Oral Surgery refers to the surgical procedures that may be performed on the tissues of the mouth, including the gum, jaw bone, tongue, and other tissues.
It can be performed by oral surgeons or periodontists.
It includes: Tooth Extractions, Dental implants, gum surgery, bone grafts, removal of cysts in the mouth, reconstruction of missing structures etc.

Extraction:

Extraction involves the pulling out of a non-restorable tooth under local anesthesia, employing special instruments. It’s a non-painful procedure because of the proper anesthesia, however, it requires special post-operative care. The vacant space left behind after removal of the “root”shall be replaced with bone naturally by the body. However this bone if not stimulated by function will start to shrink “resorb” causing volume loss and may also cause tilting of the neighboring teeth and even elongation of the opposing teeth. Which subjects them to plaque and decay.
It is always advisable to replace a missing tooth as soon as possible (within 3-6 months ideally) before further losses are encountered.

Dental implants :

Dental implants are considered artificial roots that will carry the new crown which replaces the missing tooth. They are made up of metal posts (titanium) which is biocompatible and integrates with the jaw bones firmly within 2 months. They are surgically positioned into the jawbone beneath your gums. They are of a superior quality when it comes to tooth replacement options.
The main advantage of a dental implant is that it prevents further bone loss (which happens naturally after tooth loss) by mimicking the previously existing root. It also further stimulates the remaining bone to become stronger with time, and it spares the neighboring teeth from being cut down (and so become weakened) if a “bridge” was meant to replace the missing tooth space like we used to do in the past.
They can last 20 years and more (lifetime) if maintained in a good oral hygiene and regular visits to the dentist.

Gum surgery:

It’s a gentle procedure by which the dentist can reposition/reshape or augment your gum tissues for a better function and/or aesthetics. (e.g aesthetic crown lengthening). It also include adding artificial gum to thicken weakened or thin gingival biotype, which provides a better longevity of the teeth.
Bone grafting: is a procedure that involves adding a material to the jaw bones that replaces/compensates for a missing part of the original bone volume. It is done to repair a defect and restore the size of the jaw bone and to give it an additional strength. It also helps in supporting the lips to its normal contour and position.
They come usually in the for of small particles (like sugar particles) or in other forms depending on the situation of bone defect.
They integrate with the jawbones, and are usually digested by the body enzymes and at the same time replace by the body’s own natural healthy bone. They only act as a vehicle or a scaffold to assist the body build a new bone at the required site.

The bone graft material can be natural (from the same person) or artificial (chemicals such as calcium phosphate) or can be derived from some animals or other humans; after a thorough and reliable complex sterilization processes.

Sinus lifting:

Sinus lifting is a procedure by which the surgeon repositions the boundaries of the air-filled maxillary sinus to its ORIGINAL position. The sinus usually changes its position when the associated teeth are removed for a long period of time. This change in position (a type of inflation process down: also called “pneumatization”) comes on the expense of existing remaining bone after tooth extraction. Which renders the jawbone volume less and weaker.
It is considered sometimes an essential procedure to “lift it back up” to its position in order to add a bone graft and restore the original bone volume, which facilitates the placement of a dental implant to restore the missing tooth.