My son (9) has had his first set of molars for barely a couple of years, and based on a "shadow" seen on the X-ray for one of these molars, the dentist recommends drilling the tooth, cleaning out the decay and filling in the cavity with a composite. Is a shadow on the X-ray conclusive evidence of tooth decay? Does this necessitate an invasive procedure for such a new tooth (he cleans regularly, and does not have high sugar foods)? Would it be advisable to apply sealant and wait and watch?
As advice by the dentist may be the cavity is big enough requiring Chat Doctor.  Only in initial lesions we can go for sealant more so as a preventive procedure.