Effect of Music on the Growth of Rat's Mandible

Music stimulation is related to stress reduction, increased levels of prolactin and growth hormone. In rat, music exposure since prenatal period was found to increase brain cells and body-weight of the litters. Previous studies also reported that protein-deficiency in rat could lead to decreased mandible-dimension. Objectives: To determine whether music exposure since prenatal period could affect the mandible-length of the rat-pups both in normal and in protein-deficiency conditions. Methods: Pregnant experimental Wistar rats were exposed to one-hour classic music 3 times/day (11 rats) or 1 time/day (9 rats), while the other 11 control rats had no music. At 7-days-old either the experimental or control animals were randomly differed into normal diet (19.4% protein) and protein deficiency (7.5%) groups. At 35-days-old 10 litters (5 normal, 5 protein-deficiency) from the controls, 13 litters (6 normal, 7 protein-deficiency) from the 1-time/day and 11 litters (6 normal, 5 protein-deficiency) from the 3-times/day music exposures groups were randomly selected to be terminated, the mandibles were dissected and measured using a digital caliper. Mandible's length is the distance between the most antero-inferior point of spina-interdentalis between the incisors and the most posterior point of the condylar-process. Data were analyzed using ANOVA. Results: The means of the mandible-length (mm) of the animals exposed to music, 18.68±1.12 (1x exposure) and 19.09±1.05 (3x exposures) were significantly longer than those with no music, 18.42±1.43 (P=0.048<0.05). This significance was due to the difference between animal's mandible with 3 times/day music exposure and those with no music (P=0.016<0.05). The mandible-length difference between animals with and without music was bigger in groups with protein-deficiency than in those with normal diet. Conclusions: Both in normal and in protein-deficiency conditions music exposure since prenatal period could increase the length of the rat-pup's mandible.