title: The factors that influence postoperative stability of the dental implants in posterior edentulous maxilla.
abstract: BACKGROUND
  All clinicians are aware of the difficulty of installing a dental implant in posterior maxilla because of proximate position of maxillary sinus, insufficient bone width, and lower bone density. This study is to examine which factors will make the implantation in the posterior maxilla more difficult, and which factors will affect the postoperative implant stability in this region.
  
  
  METHODS
  Five hundred seventy-three fixtures on the maxilla posterior were included for this study from all the patients who underwent an installation of the dental implant fixture from January 2010 to December 2014 at the Department of Oral and Maxillofacial Surgery in Pusan National University Dental Hospital (Yangsan, Korea). The postoperative implant stability quotient (ISQ) value, fixture diameter and length, presence of either bone graft or sinus lift, and graft material were included in the reviewed factors. The width and height of the bone bed was assessed via preoperative cone beam CT image analysis. The postoperative ISQ value was taken just before loading by using the OsstellTM mentor® (Integration Diagnostics AB, Gothenburg, Sweden). Thettest and ANOVA methods were used in the statistical analysis of the data.
  
  
  RESULTS
  Mean ISQ of all the included data was 79.22. Higher initial bone height, larger fixture diameter, and longer fixture length were factors that influence the implant stability on the posterior edentulous maxilla. On the other hand, the initial bone width, bone graft and sinus elevation procedure, graft material, and approach method for sinus elevation showed no significant impact associated with the implant stability on the posterior edentulous maxilla.
  
  
  CONCLUSIONS
  It is recommended to install the fixtures accurately in a larger diameter and longer length by performing bone graft and sinus elevation.
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Yangsan, Republic of Korea.
authors.forename: Yun-Ho
authors.initials: YH
authors.lastname: Kim
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Yangsan, Republic of Korea.
authors.forename: Na-Rae
authors.initials: NR
authors.lastname: Choi
authors.affiliation: Department of Oral and Maxillofacial Surgery, School of Dentistry, Pusan National University, Yangsan, Republic of Korea.
authors.forename: Yong-Deok
authors.identifier: 0000-0002-5807-7487
authors.initials: YD
authors.lastname: Kim
keywords: Impact factor; Implant; Posterior maxilla; Survival rate