Survival Rates of 8-mm or Shorter Tissue-Level Implants in Function for Up to 228 Months

Purpose: Advances in surface technology and the understanding of the capabilities of osseointegrating implants have led to the use of shorter implants in a variety of clinical situations. Such implant use offers a number of potential advantages in the posterior maxilla and mandible. The purpose of this retrospective study was to examine the success rates of shorter, tissue-level implants in function for at least 60 months.
Materials and Methods: A retrospective study was conducted of all patients treated between January 1, 1998, and December 31, 2012, who received tissue-level endosseous implants 8 mm or less in length, which were restored with abutments and single crowns. Patient age, sex, location of implants, and diameter of implants were examined. Time in function and stability of peri-implant crestal bone were assessed.
Results: The retrospective analysis identified 4,251 tissue-level implants that were restored with single abutments and crowns. These implants were followed for up to 228 months in function, with a mean time in function of 127.2 months. Implant success was assessed using commonly utilized metrics combined with bone sounding on the midbuccal and midlingual/ palatal aspects of the implants. The cumulative success rate was 99.5% for all implants. In the posterior mandible, the success rate for regular-neck implants was 99.3% (n = 680, mean time in function: 136.5 months) and was 99.7% for wideneck implants (n = 2,320, mean time in function: 124.5 months). In the posterior maxilla, the success rate for regular-neck implants was 97.8% (n = 211, mean time in function: 169.1 months), and for wide-neck implants, it was 99.2% (n = 1,040, mean time in function: 127.8 months).
Conclusion: The use of shorter (8 mm or less in length) tissue-level implants in the maxilla and mandible, restored with single abutments and crowns, offers a viable treatment option, assuming specific criteria and protocols are followed. These criteria and protocols are discussed.