The dirt will still be trapped inside of the CV joint, so after a while the CV joint will go bad. Dirt kills CV joints. You could change the boot, but you would have to take the joint apart and make sure you get all the dirt and sand out. If you catch it fast enough, you can get away with just changing the boot, but if the boot has been broken for a while then chances are that the joint is gonna wear out quick.

 

Agent the dirt will not stay trapped,, i just said,,CLEAN THE CV JOINT ,,spray carb cleaner, rinse off with water and repack it with grease ,, trust me like i said i have done hundreds of these .. And it is not dirt that kils cv joints is lack of grease and the metal bearings in the joint rub against each other with no lubrication and start to wear .., that is the main reason why a joint goes bad when the boot tears ,, as the wheel turn , the grease will be all spitted out .(.centrifugal force ).
If the joint is not noisy,,, remove the axle, clean the joint. repack with grease install a new boot and you are set to go..
with the 60 dollars you save take your wife ( girlfriend ) to dinner ..