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Published on: August 24, 2018
Assessment of 3D-printed customized placement guides for a temporary anchorage device in the mandibular external
Mingzhu Jiang1, Chang Xu1, Weijun Yan2
1Department of Stomatology, the First Affiliated Hospital of Harbin Medical University, Harbin, 143 Yiman Street, Nangang District, 150000, China.
Objectives:
To create and construct a customized placement guide for a temporary anchorage device (TAD) in the mandibular external oblique line area, and assess the precision and safety of TAD placement using this guide.
Materials And Methods:
This randomized clinical trial included 20 patients (mean age: 22.4 ± 4.1 years; male/female ratio: 8/12; all presenting with mild-to-moderate skeletal Class III malocclusion) who underwent TAD implantation in the mandibular buccal shelf. A total of 40 TADs were placed: 20 using the customized placement guide (guided [G] group) and 20 manually (non-guided [NG] group). In terms of accuracy, deviation between the actual and designed virtual placement position of the guided TAD placement was measured. The proximity of the TAD to the tooth root and inferior alveolar nerve canal was also evaluated to compare placement safety between the G and NG groups. Accuracy and safety assessments were conducted using 3Shape Implant Studio and Materialise Mimics. Preoperative and postoperative CBCT scans were aligned using landmark-based registration (mandibular canal, tooth roots) and surface matching algorithms. Angular deviations (between the TAD axis and the planned trajectory) and positional errors at the crown and tip were quantified with a precision of ± 0.1 mm and ± 0.5°, respectively. Statistical analysis included independent t-tests and ANOVA (α = 0.05).
Results:
The angular deviation between the actual and planned placement of TADs in the G group was 1.49°±0.67°; the difference at the crown of the TADs was 0.23 ± 0.15 mm; and the difference at the tip of the TADs was 0.52 ± 0.39 mm. The distance between the TAD and mandibular nerve canal in the G group was 6.8 ± 1.34 mm compared to 4.08 ± 0.96 mm in the NG group (P < 0.05). The distance between the TAD and the tooth root in the G group was 5.04 ± 2.24 mm compared to 1.53 ± 1.53 mm in the NG group. No contact with a tooth root was found in the G group, indicating higher safety in the G group than in the NG group.
Conclusions:
The customized TAD placement guide for the mandibular external oblique line region demonstrated superior accuracy and safety for TAD placement.
Clinical Relevance:
This TAD placement guide offers benefits for clinical orthodontic practice, supporting its wider application.
