Effects on infiltration Anesthesia induced by different concentrations of local anesthesics and epinephrine

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The most widely used dental local anesthetic in Japan contains a relatively high concentration of epinephrine.This concentration is thought to be high enough to cause cardiovascular changes, especially in the elderly or in patients with cardiovascular diseases.This study was designed to examine the effects on infiltration anesthesia induced by differentconcentrations of lidocaine and epinephrine by using SEP.Rats were anesthetized with thiamylal sodium injected peritoneally. A bipolar stimulative electrode was inserted into the pulp of the upper incisor. The pulp was stimulated electrically, and SEP was recorded from the contralateral surface of the skull . Six local anesthetics were used ; 2% lidocaine (Group 2L), 2% lidocaine containing 1 : 200,000 epinephrine (Group 2L20), 1 : 160,000 epinephrine (Group 2L16), or 1 : 80,000 epinephrine (Group 2L8), 3% lidocaine containing 1 : 160,000 epinephrine (Group 3L16), and 3% prilocaine containing 0.03 IU/ml felypressin (Group PF). 50 mu 1 of … More each combination were injectedinto the palate paraperiosteally. The amplitude of the primary SEP responses was measured, and the hanges were analyzed statistically.In all six groups, a reduction in % amplitude was found from immediately after the injection. The duration in order of their length were as follows : 2L8 (]SY.di-substituted left.[) 2L20(]SY.di-substituted left.[) PF (]SY.di-substituted left.[) 2L16(]SY.di-substituted left.[) 3L16(]SY.di-substituted left.[) 2L.The reductions was greatest in Group 3L16, followed by 2L8, and then they were similar in Groups 2L, 2L20, 2L16, and PF.The reductions in Group 3L1 6 were significantly greater than Group 2L8 until 30 min, and they were recovered rapidly after then. No significant differences were seen among Groups 2L, 2L20, 2L16, and PF.The maximum reductions were seen at 8-10 min in all groups. The value of the maximum suppression of Group 2L was 51.1 %. When this value was used as the standard of comparison (2L = 1), the potencies were as follows : 2L : 2L20 : 2L16 : 2L8 : 3L16 : PF were 1 : 1 : 1 : 1.5 : 1.9 : 1.3.The results suggest that, if the concentration of epinephrine is decreased, the concentration of local anesthetic should be increased and that 3L16 can possibly be as effective for dental local anesthesia as 2L8, as long as the dental procedure is completed within 30 min. Less