Histologic and biomechanical characteristics of orthodontic self-drilling and self-tapping microscrew implants

Park, Hyo Sang; Yen, Shue; Jeoung, Seong Hwa

Abstract

OBJECTIVE
The purpose of this study was to compare the histological and biomechanical characteristics of self-tapping and self-drilling microscrew implants.
METHODS
112 microscrew implants (56 self-drilling and 56 self-tapping) were placed into the tibia of 28 rabbits. The implants were loaded immediately with no force, light (100 gm), or heavy force (200 gm) with nickel-titanium coil springs. The animals were sacrificed at 3- and 5-weeks after placement and histologic and histomorphometric analysis were performed under a microscope.
RESULTS
All microscrew implants stayed firm throughout the experiment. There was no significant difference between self-drilling and self-tapping microscrew implants both in peak insertion and removal torques. Histologic examinations showed there were more defects in the self-tapping than the self-drilling microscrew implants, and newly formed immature bone was increased at the interface in the self-tapping 5-week group. There was proliferation of bone towards the outer surface of the implant and/or toward the marrow space in the self-drilling group. Histologically, self-drilling microscrew implants provided more bone contact initially but the two methods became similar at 5 weeks.
CONCLUSION
These results indicate the two methods can be used for microscrew implant placement, but when using self-tapping microscrew implants, it seems better to use light force in the early stages.