Articaine Bone Penetration — ORE Part 1 MCQ
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Correct answer: A — Its thiophene ring increases lipophilicity and diffusion through mandibular bone
Explanation lettering: C = shown as B · D = shown as C · B = shown as D
Articaine contains a thiophene rather than a benzene ring. This increases lipid solubility and is associated with enhanced diffusion through soft tissue and bone, helping a buccal infiltration reach pulpal tissues in mandibular molars despite the relatively dense mandibular cortex. A clinical crossover trial found mandibular first-molar pulpal anaesthesia was achieved more often with articaine than with lidocaine when both contained epinephrine. The ester group in articaine contributes mainly to plasma hydrolysis, not prevention of tissue metabolism (B). Articaine is commonly supplied with a vasoconstrictor, so C is false. Protein binding does not explain cortical diffusion (D), and successful infiltration must anaesthetise pulpal nerves rather than the periosteum alone (E).
Reference: Kanaa MD, Whitworth JM, Corbett IP, Meechan JG. Articaine and lidocaine mandibular buccal infiltration anesthesia: a prospective randomized double-blind cross-over study. Journal of Endodontics. 2006. https://pubmed.ncbi.nlm.nih.gov/16554198/