• The Journal of the Korean dental association
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• v.41 no.6 s.409
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• pp.450-454
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• 2003

The Purpose of this study is to report the effect botulinum toxin type A injection for the masseter hypertrophy patient with bruxism. Nine patients enrolled in this study were diagnosed as masseter hypertrophy associated with bruxism and the patients were injected with a 25U of botulinum toxin type A (BTXA:Lanzhou) to each masseter muscles. All nine patients showed marked reduction of masseter hypertrophy and eight patients reported the resolution of bruxism in 8 weeks after injection, with no significant complications. This preliminary study suggest that the botulinum toxin type A injection is an alternative method to treat the masseter hypertrophy with bruxism.

• Journal of Dental Rehabilitation and Applied Science
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• v.26 no.1
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• pp.69-75
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• 2010

Botulinum toxin type A(BTX-A) has been applied successfully to treat masseteric hypertrophy. However it can cause muscle weakness. This study was designed to measure the change in maximum bite force(MBF) after BTX-A injection into human masseter muscle and to evaluate the influence of a booster(repeated) injection. Thirty volunteers completed 18-week follow-up and MBF was measured. At 18 weeks after the first injection, a booster injection was given to 14 patients and they were followed up until 18 weeks from the booster injection. The mean MBF was approximately 20% lower at 2 weeks than before the injection, and it recovered gradually after 4 weeks to return to the preinjection level at 12 weeks. The MBF differed significantly between before the injection and at 2, 4, and 8 weeks after the injection(p<0.05). In booster injection group(n=14),the MBF decreased markedly at 6 weeks(p<0.05),and it recovered gradually in 12 weeks. The MBF was significantly reduced after booster injection of BTX-A into the human masseter muscle. The degree of discomfort experienced by the subjects had little effect on normal mastication.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.21 no.2
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• pp.215-219
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• 1999

This article discusses the diagnosis, anatomic consideration, and surgical management of masseter muscle hypertrophy. Surgical correction is advised for patients who have esthetic complaints. Esthetic improvement can be achieved by surgery and not by conservative treatment. Recently, the intraoral method, which leaves no scar on the face and minimizes the possibility of injury to the marginal branch of the facial nerve, has been supported by many surgeons. Patients who complained of marked swelling of unilateral or bilateral mandibular angle area and showed abnormal bony growth at the mandibular angle area and enlarged masseter muscle received mandibular angle shaving and excision of the inner layer of masseter muscle with intraoral approach. After operation, physiotherapy was done with EAST(eletrical acupuncture stimulation therapy) for encouraging the mouth opening and reducing the swelling. They showed early maximum mouth opening and reduction of swelling.

• The korean journal of orthodontics
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• v.24 no.3 s.46
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• pp.569-586
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• 1994

The purpose of this study is to investigate the effect of loss of incisal function on the thickness, growth activities, ultrastructure of the condylar cartilage and on the muscle fibers of masseter superlicialis, anterior belly of digastric muscle in the growing rats. 37 day-old-rats of which incisors had been trimmed every day received soft diet from weaning and were studied by the autoradiography, electron microscopy and muscle histochemistry. The results obtained were as follows : The thickness of the fibrous, proliferative layer in superior, posterosuperior portion of the condylar cartilage was significantly(p<0.01) reduced in experimental groups and the decrease rate of fibrous layer thickness was greater in posterosuperior portion than in superior portion of cartilage and was greater than in proliferative layer. In normal group, more cells of posterosuperior portion moved more rapidly towards the medullary cavity. In experimental group, the labelling index of posterosuperior portion was decreased in proliferative layer at 2 hours, in transitional layer at 1, 2 days, in hypertrophic layer at 4 days after injection relative to posterosuperior portion of control group. But labelling index of superior portion was not different from that of control group at all time course after injection. From the muscle histochemistry, the diameter of type IIB fibers in masseter superficialis muscle, type IIA, type IIB fibers in anterior belly of digastric muscle decreased significantly(p<0.01) relative to controls in experimental group. From electron microscopic study, in the fibrous layer of the posterosuperior portion of condylar cartilage in normal group, many fibroblast like cells near the joint cavity showed extensive remodelling activities in ultrastructure. There was no morphological changes between experimental and control group in all cartilage cell layers of superior portion but cells near the joint cavity in fibrous layer of posterosuperior portion of experimental group showed morphologically inactive state relative to control group.