| In clinical orthodontics,functional appliances are often used to treat functional mandibular retraction and hypomandibular dysplasia in patients during growth and development.The functional appliances use the force generated by the contraction of the stretched maxillofacial muscles,ligaments and other soft tissues to guide the coordinated growth of teeth,alveolar bones and jaws,thereby correcting the abnormal direction and position of jaw growth.The slow speed of neuromuscular remodeling is one of the main causes of unstable functional correction and easy relapse.Acupoint-modulated mid-frequency electrical stimulation can enhance motor nerve excitability and promote the recovery of neuromuscular function.It is currently mainly used in athletes' muscle training and rehabilitation of neuromuscular system diseases,but it has not yet been used in the process of clinical functional correction.The buccal car point is covered anatomically by the masseter muscle,and there are branches of the mandibular branch of the facial nerve and the great ear nerve distributed at the buccal car point.In Chinese medicine,it is believed that the cheek car acupuncture point is the hub of movement and qi and blood in the maxillofacial region.Acupuncture at the cheek car point can play a role in promoting blood circulation and collaterals.Clinically,buccal car point is also a commonly selected point for acupuncture treatment of facial paralysis and temporomandibular joint pain.Brain-derived neurotrophic factor BDNF is one of the important neurotrophic factors.It has the function of regulating muscle satellite cell differentiation and skeletal muscle regeneration,and plays an important role in the reconstruction of skeletal muscle.In this experiment,an animal model of mandibular advancement was established.At the same time,mid-frequency electrical stimulation was given to buccal car points to observe the changes of masseter muscle resting myoelectricity and BDNF expression in the experimental rats.To investigate the impact of remodeling of the masseter muscle in rats,the possibility of applying intermediate frequency electrical stimulation with acupoint modulation to clinical functional correction was discussed.Objective: To compare the difference between the changes in masseter muscle electromyography and the expression of BDNF in the masseter muscle during the experiment between the acupoint-modulated medium-frequency electrical stimulation and the mandibular-extended mandibular rats wearing functional appliances.The effect of stimulation on the reconstruction of masseter muscle during the process of mandibular extension provides a basis for whether it can be used as an auxiliary therapy for clinical functional correction.Materials and methods: The experimental animals were selected as SPF grade,4 weeks old,60 male SD rats were randomly divided into 3 large groups(experimental group,conditional control group and blank control group),and each large group was randomly divided according to the number of experimental observation days There are 4 groups(groups 3,7,14,21 d),a total of 12 groups(n=5).The experimental group wore a leading mandible device and received acupoint-modulated intermediate frequency electrical stimulation;the condition control group wore a leading mandible device but did not receive acupoint-modulated intermediate frequency electrical stimulation;the blank control group did not wear a leading mandibular device and did not receive acupoint-modulated intermediate frequency electrical stimulation.Record the masseter myoelectricity of rats in the resting state in different experimental periods;the rats in the corresponding group were sacrificed after completing the electromyography measurements at 3,7,14,21 d,respectively,and the experimental rats were detected by immunohistochemistry and RT-PCR The expression of BDNF protein and mRNA in masseter muscle.Results:(1)EMG results showed that the resting myoelectricity of the masseter muscle in the conditional control group and the experimental group both increased first and then decreased;compared with the blank control group,the conditional control group at the moment of wearing,3d,7d,14 d,21d muscle mass muscle electrical activity is enhanced,the experimental group at the moment of wearing,3d,7d,14 d muscle mass muscle electrical activity increased,no significant difference at 21d;compared with the condition control group,the experimental group At the moment of wearing,the electrical activity of the masseter muscle increased at 3d and 7d,and decreased at 14 d and 21 d.(2)Immunohistochemistry results showed that: compared with the blank control group,the expression of BDNF protein in the conditional control group increased at 7d,14 d,and 21 d,while the expression of the experimental group increased at 3d,7d,and 14 d,and there was no significant difference at 21 d.Compared with the condition control group,the experimental group increased at 3d and decreased at 7d,14 d,and 21 d.(3)The PT-PCR results are basically consistent with the immunohistochemical results.Conclusion: Acupoint-modulated medium-frequency electrical stimulation can up-regulate the expression of BDNF in the masseter muscle of the mandibular advancement rat at an early stage,accelerate the rate of return of the masseter muscle to normal levels,and shorten the time for the rat to complete the adaptive reconstruction of the masseter muscle. |
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