An important requirement prior to initiating endodontic or operative dental treatment is the ability to achieve and maintain profound anesthesia. Local anesthetic solutions have been utilized in clinical dentistry to alleviate or eliminate pain associated with invasive procedures as early as the 19th century. An inferior alveolar nerve block (IANB)is the standardized injection technique for mandibular molar teeth. However, IANB does not always result in successful pulpal anesthesia, especially in patients with symptomatic irreversible pulpitis. The fact that patients often feel pain during endodontic treatment of teeth with symptomatic irreversible pulpitis is a challenge for the clinician. Successful anesthesia is only achieved if no or minimal pain is achieved during access cavity preparation and canal shaping.

Various different approaches have been tested to improve the success rate of IANBs in mandibular molars with symptomatic irreversible pulpitis. These include different anesthetic techniques for IANB, different anesthetic solutions, supplemental infiltration techniques, acupuncture, and premedication before the IANB is performed. Despite these approaches, the success rate of IANBs in mandibular molars with symptomatic irreversible pulpitis ranges from 15 -57 %.

It is a well-established physiological phenomenon that heat has the property of vasodilatation and cold has the property of vasoconstriction. Cold also has analgesic and anesthetic effects. In medicine, the application of a frozen gel pack for 5 min prior to Botulinum toxin A injection resulted in a statistically significant pain reduction. In the field of neuroscience, cooling of lignocaine was also found to have beneficial effects like faster onset of action and prolonged duration of action. Dabarakis et al showed that mepivacaine at a temperature of 4°C had a longer duration of pulpal anesthesia for the maxillary first premolar than at room temperature.

Some studies have been performed to evaluate the effect of cryotherapy and cooling of lignocaine on the injection pain and efficacy of maxillary infiltration and studies on cooled lignocaine injection of IANB. It is not known whether cooling of lignocaine hydrochloride and precooling injection site will have any beneficial effect, when used for inferior alveolar nerve block (IANB).

Hence, the purpose of this study was to evaluate the effects of cooling 2% lignocaine hydrochloride with 1:2,00,000 epinephrine along with precooling injection site on the primary outcomes of onset and duration of IANB. The secondary outcome to assess is pain on injection.