8 mm, and 3.8 mm multi-fluted tapered burs. Insertion torque, bone-to-implant contact (BIC) and bone-area-fraction occupancy (BAFO) were evaluated. Drilling techniques had significantly different insertion torque values (CCW > CW > R), regardless of implant surface. While BIC was not different as a function of time, BAFO significantly increased at 6-weeks. A significantly higher BIC was observed for acid-etched compared to as-machined surface. As-machined R-drilling presented lower BIC and BAFO than acid-etched R, CW, and CCW. New bone formation was depicted at 3-weeks. At 6-weeks, bone remodeling was observed around all devices. Bone chips within implant threads were present in both osseodensification groups. Regardless of implant surface, insertion torque significantly increased when osseodensification-drilling was used in low-density bone. Osseodensification instrumentation improved the osseointegration of as-machined implants to levels comparable to acid-etched implants inserted by conventional subtractive-drilling.