Growth Changes in Craniofacial Morphology after Reducing Masticatory Muscle Activity in Adult Rats

Chi-Yang Tasi, Rouh Yi Huang

Research output: Contribution to journalArticlepeer-review


The purpose of this study was to evaluate the effects of reduced masticatory muscle activity on the growth of craniofacial bones in adult rats. In this study, botulinum neurotoxin type A (BTX-A) was injected into the masseter muscle to reduce adult rats' masticatory muscle function, and changes in the craniofacial bony form were investigated. Ten male Sprague-Dawley rats, with a body weight of about 300g at 60 days old, were used. The masseter muscles of the rats were injected with the following formula: 25 U/ml (0.3 ml) Botox in the left-side masseter muscle, and an equal amount of sterilized saline in the right-side masseter muscle. Ninety days after the injections, the rats were sacrificed, and the weight of masseter muscle was measured. Direct anthropometric measurements of the skull and mandible were made. All measurements were calculated using statistical software. The results showed significant changes in muscle weight and anthropometric measurements in the Botox-injected side. The changes included a decreased ramus height, and an increased gonial angle and teeth crown height. Changes in the vertical measurements were obvious. According to the present results, reduced masticatory function in adult rats affected not only the weight of the muscle, but also the craniofacial bony structure and dentition.
Original languageUndefined/Unknown
Pages (from-to)204-211
Number of pages8
JournalJournal of Dental Sciences
Issue number4
Publication statusPublished - 2008


  • masseter
  • botulinum toxin
  • masticatory function
  • craniofacial morphology

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