Could excess iron levels be causing my tooth decay?

Not Likely. Unless you are sucking on a sugar based source of iron, iron supplements are generally swallowed and not a source of increased decay. If you have dry mouth associated with the reason for your iron deficiency, then the dry mouth condition can increase decay.
Bacteria and sugar. Decay is caused by bacteria which are naturally occurring in your mouth. When the bacteria are fed sugar, either simple like sweets or complex like bread or sugar, they produce acid which eats into the tooth.
Iron and teeth. Excessive iron in the body does not lead to increased decay. We can see discoloration occur when iron levels are high in young children as the iron incorporates into the developing teeth. Once the teeth are erupted iron will not affect them.
Probably not. High iron levels have not been shown to be a cause of tooth decay. Tooth decay is a bacterial process enabled by food debris left around the teeth.

Related Questions

I really get cofused many search on net say phayte acid cause osteoprosies and tooth decay as it bind to ca and iron what should I do or believr>?

Interesting. Phytic acid is both an anti-nutrient in that it binds dietary sources of iron very efficiently ans well as zinc, calcium and magnesium. It is also considered an anti-oxidant since it binds free radical iron so it is a complex nutrient to fully understand. I don't think it can lower oral pH enough to directly affect tooth decay as many other acids do but it does affect calcium metabolism. Read more...
Pseudoscience. There are lots of anecdotal stories, but there are no extensive studies or evidence that show that phytic acid will create mineral deficiencies and cause osteoporosis or tooth decay. Read more...