Comparison of Anesthetic Efficacy of Mental Nerve Block Versus Inferior Alveolar Nerve Block in Mandibular Anterior Teeth and Premolars in Symptomatic Irreversible Pulpitis

Symptomatic irreversible pulpitis is a dental condition characterized by inflammation of the dental pulp, a soft tissue containing nerves and blood vessels located within the tooth's central cavity. The inflammation is severe and incapacitates the pulp's ability to heal naturally, leading to its eventual necrosis, hence the label "irreversible." The clinical manifestation of symptomatic irreversible pulpitis is excruciating, unrelenting pain, aggravated by exposure to hot or cold stimuli, and pressure. Inadequate intervention exposes the patient to the risk of infection or abscess formation, necessitating extensive dental procedures, including root canal therapy or tooth extraction.

The inferior alveolar nerve block (IANB) is a widely employed regional anesthesia technique in dentistry, utilized to provide profound anesthesia of the mandibular teeth and gingivae. It is a safe and reliable anesthesia technique commonly used in dentistry to prevent pain during procedures such as extractions, root canals, and implant placement, ensuring a comfortable experience for the patient. The mental or incisive nerve block is a dental anesthesia technique that anesthetizes the lower teeth, gums, lower lip, and chin by blocking the incisive and mental nerves, which are branches of the inferior alveolar nerve.

Local anesthesia in endodontics provides pain relief and patient comfort during procedures such as root canal therapy by blocking nerve impulses that transmit pain signals to the brain. Painful pulpitis may require pulpectomy under local anesthesia, but the effectiveness of injections can vary between teeth, with mandibular teeth being less responsive compared to maxillary teeth due to their thicker cortical bone and more complex anatomy. The inferior alveolar nerve is typically blocked in the lower molar and premolar region to achieve numbness. However, this approach may not always provide complete numbing of the nerve endings in the teeth. To enhance the likelihood of success, it is recommended to administer supplemental injections such as intra-osseous injections or applying 4% articaine through the cheek along with the inferior alveolar nerve block.

In a randomized clinical trial with 153 participants, the anesthetic success rates for mental nerve block and IANB were 53% and 47%, respectively, with no significant difference between them. However, combining both techniques by adding an IANB to MINB significantly improved the success rates to 82%. In a study conducted by Batista da Silva and colleagues, the effectiveness of 0.6 mL of 2% lidocaine and 4% articaine administered outside the mental foramen was evaluated. The results showed that using 4% articaine resulted in a 70% to 80% success rate for anesthesia.

This randomized clinical trial will be conducted at department of operative dentistry, Peshawar dental college, Peshawar. Ethical approval will be obtained from the hospital's ethical board. The sample size will be 96(48 in each group) at 5% level of significance, 80% power of test, using success for IANB to be 53% and to be mental block 80%. To participate in this study, patients needed to have exposed caries in their mandibular premolars or lower anterior causing sharp and persistent pain in response to thermal stimuli and an electric pulp tester, as well as bleeding during access opening. They also needed to have a medical history falling under American Society of Anesthesiologists class I or II and understand pain scales. Patients with allergies or contraindications to the local anesthetic, pregnant or breastfeeding women, those with a history of drug abuse, taking pain-affecting medication, or experiencing active pain in more than one tooth will be excluded.

The participants will be randomly divided into two, one receiving mental nerve block (MINB) and other IANB using block randomization technique. Each block size was eight. After obtaining informed consent, eligible patients will be randomly assigned to receive either mental nerve block or inferior alveolar nerve block. To perform an inferior alveolar block with 2% lidocaine and adrenaline 1:80,000, the dental practitioner will first explain the procedure to the patient and obtained their informed consent. The patient will be positioned comfortably in a dental chair and with their head supported. The injection site will be sterilized with an antiseptic solution, and the syringe will be loaded with the anesthetic solution. Next, the dental practitioner will inserted the needle into the mucobuccal fold adjacent to the mandibular molars and advanced it towards the mandibular foramen, aiming slightly anteriorly and superiorly. Aspirating to check for blood or resistance, the needle will be repositioned if either was present. Once the needle is correctly positioned, the dental practitioner slowly inject 1.8-1.9 mL of the anesthetic solution while checking for any signs of nerve stimulation, such as lip or tongue numbness. After completing the injection, the needle will be withdrawn and disposed of properly in a sharps container. For the mental block with 2% lidocaine and adrenaline 1:80,000, the mental foramen will be located, and the needle is inserted. After aspiration, 0.6-0.9 mL of anesthetic was injected while monitoring for nerve stimulation. The needle will then withdrawn and disposed of properly. After three minutes the anesthetic efficacy of each technique will be evaluated by assessing the pain score during access opening and instrumentation using a visual analog scale (10 point scale). Score more than 3 was considered ineffective.

The data analysis will be performed using SPSS version 22. Descriptive statistics will be calculated for all numeric and categorical data. The efficacy of two interventions (IANB and MINB) will be compared using the chi-square test. Stratification will be performed based on gender to control confounders. A significance level of P < 0.05 will be considered significance.