title: Bone-implant contact on machined and dual acid-etched surfaces after 2 months of healing in the human maxilla.
abstract: BACKGROUND
  Recent clinical studies indicate that an implant with a textured surface may be loaded sooner than traditional healing protocols have recommended. In a previous study, the 6-month bone-implant contact for dual acid-etched and machined implant surfaces was reported to be 72.96% and 33.98%, respectively. In 1991, a minimum of 50% bone-implant contact was considered necessary for loading to ensure long-term survival of the implant. This study evaluated the 2-month bone-implant contact for dual acid-etched and machined implant surfaces to determine if this criterion had been met.
  
  
  METHODS
  Custom manufactured implants (2 mm diameter and 5 mm length), having on one side a machined surface and on the other side a dual acid-etched surface, were placed in the posterior maxilla of 11 patients, allowed to integrate for 2 months, then removed using a 4 mm internal diameter trephine with irrigation. Sections were processed and stained for histologic and histomorphometric analysis. The parameters calculated for each section were: bone volume (BV%), actual percent bone-implant contact (BIC%), and expected bone contact (EBC%) as determined from 3 implant images superimposed onto the adjacent bone 150, 500, and 1,000 microm lateral to the actual implant surface and representing the bone-implant contact expected on the day the implant was placed, based on the peri-implant bone volume.
  
  
  RESULTS
  Histomorphometric analysis indicated that the mean BV% of 36.77% from all sections was closely matched to the mean EBC% of 34.36% (P<0.001). The analysis showed that after 2 months of healing, the 47.81% BIC% on the dual acid-etched side was statistically higher (analysis of variance, P<0.001) than the 19.00% BIC% on the machined side. In areas of low-density bone (<40% BV%), the difference between the BIC% for the machined and dual acid-etched sides was even greater. Nine of the 11 dual acid-etched sides had a higher BIC% than the EBC% value. In the machined group, 1 of the 11 sides had a higher BIC% value than the EBC% value. The bone surrounding the dual acid-etched surface was a woven bone with thin, connecting peri-implant bony trabeculae projecting into and between the threads. Bone on the machined side was observed mostly contacting the tips of the screw threads.
  
  
  CONCLUSIONS
  At 2 months, the mean BIC% for the dual acid-etched group increased 39.14% compared to the EBC% value, while the mean BIC% for the machined group decreased 44.70%. Based on the histomorphometric results of this study, sufficient bone for functional loading of the implant exists on a dual acid-etched surface after 2 months of healing in the posterior maxillary arch.
authors.affiliation: paulbioc@tin.it
authors.forename: Paolo
authors.initials: P
authors.lastname: Trisi
authors.forename: Richard
authors.initials: R
authors.lastname: Lazzara
authors.forename: Alberto
authors.initials: A
authors.lastname: Rebaudi
authors.forename: Walter
authors.initials: W
authors.lastname: Rao
authors.forename: Tiziano
authors.initials: T
authors.lastname: Testori
authors.forename: Stephan S
authors.initials: SS
authors.lastname: Porter
mesh_terms: D000134:Acid Etching, Dental; D000704:Analysis of Variance; D015519:Bone Density; D016723:Bone Remodeling; D015921:Dental Implants; D017267:Dental Prosthesis Design; D005500:Follow-Up Studies; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008437:Maxilla / Q000473:pathology / Q000601:surgery*; D016348:Osseointegration; D013499:Surface Properties; D016474:Weight-Bearing; D014945:Wound Healing
chemical_list: D015921:Dental Implants