The thirty-minute crown preparation

By Dr Mark Hassed

In human history there are some famous achievements that most people remember.

Sir Edmund Hillary climbing Mount Everest. Neil Armstrong landing on the moon. Roger Bannister running the 4-minute mile.

In dentistry we don't have such landmark achievements but we all turn up day after day trying our absolute best to do good, consistent high-quality work for the people we treat.

One way of measuring our effectiveness is by how long we take to do our work and a common benchmark is the crown preparation (or inlay / onlay preparation).

Typically dentists take 60-90 minutes for a crown preparation but it is possible to do it effortlessly in 30 minutes.

If you can achieve this task efficiently (without sacrificing quality) you are well on your way to being a successful dentist.

Please note well the words “without sacrificing quality”. There's no sense at all working faster if you produce garbage. Working faster only makes sense if you produce consistent high-quality.

If you can work faster with high-quality then your patients love it, your staff love it and best of all, you will love it. You get to go home earlier, earn more or both.

This article covers the basics of how the thirty-minute crown preparation is achieved.

Why faster is better 1

One of our major challenges in dentistry is iatrogenic damage — damage we cause while performing treatment.

As we all know there's a pulp sitting inside every tooth and it can be upset pretty easily. Heat it up too much, spend too long drying it, expose it for too long to oral fluids and the result can be that problem we all want to avoid — irreversible pulpitis.

Across the lifetime of the tooth pulpal damage is cumulative. Odontoblast don't sit inside the tooth saying “Cut me. Oh that was nice, cut me again.” In general surgery it's widely recognised that the longer the operative time, the greater the morbidity. Why is that not recognised in dentistry?

It's important for every dentist to prepare teeth as rapidly as possible and then get the tubules covered. This is the way to minimise iatrogenic pulp death.

In order to achieve the thirty-minute crown preparation four factors need to come together — materials, staff, systems and dentist. When all those factors line up a thirty-minute crown preparation is not just doable, its easy.

…four factors need to come together — materials, staff, systems and dentist…


Here are just a few short ideas on materials.

The first thing we need is rapid profound anaesthesia. Articaine fits the bill nicely.

Administered as an infiltration (even in the lower jaw) and then massaged into the bone it gets teeth numb inside two minutes.

Next we need an impression for the temporary. If you want to waste time with alginate, be my guest. A better way is to use a fast-setting PVS alginate substitute in a quadrant tray.

If you put it into the mouth the moment the LA comes out the tooth will be numb by the time it's set.

Then you need a sharp high-speed bur in a high-torque handpiece. Electric motors combined with red-band handpieces are best for this.

Next you need a rapid reliable haemostatic agent and perhaps cord.

Note that I said “perhaps cord”. In molars we should try and use supra-gingival margins whenever possible. Burying margins (as I was taught to do in dental school) only leads to later recession.

Next you need a reliable impression material such as a good quality PVS. If there adjacent teeth for guidance then, for a single crown, triple trays work well and give dependable results.

Finally you need a temporary material and temporary cement. If the cement comes in an automix syringe then so much the better.


Why faster is better 2

I was speaking recently with a lady I met socially and she was ruefully rubbing her face.

I asked: “What happened?”

She told me that she was at the dentist that day and they had spent 90 minutes “drilling on my tooth to make a crown.” She continued: “It was one of the worst experiences in my life!”

I asked her: “If there were two ways to do a crown. One that took 30 minutes and one that took 90 minutes which way would you choose?”

Of course she replied “30 minutes” but then she said something very interesting: “I would gladly pay an extra $200 to have the 30-minute technique rather than the 90-minute technique.”

Patients love short treatment times.

There is nothing more satisfying than when a patient sits up after a crown preparation and says with a big smile on their face: “That was so much better than last time!”


Would it shock you if I said that 90% of the practices I have visited are under-staffed? And, I think I'm being conservative.

There's no way you can work with decent efficiency if your nurse has to answer the phone, make appointments, do the sterilisation and a whole series of other jobs.

If you want to work effortlessly you need two nurses totally focussed on you. Fewer nurse than that and you have to slow down and wait for things to be ready.

Under-staffing is false economy.

When I changed to two nurses a decade ago my treatment times fell by 30-40%. And, I was no slouch to begin with! The extra nurse means that everything is ready as soon as it is needed. There is no waiting.

Ask yourself: “Does it make sense to save money on wages by cutting my productivity by 30-40%?”

Or, to put it another way, “If you became 40% more productive would that pay for an extra nurse?”


I could talk all day on systems. Put simply, systems are what you do and the order you do it in.

For every task and procedure in your office you should have a standard way of doing it that is:

  • understood and followed by every staff member
  • planned and carefully thought through
  • updated whenever better ways of doing things are discovered

Here are just a few things to think about.

How long does it take you to set up for procedures? In many offices setup times are long. I once saw an office where it took 16 minutes to set up for a root filling.

Are you sequencing things correctly? You can use the LA time or the setting time of materials to do other tasks.

Do your staff know what's next? So many dentists seem to make it up as they go along so their staff has to sit and wait for instructions instead of getting things ready in advance.

Why faster is better 3

Like everyone else I'm getting older. And, I want free time to do other things with my life.

Sure, dentistry is still fun but not to the extent I want to work at it for long, long hours.

Imagine if you could produce the same amount of dentistry you do now but do it in 30%, 40% or even 50% less time? Think of the impact that would have on your life.

Your staff would like it too. Sitting watching you go round and round a tooth drilling for 40 minutes is dull. Staff like variety and flow.


I'm not going to deceive you — it takes discipline to change and improve.

Mostly that discipline has to come from the dentist. They must resolve to get better and not revert back to old, comfortable but inefficient ways.

When I hear dentists work I can often tell how efficient they are just by the sound.

If I hear the handpiece running continuously I know the dentist is efficient. The drilling time for a crown preparation is typically less than 5 minutes.

If I hear the handpiece starting and stopping continuously then I know that they're slow. Many dentists use the handpiece like they are a little bird pecking at the tooth. Dit – dit – dit – dit – dit – dit.

When a dentist works in this manner the drilling time for a crown preparation can be 30 minutes or more. If you want to become more efficient in how you work here is a good discipline to try: Lift your foot off the pedal as seldom as possible.

Keep the handpiece running and keep the bur on the tooth.

At first doing this may seem way too fast, but with practice it becomes natural and easy. You will start to think ahead of the bur if you do this — planning your next cut as you are completing the last one.

The same suggestion applies with an ultrasonic scaler. Keep the foot on the pedal and the scaler tip on the tooth. Seriously. You don't need to stop every 2 seconds to admire your work. Just get on with it!

The dentist also needs to be committed to constant improvement. To constantly be thinking in their mind: “If I did this instead of this would it save time?”

The dentist needs to commit to the right staffing levels and getting the right materials. The dentist needs to have fully-functional equipment and sharp burs.


The thirty-minute crown preparation is easily achievable with high quality by any dentist.

It just takes the correct materials, staff, systems and most importantly the right attitude from the dentist.

The question is whether you're prepared to pay the price to achieve this level of mastery.

Adelaide 7 October

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