Effects of prilocaine local anaesthetic solutions on pulpal blood flow in maxillary canines

The effects of prilocaine local anaesthetic solutions on pulpal blood flow (PBF) in maxillary canines were investigated in nine adult subjects. Buccal infiltration of 2 ml of the following solutions were carried out: 3% prilocaine; 3% prilocaine with 0.03 IU/ml felypressin; and 3% prilocaine with 1:100,000 adrenaline. Blood flow in the anaesthetized tooth was monitored by a laser Doppler flowmeter and data stored in a computer. An electric pulp tester was used to assess pulpal anaesthesia. The duration of anaesthesia was recorded. After administration of plain prilocaine, PBF changed little throughout the experiment in all nine subjects. When prilocaine with felypressin was injected. PBF fluctuated greatly, but there was no sustained increase or decrease. In comparison, prilocaine with adrenaline caused a significant decline in PBF in every subject (p < 0.05), but then gradually started to return to the pre-injection level: there was no such change in PBF of the contralateral tooth. Injection of 3% plain prilocaine achieved a short duration of pulpal anaesthesia (median 7 min) in only three subjects. When prilocaine with felypressin was injected, eight out of nine subjects experienced pulpal anaesthesia (median duration 10.5 min). Injection of prilocaine with adrenaline caused pulpal anaesthesia in six of nine subjects (median duration 10.5 min). The use of vasoconstrictors with prilocaine anaesthetics had less pronounced effects on blood flow and shorter periods of anaesthesia than those reported previously for lignocaine with adrenaline.