title: Three-dimensional assessment of crestal bone levels at titanium implants with different abutment microstructures and insertion depths using micro-computed tomography.
abstract: OBJECTIVE
  To (i) assess the impact of insertion depth and abutment microstructure on the three-dimensional crestal bone-level changes at endosseous titanium implant using μCT and computerized image processing and (ii) to correlate the findings with previously reported histology.
  
  
  METHODS
  Titanium implants (conical abutment connection) were inserted in each hemimandible of n = 6 foxhounds with the implant shoulder (IS) located either in epicrestal (0 mm), supracrestal (+1 mm) or subcrestal (-1 mm) positions and randomly (split-mouth design) connected with machined or partially micro-grooved healing abutments. At 20 weeks, the tissue biopsies were processed for μCT and histological (HI) analyses. The volumetric dehiscence profile around the implants was computed as distance between the implant shoulder (IS) and the most coronal bone-to-implant contact (CBI) using MATLAB. The respective buccal and oral values were averaged, and agreement with the respective IS-CBI scores from HI was assessed using Bland-Altman plots.
  
  
  RESULTS
  A median net bone gain was observed for supracrestal insertion depths at both abutment types, but lower bounds of the 75% quartile experienced net bone losses. Epicrestal and subcrestal insertion depths were linked to slight bone losses, and the buccal and oral dehiscences were smaller compared to supracrestal positioning. Bland-Altman plots yielded a moderate agreement of IS-CBI values measured with μCT and HI.
  
  
  CONCLUSIONS
  The novel image processing method allowed reliable evaluations and pointed to a direct impact of insertion depths on crestal bone-level changes. Additionally, it demonstrated that HI morphometry crucially depends on the chosen cutting position.
authors.affiliation: Department of Orthodontics, Universitätsklinikum of Düsseldorf, Düsseldorf, Germany.
authors.forename: Kathrin
authors.initials: K
authors.lastname: Becker
authors.affiliation: Department of Oral Surgery, Universitätsklinikum of Düsseldorf, Düsseldorf, Germany.
authors.forename: Inka
authors.initials: I
authors.lastname: Klitzsch
authors.affiliation: Scanco Medical AG, Brüttisellen, Switzerland.
authors.forename: Martin
authors.initials: M
authors.lastname: Stauber
authors.affiliation: Department of Oral Surgery, Universitätsklinikum of Düsseldorf, Düsseldorf, Germany.
authors.forename: Frank
authors.initials: F
authors.lastname: Schwarz
mesh_terms: D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging; D000539:Alveolar Process / Q000033:anatomy & histology / Q000000981:diagnostic imaging*; D000818:Animals; D000044:Dental Abutments; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D004285:Dogs; D005260:Female; D021621:Imaging, Three-Dimensional; D008297:Male; D014025:Titanium; D055114:X-Ray Microtomography
chemical_list: D015921:Dental Implants; D014025:Titanium
keywords: abutment microstructure; histomorphometry; insertion depth; micro-CT; volumetric dehiscence profile