What are Implants?

A dental implant (also known as an endosseous implant or fixture) is a surgical component that interfaces with the bone of the jaw or skull to support a dental prosthesis such as a crown, bridge, denture, facial prosthesis or to act as an orthodontic anchor.

The basis for modern dental implants is a biologic process called osseointegration, in which material such as titanium form an intimate bond to bone.

The implant fixture is first placed so that it is likely to osseointegrate, then a dental prosthetic is added. A variable amount of healing time is required for osseointegratoin

before either the dental prosthetic (a tooth, bridge or denture) is attached to the implant or and abutment is placed which will hold a dental prosthetic /crown.

Success or failure of implants depends on the health of the person receiving the treatment, drugs which affect the chance of osseointegration, and the health of the tissues in the mouth.

The amount of stress that will be put on the implant and fixture during normal function is also evaluated. Planning the position and number of implants is key to the long-term health of the prosthetic since biomechanical forces created during chewing can be significant. The position of

implant is determined by the position and angle of adjacent teeth, by lab simulations or by using computed tomography with CAD/CAM simulations and surgical guides called stents.

The pre requisites for long-term success of osseointegrated dental implants are healthy bone and gingiva, since both can atrophy after tooth extraction.                pre-prosthetic procedures such as sinus lifts or gingiva grafts are sometimes required to recreate ideal bone and gingiva.

The final prosthetic can be either fixed, where a person cannot remove the denture or teeth from their mouth, or removable, where they can remove the prosthetic. In each case an abutment is attached to the implant fixture. Where the prosthetic is fixed, the crown bridge or denture is fixed to the abutment either with lag screws (screw type) or with dental cement (cement type).

Where the prosthetic is removable, a corresponding adapter is placed in the prosthetic so that the two pieces can be secured together.

The risks and complications related to implant therapy divide into those that occur during surgery (such as excessive bleeding or nerve injury), those that occur in the first six months (such as infection and failure to osseointegrate) and those that occur long-term (such as peri-implantitis and mechanical failure).

In the presence of healthy tissues, a well-integrated implant with appropriate biomechanical loads can have 5-year plus survival rates from 93 to 98 percent and 10-15 year life spans for the prosthetic teeth.

Long-term studies show a 16-to 20-year success (implant surviving without complications or revisions) between 52% and 76%, with complications occurring up to 48% of the time.

MEDICAL USES

The primary use of dental implants is to support dental prosthetics. Modern dental implants make use of osseointegration, the biologic process where bone fuses tightly to the surface of specific materials such as titanium and some ceramics. The integration of implant and bone can support physical loads for decades without failure.

For individual tooth replacement, an implant abutment is first secure to the implant with an abutment screw

A crown is then connected to the abutment with dental cement (cement type) or A crown fused to the abutment as one piece is connected to the fixture (implant) by a small screw (screw-retained)

Dental implants, in the same way, can also be used to retain a multiple tooth dental prosthesis either in the form of a fixed bridge or removable dentures.

An implant supported bridge (or fixed denture) is a group of teeth secured to dental implants so the prosthetic cannot be removed by the user. Bridges typically connect to more than one implant and may also connect to teeth as anchor points. A fixed bridge may replace as few as two teeth and may extend to replace an entire arch of teeth.

In both cases, the prosthesis is said to be fixed because it cannot be removed by the denture wearer.

An implant supported bridge (or fixed denture) is a group of teeth secured to dental implants so the prosthetic cannot be removed by the user. Bridges typically connect to more than one implant and may also connect to teeth as anchor points. A fixed bridge may replace as few as two teeth and may extend to replace an entire arch of teeth.

In both cases, the prosthesis is said to be fixed because it cannot be removed by the denture wearer.

Facial prosthetics, used to correct facial deformities, can use connections to implants placed in the facial bones.

In orthodontics, small diameter dental implants, referred to as Temporary Anchorage Devices (TAD) can assist tooth movement by creating anchor points from which forces can be generated.

For teeth to move, a force must be applied to them in the direction of the desired movement.

They are ideal anchor points in orthodontics. Typically, implants designed for orthodontic movement are small and do not fully osseointegrate, allowing easy removal following treatment.

Composition

A typical conventional implant consists of a titanium screw with a roughened or smooth surface. The majority of dental implants are of commercially pure titanium, which is available in four grades depending upon the amount of carbon, nitrogen, oxygen and iron contained. Cold work hardened CP4 is the most commonly used titanium for implants. Grade 5 titanium, titanium 6Al-4V (6% Al + 4% vanadium) is slightly harder than CP4 and used in the industry mostly for abutment screws and abutments.

Most modern dental implants also have a texture surface (through etching, anodic oxidation or various-media blasting) to increase the surface area and osseointegration potential of the implant.

 If C.P titanium or titanium alloy has more than

85% titanium content, it will form a titanium-biocompatible.

 Titanium oxide surface layer or veneer that encloses the other metals, preventing them from contacting the bone.

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