Effect of Postnatal Protein Deficiency on the Rat's Mandible Dimension

Previous studies have shown that severe protein deficiency (0.8-7%) started since prenatal period lead to decreased dimension of rat-pups mandible. Objective: To determine whether four-weeks postnatal protein deficiency-isocaloric with protein higher than 7% still has reducing effect on the length and height of the rat-pups mandible. Methods: Twenty-three 7-days-old Wistar rat-pups were divided into control group, which received normal diet with 19.4% protein, and 3 experimental groups which each received diet with less protein; 10%, 7.5% and 5% respectively. Rat-pups were weighed every week, sacrificed at day 35, and the mandibles were dissected and measured using a digital caliper. Mandible-length is the distance between the most antero-inferior point of spina-interdentalis between the incisors and the most posterior point of the angular process. Mandible-height is the distance between the most inferior point of the angular-process to the most superior point of the condylar-process. Data were analyzed using ANOVA. Results: The general growth of the animals with normal diet as indicated by their body-weight (gr) 65.18±7.66 were higher than those with protein restriction (10%=36.27±4.18, 7.5%=22.80±2.59, 5%=23.67±3.16) P=0.000<0.05. Both the means (mm) of the mandible-length (10%=17.61±0.13, 7.5%=16.52±0.22, 5%=16.54±0.28) and mandible-height (10%=6.91±0.25, 7.5%=6.34±0.28, 5%=6.28±0.40) of all the experimental groups were shorter than those of the controls 18.91±0.26 (mandible-length) and 7.54±0.48 (mandible-height) P=0.000<0.05. These mean-differences were all significant (P=0.00<0.05) except for the difference between mandible's height of 10% protein-deficiency and normal diet groups (P=0.070>0.05). Conclusions: Same as protein content 5%, postnatal protein-deficiency-isocaloric higher than 7% (7.5% or 10%) for four weeks not only decreased the body-weight but still also results in significant decreased of mandible-length. However, only protein-deficiency-isocaloric ≤7.5% could result in significant decreased of the height of rat-pup's mandible.