Verification and evaluation on induction scheme for bodily movement of incisor in children / 医用生物力学

Objective In order to analyze and evaluate the feasibility and effectiveness of induction scheme for bodily movement of incisor in children, the size, orientation and position of the force on tooth surface were estimated and analyzed. Methods The orthodontic jaw from a child was scanned to establish the 3D solid model including mandibular incisor, periodontal ligament and alveolar. Initial strain distributions on outer surface of the periodontal ligament were calculated by software Abaqus, and then the positive strain as the stimulation of the tooth movement was used to simulate the inducted effects from the inducer which was changed twice in succession. Results The rate of orthodontic tooth movement was about 0.27 mm per week, and the total displacement during an induction period was about 1 mm per month, showing it was in accordance with the real inducted effects in clinic. Conclusions The present study proved the feasibility of induction scheme for bodily movement of incisor in children and provided reference for formulation and optimization of induction scheme in clinic.

Synaptic connection and GABA-immunoreactivity of periodontal afferent terminals and their presynaptic endings in the trigeminal motor nucleus of the rat / 대한해부학회지

Periodontal-masseteric reflex is implicated in the control of jaw movement and masticatory force during chewing foods. This study is aimed to investigate the synaptic arrangement of mesencephalic periodontal afferents in the trigeminal motor nucleus and to identify the neurotransmitter involved in the presynaptic control of them through the intra-axonal staining of horseradish peroxidase combined with postembedding immunogold methods. Most of the labeled terminals showed synaptic contacts with the small sized dendritic shafts or distal dendrites, while synaptic contacts with the somata or proximal dendrites were not observed. More than one third of the analyzed labeled boutons received presynaptic input from pleomorphic vesicles containing ending (p-ending). About 11% of labeled boutons showed synaptic triads. All the analyzed boutons made synaptic contacts with one to four neuronal profiles and those showing synaptic contact with five or more were not observed. Labeled terminals were larger than presynaptic p-endings. A large number of the analyzed p-endings showed GABA like immunoreactivity. These observations provide evidence that periodontal afferent terminals show very simple and characteristic synaptic arrangements in the trigeminal motor nucleus and that p-endings presynaptic to them may use GABA as a neurotransmitter for presynaptic inhibition.