A bit too far

Drill a bit,  not too far.

In the tooth is a nerve:

do not disturb it




It would not have been fair to my patients if I had written what follows before I had retired from practising dentistry. If I had been one of my patients, I might have lost confidence in my dentist after reading this.

Before dental students are allowed to drill teeth on living patients, much training is required. A great deal of this is done using plastic teeth mounted in the jaws of the heads of a mannequin, known as a ‘phantom head’. The plastic teeth are held in the artificial jaws with metal screws. The screws fit into holes on the undersides of the teeth so that the crowns of the teeth appear intact. As a dental student, I spent many hours each week practicing cutting standardised cavities. The cavities had to be cut to very precise dimensions, which were neither to be exceeded nor the opposite. I recall that certain parts of the plastic teeth had to be cut to exactly two millimetres deep and much the same width. At first, I found this extremely difficult. Not only was I not yet used to using dental drills, but also the plastic cuts in an awkward way.

Eventually, the time arrived for a practical test. Unsupervised, we were required to cut one of the several cavities that we had been learning to prepare. Disaster struck. Within a few seconds of starting my tooth, I had cut too deep. The metal of the screw retaining the plastic tooth in the phantom head was staring me in the face. I called over the examiners. They studied the tooth carefully, and then one of them said to me:

“I think you have exposed the nerve, Mr Yamey.”

“We might be looking at a root treatment, here, don’t you think?” asked the other examiner.

I could not believe what I was hearing.

“I think we’re looking at a failure here,” I replied.

They agreed.

I spent another few weeks in the phantom head room, and retook the exam, which I passed with flying colours, you will be relieved to learn. Now, I was deemed ready to treat dental cavities on real teeth in real patients – under supervision, of course.

The first tooth that I had to work on had only a little decay. Nevertheless, after the intense training, which emphasised cutting teeth should be done as conservatively as possible, cutting only as little of healthy tooth tissue as was strictly necessary to retain the restoration (‘filling’), I approached my first ‘real’ tooth with much trepidation. After boring down to the two-millimetre depth that was ingrained in my mind, I could see nothing but healthy tooth – no sign of decay. I summoned the clinical teacher (the ‘demonstrator’). He looked at the tiny hole I had created with great care and laughed.

“You have not yet cut through the enamel. Keep going,” he said.

The enamel, for those who are uncertain about dental anatomy, is the outer covering of the part of the tooth that is visible in the mouth. Beneath it, is the dentine, and below that the dental pulp chamber, which contains nerves and blood vessels. Decay spreads much more rapidly through dentine than through enamel.

I looked at the demonstrator, and said:

“But in the phantom head room we were told never to go deeper than two millimetres.”

“Those were just plastic teeth,” the demonstrator replied, “forget all that.”


[Picture from “Der Zahnarzt in der Karikatur” by E Henrich]

Burne-Jones in London

Until 24th February 2019, there is an excellent exhibition of the works of the Pre-Raphaelite artist Edward Burne-Jones (1833-98) at London’s Tate Britain.



For Victorian art  

looking back to the past

Burne-Jones does excel



Back to BASIC


During the last two years (1968-69) at my secondary school, Highgate School in north London, we were taught about computing. The teacher in charge was one of the pioneers of the computer programming language called BASIC (an acronym for Beginner’s All-purpose Symbolic Instruction Code). The first version of BASIC, which was considerably simpler to use than FORTRAN or COBOL, was released in 1964. So, our teacher was advanced in introducing it to us. We learned about creating flow diagrams and then converting them into BASIC.

When I learnt BASIC back in the late sixties, the only computers available were huge main-frame machines that occupied large rooms. PCs and lap-tops were not yet available, or hardly even imagined. The school did not possess a main-frame computer. But, it did possess a keyboard attached to a telephone line. By dialling a number, the keyboard could be connected to a remote computer. It was not possible to type directly into the computer. First the programme that we concocted had to be typed on the keyboard, which converted the programme into a series of holes on a long ribbon of paper. When the programme had been transferred into the punched holes, the remoter computer was dialled, and then the long strip had to be fed into a slot on the keyboard console. Then, the author of the programme had to hold his breath. For, it would be some time before the computer sent back a message that was typed by the console onto its paper-feed. More often than not, the message would convey the sad news that the programme had an error. Then, it was back to the ‘drawing board’ to determine where we had gone wrong.

When the programme was correct, the results were exciting. Some people used the computer to do statistical work, or to generate answers to mathematical problems. I discovered how to make the computer write random poetry. I submitted some of what I produced to the school’s magazine, but it was turned down.

Several of my fellow pupils and I became obsessed with programming. We could not get enough of experimenting with programming. The console was kept locked in a wooden cabinet, which could only be opened by our teacher. Somehow or other one of us managed to get a copy of the key, and, more importantly noticed the number that our teacher dialled to access the computer. From then onwards, we had far greater access to the machine.

The IBM company lent the school a prototype of a table top computer. This could only be programmed using machine language, which is the coding that underlies languages such as BASIC, FORTRAN, and COBOL. Using machine language is real programming, and quite difficult. It was to difficult for me to master even at a very simple level.

When I went for my interview at the Physiology Department at University College London (‘UCL’), the other candidates and I were shown the room containing a large computer, which the Department possessed. The staff were very proud of these advance machines that were able to process experimental data in “real time”. Information from the measuring instruments employed in the experiments was converted into numerical data that could then be processed statistically by the computer, and then displayed to the experimenters while the experiment was proceeding.

A week or two after my interview at UCL, I went for another interview, this time at the Physiolgy Department of Chelsea College (now long since closed). After I had been several questions by the Prof and some of his colleagues, they allowed me to ask any questions I had. Having been impressed by what I had seen at UCL, I asked:

“Do you use computers in your department here at Chelsea?”

“Of course, we do, all the time” answered the Prof immediately.

After a short pause, one of his colleagues said:

“Well … actually… we don’t have any computers in this college.”

Then the Prof said something, which I found rather pathetic:

“I can understand that your first choice is UCL. However, we would be happy to offer you a place in our department providing you will promise to accept our offer if UCL does not give you one.”

Fortunately, UCL did offer me a place on their course.

I gained admission to UCL, my first choice amongst the six universities to which I applied. During our first year, we had to take a course in physics. Once a week, we spent an afternoon in the laboratory carrying out practical work. One day, we were asked to write computer programmes to solve a chosen problem. I was the only person (in our class of fifty students), who could complete the task. No one else had a clue as to how to do it. They had attended good secondary schools all over the country, but only mine had offered teaching in computer science.

After that class in the physics laboratory in 1970, I did not touch a computer until about 1997. We bought a PC, because my wife needed one for her studies. When she was not using it, I experimented with it. It operated with one of the Windows programmes. I was flummoxed. It seemed quite different to what I experienced in the late sixties. How was I going to programme it? After a short while, I realised that things had moved on a long way since I learnt BASIC.


Image source: www.quora.com