A large majority (65% to 80%) are of the benign tubular type with 10% to 25% being tubulovillous, and villous being the most rare at 5% to 10%.As is evident from their name, sessile serrated and traditional serrated adenomas (TSAs) have a serrated appearance and can be difficult to distinguish microscopically from hyperplastic polyps. Making this distinction is important, however, since SSAs and TSAs have the potential to become cancers,  while hyperplastic polyps do not.The villous subdivision is associated with the highest malignant potential because they generally have the largest surface area. (This is because the villi are projections into the lumen and hence have a bigger surface area.) However, villous adenomas are no more likely than tubular or tubulovillous adenomas to become cancerous if their sizes are all the same. Hamartomatous polyp
Hamartomatous polyps are tumours, like growths found in organs as a result of faulty development. They are normally made up of a mixture of tissues. They contain mucus-filled glands, with retention cysts, abundant connective tissue, and chronic cellular infiltration of eosinophils. They grow at the normal rate of the host tissue and rarely cause problems such as compression. A common example of a hamartomatous lesion is a strawberry naevus. Hamartomatous polyps are often found by chance; occurring in syndromes such as Peutz–Jegher syndrome or Juvenile polyposis syndrome. Peutz–Jeghers syndrome is associated with polyps of the GI tract and also increased pigmentation around the lips, genitalia, buccal mucosa feet and hands.
The extraction of a maxillary tooth (typically a maxillary first molar which lies close to the lowest point of antral floor although any premolar or molar can be affected) is the most common cause of an OAC (which can then progress to an OAF as described above). Extraction of primary teeth are not considered a risk of OAC due to the presence of developing permanent teeth and the small size of the developing maxillary sinus. Other causes
Other causes of an OAC are: maxillary fractures across the antral floor typically Le Fort I, displacement of posterior maxillary molar roots into antrum and direct trauma. An OAC can happen for many other more unusual reasons, such as acute or chronic inflammatory lesions around the tip of a tooth root which is in close proximity with the maxillary antrum, destructive lesions/tumours of the maxilla, failure of surgical incisions to heal (e.g. Caldwell-luc antrostomy), osteomyelitis of the maxilla, careless use of instruments during surgical procedures, Syphilis, implants and as a results of complex surgery (for example removal of a large cysts or resections of large tumours involving the maxilla. Diagnosis
Clinical examination and x rays can help diagnose the condition. For examples :
Valsalva test (nose blowing test): Ask the patient to pinch the nostrils together and open the mouth, then blow gently through the nose. Observe if there is passage of air or bubbling of blood in the post extraction alveolus as the trapped air from closed nostrils is forced into the mouth through any oroantral communication.