When you have a missing tooth, there are 3 basic ways it can be replaced.

A removable denture

An artificial tooth or teeth are supported on a plate that is held in position by clasps.  This traditional method is easily removed for cleaning and requires no preparation of adjacent teeth, and is cost effective.

The disadvantages are continued bone loss under the denture, and increased decay rates of adjacent teeth.and food impaction during eating

A fixed bridge

This treatment  works on the principle of joining 3 or more porcelain crowns together to replace the missing teeth. A tooth each side of the missing tooth is prepared for a crown so that the final restoration fills the missing space.

These restorations have a life of 15 -20 years, but eventually one or both the support teeth decay, require root canal treatment or may fracture leaving the patient with a larger space. 

Dental Implants

Dental Implants today are the gold standard for replacement of a tooth. It is independent of adjoining teeth and is a stand alone treatment.

Adjacent teeth do not require preparation and are left untouched. These teeth last longer and should you loose one of these teeth later in life, then the replacement implant is not affected.  

The dental implant consists of two components:
The fixture which is a titanium alloy screw of the approximate diameter of the missing tooth, which is surgically placed into the bone where the previous root had been.  This can be done at the time of extraction but more commonly 3 -6 month after tooth loss.  The dental implant has a special surface that attracts bone cells to encourage rapid fusing of the implant to the jaw.  The threaded surface provides initial stability, and greater surface area increasing the bonding affect.  

Because the fixture has a threaded inner segment a metal post can be attached to support a single porcelain crown or a framework supporting multiple teeth.  

These are rigid fixtures that are equivalent to having a new tooth.