How to get to the root of any problem much faster than before – the 5-W questioning method

Taiichi Ohno affirmed that the basis of Toyota’s scientific approach is to ask five times why a problem occurs in order to be able to learn the nature of the said problem and its relevant solution. When you encounter a problem in your practice, the 5-W questioning method modeled by the Toyota Production System becomes incumbent.

So, what are the five Ws? The five Ws or five Whys are questions whose answers are considered fundamental in information-gathering. These questions require basic discipline, so the next time a problem arises, ask yourself why five times. You’ll see that you end up with a very different result and insight than you thought.

For example:

A patient appears with a detached bracket at an SOS appointment in the afternoon.

The 5-Why method is then put into action from which respective answers are concluded:

1. Why is the bracket loose?
   Because the adhesive bond did not hold. (The composite must be changed. We need material from another manufacturer.)
2. Why didn‘t the adhesive bond hold?
   Because it was detached from the tooth, it is still preserved at the bracket. (During the preparation the assistant did not pay attention to a correct suction.)
3. Why did it break away from the tooth, but not from the bracket?
   Because the moisture control was not good at the gluing phase. (The assistant didn‘t keep a dry field properly. Or: The patient had too much saliva, it was glued at lunchtime. Or, the assistant had to wait too long for the dentist, so it was almost impossible to keep the teeth dry).
4. Why wasn’t moisture control good during the gluing phase?
   Because that day the suction was defective. (Another suction device must be purchased. Or: Probably the entire suction system is already too old and must be replaced.)
5. Why was the defective suction device not replaced before gluing? Because it was not checked in the first place. (Ok, the assistant was to blame after all …)

Possible conclusions you can derive from this practice of 5-Why questioning:

1. The functionality of the chair must be checked in the morning before the first use
   1. Staff training
   2. Creating an operating procedure
   3. Regular checking of the operating procedure
2. Create an emergency plan
   1. Replacing the suction and ordering a new one
   2. Call technician if necessary
   3. Carry out work on another treatment chair, exchange work, if possible

As you practice the 5-W questioning in casual chains, you must remember to avoid asking why more than five times. Here, the 80/20 rule is applicable, in adherence to which additional questions are not directly proportional to information or knowledge gained.

A weakness in the 5-Why method should not be overlooked, however, as it is ideal for “single-track” linear problems. As soon as a multifactorial event is found to be at the root of the problem, the individual branches of the causal chain must be eliminated individually. Nevertheless, the need for the 5-W questioning system is elementary for all levels of the system and must be practiced by all employees at all times.