Application Of Different Onlay Block Autogenous Bone Grafting In Oral Implant Prosthesis

Objective:To compare the horizontal and vertical bone volume changes of the alveolar ridge and the degree of bone graft resorption after autogenous bone harvesting with the mandibular chin,mandibular external oblique line,and ilium as donor sites in patients who underwent bone augmentation with the onlay method.Methods:A retrospective collection of 25 patients(mean age 36 years old,range from 20 to71 years old)who underwent bone augmentation surgery with block autogenous bone grafts in the Affiliated Stomatological Hospital of Zhejiang University School of Medicine from January 1,2016 to August 1,2018.Among them,19 cases were treated with mandibular chin bone harvesting,3 cases with mandibular external oblique line bone harvesting,and 3 cases with iliac bone harvesting.Patients with external oblique line and iliac bone harvesting had insufficient horizontal bone volume,and patients with chin bone harvesting had insufficient horizontal or vertical or mixed bone volume.Foreach patient,cone-beam computed tomography(CBCT)was used to obtain the radiographic data at three time points: before bone grafting,immediately after bone grafting,and before implant palcement.The horizontal width and vertical height of alveolar bone were measured at three time points,and the horizontal and vertical bone gain values and bone graft resorption rate were calculated and statistically analyzed.Results:The statistical analysis of horizontal bone gain after bone harvesting in different donor sites showed that the mean thickness of the grafted bone block in the chin bone harvesting group(6.07 ± 1.41 mm)was greater than that in the external oblique line group(4.09 ± 0.89 mm),with a statistically significant difference(p < 0.05).The mean amount of bone resorption in the chin bone harvesting group was slightly greater than that of the external oblique line,and the rate of bone resorption was similar between the two groups,both of which showed no statistical difference(p > 0.05).After 6 months of follow-up,there was no statistically significant difference in bone thickness among the iliac bone,chin,and external oblique line bone harvesting groups(p > 0.05),and the average bone gain thickness reached 3 to 5 mm.After chin bone harvesting,the mean bone volume of vertical augmentation group was slightly greater than those of the horizontal group immediately after surgery and after 6 months,and the mean bone resorption and bone resorption rate were slightly lower than those of the horizontal group,but there were no significant statistical differences(P > 0.05).Conclusion:(1)Good bone augmentation results can be obtained after onlay bone augmentation from mandibular chin,mandibular external oblique line and iliac bone harvesting.(2)The bone resorption rate of the grafted bone after 6 months was similar after bone harvesting in the mandibular chin and external oblique line.(3)After mandibular chin bone harvesting,there was no significant difference in horizontal and vertical bone graft resorption rate after 6 months,and good horizontal and vertical bone augmentation results could be obtained.