Osseodensification outperforms conventional implant subtractive instrumentation: A study in sheep

Osseodensification is a surgical instrumentation technique where bone is compacted into open marrow spaces during drilling, increasing implant insertion torque through densification of osteotomy site walls. This study investigated the effect of osseodensification instrumentation on the primary stability and osseointegration of as-machined and acid-etched implants in low-density bone. 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.