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Accuracy of surgical positioning of orthodontic miniscrews with a computer-aided design and manufacturing template

https://doi.org/10.1016/j.ajodo.2009.12.025Get rights and content

Introduction

Our objective was to enable accurate miniscrew placement after preoperative simulation. We developed a new template for miniscrew placement and evaluated its accuracy.

Methods

Eleven patients who had bimaxillary protrusion were scanned with computed tomography. The 3-dimensional computed tomography data were used to produce, with stereolithography apparatus, a template for accurate miniscrew placement. The interradicular space available for miniscrew placement was calculated in the 3-dimensional images. Postoperative computed tomography images were matched with preoperative images to calculate the deviations between the planned and actual placements.

Results

The distance for placement of a miniscrew between 2 roots was 4.12 mm (SD, 0.25 mm; range, 3.7-4.5 mm). The placed miniscrews showed an average angular deviation of 1.2° (SD, 0.43°; range, 0.6°-2.41°) compared with the plan, whereas the mean linear distomesial deviation was 0.42 mm (SD, 0.13 mm; range, 0.15-0.6 mm) at the tip.

Conclusions

The proposed template has high accuracy and will be especially useful for patients who require precise miniscrew placement.

Section snippets

Material and methods

Materialise's interactive medical image control system (MIMICS) and Magics (both, Materialise, Leuven, Belgium) are both widely used medical software programs. The miniscrew template described in this article was designed with these tools.

MIMICS is an interactive tool for the visualization and segmentation of CT and magnetic resonance images and the 3D rendering of objects. Therefore, in medicine, MIMICS can be used for diagnosis, operation planning, and rehearsal purposes. A flexible interface

Results

The interradicular safe zones for miniscrews in the 11 patients ranged from 3.7 to 4.5 mm, with an average of 4.12 ± 0.247 mm (mean ± SD). The allowed deviation ranged from 0.65 to 1.05 mm, with an average of 0.86 ± 0.125 mm (mean ± SD).

The templates were adapted to the patients in a satisfactory and stable manner. All miniscrews were placed smoothly without problems. Some miniscrews did not touch the adjacent roots (Fig 8, B). The accuracy of drilling, and the deviations of the positions and

Discussion

CT is an important diagnostic tool for the craniofacial region and is used for many applications including the study of its various components, growth, developmental anomalies, impacted teeth, management of maxillofacial trauma, treatment planning for orthognathic and reconstructive surgery, bone grafting, distraction osteogenesis, and dental implantology. Qualitative and quantitative findings and measurements from CT techniques are accurate and reproducible, and offer greater and more reliable

Conclusions

Within the limits of this study, we presented an accuracy evaluation of the CAD/CAM template for miniscrews, and the registrations of the 3D models reconstructed with the preoperative and postoperative CT data were validated. The average measured deviations of the miniscrews were in the safe range. These results verified the template's accuracy and security. The template, manufactured with the Nobel method, can provide safe placement for miniscrews.

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    The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

    Supported by grants from Shandong Science and Technology Planning Project Contract Research (2008GG30002019 and 2008GG30001001) of China.

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