Stop pushing the camel through the eye of the needle: the pull principle

The pull principle is one of the core concepts of lean management whereby the flow of work is controlled by only replacing and replenishing what has been consumed. To better visualize a pull system, take a simplified example from orthodontics. Let’s assume that you start 200 new treatments each year and one treatment lasts three years. This means that in the first year, you see 200 patients, 400 in the second year, 600 in the third. From the third year onwards you complete 200 treatments every year, but you also start 200 new treatments again.

In other words, you have an even flow of 600 patients per year. For each patient you see off, you create a vacuum, a “pull” which can be filled with a new patient. Now you see every patient every 4 weeks for control with 600 checkups per month (150 per week). Substituting recalls and repairs would mean 200 appointments per week. You may need one day for administration, then you have four days with 50 appointments each lasting 15 minutes on average.

Scenario 1:

Say you’re working with an assistant on a treatment chair. If you’re taking 50 appointments per day each 15 minutes long, you are working an average of 750 minutes (12.5 hours) per day nonstop.

  • One possible way to prevent burnout is by shortening the appointment times. But that would mean compromising on interpersonal relationships and so it is not a viable choice.
  • The next possibility in orthodontics is for you to expand your practice to accomodate more treatment chairs. Spreading 50 treatments over three rooms can mean that you only need about 4 hours per day. While this sounds better, it also calls for more investments in a larger space and equipment, as well as higher personnel expenditure including salaries, training, etc.
  • Another extremely effective method is to simply change the control intervals. If you increase the control intervals from 4 weeks to 8 weeks, the number of control appointments would be reduced by 50%! This means that with 3 rooms, 3 assistants, and 8-week intervals, you could theoretically reduce the workload to about 2 hours per day.
  • Instead of risking overrun of all three treatment rooms with a jam-packed patient waiting list (some patients may arrive early), you can close the two rooms and only work in one. This allows the assistants and dentists to be synchronized, goal-oriented, and provide better and faster results.

Scenario 2:

You start 200 treatments a year, and by the third year, you’ve compiled 600 treatments because you finish as many treatments as you start. In an attempt to meticulously manage time, you decide to work with three assistants in all three treatment rooms, working up to 4.5 hours on three afternoons a week.

A challenge you’ll face, here is that the appointment times will keep getting shorter all the while your team suffers massive overtime. And all for what? Your income will essentially remain the same despite the overload. Yet, the quality of your treatments suffers exponentially. In over 80 percent of cases, it‘s actually not the number of started treatments but the inefficient treatments that last longer than planned. Inefficient work must be optimized. You have to finish your treatments on time; the planning has to be improved! Otherwise, you‘ll work more and achieve less.

Bottlenecks rationalize WIP that stands for “Work In Progress” and defines the number of tasks that are pending. Remove the bottlenecks and you’re looking at a more successful approach of workflow in your practice.

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