No More Needles at the Dentist: Just a Tiny Electric Current Instead

Research reveals a new way to administer anaesthetic in the mouth.


If you’re scared of the dentist’s needles you’re not alone – but new research means you might not have to put off that appointment again. A study published in Colloids and Surfaces B: Biointerfaces reveals how the dentist could give you an anaesthetic using a tiny electric current instead of a needle.

The researchers behind the study from the University of São Paulo (Brazil) say their new findings could help improve dental procedures and bring relief to millions of people who are scared of needles. It would also save money and avoid contamination and infection, they say.

“Needle-free administration could save costs, improve patient compliance, facilitate application and decrease the risks of intoxication and contamination,” explained Professor Renata Fonseca Vianna Lopez, one of the authors of the study from the University of Sao Paulo. “This may facilitate access to more effective and safe dental treatments for thousands of people around the world.”

Dentists often have to carry out invasive and painful procedures in the mouth. To minimise patients’ discomfort, dentists use anaesthetics that block pain, which are administered using needles. However, many patients are extremely afraid of these injections, resulting in them postponing and even cancelling visits to the dentist.

For these patients, an additional step is needed: dentists first give them a topical painkiller to reduce the pain – and associated fear – caused by the needle. This can come in the form of a hydrogel, ointment or sprays; the most common are hydrogels that can contain lidocaine and prilocaine.

In the new study, the researchers investigated a way of getting these topical anaesthetics into the body more effectively to see if they could replace needles altogether. They found that applying a tiny electric current – a process called iontophoresis – made the anaesthetics more effective.

The researchers first prepared the anaesthetic hydrogels with a polymer to help it stick to the lining of the mouth. They added two anaesthetic drugs, prilocaine hydrochloride (PCL) and lidocaine hydrochloride (LCL). They tested the gel on the mouth lining of a pig, applying a tiny electric current to see if it made the anaesthetic more effective.

The anaesthesia was fast-acting and long-lasting. The electric current made the prilocaine hydrochloride enter the body more effectively; the permeation of the anaesthetic through the mouth lining increased 12-fold.

The researchers say the technology has applications not only in dentistry anaesthesia, but also in other areas such as cancer treatment.

“Over the last few years, our research group has been working on the development of novel drug delivery systems for the treatment of several skin and eye diseases,” said Prof. Lopez. “The skin and eyes pose challenges for drug delivery, so we have focused on improving drug delivery in these organs using nanotechnology, iontophoresis and sonophoresis, which is permeation using sound waves.”

The researchers now plan to develop an iontophoretic device to use specifically in the mouth and do some pre-clinical trials with the system. – Elsevier


(Needle-free buccal anaesthesia using iontophoresis and amino amide salts combined in a muco-adhesive formulation, Camila Cubayachi, Renê Oliveira do Couto, Cristiane Masetto de Gaitani, Vinícius Pedrazzi, Osvaldo de Freitas and Renata Fonseca Vianna Lopez, Colloids and Surfaces B: Biointerfaces, doi: 10.1016/j.colsurfb.2015.11.005, published online 10 November 2015.)