Pilocarpine alters caries development in partially-desalivated rats

This study examined the effect of pilocarpine on caries and saliva composition in rats with compromised salivary gland function. Eight litters of specific-pathogen-free female Sprague-Dawley rats were divided into five groups for surgery. Partial desalivation was performed in either of three ways: (1) Both parotid ducts were ligated; (2) both submandibular/sublingual (SM/SL) glands were excised, or (3) one parotid duct was ligated, and submandibular/sublingual glands were removed unilaterally. Completely desalivated animals and unoperated animals served as positive and negative controls, respectively. One week following surgery, groups were subdivided so that half of each group had osmotic pumps implanted which delivered pilocarpine HCl (24 mg/kg/day). All animals were infected with Streptococcus sobrinus 6715 and fed cariogenic diet ad libitum for 28 days. Caries scores, microbiological data, and saliva flow rate and composition were determined for all animals. Animals which had both SM/SL glands removed and received pilocarpine developed significantly lower sulcal caries (p < or = 0.05) compared with the animals that had both SM/SL removed but did not receive pilocarpine. The concentration of protein in parotid saliva in these pilocarpine-treated animals was unaffected, and no differences were observed in the electrophoretic profiles on SDS-PAGE. Pilocarpine appears to exert its greatest caries-protective effect when the parotid glands remain intact.