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Effect of length and insertion angle on stability of miniscrews used for retraction of anterior teeth-an in vitro study

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Original Article

Author Details : Deepak Paul*, Snehlata Verma, Rohit Khanna, Tripti Tikku, RP Maurya

Volume : 6, Issue : 1, Year : 2020

Article Page : 19-23

https://doi.org/10.18231/j.ijodr.2020.006

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Abstract

Aim: To assess the effect of length and insertion angle on stability of mini screw in synthetic bone replica used for retraction of anterior teeth.

Materials and Methods: A total of 120 titanium miniscrews (SK Surgicals) were equally divided into two groups based on their insertion in synthetic replica of bone (ORTHOBONES, 3B scientific, Germany) i.e. maxillary (Group I) or mandibular (Group II) bone. Both the groups were further divided into 8 subgroups based on length and angulation i.e. Ia60 (8mm, 60^o), Ia90 (8mm, 90^o), Ib60(11mm, 60^o), Ib90(11mm, 90^o), IIa60(6mm 60^o), IIa90(6mm 90^o), IIb60(8mm 60^o) and IIb90(8mm 90^o). Two customized angulation guiding jigs, at 60^o and 90^o angle were fabricated. Miniscrew was driven into the bone using the screwdriver. A Universal testing machine was used to conduct Shear Compressive Strength test on all the Miniscrews. Data was collected and ANOVA and Post Hoc Test were applied to get the results.
Result: For maxillary bone analogue (Group I), 11 mm miniscrew inserted at 90^o angulation had maximum values and 8 mm screws at 60^ohad minimum values of SCS. The trend for SCS of miniscrews in Group I was Ib90>Ib60>Ia90>Ia60. In mandibular bone analogue, 8 mm miniscrews inserted at 90^o angulation showed maximum stability and 6mm at 60^oshowed minimum SCS. The trend for SCS in Group II was IIb90>IIa90>IIb60>IIa60. Intergroup comparison revealed that statistical difference for IIb60>Ia60, IIb90>Ia90, IIb90>Ia60 and IIb60>Ia90 which suggest that MS inserted in mandibular analogue had better SCS than in maxilla irrespective of angulation.
Conclusion: Longer miniscrews inserted perpendicular to the bone gives maximum stability. It is also found that stability increases with increase in cortical bone thickness.

Keywords: Miniscrews, Bone, Shear compressive strength, Primary stability, TAD, Bone analogue.

How to cite : Paul D, Verma S, Khanna R, Tikku T , Maurya R , Effect of length and insertion angle on stability of miniscrews used for retraction of anterior teeth-an in vitro study. IP Indian J Orthod Dentofacial Res 2020;6(1):19-23

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