title: Peri-implant bone length changes and survival rates of implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height.
abstract: OBJECTIVE
  The aim of this study was to measure the peri-implant bone length surrounding implants that penetrate the sinus membrane at the posterior maxilla and to evaluate the survival rate of these implants.
  
  
  METHODS
  Treatment records and orthopantomographs of 39 patients were reviewed and analyzed. The patients had partial edentulism at the posterior maxilla and limited vertical bone height below the maxillary sinus. Implants were inserted into the posterior maxilla, penetrating the sinus membrane. Four months after implant insertion, provisional resin restorations were temporarily cemented to the abutments and used for one month. Then, a final impression was taken at the abutment level, and final cement-retained restorations were delivered with mutually protected occlusion. The complications from the implant surgery were examined, the number of failed implants was counted, and the survival rate was calculated. The peri-implant bone lengths were measured using radiographs. The changes in initial and final peri-implant bone lengths were statistically analyzed.
  
  
  RESULTS
  Nasal bleeding occurred after implant surgery in three patients. No other complications were found. There were no failures of the investigated implants, resulting in a survival rate of 100%. Significantly more bone gain around the implants (estimated difference=-0.6 mm, P=0.025) occurred when the initial residual bone height was less than 5 mm compared to the >5 mm groups. No significant change in peri-implant bone length was detected when the initial residual bone height was 5 mm or larger.
  
  
  CONCLUSIONS
  This study suggests that implants penetrating the sinus membrane at the posterior maxilla in patients with limited vertical bone height may be safe and functional.
authors.affiliation: Department of Dental Laboratory Science and Engineering, College of Health Science, Korea University, Seoul, Korea.
authors.forename: Hae-Young
authors.initials: HY
authors.lastname: Kim
authors.forename: Jin-Yong
authors.initials: JY
authors.lastname: Yang
authors.forename: Bo-Yoon
authors.initials: BY
authors.lastname: Chung
authors.forename: Jeong Chan
authors.initials: JC
authors.lastname: Kim
authors.forename: In-Sung
authors.initials: IS
authors.lastname: Yeo
keywords: Biomechanics; Biostatistics; Maxilla; Maxillary sinus; Sinus floor augmentation