title: A radiographical study on the changes in height of grafting materials after sinus lift: a comparison between two types of xenogenic materials.
abstract: OBJECTIVE
  The performance of implant surgery in the posterior maxilla often poses a challenge due to insufficient available bone. Sinus floor elevation was developed to increase the needed vertical height to overcome this problem. However, grafting materials used for the sinus lift technique eventually show resorption. The present study radiographically compared and evaluated the changes in height of the grafting materials after carrying out maxillary sinus elevation with a window opening procedure. This study also evaluated the difference between two xenogenic bone materials when being used for the sinus lifting procedure.
  
  
  METHODS
  Twenty-one patients were recruited for this study and underwent a sinus lift procedure. All sites were treated with either bovine bone (Bio-Oss(R)) with platelet-rich plasma (PRP) or bovine bone (OCS-B(R))/PRP. A total of 69 implants were placed equally 6-8 months after the sinus lift. All sites were clinically and radiographically evaluated right after the implant surgery, 7-12 months, 13-24 months, and 25-48 months after their prosthetic loading.
  
  
  RESULTS
  Changes of implant length/bone length with time showed a statistically significant decreasing tendency (P < 0.05). There was no significant change in the Bio-Oss(R) group (P > 0.05). In contrast, the OCS-B(R) group showed a significant decrease with time (P < 0.05). However, no significant difference was observed between the two groups (P > 0.05).
  
  
  CONCLUSIONS
  The results showed that there was significant reduction in comparison with data right after placement, after 7 to 12 months, 13 to 24 months, and over 25 months; however, reduction rates between each period have shown to be without significance. No significant difference in height change was observed between the Bio-Oss(R) and the OCS-B(R) groups.
authors.affiliation: Department of Periodontology, Dankook University College of Dentistry, Cheonan, Korea.
authors.forename: Pham-Duong
authors.initials: PD
authors.lastname: Hieu
authors.forename: Jin-Hyung
authors.initials: JH
authors.lastname: Chung
authors.forename: Sung-Bin
authors.initials: SB
authors.lastname: Yim
authors.forename: Ki-Seok
authors.initials: KS
authors.lastname: Hong