Authors : Ketan Ashokrao Gore, Ketan K.Vakil, Jeegar K Vakil, Pawankumar Dnyandeo Tekale, Prasad Eknath Yadav, Harshal A. Patil
DOI : 10.18231/j.jco.2017.033
Volume : 1
Issue : 1
Year : 2017
Page No : 30-35
Introduction: an in vitro evaluation of thread outline variation of orthodontic mini-implant for axial pullout test on the strength of the
orthodontic mini-screws.
Materials and Method: This study was done on 35 Titanium mini-screws. The mini-screws were divided into five test groups. Each
group consisted of 7 mini-screws. The mini-screws in Group A containing buttress reverse thread shape, acted as a control group for
their respective experimental group containing other thread shaped mini-screws. The 35 blocks were made with synthetic bone
support Rigid Polyurethane foam. Then the mini-implants were inserted at these point with implant driver perpendicular to the surface
of sample block. The load was smeared to the head of mini-implant at the speed of 10 mm/min of cross head. The highest load at which
the mini-implant dislodge was recorded in the universal testing machine.
Results: The results of comparison shows that Group A shows highest pullout resistance value (212.787 N) then group D (204.43N),
Group E (195.681N), Group C (182.234N) and group B (174.160N). The above pullout resistance value are in decreasing order. Reverse
buttress thread shape had highest resistance to pullout force in axial direction and buttress thread shape had least resistance to pullout
force test. While comparing the groups with control group, it was found that comparison between group A and B, and comparison
between group A and C shows the statistically significant values as p value < 0>
Conclusion: The Buttress Reverse thread design may be more useful as it shows highest pullout resistance value than other thread
shape form i.e. Rounded thread shape, Trapezoidal thread shape, 75 degree joint profile thread shape and Buttress thread shape in
decreasing order respectively.
Key Words: Mini-screws, thread shape, axial pull-out test