Introduction to lean dentistry – By Dr Sami Bahri


Sami Bahri, DDS –

Why management?

Two events, among countless others, made me realize that learning business management could help not only businesses or individuals, but entire populations. 

The first event was in preparation for World War II (WWII), when the united states congress created a training program called Training Within Industry (TWI). In a record time, TWI transformed a variety of manufacturing plants into war manufacturing plants and helped win the war.

The second event happened at the end of WWII, when Japan was devastated by two atomic bombs. “To revive its collapsed economy, Japan focused on process management. 

Improved quality, combined with lower cost, created new international demand for Japanese products, which led to huge economic growth for Japan during the 1960s.”1 This focus on process management, generated a new management system pioneered by Toyota—The Toyota Production System (TPS) on which lean management is based.

Today, more than 80 years after its inception, Lean management is still the latest phase in our collective knowledge on business management. It has proven more successful than previous management theories at Toyota, in companies worldwide, and lately in healthcare in general and dentistry.

What is Lean Dentistry

Main goal

The ideal condition for lean dentistry is to be totally responsive to patients’ needs by treating them when they want, in the amount they want, without interruption between providers. 

But how to be this responsive when patient demand is so unpredictable? the answer is flexible business systems through two factors: short treatment lead times that allow to receive patients on a short notice and flexible job descriptions that allow staff members to work wherever needed to accommodate changing demand. 

When asked about the secret for Toyota’s success, Taiichi Ohno, the Toyota executive widely credited as the chief architect of the TPS, the model for lean management, defined lead time and gave it credit for Toyota’s success: “All we are doing is looking at the time line from the moment the customer gives us an order to the point when we collect the cash, and we are reducing that time line by removing the non-value-added wastes.”2

In fact, while experimenting with management practices, “Toyota made a critical discovery: when you make lead times short and focus on keeping production lines flexible, you actually achieve higher quality, better customer responsiveness, better productivity, and better utilization of equipment and space. this discovery became the foundation for Toyota’s success globally in the twenty-first century.”3

Lead Time in Dentistry

In dentistry, lead time is measured from the moment patients call for an appointment to the moment their need is fulfilled. That lead time needs to be constantly shortened by removing waste—activities that do not help in advancing treatment. 4

Examples of those wasteful activities have been classified as what became known as the seven wastes: Transportation of materials or patients to different parts of the office, inventory accumulation (our main inventory is invisible: treatments planned but unfinished), excessive motion of workers, waiting (anyone waiting for anything), overprocessing, overproduction –performing an activity too soon, too late, in excessive quantity, and defects passed on the next staff member or to patients.

Adjust the process design to eradicate waste

When we observe any of the seven wastes, we need to eradicate it. But beware! attacking waste directly is not effective. Because, just as pain is a symptom of underlying disease, the seven wastes are symptoms of underlying weaknesses in the design of your work systems.  

For example, when patients are in pain, you do not just prescribe analgesics, you treat the root cause of that pain. Similarly, if you see the waste of patients waiting, you cannot simply ask them to stop waiting, you must treat the root cause of the wait and adjust the design of your systems by following some established technical and social guidelines.

Technical and social guidelines to adjust the process design

The following technical guidelines—the mechanics of lean management, and social guidelines—how to lead people and keep them motivated, have developed over the last eighty years.

Technical guidelines

In making things, we know two techniques: batching, adopted by classical management, and one-piece flow, adopted by lean management. (Figure 1). To  varying degrees, processes are usually a mix of the two techniques.

Consider the theoretical case of three patients, each needing three crowns. Batching would consist of making one crown at a time on each patient, for a total of nine appointments. One-piece flow, which is the ideal lean process, would treat three crowns, on one patient at a time, for a total of 3 longer appointments: a savings of six appointments.

Figure 1: Lean adopts One-Piece Flow not Baching.

If you list all the support functions needed for each appointment, you will find that one-piece flow has saved a large number of steps, thus, a large amount of unnecessary effort that you can convert into productive efforts (Figure 2).


Figure 2: In one year we have saved 1796 appointments (25% of the total number of yearly appointments) multiplied by the number of associated supporting steps.

Note that for a practitioner who sees batching as the normal way of practicing dentistry, making six additional appointments— collecting six additional times, setting up and cleaning the rooms six additional times, etc.—would seem like normal and necessary work. In contrast, a lean practitioner would call them hidden waste disguised in the form of necessary work. The premise of lean management is to constantly look for that kind of hidden waste and remove it.

Technical requirements

To understand the technical requirements of lean management one needs to understand its two types of goals. The first type is called True-North goals; those cannot be reached all the time, but they set a direction for improvement efforts. The second type is Intermediate goals; reachable goals along the direction set by True-North goals. (Figure 3)

Figure 3: True-North goals give direction; Intermediate goals ensure progress.

There are four technical, fundamental principles to creating a lean management system. Those principles are also true-north goals that cannot be reached at a 100 percent, but trying to reach them will allow for sizeable improvements:

1. One-piece flow

One-piece flow is the ideal in lean dentistry. It means to treat, in as few visits as possible, as much as the patient condition allows, with no delays between providers, no rework, and no work left to be done after the visit is finished.

2. Level the schedule

Leveling is a simple way of managing the workload with the right number of resources—employees, space, time, or finances. It divides the workload into small parts, equal to the average load needed by every working time unit and distributed evenly over the available time.

To show the advantages of loading around the average, you can consider a practice that sees 10 patients one day and 190 the next day. Its average is 100 patients per day, but it must be equipped for receiving the maximum number of 190 patients. Now, if for every 10 patients you need one employee, this practice will need 19 employees. If that same practice sees 100 patients a day (the average), that same practice will need 10 employees instead of 19, to produce the same amount of dentistry. (figure 2).

Leveling the schedule is a simple calculation that distributes work evenly across the schedule. In our case, with that simple calculation we have saved 40% of the number of people required to handle the schedule and redirected them to grow the practice.

3. Quick changeover

As we have seen, one-piece flow is the ideal state of a lean dental process. It means to perform crowns, root canals, fillings, surgery, removable prosthetics, etc. in the same appointment, and move between these procedures very quickly. We will need to change our instruments quickly, and to turn the rooms over to the next patient quickly. 

Quick changeover is a science that has been introduced by a Toyota consultant, Shigeo Shingo5, who was able to reduce the changeover time of a large press from 4 hours to less than 10 minutes. We studied his principles and were able to change between procedures or change the rooms between patients very efficiently.

4. Synchronization

Synchronization means that the different procedures and the different providers need to work together like an orchestra or like a ballet. Providers come in time to perform their part of the treatment on their common patient without making that patient wait and without making the assistant or the hygienist wait either. 

In practice, synchronization can be very complex because many providers are working on many patients and they all have unpredictable conditions. That is why we found the need to create a new position called “Patient Care Flow Manager” whose job is to orchestrate the movement of providers and patients with the goal of directing providers where they are needed, at the time they are needed. The flow manager’s goal is to provide uninterrupted treatment to every patient. 

To communicate efficiently with providers, the flow manager uses a “Kanban” (a Japanese word meaning signal), containing all the information needed to allow them to go to the next patient just-in-time for treatment (figure 5)

Social Guidelines

All the technical guidelines mentioned above are unusable unless employees are willing to execute them. That is why engaging, and motivating teams, are crucial to the success of a lean program.

When it comes to motivation, a manager’s interests conflict with those of a leader. The goal of a manager to preserve processes stable and predictable; while a leader wants to improve them and take the company to ever higher levels. This dilemma becomes even bigger when you are both, the manager, and the leader. To combine both duties, you will need a system for preserving the standards but also for improving them.

Figure 4: Working around the average load is called Leveling. It requires fewer resources to handle the schedule.

Toyota, the model company for lean management, has found a way to satisfy a leader and a manager at the same time. I can summarize it as follows: 

Preserving and Improving Standards

The main weapon in a manager’s arsenal is standard work; it describes how a procedure must be done in that practice. In classical management practices, standard work is established by management; employees must follow it. 

In lean practices, we discuss the standard work with the team until we come up with a consensus on how things should be done to simplify work for everyone.

Although agreed upon by the whole lean team, the standard is nothing but a starting point for improvement. As they try it, most of the time people find it to work partially; let’s say in 70% of the cases. Then, the team discusses a solution for the remaining 30%. When they try the new solution, they usually find that instead of solving the 30% of the cases, it solves 10%, for example. They go back to discuss the remaining 20% etc. They keep repeating the cycle until they are satisfied that 100% of the cases are covered. That is what continuous improvement (CI) looks like.

How to achieve continuous improvement

As you can see from the previous section, continuously improving the standard requires full participation from team members. That is why it is very critical for a leader/manager to know how to keep them motivated, and willing to share their experience with the established standard. To that end, Fujio Cho, a former president of Toyota Motor Company has given valuable advice (figure 4)

Go See

Direct observation is more effective than reading reports. One way is to treat any problem like a crime investigation where you do not rely on hearsay. You go to the crime scene and observe any evidence that leads you to the source of the problem. Remember we are trying to find the source of the problem so we can change the design of our process not only treat the symptoms. 

Figure 5: The flow manager uses a Kanban to synchronize provider movements and allow for just-in-time treatment.

Show Respect

After practicing a job for a while, your employees get to know the details of their jobs, better than their managers. For that reason, when we look for solutions, we should assume that they know what they are doing and not blame them for the problem. Which leads us to the next section 

Ask what in the system caused that?

Management guru, W. Edwards Deming6 , said that 94% of the problems are caused by the design of the system not by unwilling employees. Consequently, when you find a problem, you must find what in your system has caused that employee to do an imperfect job.

So, we ask:” What in the system caused you to make that mistake?” then we go back and fix the system. One of the worst mistakes is to ask people to pay attention. We must assume that when people get tired, they tend to make mistakes. We need the systems and the environment prevent mistakes.

Figure 5: The flow manager uses a Kanban to synchronize provider movements and allow for just-in-time treatment.

Where to Start?

Grasping the lean principles requires practice. I suggest you start as small as possible, one dentist, one assistant, one front desk and one hygienist. Try one-piece flow on one simple treatment plan. Observe the obstacles and solve the problems they present. 

Based on what you learned move to more complex cases and finish them in one appointment. And continue adding more complex cases to the one-piece flow at the pace of your learning.


Lean management is the latest in our collective knowledge on business management. It seeks to eradicate all process waste. Seven wasteful activities have been described as symptoms of process waste. However, to remove those wastes, we do not attack them directly, but we go back to the process design and repair in it the part that caused the waste.

Our main criterium for a better process design is a shorter treatment lead time, to make the business more flexible and more responsive to the unpredictable variation in patient demand. Shorten lead times and create more flexible systems, we need to cater to the practical aspect of lean management—one-piece flow, leveling, quick changeovers and synchronization. and to the social (human) aspect of lean management—go see, ask why and show respect.

All processes must be continually improved by team members who can recognize hidden waste when it happens and know how to eradicate it. This brings us to the most important message in lean management, you must invest in people first, because they are the ones who will help you build and improve systems that will raise you to success and prosperity.


1. Anderson, Katie. Learning to Lead, Leading to Learn: Lessons from Toyota Leader Isao Yoshino on a Lifetime of Continuous Learning. Integrand Press. Kindle Edition.

2. Ohno, Taiichi; Toyota Production System: Beyond Large-Scale Production (Kindle Locations 38-40) Kindle Edition 

3. Liker, Jeffrey. The Toyota Way, 14 management principles from the world’s greatest manufacturer, second edition, McGraw Hill, 2021, p.13

4. Bahri, Sami; The lean dentist: Establishing one-piece flow in patient treatment. Lean Enterprise Institute, Inc., June 2016. 

5. Shingo, Shigeo; A Revolution in Manufacturing: The SMED System 

6. Deming, W. Edwards. The new economics for industry, government, education MIT, Center for advanced engineering study 1993 page 135 

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