thanks 2thdoc for ur reply 🙂 ,
wel i asked the same question from my oral path professor, he also told me that according to his experience in a normal health oral cavity ideally these changes doesn't have any effect nor he had experienced any complain. but he pointed out tht there is transient decrease in immunity of person due to rapid change of oral cavity temperature so in immunocompromised patients there is increase in chance of infection.
also he said that it good to have cold thing after a hot drink because hot stuff causes more damage to oral soft tissue and also GIT lining.
so thts all i til now had come to know