Putting technology where my mouth is

As technology continues to permeate every aspect of life in the modern world, it is sometimes encountered in unexpected places.

Although perfectly logical in hindsight, I was a little surprised to encounter a 3D computer-aided design (CAD) and manufacturing (CAM) facility at my local dentistry, but equally as grateful to have something else to think about as the dentist prepared to rip the nerves out of an ailing tooth.

As the dentist administered two conventional anaesthetic injections and about five doses of a special anaesthetic, also delivered by needle, he filled my head with pleasant images of a rehabilitated tooth courtesy of his Cerec solution by European-based Sirona Dental Systems.

The first surprise was that the dental Cerec solution has been in SA for around 14 years, but not having needed a crown before, it was new to me.

Ramming various sized tubular files down each root of the ill-fated tooth, the dentist imparted the news that the Cerec system meant only one return visit for the crown. This was good news as he fitted up another file to hollow out yet more of each root cavity.

Technology in healthcare has obviously come a long way in the past few decades, but I still think the blowtorch thing needs some attention.

Warwick Ashford, portals managing editor

The CAD CAM solution was a stark contrast with the blowtorch used to heat a dental tool until it was red hot before it was used to melt some compound into the hollowed out roots right inside my mouth cavity. In this regard, I felt technology had failed me a little. Surely there must be some less psychologically damaging alternative?

According to the Cerec Web site, it is the world`s only system for the fabrication of ceramic dental restorations in one visit. While I`m willing to accept this as true, the site also claimed the solution meant fewer injections and less drilling, but there was still far too much of both for my liking.

To be fair, in the past crowns or any other restorative dentistry required at least two visits. One to prepare the tooth, take an impression, and put in a temporary restoration and another to pry off the temporary restoration and fix the permanent one in place.

After discovering that most of the horror stories about root canal treatments were unfortunately true, at least I had only one return visit to deal with the crown from start to finish. Not much consolation, but it was better than nothing. You have got to love technology.

The restoration visit was relatively painless. OK, there was still an injection, but only one, and with the nerve removed, the preparation drilling procedure was almost exhilarating, knowing the capacity for pain was gone. And then there was the fun technology bit.

The Cerec acquisition unit is mobile and houses a Pentium 4 processor, 2Gb RAM, GeForce 6800 graphics card and the Cerec camera, which uses infrared waves to make all the necessary measurements.

First, a 3D digital image of the tooth was made to act as a guide for the finished product. No gagging on that dreadful cement stuff usually used for impressions. Next, another image is recorded of the tooth after the reduction (a euphemism for endless drilling) and then the really interesting part, the CAD.

Although the Cerec solution was developed 20 years ago at the University of Zurich in Switzerland, the 3D modelling capability was introduced only in 2003. This latest version of the technology was an upgrade of hardware and software and is used by around 30 dentists in SA.

The Cerec acquisition unit combines the two images to generate a 3D model of the crown. The dentist then takes over, using a track ball interface to make finer adjustments to the model, checking material thickness and overall shape. Although I needed a crown, the Cerec software also enables other tooth restorations such as inlays or fillings, partial crowns and veneers.

By now the numbness from the injection was beginning to wear off and I was really having fun. "Would you like to watch the milling process?" asked the dentist. What a question!

The 3D model was sent wirelessly to a special milling unit that forms the second part of the Cerec system as we headed in that direction. Into the milling unit the dentist fitted a rectangular porcelain block that had been colour matched to the original tooth.

The ceramic/porcelain material used in the Cerec system was one of the important breakthroughs that made the system practical to use. The material is said to be one of the most biocompatible restorative material used in dentistry and is healthier than its forerunners because it contains no metal.

Unlike conventional laboratory ceramic, the Cerec material`s hardness is very close to that of natural tooth, which allows it to wear down naturally as well as expand and contract at the same rate as the natural tooth to prevent the tooth cracking associated with other restoration materials.

With the flick of a switch, two high-speed diamond cutting heads flew into action, chiselling the porcelain block according to the CAD model. Within about 10 minutes, the perfectly shaped crown was ready for polishing and gluing into place.

The Cerec restoration material is chemically bonded to the tooth, which means as much healthy tooth tissue as possible can be saved. "No need to file tooth down to a stump as would be required for conventional crowning," the dentist said, and I was completely sold. In the very first visit, I felt confident that my strategy of selecting a new dentist based on technology had paid dividends.

Technology in healthcare has obviously come a long way in the past few decades, but I still think the blowtorch thing needs some attention.

Theoretically, the Cerec system is less expensive than traditional dental restorations, but considering the dentist probably had to make a fairly significant investment in the Cerec equipment, I am waiting with bated breath for the account when I will be forced to get real about how much of a contribution to that investment I will have to make.