A Comparison of Different Volumes of Articaine for Inferior Alveolar Nerve Block for Molar Teeth with Symptomatic Irreversible Pulpitis Ramin Abazarpoor, DMD,* Masoud Parirokh, DMD, MSc, † Nouzar Nakhaee, MD, ‡ and Paul V. Abbott, MDS § Abstract Introduction: Achieving anesthesia in mandibular molar teeth with irreversible pulpitis is very difficult. The aim of this study was to compare the efficacy of 1.8 mL and 3.6 mL articaine for an inferior alveolar nerve block (IANB) when treating molars with symptomatic irreversible pulpitis. Methods: In a randomized, double-blind clinical trial, 82 first mandibular molar teeth with symptomatic irreversible pulpitis randomly received conventional IANB injection either with 1 (1.8 mL) or 2 cartridges (3.6 mL) of 4% articaine with 1:100,000 epinephrine. The patients recorded their pain before and during access cavity preparation as well as during root canal instrumentation using a Heft- Parker visual analog scale. No or mild pain was consid- ered as successful anesthesia. Data were analyzed by t and chi-square tests. Results: Eighty patients were eligible to participate in this study, which showed that 3.6 mL articaine provided a significantly higher success rate (77.5%) of IANBs compared with 1.8 mL of the same anesthetic solution (27.5%) although neither group had 100% successful anesthesia (P < .001). Conclusions: Increasing the volume of articaine pro- vided a significantly higher success rate of IANBs in mandibular first molar teeth with symptomatic irrevers- ible pulpitis, but it did not result in 100% anesthetic suc- cess. (J Endod 2015;41:1408–1411) Key Words Anesthesia, articaine, inferior alveolar, irreversible pulpitis, mandibular molar, nerve block, symptomatic, volume R oot canal treatment is a procedure in which pulp tissue and bacteria are removed from the root canal system (1). A major concern for dentists during root canal treatment is to provide profound anesthesia during the procedure (2). Numerous studies have been performed to assess methods to overcome pain and discomfort during root canal treatment using various techniques, equipment, and anesthetic solutions (3–8). Teeth with irreversible pulpitis have shown greater difficulty in achieving anesthesia during endodontic treatment. In addition, achieving anesthesia in mandibular molar teeth with irreversible pulpitis is more difficult compared with other posterior teeth with the same condition (9). An inferior alveolar nerve block (IANB) is the most common anesthetic technique used to provide anes- thesia for mandibular molars (10). Lidocaine is the mostly widely used anesthetic agent in dentistry (11, 12). Articaine is an anesthetic solution that was approved by the Food and Drug Administration for use in dentistry in the United States in 2000 (13). Articaine is claimed to provide faster onset and longer duration of pulp anesthesia compared with lidocaine (14). Several investi- gations have compared the anesthetic efficacy of articaine with other anesthetic agents (15–19). The results of these studies have shown no significant difference between articaine and lidocaine when used for IANB injections (15–18). It is a mistake if a dentist assumes that soft tissue anesthesia is a sign of successful pulp anesthesia. Soft tissue anesthesia after the administration of an IANB only indicates that the injection has been administered at the correct site, but it does not guarantee pulp anesthesia. Successful pulp anesthesia success is only achieved if no or minimal pain is reported by the patient during access cavity preparation and root canal instru- mentation (9). One of the suggested methods to overcome the failure of anesthesia after the administration of an IANB is to increase the volume of the anesthetic solution (20–25). Most of the previous investigations have reported that increasing the volume has no significant effect on anesthesia success. However, these studies have only used lidocaine as the anesthetic solution (20–23, 25). The aim of this investigation was to compare the anesthetic success of IANBs with articaine in teeth with symptomatic irreversible pulpitis without spontaneous pain when either 1.8 mL or 3.6 mL was used. Materials and Methods The protocol of this study and the informed consent document were approved by the Ethics Committee of Kerman University of Medical Sciences, Kerman, Iran (no. KA/ 92/476). The sample size calculation, which was based on a type I error of 0.05 and a power of 0.8, indicated that ideally a sample size of 30 in each group would be required to detect a 20% difference in the success rate of 2 test groups. The inclusion criteria were as follows: healthy adult patients 18–65 years old hav- ing a mandibular first molar tooth with symptomatic irreversible pulpitis and a normal periapical radiographic appearance. The teeth were tested with an electric pulp test (Parkell Inc, Farmingdale, NY) and a cold test (Roeko Endo Frost; Roeko, Hangenav, Germany) to determine pulp sensibility. The teeth were diagnosed as having symptom- atic irreversible pulpitis if the patients had lingering pain and a prolonged response to the cold test (more than 10 seconds). From the *Oral and Dental Diseases Research Center and † Endodontology Research Center, Kerman University of Medi- cal Sciences, Kerman, Iran; ‡ Neuroscience Research Center, Kerman, Iran; and § School of Dentistry, University of Western Australia, Perth, Australia. Address requests for reprints to Dr Masoud Parirokh, Endo- dontology Research Center, Kerman University of Medical Sci- ences, Kerman, Iran. E-mail address: masoudparirokh@gmail. com 0099-2399/$ - see front matter Copyright ª 2015 American Association of Endodontists. http://dx.doi.org/10.1016/j.joen.2015.05.015 CONSORT Randomized Clinical Trial 1408 Abazarpoor et al. JOE — Volume 41, Number 9, September 2015