Evaluation of miniscrew angulation in the posterior maxilla using cone-beam computed tomographic image

Abstract

Objective: This study aimed at evaluating whether changes in the insertion angle is a determining factor in the positioning of the miniscrews body in a region with larger interradicular space in the posterior maxilla. Methods: Analysis of 60 posterior maxillary quadrants were made using images obtained by means of cone-beam computed tomographic image (CBCT), with 0.076-mm voxel, which presented a real miniscrew inserted in the mesial region of the maxillary first molars, serving as reference point for the placement of the virtual miniscrews. Measurements of the distances between roots were made in three points on the body of the virtual miniscrews (A, B and C), at four different angulations, 70o, 60o, 50o and 40o (T1 to T4), in relation to the long axis of the second premolar. This evaluation was made in four groups, selected in accordance with the disposition of the roots of the second premolars and first molars: Group 1 (all types of roots), Group 2 (convergent roots), Group 3 (divergent roots) and Group 4 (parallel roots). Results: There were no statistically significant differences in the measurements of points A, B and C, at the different angles (70o, 60o, 50o and 40o) and in the different groups (p > 0.05). Conclusions: Changes in the insertion angle is not a determinant factor in the positioning of miniscrews body in regions with larger interradicular space in posterior maxilla.

Evaluation of Optimal Sites for the Insertion of Orthodontic Mini Implants at Mandibular Symphysis Region through Cone-Beam Computed Tomography

“…In clinical practice, in cases of inadequate bone quality and/or quantity, it is prudent to place orthodontic mini implants more apically and with certain angulations [ 17 , 18 ]. For example, it is advised to place a mini implant with an angle of 60–70 degrees to the occlusal plane at the infrazygomatic region to avoid root damage [ 8 ].…”

Evaluation of Optimal Sites for the Insertion of Orthodontic Mini-implants at Mandibular Symphysis Region Through Cone-beam Computed Tomography

“…15,16 In clinical practice, in case of inadequate bone quality and/or quantity, it is prudent to place orthodontic mini-implants more apically and with certain angulations. 17,18 For example, it is advised to place a miniimplant with an angle of 60-70 degrees to the occlusal plane at the infrazygomatic region to avoid root damage. 19 Due to limited inter-radicular space of the mandibular anterior areas, it is very likely that root damage is encountered during the insertion of mini-implants at this area.…”

Mechanical Evaluation of the Stability of One or Two Miniscrews under Loading on Synthetic Bone

“…What emerges from our results is that often the use of a single screw is not useful to develop a reliable and predictable biomechanical system. Therefore the possibility of using two screws should always be considered [ 19 , 20 , 21 ]. This, in addition to the biomechanical advantages described, involves limits linked to the need to find two nearby sites suitable for positioning which in turn must be aimed at a single system, therefore allowing the simultaneous engagement of an orthodontic wire [ 24 , 25 , 26 ].…”

“…Success rates are between 70 and 100% [ 10 , 11 , 12 ], with an overall failure rate of 13.5% [ 13 , 14 , 15 , 16 ]. In the past, different solutions such as using a larger-diameter miniscrew, changing the insertion site [ 17 , 18 , 19 ] or secondary insertion [ 20 , 21 ] have been analyzed to overcome the loss of stability. We hypothesized that adding a second miniscrew could increase the anchorage reducing the risk of movements under the orthodontic load of the proximal miniscrew.…”