| Objective: To evaluate radiographic and histologic performance following maxillary sinus augmentation with xenogeneic bone mineral Bio-Oss alone over time.Methods: Twenty-four patients with severely atrophic maxillae were treated with 25 maxillary sinus augmentations using Bio-Oss alone.Patients were divided into three groups randomly.After 4~6 month(short-term group),6~9 month(medium-term group)and 9~12 month(long-term group)healing period,cylindrical specimens were biopsied from the augmented area,and implants were placed at the same time.Cone beam computed tomography(CBCT)scans were performed for measurements of vertical bone height(VBH)under the sinus.The new bone formation of specimens was analyzed by histology and micro-computed tomography.The results were compared and analyzed with one-way ANOVA.Results: Eight patients were involved in short-term group,obtaining 11 specimens,and 14 implants were placed after a mean healing period of 5.22 ± 0.61 month.Seven patients(8 sites)were involved in medium-term group,obtaining 10 specimens,and 16 implants were placed after a mean healing period of 7.11 ± 1.02 month.Nine patients were involved in long-term group,obtaining 12 specimens,and 16 implants were placed after a mean healing period of 11.03 ± 1.12 month.CBCT showed bone height gain of(12.94 ± 3.71)mm,(14.29 ± 2.46)mm and(15.19 ± 4.10)mm respectively(P=0.44).Microradiographic analysis indicated better bone volume fraction,bone surface density,trabecular thickness,trabecular separation,structure model index in long-term group and medium-term group than in short-term group,and the differences were significant(P=0.005,P=0.016,P=0.045,P=0.041,P=0.023).There were no significant differences found between medium-term group and long-term group of the above parameters(P>0.05).In comparison of native bone and augmented bone,no significant difference of bone volume fraction were found in short-term group(P=0.861).Bone volume fraction of medium-term group and long-term group showed P values of 0.033 and 0.010,respectively,indicating a statistically significant difference.Histomorphometrically,new bone formation occurred along the surface of Bio-Oss after 4~6 months.Vital bone formation were(18.03 ± 6.04)%,(20.60 ± 5.17)% and(21.28 ± 7.08)%,respectively,for three groups.There was no significant difference in the amount of newly formed bone among groups(P=0.58).The percentage of residual Bio-Oss were(37.30 ± 5.04)%,(28.23 ± 5.34)% and(20.59 ± 7.45)%,and a significant difference was found amoung groups(P<0.01).The percentage of bone marrow in long-term group is higher than short-term group and medium-term group(P=0.001,P=0.015).The ratio of vital bone/Bio-Oss in long-term group is also higher than short-term group and medium-term group,and there was a significant difference between long-term group and short-term group(P=0.01).Conclusions: The use of Bio-Oss as the sole graft is reliable and can lead to satisfactory bone formation after a 6~9 month healing period.As time passing by,newly formed bone increased,while Bio-Oss became integrated. |
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