The 30-minute crown preparation

Some achievements in human history need no introduction. Sir Edmund Hillary climbing Mount Everest. Neil Armstrong landing on the moon. Roger Bannister running the 4-minute mile.

In dentistry our achievements are quiet but still meaningful. We turn up every day trying to meet our patients' needs. One way of measuring our effectiveness is by how long we take to do our work and a common benchmark for that is the crown preparation. For most dentists, knowing how to do a crown preparation faster — without sacrificing quality — is one of the highest-leverage efficiency improvements available.

Having watched dozens of dentists at work it's typical for them to take 60–90 minutes for a crown preparation. However, more than a few dentists do it effortlessly in 30 minutes or even less. If you can achieve this, without sacrificing quality, you are well on your way to being successful.

Those three words — without sacrificing quality — matter enormously. There's no sense in working fast if you produce poor results. Working fast only makes sense if you produce clinically acceptable results.

If you can work fast with acceptable quality your patients will love it, your staff will love it and best of all, you will love it. You can go home earlier, earn more or both. This article covers the basics of how the 30-minute crown preparation is achieved.

Before we get into the nuts and bolts of the procedure there are two things that we need to cover.

The hidden cost of slow dentistry

One of our major challenges in dentistry is iatrogenic damage — damage we cause while performing treatment. Understanding how to minimise iatrogenic damage in crown prep is not just an efficiency question — it's a clinical one, and the two turn out to be the same answer.

As we all know there's a pulp sitting inside vital teeth and it can be upset pretty easily. Heat it up too much, dry it out too long, expose it to oral fluids for an extended period and the result can be the problem we all want to avoid — irreversible pulpitis.

Across the lifetime of the tooth pulpal damage is cumulative. Odontoblasts don't sit inside the tooth saying: "Cut me. Oh that was nice, cut me again." They don't like being cut. In general surgery it's widely recognised that the longer the operative time, the greater the morbidity. The same applies in dentistry.

To minimise iatrogenic damage it's important to prepare teeth rapidly and then get the tubules covered.

What patients actually want

I was speaking recently with a lady I met socially and she was rubbing her jaw. I asked her: "What happened?"

She told me that she had been 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 and they both produced the same result, which would you choose?"

She looked at me like I was stupid and replied: "30 minutes of course." But then she continued by saying something profound: "I would gladly pay an extra $200 to have the 30-minute technique rather than the 90-minute technique."

Let that sink in for a moment.

Dentists often think they are getting paid for time — the more time they take the more they should charge. If a procedure goes extra well and is completed quickly we sometimes discount.

But patients love short treatment times. There is nothing more satisfying than when a patient sits up after a crown preparation and says with a smile on their face: "That was so much better than last time!" This is one of the most underappreciated dental efficiency tips for crown preparations — speed, done well, is itself a clinical outcome that patients notice and remember.

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 30-minute crown preparation is not just doable, it's easy. Let's look at the factors one at a time.

Materials

Materials matter more than most dentists realise — and the right choices eliminate minutes from the clock. Getting the dental crown preparation technique right starts here, before the bur touches enamel.

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. A fast-setting PVS in a quadrant tray works brilliantly. If you put it into the mouth the moment the LA comes out the tooth will be numb by the time it has set.

Then you need a sharp high-speed bur in a high-torque handpiece. Electric motors combined with red-band handpieces are great for this — you lean on them, they cut. Air turbines drop RPMs the moment you start to cut so if you listen to dentists prepping teeth you hear them backing off repeatedly to get the speed back up. By the way, red-band handpieces are great for cutting through non-precious alloy.

How many burs do you need? I've seen crown kits with 9 burs but mostly for posteriors I only used one bur. The extra efficiency I might have gained by changing burs wasn't compensated for by the time taken to change them.

Next you need a rapid reliable haemostatic agent and perhaps cord. Note that I said "perhaps cord." In molars I created supra-gingival margins whenever possible. Burying margins, as I was taught to do in dental school, only leads to recession.

Next you need a reliable impression material such as a good quality PVS or a scanner. If there are 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 temporary material and cement come in an automix syringe then so much the better.

Staff

Would it shock you if I said that 90% of the practices I have visited are understaffed? 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 series of other jobs. If you want to work effortlessly you need two nurses totally focussed on you. Fewer nurses than that and you have to slow down and wait for things to be ready. This is one of the most practical ways to reduce crown prep time — and it costs far less than the productivity it unlocks.

Understaffing is false economy. When I changed to two nurses twenty years ago my treatment times fell by 40%, and I was no slouch to begin with. The extra nurse means that everything is ready the moment I need it. There is no waiting.

Ask yourself: "If I became 40% more productive would that pay for an extra nurse?"

Systems

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, and 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 comes 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.

Dentist

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 to old, comfortable but inefficient ways. They need to be committed to constant improvement. To constantly be thinking: "If I did it this way instead, would it save time?"

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 a couple of minutes. If I hear the handpiece starting and stopping continuously then I know that they're slow. Many dentists use the handpiece like 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 improve your efficiency here is a good discipline: keep your foot on the pedal and the bur on the tooth.

At first doing this may seem 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.

Seriously. You don't need to stop every 10 seconds to admire your work. Just get on with it.

My personal experience with putting those factors together changed my life. A patient who came in with a broken tooth was able to walk back out the door 30 minutes later with the temporary in place. The best time I ever achieved for a crown prep from when the patient sat down to when they were finished with the temporary in place was 14 minutes.

Conclusion

Hillary, Armstrong, and Bannister didn't achieve their landmarks by accident. They prepared, refined, and committed. The thirty-minute crown preparation asks for the same — the right tools, the right team, the right systems, and above all, the resolve to keep improving.

Make that investment, and the rewards flow in every direction — to your patients who leave the chair relieved rather than exhausted, to your team who work with flow rather than friction, and to you, with time and energy left over at the end of the day for the life you actually want.

That's well within reach. The only question is whether you're ready to start.

If you'd like to go deeper on dental efficiency tips and systems, my Efficiency course covers the full system built on decades of real chairside experience. You might also find The Productivity Paradox and The Jack of All Trades Is Going Broke useful companion pieces.

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