Controllable Jet Injection of Dental Local Anaesthetic

Objective: Fear of dental procedures is a common barrier to effective dental care. A promising technique to overcome dental anxiety is needle-free jet injection, which involves delivering local anaesthetic as a high-speed jet capable of penetrating the oral mucosa without a needle. Previous efforts have used loud, uncontrolled injectors designed for transdermal delivery that have failed to achieve significant uptake in dental practice. Methods: In this work, we present and validate a controllable jet injection device driven by a silent electric motor for the delivery of dental local anaesthetic. The injector includes a novel tubular attachment at its distal end, which allows the delivery to be performed comfortably throughout the mouth. The expected pressure loss resulting from the use of this attachment is analysed. This analysis predicted that a 75 mm long tubular attachment of 0.53 mm radius would result in negligible pressure loss. To validate delivery in human tissue, the injection system was used to perform 18 injections into the mouths of two Thiel-embalmed human cadavers. These injections were visualised using cone-beam computed tomography (CBCT). Results: Benchtop testing of the prototype injector verified the expected pressure loss along the attachment. The CBCT scans demonstrated that the fluid was successfully delivered to the desired locations, adjacent to the root apex of the teeth, at every injection site. Conclusion: These outcomes validate the performance of this novel needle-free injector, demonstrating its potential as a tool to reduce dental anxiety. Clinical and Translational Impact Statement— Our controllable jet injection device overcomes key limitations associated with previous attempts to deliver dental local anaesthetic needle-free. This could greatly reduce barriers to effective dental care.