Does the tire tread reduce the likelyhood of getting a puncture? I've been using the last year thickslicks to driver mainly inside my city and I usually tried to don't go through anything else but asphalt to prevent punctures.

I've been wondering if going through a rocky path (or something similar with lot of little rocks) with thickslicks (700x28)  and pressure around 100psi is more likely to get a puncture than the traditional wider and with tread tires that most MTB bikes have.

Example with no tread:



And with:
It depends. Tread pattern affects puncture probability in two opposite ways:


Slick tires often, but not always, have thinner rubber, which offers less protection.
Knobs are generally too thick to be punctured through and put some distance between ground and the flat parts of the tire, but on the other hand the part between knobs may be very thin.
Tires with grooved tread may be punctured because small pieces of gravel or glass get stuck in grooves and eventually dig through the rubber. This happens very rarely with slick or knobby tires.


In your case, you should be worried about pinch flats, which happen when the tire is pinched between a rock and rim. 28mm may be just enough for smooth cobblestone roads but is very narrow for rocky or soft terrain.