3D Scanners

For some time I have been experiencing a heat-sensitive tooth; a visit to the dentist resulted in a specialised toothpaste on prescription, which should have reduced the sensitivity. The tooth in question was an upper molar just in front of a wisdom tooth, a more difficult tooth to access but less visible in general day-to-day proceedings. On another visit to the dentist the X-ray machine was unfortunately not working, but drilling of the tooth revealed some apparent decay. The dentist knew that this was probably not going to cure the sensitivity, so put a temporary cap on the molar and I subsequently returned a few weeks later when the X-ray machine was working again. The subsequent image was available on the monitor to be viewed in a very short time period and I could recognise the teeth, gums and bone. The area of interest, though, was much less discernible. The options were to have root canal surgery, which would be difficult due to the position of the tooth, have an extraction or to have the tooth capped. I chose the capping option and, due to the position of the tooth, chose the basic metal option, as the only people likely to see it would be myself and future dentists.

A further appointment was made and this was to grind off parts of the tooth to make it a rectangular shape, to which the metal crown could be fixed. The next part was of interest to me, as the dentist then used an interoral scanner to capture direct optical impressions. This consisted of a probe or wand that was moved around the mouth to capture an accurate image of the remaining piece of tooth and also the mating surface of the corresponding teeth, enabling an accurate cap to be manufactured. I have since researched the technology using a search engine and it works in a similar way to other 3D scanners, by projecting a light source, either laser or structured light, onto the teeth, correctly termed ‘dental arches’. The resulting images of the dentogingival tissues captured by the imaging sensors in the wand were processed by the scanning software, thus creating a 3D model. The image on the dentist’s laptop was very detailed and could be viewed from different positions and in different colours; I was impressed. The traditional way would have been to make a plaster-cast model, but this was a much quicker and user-friendly option. I will have returned to the dentist by the time you are reading this article and should have a perfectly fitted cap in place.

This dental work came not long after the North East Scottish Branch meeting, titled: ‘A practical guide to laser profiling’, by David Emery of Matrix Inspection, where similar technology is being used to inspect industrial components on a much larger scale than my mouth. The size of the dental equipment, which is quite robust and waterproof, then got me thinking: are there any NDT applications that could benefit from this? One that comes to mind is a boiler tube survey, but would it be equal or more accurate than an eddy current inspection? It would be more accurate than the borescope visual testing (VT) inspections and able to provide a record of the test, but probably not as quick. Looking on the internet, it would appear that the current industrial scanners are quite compact, but not as small as the one the dentist used. It will be interesting to see if this small medical device does come into the NDT tool chest and, on a personal level, whether my sensitivity issue is resolved at last.

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