EFFECTIVENESS OF PHENTOLAMINE MESYLATE IN REVERSAL OF LOCAL ANESTHESIA: SYSTEMATIC REVIEW AND META-ANALYSIS.

Background: The aim of the present paper is to summarize the effectiveness of Phentolamine mesylate on the reversal of local anesthesia (LA).

Methodology: Seven electronic databases were searched for randomized clinical trials in patients who received LA (population) and either received a Phentolamine injection (intervention) after LA compared to placebo or sham (control) to cause a return of normal sensation (outcome). Risk of bias assessment was performed using Cochrane risk of bias assessment tool 2.0. The hazard ratio (HR) was calculated as the event (time to return to the normal sensation) was a time-dependent event, as well as the weighted mean difference (WMD), was computed. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) was used to assess the certainty of the evidence.

Results: Ten studies met our inclusion criteria and were included in this review. After pooling the results quantitatively, the value of the HR in the tongue was 0.56 (95% CI: 0.41-0.75, P<.001); in lower lip, the value was 0.56 (95% CI: 0.38-0.83, P = .004) and for upper lip, the value was 0.50 (95% CI: 0.31-0.80, P = .004). The WMD for the time to return for normal sensation was -47.71 min for the tongue (95% CI: -73.63 to -21.80 min, P<.001), -73.29 min for lower lip (95% CI: -88.41 to -58.16 min, P<.001) and -86.86 min for upper lip (95% CI: -101.16 to -72.57 min, P<.001). There is a high certainty of evidence that patients who have been administered local anesthesia may achieve faster recovery of normal sensation in tongue, and moderate certainty of evidence for return of normal sensation in lower lip and upper lip, if Phentolamine was administered after the local anesthesia. The adverse effects were reported in a few studies and were minor, not necessitating any medical intervention.

Conclusions: Phentolamine might be a useful adjunct in patients who desire an earlier return of normal sensation and function after local anesthesia. Future research should be directed to study the cost-effectiveness or dental patient-reported outcomes of Phentolamine after local anesthetic injections.