Abstract

The effects of chronic morphine administration on tooth pulp thresholds in dogs have been studied.

Morphine sulfate, 3 mg/kg, t.i.d., loses the property of raising the tooth pulp threshold with time. After 16 days essentially no response was observed. Doubling the dose gave increased response only on the first dose. Subsequent 6 mg/kg doses and 12 mg/kg doses were ineffective. Following 25 days of chronic administration no threshold increase was obtained with 24 mg/kg in either animals treated with 3 mg/kg, t.i.d., or those given the increasing doses. This dose, however, gave an increased response in animals given 3 mg/kg intermittently.