when you eat sugar, enzymes in your saliva start to break down the sugar in your mouth. One of the products of that reaction is lactic acid. Also there is bacteria in everyone's mouth that causes cavities, and thrives on a sugar environment. The problem with sucking on sweets for extended periods of time, or also on another note, slowly sipping soft drinks for extended periods is that it basically creates an acid bath which destroys your teeth. There is also the issue of eating excess sweets which can lead to weight problems and type 2 diabetes. I would suggest that some sweets are ok but you would be better off eating something that doesnt stay in your mouth a long time. And remember always brush after eating! Good luck!