Yes if u have a tooth in the sinus then the no. of complications that might occur during its extraction are more.Usually it may lead to sinus infection known as sinusitis that causes the pus to accumulate ,also causing the swelling of the lining of the sinus mucosa which leads to blockage of nasal tracts.Thus it even puts pressure on other teeth and can cause their displacements.,The most important thing u can do is go to an experienced dentist (oral surgeon ) who has experience of dealing with such cases as there will be less complications post operatively if u get operated by experienced hand ...........for more info refer the link..........http://www.identalhub.co/articlecategory-wisdom-teeth-47.aspx