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Compendium
May 2016
Volume 37, Issue 5
Peer-Reviewed

A more predictable option is the use of NDIs, which can be placed in residual bone and support a fixed provisional restoration during the first phase of restoring function and during the time necessary for graft healing. The NDIs in the Nos. 7 and 12 positions were retained in the final prosthesis for the following reasons: First, they supported the provisional while the conventional-diameter implants—Nos. 8, 9, and 11—were allowed to integrate, which avoided transmucosal loading and provided a fixed provisional. Second, the width gained following block grafting in the No. 12 area was insufficient to place a conventional-diameter implant and still maintain at least 1 mm of buccal bone. Third, these implants continued to be stable with no bone loss and were, therefore, included as abutments in the final splint.

Narrow-diameter implants are designed to be placed with a nonsubmerged protocol and then immediately loaded to support fixed interim prostheses.15 Findings from histologic studies have confirmed their bone integration at the light microscopic level, and their removal has been noted to be difficult.5,13 In a systematic review of the literature, Klein et al3 reported a survival rate between 90.9% and 100% for implants with diameters of less than 3 mm (the mean functional follow-up ranged between 12 and 96 months). Shatkin and Petrotto11 in a retrospective analysis of 5640 mini implants supporting fixed and removable prostheses found an overall implant survival rate of 92.1%. Although NDIs were originally introduced to support provisional restorations, the Food and Drug Administration, considering high-survival–rate data, approved their use for long-term prosthodontic treatment in 2004.7

Although some in vitro studies16,17 reported a higher risk for overload and fracture for NDIs, these findings have not been confirmed clinically. When NDIs are used properly, long-term success without complications can be achieved, as this report demonstrates.

Using an increased number of implants was suggested to overcome the risk for overload complications.16 A more predictable alternative is to splint NDIs to conventional-diameter implants. This strongly reduces stress levels in the surrounding bone tissue18,19 and may provide a more even distribution of strains during off-axis loading that could occur clinically.20

While the 11-year follow-up in the present case report demonstrates that long-term success could be achieved using this protocol, patient compliance played a key role in the outcome. In addition, the London dentist reported that the patient had professional dental maintenance every 3 months while in London. The patient’s oral hygiene was optimal for the duration of the treatment and then for years following the delivery of the final restoration. The patient also followed post-surgery instructions to not chew on the provisional or overload the implants for 3 to 4 months. The patient’s expectations were fully satisfied, and he was grateful for the treatment received.

Conclusion

Maxillary atrophic anterior ridges represent a challenge for the surgeon and restorative dentist. A well-planned treatment protocol, based on the close collaboration between the treating clinicians and laboratory, is a prerequisite for success. Through the careful evaluation and planning of the case, the clinicians must assess the advantages and disadvantages of the various therapy alternatives, selecting the most appropriate option to achieve long-term success and satisfy patient expectations.

When bone-regeneration procedures are needed in order to place and restore an implant-supported restoration, various techniques have shown a high percentage of success. A requirement for effective bone regeneration is the avoidance of loading and movement during the healing process. A fixed interim restoration supported by NDIs protects the augmented site and represents a more comfortable and acceptable solution for most patients when compared to a removable denture. The use of NDIs presents a valuable modality in supporting fixed provisionals and does not require adjacent teeth to be prepared. Furthermore, these implants achieve excellent osseointegration and may be used long term to support the definitive prosthesis when splinted to standard-diameter implants.

Disclosure

The authors had no disclosures to report.

About the Authors

Stuart J. Froum, DDS
Clinical Professor and Director of Clinical Research
Ashman Department of Periodontology and Implant Dentistry
New York University College of Dentistry
New York, New York
Private Practice
New York, New York

Sang-Choon Cho, DDS
Clinical Assistant Professor
Director of Advanced Program for International Dentists in Implant Dentistry, and Co-Director of Clinical Research
Ashman Department of Periodontology and Implant Dentistry
New York University College of Dentistry
New York, New York

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