1. Date : 2012/03/27
Reporter : 傅超俊

2. Introduction
Reduced alveolar bone dimensions combined with pneumatization of the maxillary sinus after missing teeth is considered to be an indication for augmentation procedures
Sharan & Madjar 2008; Pramstraller et al. 2011
Previous studies estimated these dimensional changes were based on panoramic radiographs
Saglam 2002; Juodzbalys & Raustia 2004; Sharan & Madjar 2008;
Van Der Weijden et al. 2009

3. Aim the aim of this study was to
Estimate the outcome of autologous bone graft resorption after staged sinus floor augmentation surgery by CBCT
Determine which parameters influence the outcome

4. Material and Method
the study population took place between 2006 and 2009
20 edentulous patients
18 patients received bilateral and 2 received a unilateral sinus augmentation, resulting in a total of 38 augmented sinuses
at least 10 years edentulous
12 women (mean 56 years ;SD = 8 years) and 8 men (mean 56 years; SD = 14 years)

5. CBCT imaging
i-CAT® 3D Imaging System (Imaging Sciences International Inc, Hatfield, PA, USA) with a field of view of 22 X 16 cm and 0.4 mm voxel size
t = 0
before surgery
t = 1
2 weeks after surgery
t = 2
after a graft healing interval of several months (median = 4 months;).

6. Alveolar crest dimension analysis

7. 110 gray value

8. Result Alveolar crest dimensions analysis

13. Discussion Alveolar crest dimensions
Bone resorption after extraction
At least ten years edentulous
Alveolar bone high and width
alveolar bone height showed a significant decrease from the first premolar to the molar sites
Pramstraller et al. (2011) and Farina et al. (2011)
bone height showed a high correlation
bone width showed a lower correlation

14. Bone graft volume Measure bias
using CBCT with a relative error below 1%
Stratemann et al. 2008
selection of the ROI
Decalcification and reduction of trabecular bone
Scatter levels and image artifacts produced by CBCT scanners are higher
mostly influenced by the used device, imaging parameters, and positioning of the patient
Nackaerts et al. 2011
at least a gray value of 110

15. Bone graft volume resorption rate of 25%
50% loss volume of autologous bone grafts (150 Hounsfield unit /HU)
Johansson et al. 2001
volume reduction of 26% (400 HU)
Kirmeier et al. 2008

16. Bone grafts derived from intraoral donor sites resulted in a significant 10% higher total bone volume compared with iliac grafts
Particulation of a bone graft resulted in a significant lower amount of bone volume compared with block grafting.
Klijn et al. 2010

17. Conclusion
An overall mean volume reduction of 25% was found after 4 months of healing time
High alveolar bone height, graft resorption is increased
Resorption of autologous bone grafts decreases with patient age