The influence of new immediate tissue level abutment on crestal bone stability of subcrestally placed implants: A 1-year randomized controlled clinical trial

Clin Implant Dent Relat Res. 2021 Apr;23(2):259-269. doi: 10.1111/cid.12979. Epub 2021 Feb 2.


Background: The relation between implant abutment disconnection (AD) and increased crestal bone loss is still debated.

Purpose: To compare bone changes below implant-abutment junction of subcrestally placed implants between: (1) implant level restorations, that underwent four ADs and (2) implants with immediate tissue level abutment with no AD, 1 month (T2) and 1-year (T3) after final restoration delivery.

Materials and methods: Sixty-four patients received 64 bone level implants with platform-switching and conical connection in edentulous sites of posterior mandible and maxilla. All implants were placed 1.5 mm subcrestally and distributed among: (1) control group, that received a regular healing abutment and (2) test group with immediate tissue level (ITL) abutment, which was torqued to implants during surgery, transforming bone level implant to tissue level type. After 2-3 months of healing and a 1-month temporization, final zirconia-based screw-retained crowns were delivered to both groups. Crestal bone levels were calculated after final crown delivery (T2); after 1-year follow-up (T3) and compared using Mann-Whitney U test (p ≤ .05).

Results: Early bone loss of the test and control groups was 0.14 ± 0.27 mm and 0.64 ± 0.64 mm, respectively; the 0.5 mm difference was statistically significant (p = .0001). Late bone loss was 0.06 ± 0.16 mm and 0.21 ± 0.56 mm for the test and control group, respectively; the 0.15 mm difference between the groups was no more statistically significant (p = .22). Both groups displayed bone gain, 0.08 and 0.43 mm, respectively, and the overall crestal bone loss was reduced.

Conclusions: Immediate tissue level abutments can significantly reduce early bone loss when measured 1 month after final prosthesis delivery, however, after 1-year follow-up, difference between the groups was no more statistically significant.

Keywords: alveolar bone loss; definitive abutment; dental implant-abutment design; platform switching; randomized controlled trial.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Alveolar Bone Loss* / etiology
  • Crowns
  • Dental Implant-Abutment Design
  • Dental Implantation, Endosseous
  • Dental Implants*
  • Dental Restoration, Temporary
  • Follow-Up Studies
  • Humans


  • Dental Implants