Suitability of virtual plaster models superimposed with the lateral cephalogram for guided paramedian orthodontic mini-implant placement with regard to the bone support.

Stephan Christian Möhlhenrich,Ali Modabber,Anna Bock,Kristian Kniha,Andreas Prescher,Frank Hölzle,Golamreza Danesh,Maximilian Brandt

doi:10.1007/s00056-020-00238-2

Abstract

PurposeThe purpose of this study was twofold: first, to evaluate the precision of guided orthodontic mini-implant (OMI) placement planned on virtual superimposition of plaster models and lateral cephalograms with regard to the bone support and, second, to investigate the effects of silicone guide extension.MethodsA total of 40 OMIs were placed in the paramedian area of the anterior palates of 20 cadaver heads. Digitalized models and the corresponding lateral cephalograms were superimposed for planning the OMI positions, and tooth-supported (TS) and soft-tissue-supported (STS) templates were manufactured. Thereafter, postoperative cone beam computed tomography (CBCT) was performed, and the straight (A) and right-angle distance (B) from the implant tip to the nasal floor, the distance from the implant shoulder to the hard palate (C) and the angle (α) between the implant and palate plane with the preoperative (T0) and postoperative (T1) positions were measured.ResultsThe postoperative distances A, B, and C were less than the planned implant positions. However, significant difference between T0 and T1 was only noted in terms of distance A using the TS templates (T0: 4.7 ± 2.3 mm, T1: 3.0 ± 2.3 mm; p = 0.008) and distance B using the STS template (T0: 3.1 ± 3.5 mm, T1: 2.3 ± 3.2 mm; p = 0.041). There were no significant differences in all average deviations (∆ Ceph/CBCT) between the two templates.ConclusionsGuided OMI placement planned by virtual superimposition of digitized models and the corresponding lateral cephalogram is fundamentally feasible. However, the position closer to the nasal floor needs critical assessment for correct implantation. The silicone template expansion seems to have only a minor effect on transfer accuracy.

Highlights

Orthodontic mini-implants (OMI) for skeletal anchorage are being increasingly employed in routine clinical practice because of their relatively easy insertion and removal along with their relative inexpensiveness [2]
There were no significant differences in average deviations (Ceph/cone beam computed tomography (CBCT)) between the two templates in terms of distances A, B, and C
There were no significant differences between the preoperative planning and postoperative implant positions as well as between the two templates

Summary

Introduction

Orthodontic mini-implants (OMI) for skeletal anchorage are being increasingly employed in routine clinical practice because of their relatively easy insertion and removal along with their relative inexpensiveness [2]. The need for patient compliance is largely reduced with OMI, and borderline cases can undergo orthodontic treatment without surgery [1, 16, 25]. Kuroda et al observed a success rate of 35.3% in root contacts following lower jaw implementation [15]. Other studies concluded that root contact is associated with reduced mini-implant success rates [6, 15, 22]. Kadioglu et al contended that the root surfaces in contact with OMIs rapidly and almost totally repair after the removal of the implant or the orthodontic force [11]

Objectives

Methods

Results

Conclusion