Peter R. Hunt, BDS, MSc, LDSRCS Eng


November 16, 2011

Implants: The Modern Solution for Missing Teeth

Dental implants are increasingly valuable tools in modern dentistry. Although they have been available for more than a quarter of a century, only in the last decade has technology advanced so that implants can be considered the optimal solution for missing teeth. Instead of endless rounds of heroic attempts to save a failing tooth, it is increasingly simpler, less invasive, and more cost-effective to replace the failing tooth with a dental implant.

If relatively little tooth structure remains supragingivally or furcation involvement is incipient, then conventional therapy could be tedious, time-consuming, and short-lived. If root caries are rampant, periodontal disease is aggressive, or systemic health is in decline, then aggressive therapy to save a failing dentition could be as counterproductive as it is contraindicated. Interceptive implant therapy should be considered under these circumstances.

Today, most dental implants can be placed in simple 1-stage surgical procedures. Long-term survival rates have been steadily improving, even in smokers. Restorative processes are simpler and more reliable.

Modern dental implants are generally made from titanium, with a threaded and rough microsurface on the outside. They come in lengths ranging from 7 to 16 mm and diameters from 3.5 to 6.0 mm. Increasingly, implants tend to be manufactured so that tapering aids initial stability. A special subclass of 1-piece small-diameter implants is also available.

Dental Implants

The 4 portionsof implants (Figure 4) are:

  • Implant body;

  • Collar;

  • Connection; and

  • Abutment.[1]

Figure 4. Schematic of a dental implant.

Implant body. The implant body is the portion inserted in the bone, with an exterior surface designed to osseointegrate (fuse) to the bony surface with which it comes into contact.

The rough surface interfacing with bone is generally achieved by abrasively blasting the exterior surface before it is treated with special acids. This creates an extremely porous microsurface, which facilitates osseointegration.[2]The improved osseointegration of modern implants has resulted in higher survival rates over earlier-generation systems.[3]

Collar. The collar is the upper part of the implant body that traditionally starts the passage through the gingival complex into the mouth.

With early implants, bone and gingiva levels used to "die-back," "lose bone," or "develop biologic height" when exposed to the oral environment. A variety of collar designs were developed to try and minimize this bone loss. The implants have now improved so that bone loss with modern systems is greatly reduced, with the result that implants are now electively placed deeper into the bone.

Connection. This is a 2-part device. The first part lies generally inside the implant body. The other component of the abutment or restorative device fits inside and is secured with a screw.

This portion can make a restoration either extremely difficult or quite simple. Problems can result if the connection is weak, fragile, easily worn, or has high rotational instability. Clinical procedures can become complex, tedious, and liable to fail. If not stable, screws can loosen and restorations can fall off. In contrast, deep, strong connections with good rotational stability make life simple for the restorative dentist and allow for fabrication of more durable restorations.[4]

Abutment. This device fits into the connection and emerges to pass through the gingival complex with an "emergence profile" (the form passing through the gingival complex) and a final portion, which retains the final crown.

As the trend to place implants deeper continues, development of the "emergence profile" in the abutment becomes more important. When placed properly, the portion of the implant emerging from the gingiva allows the implant to reproduce the shape, appearance, and color of a tooth. Traditionally made of titanium, abutments have also been made with a cast gold process and increasingly with zirconia, at least in the emergence and restorative portion of the implant. This material allows for a custom form, provides the optimal gingival reaction, and has a natural color. A conventional crown provides the final restoration.

A Natural Result

Implant-based restorations can only appear natural when the surrounding soft and hard tissues in the region appear "normal." As in this case, soft and hard tissue augmentation is often required at the time of implant placement to generate the desired aesthetic and functional result.


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