Measurement of orthodontic tooth movement in lower anterior teeth by means of magnetic resonance imaging- a prospective pilot study.

Abstract

Background: During orthodontic treatment, the risk of gingival recession may increase, especially in the mandibular anterior region due to thin alveolar bone. This prospective pilot study aimed to develop a standardized evaluation method based on magnetic resonance imaging (MRI) for analysing tooth movements and tissue dimensions and to investigate the impact on periodontal parameters during orthodontic levelling.

Materials and methods: Participants aged 12 to 18 with lower jaw crowding underwent MRI scans before (T0) and five months into orthodontic treatment (T1). The following tissue dimensions were analysed: thickness of free and supracrestal gingiva (FGT, SGT), thickness of buccal alveolar bone (ABT) at three measurement levels (ABT2, ABT4, ABT8), and gingiva and alveolar bone height (GH, ABH). Additionally, tooth positions (apex position and tooth axis inclination) were determined.

Results: Ten patients (60% female, 40% male) aged 14.33 ± 1.35 years were included after the exclusion of 3 datasets due to motion artefacts. MRI measurements showed significant changes in tooth inclination (2.93 ± 4.77°, p < 0.001), bucco-lingual apex position (-0.45 ± 1.03 mm, p = 0.006), SGT (-0.07 ± 0.19 mm, p = 0.020), ABT8 (0.42 ± 0.59 mm, p < 0.001), ABH (-0.29 ± 0.68 mm, p = 0.006) and GH (0.31 ± 0.9 mm, p = 0.030) between T0 and T1. Inclination changes correlated negatively with FGT (R = -0.422, p < 0.001) and positively with ABT8 (R = 0.404, p = 0.032). Furthermore, ABT8 correlated negatively with buccal apex movement (R=-0.392, p = 0.042). Intra- and interclass correlation coefficients were excellent (0.988 and 0.975).

Conclusion: Periodontal tissue changes correlated with tooth inclination or apex position changes due to orthodontic treatment. The pilot study has demonstrated the feasibility of dental MRI as a radiation-free alternative to cone-beam computed tomography for monitoring orthodontic treatment. However, the methodology was susceptible to motion artefacts.

Trial registration: ISRCTN, ISRCTN12689212. Registered 11 April 2024 Retrospectively registered, http//www.isrctn.com/ISRCTN12689212 .