| Objective:To observe the changes in the mesial and distal alveolar crestal bone level,the preservation of the buccal bone and the condition of the surrounding soft tissue at different time points(preoperative,1 years,1-3 years and 3-5 years,more than 5 years)after immediate implant placement at different depths in maxillar anterior teeth.In order to maintain the long-term stability of soft and hard tissue around implant prosthesis after immediate implant restoration,it’s necessary to ensure the suitable depth of implant inserting.Methods:Part One:19 implants of 19 patients were collected according to cer-tain inclusion criteria.Grouped according to the distance(Implant Shouder Cemento-Enamel Junction,ISCEJ)between the implant shoulder and the adjacent enamel cementum and the implant system.Group A:2mm<ISCEJ ≤ 3mm(5 implants);Group B:3mm<ISCEJ ≤ 4mm(nine implants);Group C:ISCEJ>4mm(5 implants in total);Ankylos Group:15 Implants;Bego Group:4 implants.All patients underwent immediate implant placement after extracting the teeth.The time points for the study were the day of the surgery(T0),the day installing the implant superstructure(T1),the period of one year after loading(T2),the first year to the third year after loading(T3),the third to the fifth year after loading(T4).it was more than 5 years after loading(T5);the time period for the study was divided into five segments:the time from the implantation of the implant to the day of the denture loaded(T1-T0),the time during the first year after the denture loaded(T2-T1),the time of 1 year to 3 years after denture loaded(T3-T2),the time of 3 years to 5 years after denture loaded(T4-T3),the time more than 5 years after denture loaded(T5-T4).The survey indicator is the changes of the height of the buccal alveolar in the mesial and distal around implants.SPSS 22.0 was used to perform statistical analysis of variance data and t-test statistical methods,P<0.05 was considered statistically significant.Part two:19 implants of 19 patients were included according to certain inclusion criteria.All patients underwent immediate implant placement after extracting the teeth.CBCT and intraoral photos were taken at an average of 40.7 months(20-77 months)after denture loaded.The thickness of the buccal bone plate was assessed at 3 levels,the implant platform,1 mm and 2 mm below the platform.,and each level has three point,the centre,the mesial and the distal.The buccal bone crest height was evaluated at three points in the mesio-distal direction:the centre point,the mesial point and the distal point of the implant(the buccal bone plate above the implant platform marked as "+",and the buccal bone plate was lower than the implant platform recorded as "-");The angle between the long axis of the implant and the long axis of the crown(Implant Crown Angel,ICA)was measured using CBCT;the soft tissue around the prosthesis was scored by PES using the intraoral photograph.Pearson correlation analysis was performed using SPSS 22.0 software,P<0.05 was a statistically significant correlation.Results:Part one:In group A,B,and C,the height of buccal alveolar bone were significantly changed in the T1-T0 and T2-T1,and most bone resorption was observed in group C(P<0.05).In two time periods,the height of alveolar bone of the mesial and the distal alveolar bone was absorbed about-0.69±0.27mm(mesial),-0.47±0.21mm(mesial),-1.13±0.59mm(distal),-0.48±0.09mm(distal).There was no significant difference in bone resorption among the three groups after denture loaded one year(P>0.05).At different time points in the same group,the height between the mesial and the distal alveolar bones of A,B and C groups were not statistically significant.(P>0.05),but the bone height absorption gradually decreased(P<0.05).By comparing the changes in the height of the mesial and the distal alveolar ridge in Ankylos group and Bego group,there were no significant differences(P>0.05).Part two:There was no correlation between the PES score(10.89±1.43)and the mean vertical height of the buccal bone plate(0.56±0.88mm)and the mean thickness of the buccal bone plate(1.27±0.70mm)(P>0.05).The correlation coefficients of ICA(7.54±8.41。)and the average vertical height of the buccal bone plate(0.56±0.88mm),the average thickness of the buccal bone plate(1.27±0.70mm)were respectively-0.489,-0.609(P<0.05),showing a significant negative correlation.The correlation coefficient of the average thickness of the buccal bone plate(1.27 ± 0.70 mm)with the average height of the vertical bone(0.56±0.88mm)was 0.74,which had statistical significance(P<0.05).Conclusions:1.Immediate implant placement can not prevent the absorption of alveolar bone during the process of bone remodeling.The absorption after implantation occurs mainly from the operation to the denture loaded 1 year.2.The depth of immediate implantation more than 4mm,the bone absorption in the proximal and distal alveolar ridge was significantly greater than that the depth rang 2 to 4mm.3.There was no significant difference in changes of the height of alveolar ridge inthe mesial and distal around implant with platform switching or platform matching after implantation.4.There was no correlation between the PES and the thickness of the implantbuccal bone plate and the vertical height of the bone plate(p>0.05),in the postoperative average of 40.7 months.5.The angle between the long axis of the implant and the long axis of the implant is negatively correlated with the average thickness and the average height of the labial bone plate.6.There was a significant positive correlation between the thickness of the buccal bone plate and the vertical height of the buccal bone plate.The thicker buccal bone plate was,the higher buccal bone was. |
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