orthoThe Securus orthoTAD is the only orthodontic skeletal anchor designed with a patented concave collar, and is site specific, meaning designed for a specific morphological location. This is similar to an orthopedic bone screw design. This was evaluated recently as a masters’ thesis and the findings showed a significant reduction in failure using these design principles.

A thesis submitted to the Department of Orthodontics, Oregon Health and Science University School of Dentistry in partial fulfillment of the requirements for the M. S. degree

Effect of mini-implant collar design on orthodontic skeletal anchorage

Master of Science Candidate: Holly J. Grimslid, DMD

Studies have documented the use of titanium mini-implants in providing skeletal anchorage for orthodontic tooth movement. Clinical success rates are variable and typically reported between 70% and 100% . The purpose of this in-vitro study was to test the hypothesis that mini-implants with collars give the orthodontist superior force resistance, superior stability (anchorage) and cause less surface bone strain compared with mini-implants without collars.

Materials and Methods

Thirty titanium alloy mini-implants, 1.5 X 10.5 mm, were placed in bone analogue specimens with cortical bone thicknesses 1.0 mm, 1.5 mm and 2.0 mm (n=10 each), and the maximum insertion torque (MIT) was recorded. Half were mini-implants with collars, half were without collars, and all were subjected to a tangential force loading perpendicular to the mini-implant through a lateral displacement of 1.5 mm. Statistical analyses, consisting of 2 x 3 factorial analysis of variances (ANOVA‟s) and Tukey‟s post-hoc testing were used to compare mini-implant collar group mean force-deflection values, yield points, MIT‟s and slope of the force- deflection curves. Additionally, eight mini-implants were placed in bone analogue specimens with a cortical bone thickness of 2.0 mm. Half were mini-implants with collars, half were without collars, and all were subjected to a similar tangential force through 30N. Electronic speckle pattern interferometry (ESPI) was used to detect surface strain values on the compression side of mini-implants loaded either once or multiple times (n = 4 each). Specific strain values (με/N), slope of the specific strain–deflection curve and mini-implant displacement were evaluated.
Results

Deflection force values were significantly greater for mini-implants with collars. The slope of the mean anchorage force to displacement curve was significantly greater for mini-implants with collars. Specific strain values were greater for mini-implants loaded multiple times and mini-implant displacement was greater for mini-implants without collars.

Conclusions

Mini-implant collars provide the orthodontist with superior anchorage force resistance, reduced cortical bone stress, and superior stability compared with mini-implants without collars.