Authors : Deepak Paul, Snehlata Verma, Rohit Khanna, Tripti Tikku, RP Maurya
DOI : 10.18231/j.ijodr.2020.006
Volume : 6
Issue : 1
Year : 2020
Page No : 19-23
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, 60o), Ia90 (8mm, 90o), Ib60(11mm, 60o), Ib90(11mm, 90o), IIa60(6mm 60o), IIa90(6mm 90o), IIb60(8mm 60o) and IIb90(8mm 90o). Two customized angulation guiding jigs, at 60o and 90o 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 90o angulation had maximum values and 8 mm screws at 60ohad 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 90o angulation showed maximum stability and 6mm at 60oshowed 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.