| Over the past few decades,implants have become one of the most important biomaterials for repairing missing teeth.Residual bone height(RBH)was insufficient due to poor bone mass,alveolar bone atrophy and maxillary sinus gasification after tooth loss,so implants could not be directly used to repair the missing area of maxillary posterior teeth,and incremental bone surgery was needed to increase the vertical height of alveolar bone.Fenestration of the maxillary sinus floor is a common surgical method,especially suitable for severe alveolar bone atrophy in the area of missing teeth.When 4mm< RBH<6 mm,the simultaneous implantation or delayed implantation of implants by windowing maxillary sinus floor lift can achieve good initial stability.When RBH<4mm,the windowing maxillary sinus floor lift and delayed implantation are recommended.At present,there is still some controversy about the selection of bone graft materials for maxillary sinus floor elevation.Autologous bone has incomparable advantages such as bone inductance,osteogenesis and bone conductivity,but the complications of the donor site and the high absorbency after autologous bone implantation have affected the use of autologous bone alone to some extent.Various bone replacement materials,including allograft,allograft,inorganic materials and growth factors,are widely used to reduce the need for autologous bone during bone grafting and thus simplify the surgical procedure.Deproteinized bovine bone mineral(DBBM)has bone conduction,stable properties and slow absorption.A large number of animal experiments and clinical studies have proved that it has a reliable osteogenic effect,and its characteristics of low replacement rate guarantee the stability of new bone formation in the maxillary sinus floor.However,due to the lack of bone induction,DBBM is often recommended to be mixed with autologous bone for maxillary sinus floor lift,increasing the need for autologous bone.In recent years,some scholars tried to use DBBM alone as the bone graft material for maxillary sinus floor lifting,and clinical reports preliminarily confirmed its feasibility.At that time,there was still insufficient evidence of evidence-based medicine.There is still a big controversy about the time of delayed implantation of maxillary sinus floor elevation using DBBM alone.In 2011,this project was designed and carried out respectively on DBBM used in the bottom of the fenestration of maxillary sinus raising grown prospectie clinical trial research and extension delay time of clinical randomized controlled studies,this topic proposed focusing on the prospectie cohort of clinical trials and clinical randomized controlled trial cases follow-up study for more than three years,through the clinical and imaging examination,evaluation of implant retention,complications and surrounding soft tissue health and marginal bone resorption,and through the analysis of CBCT bone reconstruction condition after the operation,observe the thickness of the bottom of the maxillary sinus mucosa and flowing.To further clarify the feasibility of using DBBM alone for bone grafting in maxillary sinus floor and the timing of delayed implantation,it provides certain reference for clinical work.Part Ⅰ: Deproteinized bovine bone was used in the clinical evaluation of delayed implantation of maxillary sinus floor elevation by windowing for more than three yearsObjective: To evaluate clinical effect of deproteinized bovine bone for delayed implantation after maxillary sinus floor elevation.Material and methods: Fifty-five patients were enrolled in this study according to inclusion and exclusion criteria,clinical and imaging examinations were performed to evaluate implant retention,complications,surrounding soft tissue health and marginal bone resorption.Results: Among the 55 enrolled patients,41 were followed up,47 were treated with maxillary sinus floor lift and 82 implants,with an average follow-up time of 51.77±14.39months(33—78 months),with a case follow-up rate of 75.8%,an implant follow-up rate of 73.9% and a survival rate of 98.8%.The results of bone resorption at the implant edge were 0.64±0.63mm(-0.28mm—1.47mm)in the near and 0.49±0.73mm(-0.51 mm —1.21mm)in the far,the improved bleeding index was 0.46±0.72,the improved plaque index was 0.60 ± 0.87,and the keratinized mucosa width was 2.14 ± 1.22 mm.The incidence of peri-implant mucositis was 28.4% among 23 implants,and there was no complication of peri-implant inflammation.Conclusion: This study shows that under the condition of insufficient sinus ridge spacing in the maxillary posterior area,it is feasible to use bovine bone alone to remove protein for delayed implantation of maxillary sinus floor elevation by windowing,and the clinical effect is reliable.Part Ⅱ: Longitudinal response of membrane thickness and ostium patency following sinus floor elevation.Objective: To evaluate the effect of fenestration on maxillary sinus mucosa.Material and methods: The samples were the same as experiment 1.In the 47 sides of maxillary sinus that were followed up,mucosal thickness and maxillary sinus patency were measured in CBCT before surgery,during bone healing period,after implantation,and after 3 years of reexamination.Results: There were 34 cases in the normal group,10 cases in the thickening group and 3 cases in the cyst group.During the operation,there were 4 cases with mucosal perforation,2 cases in the normal group,1 case in the thickening group and 1 case in the cyst group.There were 37 cases with normal maxillary sinus mucosa,8 cases with thickened mucosa,and 2 cases with cyst at the 3-year follow-up.The thickness of the normal mucosa group was 1.02±0.44 mm,and that of the thickening group was 2.51±0.75 mm,and that of the normal mucosa group was 1.17 ± 0.75 mm and that of the thickening group was 2.71±0.70 mm during the 3-year follow-up.No statistical difference was found between the preoperative and three-year follow-up results of maxillary sinus patency.Conclusion: This experiment confirmed that the use of DBBM alone in maxillary sinus floor elevation had no significant adverse effect on the mucosal health of maxillary sinus.Part Ⅲ: Bone remodeling of deproteinized bovine bone mineral after SFE via later approach.Objective: To study the changes of the three-dimensional volume of the bone graft area in the maxillary sinus floor,and to elucidate the stability of new bone grafted by DBBM alone.Material and methods: The samples were the same as experiment 1,and a total of47 maxillary sinus patients were followed up.All patients were followed up for CBCT imaging before surgery,immediately after maxillary sinus floor elevation,after bone healing,after repair,and for 3 years.Results: The mean bone graft volume after maxillary sinus floor elevation was1008.65±369.43mm3.After the bone healing period of 6.94±1.44 months,the volume of new bone was 916.85±346.81mm3,and the rate of new bone osteogenesis was 90.82%(P <0.001).After implant implantation,after the healing period of 6.69±1.13 months,the volume of new bone decreased to 855.46±302.41mm3,and the absorptivity of new bone volume absorption rate was 5.41%(P=0.132).At an average follow-up of 51.77 months after implant repair,the volume of new bone was 795.32 ± 252.89mm3 and the bone volume absorption rate was 9.69%.Mucosal perforation was observed during maxillary sinus floor elevation,and the stability of DBBM materials was not affected after perforation repair.Conclusion: The effect of single DBBM on osteogenesis of maxillary sinus floor elevation is reliable and the volume of new bone is relatively stable.Part Ⅳ:A 3-year randomized controlled clinical study of deproteinized bovine bone materials for delayed implantation with different healing times during fenestration of maxillary sinus floor liftObjective: To study the clinical effect of simple DBBM as a window method for lifting bone grafts in maxillary sinus floor in 3 years by using a randomized controlled clinical trial to shorten bone healing time.Material and methods: According to the inclusion and exclusion criteria,20 cases of the 19 patients enrolled in this study underwent fenestration maxillary sinus floor elevation.The healing time was 5 months in the experimental group and 8 months in the control group.After three years of loading,the clinical effect of delayed implant implantation at different bone healing time after maxillary sinus floor lifting with DBBM alone was compared,as well as the physiological condition of maxillary sinus and the changes of DBBM.Results: The average follow-up time of 5 months for bone healing and 8 months for bone healing was 64.57±14.01 months(37—78 months)for the implant load over 3 years.The follow-up time of 4 patients was lost to follow-up,the case follow-up rate was 80%,and the implant retention rate was 90.9% and 100%,respectively,P=0.31,with no statistical significance.The rate of bone volume change: r25-mon was 15.62 ± 7.09%,r28-mon was 11.40 ± 11.99%,P=0.417,with no significant difference.There were no statistically significant differences in other relevant clinical indicators(marginal bone resorption,peripheral soft tissue condition,and maxillary sinus mucosal thickness)(P>0.05).Conclusion: There was no difference in the physiological condition of the maxillary sinus and the volume change of bone graft material in the 3-year clinical effect of delayed implant implantation with different bone healing time after maxillary sinus floor elevation with DBBM alone. |
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