title: Prospective randomized controlled clinical study comparing two dental implant systems: demographic and radiographic results at one year of loading.
abstract: OBJECTIVE
  To compare the clinical and radiographic outcomes of implants and implant-supported reconstructions using a 1-piece (STM) and a 2-piece (BRA) dental implant system.
  
  
  METHODS
  Sixty patients were randomly assigned to receive STM or BRA implants. The implants restored with fixed or removable prostheses. Baseline measurements (day of loading) and 1-year measurements included demographic and radiological parameters with details of the surgical procedures, type of prosthesis, survival of implants, and marginal bone-level changes. The Mann-Whitney U-test and the paired t-test were used to analyze the data between the two groups and within the groups within 1 year on an implant- and patient-based level.
  
  
  RESULTS
  In all 60 patients, implants were placed and supported 65 final reconstructions (33 BRA, 32 STM). One implant was lost in the STM group at 9 months (98.5% survival rate), none were lost in the BRA group (100%). On the implant level, the median marginal bone levels were -1.02 mm (interquartile range (IQR) 0.41 mm) at baseline and -1.08 mm (0.59 mm) 1 year later (BRA) and -0.51 mm (0.93 mm) and -0.75 mm (1.14 mm) (STM). The patient level values were -0.98 mm (0.47 mm) at baseline and -1.10 mm (0.71 mm) 1 year later (BRA) and -0.43 mm (0.59 mm) and -0.71 mm (0.97 mm) (STM). The differences between the two groups at both time-points were statistically significant in the patient-level analysis with higher bone levels for the STM group (P < 0.05). The changes in mean marginal bone levels on the implant level amounted to -0.05 mm (SD±0.32 mm) (BRA) and to -0.27 mm (±0.52 mm) (STM). Patient-level values were -0.06 mm (± 0.37 mm) (BRA) and -0.25 mm (±0.35 mm) (STM). These differences between the groups reached statistical significance on the patient level with less bone loss in the BRA group (P < 0.05).
  
  
  CONCLUSIONS
  Within the first year of functional loading, high survival rates and minimal changes of marginal bone levels were found for both implant systems used.
authors: Clinic of Fixed and Removable Prosthodontics and Dental Material Science, Center of Dental Medicine, University of Zurich, Zurich, Switzerland.
authors: Daniel S
authors: DS
authors: Thoma
authors: Ignacio
authors: I
authors: Sanz Martin
authors: Goran I
authors: GI
authors: Benic
authors: Malgorzata
authors: M
authors: Roos
authors: Christoph H F
authors: CH
authors: Hämmerle
mesh_terms: D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000601:surgery; D003442:Crowns; D003758:Dental Implantation, Endosseous / Q000379:methods*; D015921:Dental Implants; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D011859:Radiography; D013557:Switzerland; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants
keywords: crown; dental implants; fixed, partial, denture; humans; radiographic; survival