title: Crestal approach for maxillary sinus augmentation in patients with ≤ 4 mm of residual alveolar bone.
abstract: OBJECTIVE
  Less morbidity is the major advantage to a one-stage crestal approach to maxillary sinus elevation. However, the ability to ensure high primary implant stability in a severely atrophied ridge is of chief concern. The purpose of this study is to measure and compare the success rate of implants placed at the time of crestal approach sinus lift in patients with ≤ 4 mm of residual alveolar bone (RAB) and >4 mm of RAB.
  
  
  METHODS
  In this three-site multicenter study, one hundred two patients, 53 males and 49 females, (23-89 years old; mean = 56.2) were evaluated. Three experienced surgeons (>15 years) performed the crestal approach sinus lift microsurgeries with simultaneous implant placement. At baseline and at the follow-up appointments, calibrated examiners measured radiographic interproximal bone level using ImageJ for Windows after calibration of the radiographs. References for the bone level measurements were the platform, first and second threads of the implants. Statistical analyses, using STATA version 12, stratified patients according to RAB height (group 1: RAB of ≤ 4 mm; n = 35 and group 2: RAB > 4 mm; n = 67), age, gender, and treatment center.
  
  
  RESULTS
  The success rate was 100% for group 1 and 98.51% for group 2 at 6 to 100 months postprosthetic loading (mean = 29.7 months). The peri-implant bone loss averaged 0.55 mm (interquartile range [IQR] = 0.5 [0-1]) in group 1 and 0.07 mm (IQR = 0 [0-0]) in group 2. There was no statistically significant difference between the two groups. Clinical outcomes were independent of age, gender, and treatment center.
  
  
  CONCLUSIONS
  The RAB height did not increase crestal bone loss or reduce the success rate of the implants and associated prostheses. The crestal approach should be considered a viable technique for use in patients with residual bone height of ≤ 4 mm and merits further evaluation.
authors.affiliation: Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA, USA.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Gonzalez
authors.forename: Mao-Chi
authors.initials: MC
authors.lastname: Tuan
authors.forename: Kang Min
authors.initials: KM
authors.lastname: Ahn
authors.forename: Hessam
authors.initials: H
authors.lastname: Nowzari
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D016301:Alveolar Bone Loss / Q000209:etiology; D000539:Alveolar Process / Q000000981:diagnostic imaging / Q000473:pathology; D001284:Atrophy; D064592:Autografts / Q000637:transplantation; D018786:Bone Substitutes / Q000627:therapeutic use; D016025:Bone Transplantation / Q000379:methods; D002130:Calcium Phosphates / Q000627:therapeutic use; D015331:Cohort Studies; D003758:Dental Implantation, Endosseous / Q000379:methods; D015921:Dental Implants; D017268:Dental Prosthesis Retention; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008437:Maxilla / Q000000981:diagnostic imaging / Q000473:pathology / Q000601:surgery*; D008866:Microsurgery / Q000379:methods; D008875:Middle Aged; D059546:Sinus Floor Augmentation / Q000379:methods*; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D018786:Bone Substitutes; D002130:Calcium Phosphates; D015921:Dental Implants; C485817:beta-tricalcium phosphate
keywords: bone graft; crestal approach; implant; sinus graft