Effect of precooling injection site and cold anesthetic administration on injection pain, onset, and anesthetic efficacy in maxillary molars with symptomatic irreversible pulpitis: a randomized controlled trial.

Objective: This randomized controlled clinical trial assessed the analgesic and anesthetic effects of precooling the injection site and administration of refrigerated 2% lignocaine HCl with 1:100,000 epinephrine (LE) in maxillary molars with symptomatic irreversible pulpitis (SIP).

Materials And Methods: Sixty patients diagnosed with SIP (preoperative pain score ≥ 85 mm) in maxillary first molars were randomly allocated to two groups. In group I (control), topical gel was applied for a minute followed by conventional LE infiltration, whereas in group II (experimental), topical ice application for 15 s and refrigerated (4-6 °C) LE administration was done prior to endodontic treatment. The primary outcome measure was anesthetic efficacy that was defined as none to weak pain (≤ 36 mm) as measured on Heft Parker visual analog scale (HP-VAS) following access cavity preparation. Pain on injection and onset constituted the secondary outcome measures. The pain on injection was measured using HP-VAS, whereas the onset of anesthesia was assessed using an electric pulp tester (EPT) which was applied on the experimental tooth every minute until no response was elicited. Mann-Whitney U test was performed to analyze the data (p < 0.01).

Results: Experimental group reported a success rate of 86.6% when compared to control group (26.6%) and a statistically significant reduction on injection pain (20.0 mm vs 54.5 mm) (p < 0.01). The onset of anesthesia for experimental group was 2.4 min which was also significantly lower than control group (4.5 min) (p < 0.01).

Conclusions: Cryotherapy can serve as an effective alternative to conventional anesthesia for achieving success, reduced pain, and faster onset during endodontic treatment of maxillary molars with SIP.

Clinical Relevance: Precooling the injection site and cold LE administration can result in effective pulpal anesthesia during endodontic management of maxillary molars in SIP patients.