title: Radiographic evaluation of marginal bone levels adjacent to parallel-screw cylinder machined-neck implants and rough-surfaced microthreaded implants using digitized panoramic radiographs.
abstract: OBJECTIVE
  The purpose of this split-mouth study was to compare macro- and microstructure implant surfaces at the marginal bone level during a stress-free healing period and under functional loading.
  
  
  METHODS
  From January to February 2006, 133 implants (70 rough-surfaced microthreaded implants and 63 machined-neck implants) were inserted in the mandible of 34 patients with Kennedy Class I residual dentitions and followed until February 2008. The marginal bone level was radiographically determined, using digitized panoramic radiographs, at four time points: at implant placement (baseline level), after the healing period, after 6 months of functional loading, and at the end of follow-up.
  
  
  RESULTS
  The median follow-up time was 1.9 (range: 1.9-2.1) years. The machined-neck group had a mean crestal bone loss of 0.5 mm (range: 0-2.3) after the healing period, 0.8 mm after 6 months (range: 0-2.4), and 1.1 mm (range: 0-3) at the end of follow-up. The rough-surfaced microthreaded implant group had a mean bone loss of 0.1 mm (range: -0.4-2) after the healing period, 0.4 mm (range: 0-2.1) after 6 months, and 0.5 mm (range: 0-2.1) at the end of follow-up. The two implant types showed significant differences in marginal bone levels (healing period: P=0.01; end of follow-up: P<0.01).
  
  
  CONCLUSIONS
  Radiographic evaluation of marginal bone levels adjacent to machined-neck or rough-surfaced microthreaded implants showed that implants with the microthreaded design caused minimal changes in crestal bone levels during healing (stress-free) and under functional loading.
authors.affiliation: Department of Prosthodontics, University Hospital Erlangen, G-91054 Erlangen, Germany. Dr.A.Nickenig@t-online.de
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Nickenig
authors.forename: Manfred
authors.initials: M
authors.lastname: Wichmann
authors.forename: Karl Andreas
authors.initials: KA
authors.lastname: Schlegel
authors.forename: Emeka
authors.initials: E
authors.lastname: Nkenke
authors.forename: Stephan
authors.initials: S
authors.lastname: Eitner
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology*; D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000502:physiology* / Q000601:surgery; D016723:Bone Remodeling; D003758:Dental Implantation, Endosseous / Q000295:instrumentation; D015921:Dental Implants / Q000009:adverse effects*; D017267:Dental Prosthesis Design / Q000009:adverse effects*; D019094:Dental Prosthesis, Implant-Supported; D003829:Denture, Partial; D005500:Follow-Up Studies; D006801:Humans; D008334:Mandible; D008875:Middle Aged; D016348:Osseointegration / Q000502:physiology*; D019252:Radiography, Dental, Digital; D011862:Radiography, Panoramic; D013499:Surface Properties
chemical_list: D015921:Dental Implants