| Objectives: To measure and analyze the distribution of supracrestal soft tissue heigh at partially edentulous posterior sites,to explore the related factors affecting the thickness of soft tissue in the parietal region,and to evaluate the clinical effect of advanced platelet-rich fiber in increasing the thickness of soft tissue.The difference of marginal bone changes in the short term and the subjective evaluation of the patients were observed in order to provide reference for the design of implant therapy with insufficient gingival thickness.Methods: 1.148 patients(including 69 males and 79 females)with an average age of 47.40 years old eligible for healthy gums were screened through medical history collection and clinical examination.The supracrestal soft tissue heigh was obtained by transgingival measurement and the basic information of the patients was recorded,CBCT was taken under the state of insufflation to obtain three-dimensional reconstruction images in in 50 patients and the STH and buccal gingival thickness were measured.T-test was used for difference analysis,and Pearson correlation coefficient was used for correlation analysis.2.Clinical intervention: According to the inclusion and exclusion criteria,30 implant sites were selected from patients with partial dentition defects who were repaired by conventional implant dentures and the supracrestal soft tissue heigh was not thick enough with 2mm.They were divided into A-PRF group(n=15),and control group(n=15).All patients were treated with two-stage healing implant procedure,experimental groups of patients in the same period of implant implantation with different materials for soft tissue augmentation,the control group did not do special treatment.The STH was measured before implantation(T0),immediately after operation(T1),14 days after operation(T2),1month after operation(T3)and 3 months after operation(T4).CBCT or DR apical radiography was taken to record the marginal bone level,the marginal bone changes ΔMBC1 from immediate to secondary stage,Δ MBC2 from secondary stage to denture and Δ MBC3 from immediate to denture were calculated.And gingival samples were taken for histological observation 3 months after operation.The main outcome index was the effect of soft tissue augmentation,and the secondary outcome was to compare marginal bone changes,operation time and patient pain score.SPSS.25 statistical software was used for data processing,and t-test or Wilcoxon test was used to analyze the differences between groups.Results: 1.The STH in the edentulous area was measured in patients with dentition defects.it was found that the average thickness of STH in the maxillary region and mandible was 3.33 ±0.83 mm and 2.16 ±0.62 mm respectively.Gender is also the main factor affecting the thickness of crest soft tissue,the average thickness of male is 2.97 ±0.97 mm,the average thickness of female is 2.46 ±0.83 mm,there is significant statistical difference,and the underthickness of STH mainly occurs in female group,accounting for 48.1%.Age has no significant effect on the distribution of STH.The thickness of crest soft tissue in smoking patients is significantly larger than that in non-smoking patients;with the extension of tooth loss,STH gradually becomes thinner.There was no significant difference between the results of transgingival measurement and CBCT measurement of gingival thickness at different points.Bland-Altman analysis showed that the results of the two methods were consistent.2.For patients with insufficient STH,the thickening effect of modified platelet-rich fibrin was 1.17 ±0.15 mm.According to the analysis of soft tissue thickness at different time points,it was found that there was significant difference in STH between the experimental group and the control group immediately after operation,14 days after operation and 1 month after operation.Graft contraction began immediately after operation.The marginal bone changes Δ MBC1 from immediate to second stage and Δ MBC2 from second stage to dentures were compared by Wilcoxon signed rank sum test or paired t test,there was no statistical difference in the experimental group,but there was significant change in the control group(P <0.05),and there were significant differences in Δ MBC1,Δ MBC2 and Δ MBC3 between the two groups,and the pain score of the two groups reached the peak one day after operation,and then decreased gradually.The histological examination results of the two groups were similar,but there was no significant difference in the positive area of fibrosis and vascularization between the two groups.Conclusions: 1.The STH at partially edentulous posterior sites was related to sex,location of missing teeth,smoking habit and time of missing teeth.Deficiency of STH mostly occurred in the mandibular posterior area of female patients,and the thickness of soft tissue of crest in smoking group was significantly thicker,and STH was not related to the age,but negatively correlated with the time of missing teeth.Both transgingival measurement and CBCT measurement can truly reflect the STH of edentulous area,which is feasible.2.During the observation period of this study,A-PRF membrane can be used as a soft tissue substitute to augmentation the supracrestal soft tissue heigh of patients with thin gingival biotype.Initial gingival thickness < 2mm has a slight effect on the marginal bone changes after implantation.After the placement of the healing abutment,the bone resorption at the site of STH deficiency is obvious. |
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