we removed this update and MathType worked fine.

KB3178674

I've experienced the same problem and removing KB3178674 solve the issue.
The display problem in word 2016 disappeared immediately.
Don't forget to exclude KB3178674 from the updates.

KB3178720 published yesterday solve the issue inside Word.
BUT the issue come back in PDF if you create it by save as / pdf format.

The only solution for now is to uninstall KB3178720
Don't forget to exclude KB3178720 and KB3178674 from the updates list.

Microsoft know the issue and is searching for a solution: https://support.office.com/fr-fr/art...e-e337ae8f0b86
But Microsoft don't tell us when the solution will be published... Let's see what happens next Tuesday...