title: Influence of placement depth and abutment connection pattern on bone remodeling around 1-stage implants: a prospective randomized controlled clinical trial.
abstract: OBJECTIVE
  The aim of this study is to evaluate peri-implant marginal bone level changes in relation to crestal or subcrestal implant placement and type of fixture/abutment connection 3 months after implant placement.
  
  
  METHODS
  The duration of the study was 3 months. A total of 105 implants were placed in 81 subjects following a one-stage surgical procedure and assigned into four groups. In the first and second groups, implants with a screwed tapered internal connection were placed subcrestally and crestally, respectively, while in the third and fourth groups, implants with an internal conical seal connection were similarly placed. Clinical recordings and standardized periapical digital radiographs were taken the day of implantation and 3 months later, before placement of the final prosthetic restoration. The modified plaque index (mPLI), modified gingival index (mGI), and probing depths (PD) were recorded at four sites around each implant, and the vertical distance between fixture/abutment junction and alveolar crest at the mesial and distal sites of each implant utilizing subtractive radiography were all measured on placement and at 3 months.
  
  
  RESULTS
  There was no statistically significant difference between the four groups for PD. The highest values of mPLI and mGI were recorded for Group 2. The mean (±SE) peri-implant bone loss was recorded as follows: Group 1: 0.68 ± 0.07 mm, Group 2: 0.79 ± 0.06 mm, Group 3: 0.49 ± 0.06 mm, and Group 4: 0.40 ± 0.07 mm. The statistical analysis revealed significant differences in bone resorption between groups with different abutment connections.
  
  
  CONCLUSIONS
  The connection between fixture/abutment rather than vertical implant placement in relation to alveolar bone level seems to affect peri-implant marginal bone resorption.
authors.affiliation: Molecular Immunopharmacology and Drug Discovery Laboratory, Department of Integrative Physiology and Pathobiology, Tufts University School of Medicine, Boston, MA, USA.
authors.forename: Iro
authors.initials: I
authors.lastname: Palaska
authors.affiliation: Department of Preventive Dentistry, Periodontology & Implant Biology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Phoebus
authors.initials: P
authors.lastname: Tsaousoglou
authors.affiliation: Department of Preventive Dentistry, Periodontology & Implant Biology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Ioannis
authors.initials: I
authors.lastname: Vouros
authors.affiliation: Department of Preventive Dentistry, Periodontology & Implant Biology, School of Dentistry, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: Antonis
authors.initials: A
authors.lastname: Konstantinidis
authors.affiliation: Department of Agronomy, School of Agriculture, Aristotle University of Thessaloniki, Thessaloniki, Greece.
authors.forename: George
authors.initials: G
authors.lastname: Menexes
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000209:etiology*; D016723:Bone Remodeling; D059605:Dental Implant-Abutment Design; D003758:Dental Implantation, Endosseous / Q000379:methods*; D003774:Dental Plaque Index; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010512:Periodontal Index; D011446:Prospective Studies; D016896:Treatment Outcome
keywords: bone implant interactions; clinical assessment; clinical research; clinical trials; diagnosis; periodontology