[mrb]

You probably don't brush correctly: you need to apply sufficient pressure on your teeth so the bristles can scrub the enamel well enough. Or else there is no way your head has no visible deterioration after 5 months at 5 min per brushing.

[frowin]

The brushes have this sensor for a reason. Too much pressure may harm your gum. The article talks about a ultrasound brush, no pressure required.

[mschild]

The toothbrush has an integrated pressure sensor and starts vibrating when you apply too much

[mrb]

Then I don't believe you have no visible deterioration.