Minimal Intervention Dentistry is all about reducing drilling and preserving as much strong, healthy tooth as possible.

Traditionally dentists have treated decay by drilling away far too much sound enamel. The reason is easy to understand. Years ago the only decent filling material was grey, metallic amalgam. It was tough and durable but did not adher to tooth substance so the only way to keep it in place was mechanically, by locking it into a hollowed out cavity. This undercutting weakened the tooth and sometimes damaged the nerve.

Today dentists have the option of using white adhesive composite resin, so there is no excuse for excessive drilling. Unfortunately old habits die hard. The cavity designs which were advocated a hundred years ago are basically still taught and used today.

DECAY, BETWEEN THE TEETH AND DIFFICULT TO REACH

 Here is an illustration. Consider an average, everday dental decay.

This one is at the side of a tooth, where it abuts against its neighbour.

It is effectively between the teeth. An X-ray proves it is there but it is hard to spot with the eye.

There is no ready access to the lesion since the nextdoor tooth is jammed against it.

 

The usual approach is to drill across the biting surface and then sink a trough between the teeth.

A great deal of sound enamel is destroyed in the process—in fact more healthy tooth is removed than that which is diseased.

There are better alternatives. Back in 1986 two dentists, a Melbournian and an American, described a clever improvement.

They suggested burrowing through the tooth and preserving the edge or marginal ridge. The resultant preparation was virtually a tunnel from the biting surface, through to the decay in the wall of the tooth.

Part of the reason this technique emerged was that the new white composite resin materials were proving reliable. These were soft and easily manipulated before setting with exposure to white light.

Unlike the old amalgam, the new composites could readily be worked into the narrow confines of the prepared cavity.

This Tunnel Restoration retained much more healthy tooth than previously but it was difficult to perform and never really caught on.

Shortly after this time a few more developments took place.

Another Australian, Graham Craig, began working with silver fluoride solutions and realized that it immediately disinfected the surface of decay and, at the same time, stimulated rehardening. It effectively arrested decay.

People find it difficult to imagine decay actually stopping and reversing but this is often seen naturally on the surface of teeth.  If rotting has only progressed superficially and diet and cleaning improve, the enamel can recalcify and take up mineral that was previously lost. The area leaves a tell-tale mark but is like a scar on the skin - tougher and more resistant than it was originally.

He suggested simply removing the bad decay in the soft dentine while giving the weakened side wall a chance to remineralise.

In the meanwhile the American, Hunt, refined the Tunnel Restoration and argued that, unless the tooth had collapsed, it was not always necessary to drill through the edge of the enamel wall.

In 2002 I published an article in the ADA News Bulletin proposing that the two approaches could be combined. The drilling would merely target the dangerous decay in the central part of the tooth while silver fluoride could be used to kill off any remaining bacteria and help repair the softened enamel at the side.

Because the tunnel and the filling stopped short of breaking through the tooth I called it a Terminated Tunnel.

I have practiced this type of filling successfully for a number of years now.  It preserves more natural tooth than with any other design and is quicker and easier for both the dentist and patient.

It certainly can not be used in all cases but for moderate sized decay I believe it is the technique of choice.

You may like to read up on this approach and the philosophy behind it.

The Terminated Tunnel Restoration and The Case For Minimal Intervention Dentistry are published articles. They are written for the profession but they do provide a much more detailed insight.

The newsletters have some interesting angles too. See World’s Fastest Dentists and New Ideas.

THE TERMINATED TUNNEL RESTORATION