I would go to the dentist. My dd chipped a tooth at aroun 16 or 17 months. We took her to the dentist only to find out that she has soft enamel, and has required regular dental care since then. I wish we had taken her before the chipped tooth, because at 18 months she had to have dental surgery, which included several fillings, caps on the front teeth and one pulled tooth.
I won't lie to you, it ain't going to be fun, but it will be worth it to go the dentist now. Best case scenario, your son's teeth are fine, and dentist smooths out the chipped one. Worst case, enamel problems, but you catch them now, while you can still do something about it. If you go, I recommend Rescue Remedy starting the night before to make the baby more calm for the visit.