Yes, removal of your son’s front teeth would definitely affect his ability to make words like “feelings” and “four.” Very slowly, make just the initial “F” sound yourself. Notice the importance of your upper front teeth. Without them, the “f” sound is difficult. From the things you mention (knowing his ABC’s, his ability to count) it sounds as though he is developing normally for his age. Unless he has other disabilities you do not mention, it does not sound as though he would need to be in any sort of special educational program.
Our parenting advice is given as suggestions only. We recommend you also consult your healthcare provider, and urge you to contact them immediately if your question is urgent or about a medical condition.