Sacramento Dental Implant Characteristics

Selecting implant characteristics that maximize the available surface area for bone contact is crucial in implant restoration success. This is especially true in poor-quality and immediate fresh extraction sites. The distribution of force in natural teeth depends on micromovement induced by the periodontal ligament. Force distribution in implants differs from that in natural teeth in that implants do not have micromovement. Hence most of the force factor (vertical and lateral) is concentrated at the crest of the ridge. Appropriate implant design selection is imperative to lower the magnitude of loads imposed on the implant-bone interface. It has been shown that roughened titanium surfaces- as compared with smooth titanium surfaces - can improve the clinical prognosis of implants by providing a higher percentage of bone- implant contact and higher removal torque values in mechanical testing.'

Moreover the literature has also addressed the effects of implant shape, diameter, length, and thread design on osseointegration. Growing bone concentrates referentially on protruding elements of the implant surface such as ridges, crests, and edges of threads - when load is transferred. Finite-element-analysis studies of implants indicate that bone stress distribution and magnitudes vary with implant shape. It is for this reason that most implant designs are threaded, because the thread shape is particularly important in changing force at the bone interface. The significance of implant length is found in initial stability and overall amount of implant-bone interface. The increased length recommended under biological principles can provide resistance to torque or shear forces when the abutment is screwed in place. Less favorable success rates for shorter implants were observed in clinical studies.

Wider root-form implants have a greater area of bone contact than narrow implants of similar height and design because of their increased circumferential bone-contact areas. This is important because a wider table can seal the crestal extraction site and the improved surface can encourage early bone formation. However a wide anterior implant must be placed judiciously to prevent recession and interdental bone necrosis that can damage the anterior aesthetics.

The original Branemark protocol required externally hexed implants to restore fully edentulous arches, splinting the implants via a bar with a fixed prosthesis. The external hex, which was only 0.7 mm in height, was not designed for single teeth to prevent antirotation. Implant manufacturers had to compensate for antirotation by changing the type of screw, the precision fit over the hex, and the amount of torque used to secure the new screws. Today many implant systems have internal connections. One of the first internally hexed implants was designed with a 1.7 mm deep hex. This feature is intended to distribute intraoral forces deeper within the implant to protect the retention screw from excess loading and to reduce the potential of microleakage. Internally connected implants also provide superior strength for the implant / abutment connection.'

It is essential to be able to identify prior to surgery the qualitative bone factors such as bone height, volume, and thickness of the cortical plates by CT scan. A full contoured diagnostic wax-up of the missing tooth can be made and used as a template for the fabrication of a radiopaque surgical stent. The patient wears the stent during the CT scanning. The use of computer-guided treatment planning in the anterior maxilla using software imaging and prefabricated drill guides made from the CT data can be beneficial for accurate results. The advantages of such techniques are avoiding vital anatomic structures (nerves, incisal foramen), gaining more precision and predictable results by placing the implants in correct positions, and maximizing existing bone volume.

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