Clinical Study On The Immediate Loading Of Single Implant In The Posterior Area With Permanent Restoration

Purpose:For a long time,the non-loading healing period of 3-6 months has been considered as the basic premise to realize osseointegration.In recent years,due to the improvement of implant surface design and the development of implant concept,the loading protocols of implant denture have changed greatly.However,there is no relevant clinical study on the immediate loading of single implant in the posterior area with permanent restoration.This paper discusses the effects of two loading protocols on the peri-implant soft and hard tissue by using permanent restoration to carry out immediate loading and conventional loading on a single implant in the posterior area,in order to provide a clinical basis for the loading protocols of a single implant in the posterior area.Methods:Patients with single posterior tooth loss from September 2019 to January 2021 were selected.According to the inclusion and exclusion criteria,26 patients were included.One patient in the immediate loading group withdrew due to implant loosening one month after restoration.Finally,25 patients completed a one-year follow-up.There were 12 patients in the immediate loading group,with an average age of 44.42 ±13.32 years,including 4 males and 8 females.There were 13 patients in the conventional loading group,with an average age of 45.77 ± 16.13 years,including 4 males and 9 females.The immediate loading group was received restoration within 1 week after operation,while the conventional loading group was received restoration after 3 months post operation.Both groups were loaded with permanent restorations.All patients were followed up at baseline（T0）,1 week（T1）,1 month（T2）,3 months（T3）,6months（T4）and 12 months（T5）after definitive crown.The following indexes were recorded: Hounsfield units of implant site,insertion torque,implant stability quotient at baseline,mesial and distal emergence angle of restorations,mesial and distal marginal bone level changes,gingival papilla index（GPI）,gingival index（GI）,modified plaque index（m PLI）,incidence of complications,implant success rate and patient satisfaction.Results:1.In the immediate loading group,one implant loosened one month after loading,and the other 25 implants were successfully osseointegrated.The implant success rates of the immediate loading group and the conventional loading group were 92.31% and 100% respectively（P>0.05）.2.No mechanical and biological complications occurred in the immediate loading group.There were no biological complications in the conventional loading group.One patient developed porcelain fracture at distal marginal ridge of the restoration occlusal surface one year after permanent restoration.The mechanical complications in the conventional loading group were 7.69%（P>0.05）.3.Marginal bone level（1）Mesial marginal bone level: In the immediate loading group,the marginal bone level changes at 1 week,1 month,3 months,6 months and1 year after loading were-0.02 ± 0.04 mm,-0.19 ± 0.21 mm,-0.17 ± 0.32 mm,-0.11 ± 0.35 mm and-0.12 ± 0.44 mm respectively.The marginal bone level changes in the conventional loading group at 1 week,1 month,3months,6 months and 1 year after loading were-0.03 ± 0.04 mm,-0.12 ±0.10 mm,-0.12 ± 0.19 mm,-0.10 ± 0.19 mm and-0.11 ± 0.21 mm respectively.There was no statistically significant difference between the two groups（P>0.05）.（2）Distal marginal bone level: In the immediate loading group,the average marginal bone level changes at 1 week,1 month,3 months,6months and 1 year after loading were-0.01 ± 0.06 mm,-0.13 ± 0.21 mm,-0.07 ± 0.39 mm,-0.09 ± 0.44 mm and-0.05 ± 0.52 mm.The average marginal bone level changes in the conventional loading group at 1 week,1 month,3 months,6 months and 1 year after loading were 0.00 ± 0.05 mm,-0.08 ± 0.14 mm,-0.05 ± 0.23 mm,-0.05 ± 0.26 mm and-0.04 ± 0.27 mm.There was no statistically significant difference between the two groups（P>0.05）.4.Emergence angle of restorations and marginal bone level changes: In the subgroup analysis of immediate loading group and conventional loading group,there was no statistically significant difference in marginal bone level changes with emergence angle of restorations < 30 ° or ≥ 30 ° at each follow-up time（P>0.05）.There was no linear correlation between marginal bone level changes and emergence angle of restorations after one year of implant loading in both groups（P>0.05）.5.Clinical index: There was no statistically significant difference in mesial and distal gingival papilla index（GPI）and modified plaque index（m PLI）between the two groups（P>0.05）.The difference of GPI in immediate loading group during one-year follow-up was statistically significant（P<0.05）.There was a significant difference in gingival index between the two groups on the day of loading and 1 week after loading（P<0.05）,and there was no significant difference between the two groups at other follow up time points（P>0.05）.6.Patient satisfaction: In the 11 th question "will you introduce friends or family members to the implant treatment of this protocol,the immediate loading group was 89.17 ± 4.69 and the conventional loading group was84.23 ± 4.94（P<0.05）.There was no significant difference in other problems between the two groups（P>0.05）.Conclusion:Under the condition of observing the indications and obtaining sufficient primary stability of the implant,immediate loading of single implant in the posterior area with permanent restoration is a safe and reliable treatment option.The peri-implant soft and hard tissue were stable,and high patient satisfaction was obtained.