I'm a ex-dentist and holder. In my view, this announcement was...

I'm a ex-dentist and holder. In my view, this announcement was to be expected - dental surgeries are temporarily closed and even the ones open for emergencies will not be using as much resin (aesthetic product) or whitening products (although patients may still be dropping into practices that are open to pick up refills). Even in toothache situations, there are products other than resin that can be more quickly be placed as a temporary measure.
However in my experience, the increase in cosmetic dentistry is unlikely to be dimmed for long once things return to normality. Patients now of both sexes and all ages are extremely appearance conscious and will often scrimp and save to afford an upgraded appearance. Things that will drive sales in the long-term will be a perception by dentists that the product gives a better aesthetic result / has easier handling properties than other products on the market.
The decline in amalgam sales is terminal and will never be reversed.