Maples unfortunately are somewhat prone to this kind of bark-splitting. The good news is that they often are able to heal the wounds and recover. There are many causal factors that can contribute to this happening. The actual split probably occurred in an event know as frost-crack. This happens when thin-barked trees are exposed to sudden changes in temperature. For example, during the winter when the sun strikes them in the morning. The problem can be more likely when trees are fertilized during the growing season because this leads to vigorous growth and thinner bark. Try to avoid making summer lawn applications of fertilizer that are within the reach of the trees roots (the drip line).
To hasten this tree's recovery I would recommend minimizing the amount of moisture that reaches the wounded portions of the trunk. You can carefully cut away the loose bark, but try not to damage any of the wound healing callous tissue. Removing the loose bark will keep moisture and pests from gathering underneath. If you can adjust the sprinkler system so that it does not strike the trunk of the tree, that would also be a great idea. You will probably see some early fall color in portions of the canopy supplied by the vascular cambium on that side of the tree this year. However, with some TLC this tree will hopefully provide you with many more years of service.

Should we apply any wound dressing on the area that has lost it's bark?

Wound dressing is not recommended.