[Different concentration of lidocaine used for an exodontia of the impacted mandibular third molar]

To investigate the anesthesia outcomes of 1% lidocaine with 1∶100 000 epinephrine (EPI) for inferior alveolar nerve, lingual nerve and buccal nerve block, compared with 2% lidocaine with 1∶100 000 EPI.

A study with a cross-over design, with each patient also serving as their own control, was implemented to estimate the clinical outcomes. Predictor variable was 1% lidocaine with 1∶100 000 EPI versus 2% lidocaine with 1∶100 000 EPI. Outcome variables were patients' responses to pain on injection, onset time of anesthetizing, efficacy of anesthesia, and the time to sensation return for the lower lip and tongue. Patients reported pain level at every experimental stage with a 10-point Numerical Rating Scale(NRS). Three weeks later, the patients were tested with the alternate drug combinations. The same outcomes were assessed. A verification of treatment difference was performed using SPSS 17.0 software package.

Twenty-one patients were recruited and completed the study protocol. Sixty-two percent of the patients were women and 38% were men with a median age of 24 years [interquartile range (IQR), 20-30 yr]. Patients reported significantly lower pain scores with 1% lidocaine (1.09,95%CI，0.77-1.41) on injection, compared with 2% lidocaine (1.66, 95%CI, 1.33-1.99) (P=0.010). Patients undergoing 1% lidocaine with 1∶100 000 EPI (52-63 s) had a markedly quicker onset time of anesthetizing than those using 2% lidocaine with 1∶100 000 EPI (259-335 s, P=0.000). The efficacy of anesthesia between 2 groups was not significantly different (P=0.751). Among the patients with the pain values of 1~3, there were 9 patients(100%) perceiving slight pain when splitting teeth was performed in 1% lidocaine group, while 4 patients(57%) felt slight pain when elevating soft flaps was performed and 3 patients(43%) perceived mild pain when splitting teeth was performed in 2% lidocaine group (P=0.019). The time to sensation return for the lower lip and tongue was significantly different between the 2 drug formulations (P=0.000), with an extended period of average 61 min (52-69 min) in 2% lidocaine group.

1% lidocaine with EPI plays a similar role in clinical outcomes for inferior alveolar nerve, lingual nerve and buccal nerve block as 2% lidocaine with EPI, which produces lower pain on injection as well as a relatively short time to sensation return. The reasons for slight pain during surgical operation are a relative lower efficacy of anesthesia on the inferior alveolar nerve in 1% lidocaine group, and on the buccal nerve anesthesia in 2% lidocaine group.