title: Randomized controlled clinical trial comparing two dental implants with different neck configurations.
abstract: BACKGROUND
  Peri-implant bone levels can vary according to the implant neck macro-design and the implant-abutment interface.
  
  
  OBJECTIVE
  To compare the changes in soft and hard tissues when using a one-piece implant with a machined collar (TG) versus a two-piece implant with a progressive platform widening and a platform switching connection (SP).
  
  
  METHODS
  Partially edentulous patients willing to receive one or two implants in the posterior maxilla or mandible were randomized to the control (TG) or to the test group (SP). Final prostheses were delivered after 12 months. Radiographic measurements of interproximal bone levels (primary outcome) were assessed at implant loading and 1-year postloading. Clinical, patient related outcomes and adverse events were assessed at loading and after 6 and 12 months.
  
  
  RESULTS
  Sixty-one implants were placed in 47 patients, 37 patients (18 in the TG group and 19 in the SP group), and 47 implants (23 TG and 24 SP) completed the 24-months follow up. At the patient level, a significantly greater bone resorption from baseline to implant loading was observed in the SP group (-0.42 ± 0.45 vs -0.07 ± 0.45; P = .001*), while from loading to the final visit, the TG group had significantly greater bone loss than the SP group (-0.26 ± 0.22 vs -0.11 ± 0.2; P = .020*). At 24 months after surgery, there were no significant differences between both groups (control: 0.33 ± 0.49 vs test: 0.53 ± 0.53; P = .230). Similarly, no significant differences were observed for the secondary outcomes.
  
  
  CONCLUSIONS
  Both types of implant reported high survival rates and similar bone level changes, clinical parameters, and patient related outcomes after 12 months of loading.
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Sanz-Martín
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.
authors.forename: Ignacio
authors.initials: I
authors.lastname: Sanz-Sánchez
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Noguerol
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.
authors.forename: Susy
authors.initials: S
authors.lastname: Cok
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.
authors.forename: Alberto
authors.initials: A
authors.lastname: Ortiz-Vigón
authors.affiliation: Section of Post-graduate Periodontology, Faculty of Odontology, University Complutense of Madrid, Spain.|ETEP (Etiology and Therapy of Periodontal Diseases) Research Group, University Complutense, Madrid, Spain.
authors.forename: Mariano
authors.initials: M
authors.lastname: Sanz
mesh_terms: D015921:Dental Implants; D017267:Dental Prosthesis Design; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged
chemical_list: D015921:Dental Implants
keywords: controlled clinical trial; dental implants; machined collar; platform switching