By contrast veneer porcelain (or even metal) will cause wear on natural dentition due to its highly porous structure which acts like sandpaper.
 
To illustrate this phenomenon by a practical example: Rub wood against a smooth glass pane and nothing will happen but, rub wood against wood and it will splinter. As two materials of the same kind meet (tooth against tooth), natural dentition will inevitably wear also. However, when natural tooth meets smooth Zirconia (like wood against glass) no abrasion occurs.

The abrasive nature of any material is determined by its degree of surface polish and inherent density.

The ”softer” enamel will glide over polished, much harder Zirconia without wear.

The study results in short: by zirkonzahn company 
-  Polished Zirkonzahn Prettau Zirconia causes practically no abrasion.

 Veneer porcelain as well as natural dentition cause more abrasion than polished Prettau zirconia.