Clonidine versus Adrenaline as an Adjunct to Lignocaine on Haemodynamic Parameters during Nerve Block for Third Molar Surgical Removal - A Systematic Review and Meta-Analysis

BACKGROUND: Adrenaline or clonidine is used as adjuncts in conjunction with lignocaine to improve the depth of local anaesthesia in dental procedures. OBJECTIVES: This systematic review and meta-analysis intends to compare the haemodynamic parameters when clonidine or adrenaline is used in conjunction with lignocaine for third-molar surgical removal. DATA SOURCES: Cochrane, PubMed and Ovid SP databases were searched using “MeSH” terms (((nerve block) OR (IANB)) AND ((clonidine) OR (adrenaline))) AND (lignocaine). STUDY ELIGIBILITY CRITERIA: Clinical studies where Clonidine + lignocaine and Adrenaline + lignocaine were compared directly during nerve block administration exclusively for third molar surgical removal were selected. PARTICIPANTS, STUDY APPRAISAL: This current systematic review is registered in Prospero database CRD42021279446. Two independent reviewers were involved in collection, segregation and analysis of electronic data. The data were compiled in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Search was conducted till June 2021. SYNTHESIS METHODS: Qualitative analysis of the selected articles was performed for systematic review. Meta-analysis is performed using RevMan 5 Software. Heterogeneity through the I(2) statistics. Change in the haemodynamic parameters was the primary outcome evaluated, and secondary outcomes evaluated were onset and duration of anaesthesia in both the groups. RESULTS: In all databases, 1141 records were screened, out of which a total of 21 articles were included for the evaluation for full-text analysis. Out of these, 16 articles were excluded and 5 articles were included for the final systematic review. Meta-analysis was performed only for 4 studies. CONCLUSION: Amongst the evaluated haemodynamic parameters, there was a significant reduction in the heart rate (baseline to intraoperative period) in clonidine and lignocaine groups than in adrenaline and lignocaine groups during nerve block administration for third molar surgical removal. There was no significant difference between other primary and secondary outcomes evaluated. LIMITATIONS: Blinding was not performed in all the studies, randomisation was performed in only three studies. The volume of local anaesthesia deposited varied in the studies (2 mL in three studies and 2.5 mL in two studies). Most of the studies (n = 4) were evaluated on normal adults and only one study evaluated mild hypertensive patients.