title: Astra Tech and Brånemark System implants: a prospective 5-year comparative study. Results after one year.
abstract: BACKGROUND
  Endosseous dental implants are used frequently, and many implant systems are available. The scientific documentation of the implant system presents a great variation, and it is often difficult to compare studies of different systems.
  
  
  OBJECTIVE
  The aim of this study was to compare two Swedish implant systems (Astra Tech and Brånemark System implants), in a prospective randomized study.
  
  
  METHODS
  Sixty-six patients were equally distributed between the two implant systems; 184 Astra Tech and 187 Brånemark System implants were used. The patients have been followed annually with clinical and radiographic examinations. The results after 1 year are reported.
  
  
  RESULTS
  The abutment procedure was found to be easier and less time-consuming with Astra Tech than with Brånemark implants. The operation times in minutes (mean +/- SEM) were for the respective implant 35 +/- 4.0 and 51 +/- 4.8 in the maxilla and 32 +/- 3.8 and 43 +/- 2.4 in the mandible. The differences in both cases were significant: p < .02 and p < .05, respectively. The failure rate for Astra Tech implants was 0.5% and for Brånemark implants 4.3%. The difference was significant (p < .05); however, taking into account that five of the eight implant losses in the Brånemark implant group occurred in one patient, an intraindividual correlation cannot be excluded. Therefore, this result should be interpreted with caution. The marginal bone level changes were examined already from the fixture installation. The major bone loss was found between fixture installation and baseline. This bone loss was several times greater than the bone loss between the baseline and the 1-year follow-up. The total bone loss during the observation period did not differ significantly between the systems, but they had different resorption patterns. The bone loss in the upper jaw between baseline and 1-year follow-up was 0.22 +/- 0.14 and 0.03 +/- 0.09 mm for the Astra Tech and Brånemark implants, respectively. In the lower jaw, the loss was -0.31 for both systems. The frequency of plaque accumulation and bleeding on probing did not differ between the implant systems.
  
  
  CONCLUSIONS
  Abutment connection with Astra Tech implants was simpler than the corresponding surgery with Brånemark System implants and the survival rate of Astra Tech implants was higher than that of Brånemark system implants.
authors.affiliation: Department of Oral and Maxillofacial Surgery, University Hospital, SE-58185, Linköping, Sweden.
authors.forename: P
authors.initials: P
authors.lastname: Astrand
authors.forename: B
authors.initials: B
authors.lastname: Engquist
authors.forename: S
authors.initials: S
authors.lastname: Dahlgren
authors.forename: E
authors.initials: E
authors.lastname: Engquist
authors.forename: H
authors.initials: H
authors.lastname: Feldmann
authors.forename: K
authors.initials: K
authors.lastname: Gröndahl
mesh_terms: D000328:Adult; D000368:Aged; D016301:Alveolar Bone Loss / Q000209:etiology; D000704:Analysis of Variance; D000044:Dental Abutments; D003758:Dental Implantation, Endosseous; D015921:Dental Implants / Q000009:adverse effects; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention; D019232:Dental Restoration Failure; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D011336:Probability; D011446:Prospective Studies; D016896:Treatment Outcome
chemical_list: D015921:Dental Implants