title: The effect of internal versus external abutment connection modes on crestal bone changes around dental implants: a radiographic analysis.
abstract: BACKGROUND
  To the best of our knowledge, the influence of external versus internal implant-abutment connections on crestal bone remodeling has not been reported. The aim of the present study is to investigate the influence of the abutment connection on peri-implant crestal bone levels (CBLs) using radiographic recordings.
  
  
  METHODS
  Radiographic recordings from 40 single-tooth implants (20 external and 20 internal octagonal connections; one implant/patient) in 40 patients (15 males and 25 females; mean age: 54.3 years) were selected for analyses. The radiographic evaluation included the following: 1) linear bone change (LBC); 2) dimensional change (DC); and 3) angle between the implant and adjacent bone (AIB). Differences in LBC, DC, and AIB between implant placement and 1 year after loading for each system were evaluated using a paired t test. Comparison of LBC, DC, and AIB between systems at 1 year after loading was done using analysis of covariance. The significance level was set at P ≤0.05.
  
  
  RESULTS
  Radiographic CBLs (LBCs) were reduced at 1 year after loading compared to those at implant placement to reach statistical significance for the external connection (P = 0.000) but not the internal connection (P = 0.939). CBL changes were significantly greater for the external compared to the internal connection (P = 0.000). Similarly, the DC for the external connection was significantly greater compared to that for the internal connection (P = 0.004).
  
  
  CONCLUSIONS
  Within the limitations of this study, the implant-abutment connection technology appears to have a significant impact on peri-implant CBLs, with the external connection paralleled by a significant reduction of CBLs.
authors.affiliation: Department of Periodontology, School of Dentistry and Dental Research Institute, Seoul National University, Seoul, Korea.
authors.forename: Ki-Tae
authors.initials: KT
authors.lastname: Koo
authors.forename: Eun-Jeong
authors.initials: EJ
authors.lastname: Lee
authors.forename: Jae-Yoon
authors.initials: JY
authors.lastname: Kim
authors.forename: Yang-Jo
authors.initials: YJ
authors.lastname: Seol
authors.forename: Jung Suk
authors.initials: JS
authors.lastname: Han
authors.forename: Tae-Il
authors.initials: TI
authors.lastname: Kim
authors.forename: Yong Moo
authors.initials: YM
authors.lastname: Lee
authors.forename: Young
authors.initials: Y
authors.lastname: Ku
authors.forename: Ulf M E
authors.initials: UM
authors.lastname: Wikesjö
authors.forename: In-Chul
authors.initials: IC
authors.lastname: Rhyu
mesh_terms: D000134:Acid Etching, Dental / Q000379:methods; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging; D000539:Alveolar Process / Q000000981:diagnostic imaging*; D016723:Bone Remodeling / Q000502:physiology; D000044:Dental Abutments; D045662:Dental Etching / Q000379:methods; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008334:Mandible / Q000000981:diagnostic imaging; D008437:Maxilla / Q000000981:diagnostic imaging; D008875:Middle Aged; D019252:Radiography, Dental, Digital / Q000379:methods; D013499:Surface Properties
chemical_list: D015921:Dental Implants