Crestal bone changes in macrogeometrically similar implants with the implant–abutment connection at the crestal bone level or 2.5 mm above: a prospective randomized clinical trial

<jats:title>Abstract</jats:title><jats:sec><jats:title>Objective</jats:title><jats:p>Crestal bone loss around dental implants is a criterion for success as this could prevent loss of implant and superstructure. The macrogeometry of the implant could influence bone remodelling when the implant–abutment connection is placed at crestal bone level or above. The aim of this study was to evaluate crestal bone remodelling in a randomized clinical prospective trial in macrogeometrically similar implants with the prosthetic connection at the crestal bone level and 2.5 mm above. The null hypothesis was that there was no difference in crestal bone loss after 1 year of early loading.</jats:p></jats:sec><jats:sec><jats:title>Material and methods</jats:title><jats:p>Patients were referred to Academic Centre of Dentistry Amsterdam for implant placement. Patients were subjected to inclusion and exclusion criteria and received a minimum of two implants: an implant with the prosthetic abutment connection at the crestal bone level (minimized collar [<jats:styled-content style="fixed-case">MC</jats:styled-content>], bone level) and one with the prosthetic abutment connection 2.5 mm supracrestal (long collar [<jats:styled-content style="fixed-case">LC</jats:styled-content>], tissue level). The mesial or distal location of each implant type was blinded for the patient and randomized. The implants were loaded splinted after 3 weeks of healing. The primary outcome was bone‐level change assessed after 1 year of loading.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>Thirty‐three patients fulfilled the inclusion criteria. Thirty‐nine Thommen <jats:styled-content style="fixed-case">SPI ELEMENT LC</jats:styled-content> implants and 39 <jats:styled-content style="fixed-case">MC</jats:styled-content> were placed, and each fixed dental prosthesis was supported by one <jats:styled-content style="fixed-case">LC</jats:styled-content> and one <jats:styled-content style="fixed-case">MC</jats:styled-content> implant. The intraclass correlation of measures performed by the first and second X‐ray examiner was as follows: on the mesial side of the <jats:styled-content style="fixed-case">MC</jats:styled-content> implant 0.990 (0.980–0.995; 95% confidence interval [<jats:styled-content style="fixed-case">CI</jats:styled-content>]), 0.980 (0.962–0.990; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>) on the distal side of the <jats:styled-content style="fixed-case">MC</jats:styled-content> implant, 0.979 (0.959–0.989; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>) and 0.988 (0.978–0.994; 95% <jats:styled-content style="fixed-case">CI</jats:styled-content>) on the mesial and distal side of the <jats:styled-content style="fixed-case">LC</jats:styled-content> implant, respectively. The mean bone loss of the <jats:styled-content style="fixed-case">MC</jats:styled-content> implant was 0.4 ± 0.4 mm. The mean bone loss of the <jats:styled-content style="fixed-case">LC</jats:styled-content> implant was 0.2 ± 0.5 mm. The paired samples <jats:italic>t</jats:italic>‐test showed a statistically significant difference (<jats:italic>P</jats:italic> < 0.05) between the <jats:styled-content style="fixed-case">MC</jats:styled-content> and <jats:styled-content style="fixed-case">LC</jats:styled-content> implants.</jats:p></jats:sec><jats:sec><jats:title>Conclusion</jats:title><jats:p>Dental implants at bone level show statistically significantly (<jats:italic>P</jats:italic> < 0.05) more crestal bone change after 1 year of loading than a tissue‐level implant.</jats:p></jats:sec>