Unilateral section of the lateral pterygoid muscle in the growing rat does not alter condylar growth

The lateral pterygoid muscle is generally considered to be an important factor for regulation of the mandibular growth. The mandibular condyle has been studied in 317 Sprague—Dawley 4, 5 and 6—week—old rats: 148 control and 169 operated rats in which the lateral pterygoid muscle had been sectioned. Condylar growth was determined by administration of oxytetracycline and alizarin red S and measured in 70 control and 48 operated animals. Unilateral section of the lateral pterygoid muscle did not inhibit the growth of the condylar cartilage. The differences in growth rate between control and operated animals were not significant at the 5 per cent level. In both control and operated groups the same growth pattern, generally decreasing with age and more pronounced in posterior region of the condyle, was observed.