Abnormal incisor teeth and body weight in the obese mouse (genotype ob/ob).

Inherently obese mice (genotype ob/ob) developed abnormal incisor teeth at 26 weeks of age. Up to that age, their teeth were indistinguishable by visual criteria, from those of lean (wild-type) litter-mate mice. Radiography and preliminary histology suggested impaction of the tooth in its alveolus (socket) due to the disorganized production of enamel and dentine. Incidence was high (92 per cent) in obese and zero in lean mice. Upper incisor teeth were more severely affected than lower. The severity of teeth lesions could not be correlated with age or body weight. Both sexes were equally affected. The onset of teeth lesions marked the end to the rapid rise in body weight characteristic of the obese mouse. An irregular fall in body weight ensued which could be alleviated by powdering the pelleted food. This indicated the fall to be a consequence of impaired function of the incisor teeth. Abnormality of the teeth was entirely prevented by feeding obese mice from weaning, a similar amount of food to that eaten by lean mice. The high circulating levels of adrenocorticosteroids in the obese mouse are suggested as a cause of the incisor tooth abnormality.