Does the caloric count of bread decrease if the bread is toasted?
Yes but not in a manner significant enough to matter for any real purpose you would be concerned with. All forms of cooking destroy at least some of the caloric content of the food, many forms of cooking involve oils and fats being added so there’s a net increase in calorie count in the finished product, but just simple toasting would destroy some of the bread, and thus lower the calorie count–very minutely.
Mostly what toasting does is remove water content from bread, and water has no calories.