title: The effect of different implant neck configurations on soft and hard tissue healing: a randomized-controlled clinical trial.
abstract: OBJECTIVE
  to compare the soft and hard tissue healing and remodeling around tissue-level implants with different neck configurations after at least 1 year of functional loading.
  
  
  METHODS
  eighteen patients with multiple missing teeth in the posterior area received two implants inserted in the same sextant. One test (T) implant with a 1.8 mm turned neck and one control (C) implant with a 2.8 mm turned neck were randomly assigned. All implants were placed transmucosally to the same sink depth of approximately 1.8 mm. Peri-apical radiographs were obtained using the paralleling technique and digitized. Two investigators blinded to the implant type-evaluated soft and hard tissue conditions at baseline, 6 months and 1 year after loading.
  
  
  RESULTS
  the mean crestal bone levels and soft tissue parameters were not significantly different between T and C implants at all time points. However, T implants displayed significantly less crestal bone loss than C implants after 1 year. Moreover, a frequency analysis revealed a higher percentage (50%) of T implants with crestal bone levels 1-2 mm below the implant shoulder compared with C implants (5.6%) 1 year after loading.
  
  
  CONCLUSIONS
  implants with a reduced height turned neck of 1.8 mm may, indeed, lower the crestal bone resorption and hence, may maintain higher crestal bone levels than do implants with a 2.8 mm turned neck, when sunk to the same depth. Moreover, several factors other than the vertical positioning of the moderately rough SLA surface may influence crestal bone levels after 1 year of function.
authors.affiliation: Department of Restorative Dentistry, National Dental Center of Singapore, Singapore.
authors.forename: Wah Ching
authors.initials: WC
authors.lastname: Tan
authors.forename: Niklaus P
authors.initials: NP
authors.lastname: Lang
authors.forename: K
authors.initials: K
authors.lastname: Schmidlin
authors.forename: Marcel
authors.initials: M
authors.lastname: Zwahlen
authors.forename: Bjarni E
authors.initials: BE
authors.lastname: Pjetursson
mesh_terms: D000328:Adult; D016301:Alveolar Bone Loss / Q000000981:diagnostic imaging / Q000209:etiology / Q000517:prevention & control*; D015519:Bone Density; D001861:Bone Regeneration; D016009:Chi-Square Distribution; D003758:Dental Implantation, Endosseous / Q000009:adverse effects; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D057873:Peri-Implantitis / Q000517:prevention & control; D016459:Prosthesis-Related Infections / Q000517:prevention & control; D011859:Radiography; D018709:Statistics, Nonparametric; D016896:Treatment Outcome; D014945:Wound Healing
chemical_list: D015921:Dental Implants