Comparing the Effectiveness of 2% Lignocaine, 4% Tetracaine, and Ice as Topical Anesthesia for Greater Palatine Nerve Block: A Three-Arm Randomized Controlled Trial.

Despite the advancements in dentistry, the administration of local anaesthesia remains a source of fear and pain for many patients. The discomfort associated with injections is a significant contributor to dental anxiety, causing psychological trauma. Palatal injections, among various intraoral injections, are particularly known for being more painful.

Numerous modalities have been explored in the literature to alleviate the pain induced by needle pricks. These include the application of topical anaesthetic agents, warming and buffering of the anaesthetic solution, adjustment of infiltration flow rates, counter-irritation, vibration or pressure, acupuncture, hypnosis, computer-controlled delivery systems (such as the WAND), and the use of devices like vibrajet, dental vibe, or jet injectors.

While the use of topical anaesthesia is widely favoured to mitigate needle penetration pain, some studies suggest that its impact may be marginally superior to a placebo effect. Conversely, Martin et al.  concluded that the pain intensity experienced by patients is reduced when they are aware that topical anaesthesia has been applied to alleviate pain. Various topical anaesthetic agents are available, with lignocaine being a commonly used amide local anaesthetic. Lignocaine, available in multiple forms like gel, patches, sprays, and solutions, is predominantly used as 2% lignocaine jelly in dentistry.

Tetracaine is an ester derivative of PABA. Its lipid solubility and anesthetic efficacy was elevated by replacing a hydrogen of the p-amino group with a butyl. In fact, tetracaine is 5 to 8 times more efficacious than cocaine and is the most potent among dental topical anesthetics. Products are available in the form of a spray solution or ointment in concentrations ranging from 0.2 to 2.0%. Products with 0.15% concentrations are sold as injectable agents. On the other hand, cryoanesthesia offers an alternative approach to diminish and eliminate pain perception. Cryoanesthesia involves applying ice or refrigerant spray to counter nerve conduction of pain at the injection site. Studies suggest that it is efficient, effective, and cost-effective, also reducing edema, nerve conduction velocities, cellular metabolism, and local blood flow.

While there is substantial evidence in the literature comparing tetracaine with ice or 2% lignocaine with ice, there is a scarcity of literature comparing all three—4% tetracaine, 2% lignocaine, and ice—simultaneously to determine their efficacy in palatine nerve blocks. Therefore, this study aims to compare the efficacy of an ice stick in reducing needle prick pain with 4% tetracaine and 2% lignocaine during the administration of greater palatine nerve blocks.