Abstract: Objective To measure and analyze the changes of hard tissue before and after guided bone regeneration in patients with moderate to severe alveolar bone defects. Methods Guided bone regeneration surgery using absorbable membrane fixed with pins was performed. And the bone graft with the xenograft bone plus autologous bone （about 50% each）were used in the surgery. CBCT (cone beam computed tomography) was performed before and after surgery. The data were registered by three-dimensional reconstruction, and the changes of bone width and alveolar bone volume at 2 mm and 8 mm from the alveolar crest before and after guided bone regeneration were measured. The results were statistically analyzed by paired t test. Results After guided bone tissue regeneration, the bone width from the crest of alveolar ridge at 2 mm increased from （5.59±3.82）mm to （11.75±4.65）mm; while the bone width at 8 mm increased from （7.72±3.32）mm to （13.58±4.26）mm. The difference in bone width increment was statistically significant (P<0.01), The difference in volume change of the alveolar bone was statistically significant (P < 0.01). Conclusion Guided bone regeneration surgery using absorbable membrane fixed with pins and xenograft combining autologous bone, has a good horizontal increment effect on the alveolar ridge with moderate to severe alveolar bone defect.

Key words: Guided bone regeneration, Moderate to severe horizontal alveolar bone defect, Bone increment effect