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

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.

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.

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).

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.