Comparing The Three Retentive Methods For Single-tooth Implant In The Posterior Regions:A Retrospective Study

Objective: The retrospective study was conducted to analyze and compare the clinical effects of three different retentive methods for implant-supported prostheses on the clinical cases of patients with single posterior tooth loss,which provide a reference for clinical selection of the retentive methods.Materials and methods: Patients with single tooth implant-supported prostheses in the posterior region in the Stomatological Center of Qingdao Municipal Hospital Affiliated to Qingdao University between January 2015 and December 2018 were collected.The patients in the study were divided into three groups according to different retentive methods for implant-supported prostheses.Screw-retained group: Implant superstructures with para-oral adhesion were screw-retained in-oral.Modified cement-retained group: Implant superstructures with occlusal hole for adhesive overflow were cement-retained in-oral,and the occlusal hole was sealed with resin.The control group: Patients were treated with implant-supported fixed dental prostheses by the traditional cement-retained method.To retrospect the medical history of all cases in the study.And the follow-up was conducted for clinical and imaging examination.The evaluation indexes that include Survival Rate(SR),modified Plaque Index(m PLI),modified Sulcus Bleeding Index(m SBI),Probing Depth(PD),Marginal Bone Loss(MBL)and mechanical complications were recorded in examination,and were compared and analyzed by the SPSS 23.0 software package.Results: A total of 162 cases met the inclusion criteria of this study,among which 8 patients were lost to follow-up,with a follow-up rate of 95.06%.Finally,154 patients participated in and completed the study,including 50 subjects treated with screw-retained prostheses,48 subjects treated with modified cement-retained prostheses,and 56 subjects treated with traditional cement-retained prostheses.Compared with the baseline data,there was no significant difference in age,follow-up time,gender,dental position implant diameter and implant length among the three groups(P>0.05).During the follow-up period,all the 154 implants met the implant survival standard,and the implant survival rate of the three groups of implant dentures was 100%.The m PLI,m SBI and PD of the control group were all significantly higher than that of the modified cement-retained group and screw-retained(P<0.05).There was no significant difference in m PLI,m SBI and PD between the modified cement-retained group and screw-retained(P>0.05).And there was no statistically significant difference in MBL between the three groups(P>0.05).There were two crowns(4.17%)suffering from resin off and were resealed again in the modified cement-retained group.No other mechanical complications such as abutment broken or loose,screw broken or loose,porcelain fracture or chipping and so on were found in the study.Conclusion: During the observation period of this study,there was no statistically significant difference in SR,MBL and mechanical complications between the three groups.However,in the aspect of maintaining the health of the soft tissue around the implant,screw-retained method or modified cement-retained method has more advantages than traditional cement-retained method.Under the strict control of indications,good clinical effects can be obtained.