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. 2018 Mar 15;10(2):8.
doi: 10.1038/s41368-017-0001-y.

Orthodontic tooth separation activates the hypothalamic area in the human brain

Yoshiko Ariji  1 , Hisataka Kondo  2 , Ken Miyazawa  3 , Masako Tabuchi  3 , Syuji Koyama  4 , Yoshitaka Kise  5 , Akifumi Togari  2 , Shigemi Gotoh  3 , Eiichiro Ariji  5
Affiliations

Orthodontic tooth separation activates the hypothalamic area in the human brain

Yoshiko Ariji et al. Int J Oral Sci. .

Abstract

Objectives: An animal experiment clarified that insertion of an orthodontic apparatus activated the trigeminal neurons of the medulla oblongata. Orthodontic tooth movement is known to be associated with the sympathetic nervous system and controlled by the nucleus of the hypothalamus. However, the transmission of both has not been demonstrated in humans. The purpose of this study were to examine the activated cerebral areas using brain functional magnetic resonance imaging (MRI), when orthodontic tooth separators were inserted, and to confirm the possibility of the transmission route from the medulla oblongata to the hypothalamus.

Methods: Two types of alternative orthodontic tooth separators (brass contact gauge and floss) were inserted into the right upper premolars of 10 healthy volunteers. Brain functional T2*-weighted images and anatomical T1-weighted images were taken.

Results: The blood oxygenation level dependent (BOLD) signals following insertion of a brass contact gauge and floss significantly increased in the somatosensory association cortex and hypothalamic area.

Conclusion: Our findings suggest the possibility of a transmission route from the medulla oblongata to the hypothalamus.

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Conflict of interest statement

Conflict of interest

The authors declare that they have no conflict of interest.

Ehical approval

The current study was performed with the approval of the University Ethics Committee (No. 420). This study was planned and performed in accordance with the code of ethics of the World Medical Association (Declaration of Helsinki).

Figures

Fig. 1
Fig. 1. BOLD signal increases during insertion of apparatuses.
a During insertion of floss; b during insertion of the brass contact gauge. Arrows show the thalamus
Fig. 2
Fig. 2. Group analysis based on individual activation sites and magnitude SMC primary somatomotor cortex (BA 1–4).
BA, Brodmann area; BG, caudate nucleus putamen and pallidum; CG, cingulate gyrus; FAA, frontal association area (BA 11, 44); HA, hippocampus and amygdala; OAA, occipital association area plus cuneus and lingual gyrus; PAA, parietal association area (BA 5, 40); PHG, parahippocampal gyrus; TAA, temporal association area (BA 20–22, 37–38)
Fig. 3
Fig. 3. Schema of the hypothesis regarding the cerebral activated sites and transmission routes at the insertion of the orthodontic appliances.
Vc, neuron trigeminal spinal subnucleus candalis neuron; VM, nucleus ventromedial nucleus
Fig. 4
Fig. 4. Orthodontic apparatuses used in this experiment.
a GUM expanding dental floss with wax; b self-made brass contact gauge
See this image and copyright information in PMC

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