The Math of Dental Practice Growth


By David J. Ahearn, DDS & Timothy Gagnon

Practice growth is a topic that many people address, but few are successfully able to predict with accuracy. It’s no mystery though. Take away the crystal ball, smoke and mirrors and what do you have left? Numbers. Once you have your marketing, staffing and clinical mastery in order, you’ll find a pretty steady stream of New Patients (“NP’s”). While operative needs for these patients will vary, most will fall into a very predictable hygiene schedule, which then forms the basis for a very functional predictive model.

Let’s say you raise your NP average to 100 per month. If the average NP visit is 90 minutes with a hygienist (full exam and cleaning), that equals 150 hours of hygiene each month. (An important premise of this article is that NP’s are seen primarily in Hygiene columns, not Doctor columns. We assume Doctors in a growing practice will be – and should be – occupied with doing dentistry.)

Maybe you can handle this with your present staff, maybe not. For the purposes of this article, we assume that – RIGHT NOW – you’ve geared up for the influx of NP’s soon to be walking through your doors (if they’re not already). With that said, what we’ll address here is the fact that New Patients become Returning Patients… and you need to be ready for the long-term growth impact of that.

How many of those NP’s will become long-term patients? First, you have to figure that about 20% of all NP’s will be transient emergency cases. Once their critical needs are met, odds are they aren’t likely to re- turn on a regular basis. This leaves you with 80 effective NP’s per month, of which some percentage will fall into a regular 3 to 6 month cleaning schedule. This is your recall percentage. What’s a good recall rate? 70% would be great, but we’ll work with 50% to be conservative.

So…(ignoring Perio maintenance patients) in just 6 months, 40 of those 100 NP’s will come back for a cleaning. At 50 minutes per cleaning visit, those 40 returning patients represent about 33 NEW hours of hygiene EACH month after 6 months… or about a quarter of a full-time hygienist’s schedule (140 hours). Those 33 hours keep getting added to the schedule every month, but as New Patient #1 returns for their second bi-annual hygiene appointment (at 12 months), those 33 hours begin to stack and your schedule now has 66 additional hours, or about one-half of a hygienist’s monthly capacity.

This cycle repeats, continuously stacking 33 new hygiene hours a month as long as you keep bringing in new patients, and they keep returning at six month intervals. In 24 months, you’ve added enough hours to require an additional full-time hygienist. In fact, if you haven’t hired a part-timer before now, then your staff is probably feeling the strain.

Total Hygiene Hours per Year Based on 80 Effective NP’s per month with a 50% Recall Rate

At 12 Months:

2400 Total Hygiene Hours
640 hours of Recall Cleanings

At 24 Months:

3040 Total Hygiene Hours
1280 hours of Recall Cleanings

At 36 Months:

3680 Total Hygiene Hours
1920 hours of Recall Cleanings

Recall Cleanings constantly increase your total Hygiene hours. At some point, depending on your Recall Rate, they surpass the combined hours spent performing NP Exam, Initial Cleaning and Perio.

“Hey, what about Perio?”

Right. Roughly one-third of all NP’s are likely to have periodontal needs. This is because they aren’t just new to you – it’s likely they haven’t sought regular dental care from anyone for years. Of the initial 80 effective NP’s, about 13 will be scheduled for immediate recall (within a few weeks, typically). At 60 minutes per Perio treatment, these patients will add an additional 13 hours of hygiene time per month on top of their initial exam and cleaning. This adds to the total initial hygiene hours required per NP.

“Great. But hygiene is only part of my practice… how does that help me predict total growth?”

Now let’s apply this to your practice production as a whole. A pretty standard ratio is three full-time Hygienists (running three columns of hygiene), to one full-time Doctor (running two columns of operative with one column of overflow). At this ratio you’ll need to add an associate for every three hygienists you bring on. We’ve already calculated that 100 NP’s per month require one new hygienist every 24 months (or sooner, depending on recall percentage)… meaning that in five to six years, you’ll need to bring on three new hygienists and one new associate – and have somewhere to put them!

While you might be startled by these numbers, remember… this doesn’t take into account above average recall percentages or the demand of your existing patient base. The graph (right) shows the impact of increased Recall Rates. At 70% recall, the 24 month hygienist cycle drops to only 18 months, compressing the expansion time-frame considerably.

“OK, I’ll think about it for a few years. I’ve got time.”

Not as much as you think. Remember – growth is a continuous process. You won’t come to work one morning and say, “OK. Time to add three Hygienists and find an Associate.” Long before that point is reached, most practices start to feel the squeeze. You very well may want to begin assessing your present space’s potential – or limitations – right now. Do you have room for another Hygienist? What about three? Where would you put an associate? What about increased support staff? Will the staff lounge accommodate these increasing numbers?

The average concept-to-completion time-frame for construction is nine to twelve months. By the time you need to bring on an associate with two-to-three rooms of their own, if you haven’t started planning for it, you’re already a year behind.

The clock is ticking, and the numbers are starting to pile up…




Still unsure about that expansion?

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