Do aircraft dump fuel before landing?

Not normally.

This is an emergency procedure sometimes done because the maximum takeoff weight is usually larger than the maximum landing weight on aircraft carrying large passenger or freight loads.

The dumping of fuel is one action that can be used in an inflight emergency; however, I can guarantee that the takeoff weight of ANY aircraft (unless refueled in flight) is ALWAYS greater than said aircraft's landing weight. Fuel used enroute will always reduce the gross landing weight.

Aircraft are generally serviced with enough fuel to make its primary destination and an alternate runway (due of emergency). The landing weight can be adjusted by dumping fuel (normally) in case of damage to the aircraft or destination runway conditions (snow/ice, rain) requiring a lighter aircraft gross landing weight.

Naval aircraft operating from Carriers routinely dump fuel to adjust for landing conditions (wet deck, reduced landing area, slower ship speed into the wind, etc...).