Opioids are central analgesics that act on the CNS (central nervous system) and PNS (peripheral nervous system). We investigated the effects of codeine (COD) and tramadol (TRAM) on local anesthesia of the sciatic nerve. Eighty Wistar male rats received the following SC injections in the popliteal fossa: local anesthetic with epinephrine (LA); local anesthetic without vasoconstrictor (LA WV); COD; TRAM; LA + COD; LA + TRAM; COD 20 minutes prior to LA (COD 20' + LA) or TRAM 20 minutes prior to LA (TRAM 20' + LA). As a nociceptive function, the blockade was considered the absence of a paw withdraw reflex. As a motor function, it was the absence of claudication. As a proprioceptive function, it was the absence of hopping and tactile responses. All data were compared using repeated-measures analysis of variance (ANOVA). Opioids showed a significant increase in the level of anesthesia, and the blockade duration of LA + COD was greater than that of the remaining groups (p < 0.05). The associated use of opioids improved anesthesia efficacy. This could lead to a new perspective in controlling dental pain.

A proposta deste estudo prospectivo, randomizado e duplo cego foi comparar o período de latência e duração da anestesia pulpar utilizando lidocaina 2% com epinefrina 1:100.000, articaina 4% com epinefrina 1:100.000 e articaina 4% com epinefrina 1:200.000 no bloqueio do nervo alveolar inferior (BNAI). Trinta pacientes receberam 1,8 mL de cada uma das soluções anestésicas no BNAI. Os períodos de latência e duração da anestesia pulpar foram determinados usando estimulação pulpar elétrica. O tempo médio da latência da anestesia pulpar foi 8,7, 7,4 e 7,7 min e da duração média da anestesia pulpar foi 61,8, 106,6 e 88,0 min para lidocaina 2% com epinefrina 1:100.000, articaina 4% com epinefrina 1:100.000 e articaina 4% com epinefrina 1:200.000, respectivamente. Para latência houve somente diferença significante entre lidocaina 2% com epinefrina 1:100.000 e articaina 4% com epinefrina 1:100.000 (p=0,037). Para a duração houve diferença significante para todas as soluções anestésicas locais (p≤0,05). Em conclusão, articaina 4% com epinefrina 1:100.000 exibiu mais rápida latência e também obteve mais longa duração da anestesia pulpar no BNAI.

The purpose of this prospective, randomized, double blind study was to compare the onset and duration periods of pulpal anesthesia using 2% lidocaine with 1:100,000 epinephrine, 4% articaine with 1:100,000 epinephrine and 4% articaine with 1:200,000 epinephrine in inferior alveolar nerve block (IANB). Thirty subjects received 1.8 mL of each of the three local anesthetic solutions in IANB. Onset and duration periods of pulpal anesthesia were determined using electric pulp stimulation. The mean time of onset of pulpal anesthesia was 8.7, 7.4 and 7.7 min and the mean duration of pulpal anesthesia was 61.8, 106.6 and 88.0 min for 2% lidocaine with 1:100,000 epinephrine, 4% articaine with 1:100,000 epinephrine and 4% articaine with 1:200,000 epinephrine, respectively. For onset, there was only a significant difference between 2% lidocaine with 1:100,000 epinephrine and 4% articaine with 1:100,000 epinephrine (p=0.037). For duration, there was significant difference for all the local anesthetic solutions (p≤0.05). In conclusion, 4% articaine with 1:100,000 epinephrine exhibited faster onset and also had longest duration of pulpal anesthesia in IANB.