Dietary lipids, prostaglandin E2 levels, and tooth movement in alveolar bone of rats

Abstract

A previous study showed that certain dietary lipids can alter arachidonic acid concentrations in alveolar bone. Because arachidonic acid is a precursor of prostaglandin (PG) E₂, which is known to play an important role in orthodontic tooth movement, the purpose of the present study was to determine the effect of dietary lipids on PGE₂ levels and tooth movement. Two groups of male Sprague-Dawley rats (20/group) were fed nutritionally adequate purified diets containing 10% corn oil (group I, rich in n-6 fatty acids) or 9% ethyl ester concentrate of n-3 fatty acids + 1% corn oil (group II rich in n-3 fatty acids). After 5 weeks of feeding the diets, orthodontic force of 56 g was applied to the maxillary incisors to tip them distally. Prior to killing the rats at day 4 and 8 of orthodontic force application, tooth movement was measured by computerized image analysis. Premaxillae were dissected out free of soft tissue and incisors. The alveolar bone was frozen in liquid nitrogen, pulverized, and lipids were extracted. The concentrations of arachidonic acid and fatty acid composition of total phospholipids were measured by gas chromatography. PGE₂ levels were measured by enzyme immunoassay. Arachidonic acid and PGE₂ concentration were significantly lower (P < 0.001) in alveolar bone of rats in group II than in group I. The tooth movement was also significantly lower (P < 0.02) in group II than in group I at both 4 and 8 days. The results suggest that PGE₂ levels in alveolar bone and orthodontic tooth movement can be affected by the type of dietary fat.